Difference between revisions of "AY Honors/Renewable Energy/Answer Key"

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'''Renewable energy''' is energy from a source which can be managed so that it is not subject to [[depletion]] in a [[human timescale]] . Sources include the [[sun]]'s rays, wind, waves, rivers, tides, [[biomass]], and [[geothermal]]. Renewable energy does not include energy sources which are dependent upon [[limited resource]]s, such as [[fossil fuels]] and [[nuclear power|nuclear fission power]].
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<!-- 1. What is renewable energy? -->
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Renewable energy is energy whose origins are continually and naturally replenished without human intervention. Examples of renewable energy sources include sunlight, wind, and waves.
  
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==General information==
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As the demand for energy resources continues to climb, mankind is faced with the dilemma of depleting the earth's resources to meet the demand. With the discovery of processes designed to harness clean and renewable energy, depletion of such resources will not be an issue, since they are naturally replenished. In addition, these processes have much less of an environmental impact than conventional methods used to harness resources such as oil.
  
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Most renewable forms of energy, other than geothermal, are in fact stored solar energy.  Water power and wind power represent very short-term solar storage, while biomass represents slightly longer-term storage, but still on a very human time-scale, and so renewable within that human time-scale.  Fossil fuels, on the other hand, while still stored solar energy, have taken millions of years to form, and so do not meet the definition of renewable. Renewable means not just for 10 years but for 100 or 1000.
 
  
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Renewable energy resources may be used directly as energy sources, or used to create other forms of energy for use. Examples of direct use are [[solar oven]]s, geothermal [[heat pump]]s, and mechanical [[windmill]]s.  Examples of indirect use in creating other energy sources are [[electricity generation]] through [[wind generator]]s or [[photovoltaic]] cells, or production of fuels such as [[ethanol]] from [[biomass]] (see [[alcohol as a fuel]]).
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<!-- 3. Describe how each of the following sources is used as a renewable source of energy. Draw an illustration depicting the usage of at least 3 of these renewable sources of energy. -->
  
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==Pros and cons of renewable energy==
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Wind Power is energy that has been converted from the natural movement of wind by the use of devices such as wind turbines. It is clean, largely available, and produces no greenhouse gas emissions.
  
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Renewable energy sources are fundamentally different from fossil fuel or nuclear power plants because of their widespread occurrence and abundance - the [[sun]] will 'power' these 'powerplants' (meaning sunlight, the wind, flowing water, etc.) for the next 4 billion years. The primary advantage of many renewable energy sources are their lack of greenhouse gas and other emissions in comparison with fossil fuel combustion. Some renewable sources do not emit any additional [[carbon dioxide]] and do not introduce any new risks such as [[nuclear waste]].  In fact, most biomass actively sequesters carbon dioxide while growing.
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Bioenergy is biomass energy, which is energy from organic matter. Wood, plants, even the fumes from landfills can be used as a biomass energy source.
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Ethanol is a fuel made from corn, sugar cane and other sources used in auto and jet fuel.
  
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A visible disadvantage of renewables is their visual impact on local environments. Some people dislike the aesthetics of [[wind turbine]]s or bring up nature conservation issues when it comes to large solar-electric installations outside of cities. Some people try to utilize these renewable technologies in an efficient and aesthetically pleasing way: fixed solar collectors can double as noise barriers along highways, roof-tops are available already and could even be replaced totally by solar collectors, [[photovoltaic cell|amorphous photovoltaic cells]] can be used to tint windows and produce energy etc.
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Geothermal energy is energy that is created and stored in the earth. It can be used for heating for large areas, mineral recovery, and industrial process heating.
  
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Some renewable energy capture systems entail unique environmental problems. For instance, wind turbines can be hazardous to flying birds, while hydroelectric dams can create barriers for migrating fish - a serious problem in the Pacific Northwest that has decimated the numbers of many salmon populations.
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Hydropower is energy that is comes from falling water. Most commonly electricity from dams or run of the river generation turbines is created. Other uses are irrigation and (in pioneer times) falling water was directly harnessed with water wheels for the operation of gristmills and sawmills.
  
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Another inherent difficulty with renewables is their variable and diffuse nature (with the exception being [[geothermal energy]], which is however only accessible where the earth's crust is thin, such as near [[hot spring]]s and natural [[geyser]]s). Since renewable energy sources are providing relatively low-intensity energy, the new kinds of "power plants" needed to convert the sources into usable energy need to be distributed over large areas. To make the phrases 'low-intensity' and 'large area' easier to understand, note that in order to produce 1000 kWh of electricity per year (a typical per-year-per-capita consumption of electricity in Western countries), a home owner in cloudy [[Europe]] needs to use eight square meters of [[solar panel]]s (assuming a below-average [[energy efficiency]] of 12.5%). Systematic electrical generation requires reliable overlapping sources or some means of storage on a reasonable scale ([[hydroelectricity|pumped-storage hydro system]]s, batteries, future hydrogen [[fuel cell]]s, etc.). So, because of currently-expensive energy storage systems, a small stand-alone system is only economic in rare cases, or in applications where the connection to to the global energy network would drive costs up sharply.
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Ocean Energy is energy that is comes from the ocean, which can be responsible for two types of energy: mechanical energy from the tides and waves, and thermal energy from the heat of the sun. It can be used for generating electricity.
  
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The geographic diversity of resources is also significant. Some countries and regions have significantly better resources than others in particular RE sectors. Some nations have significant resources at distance from the major population centres where electricity demand exists. Exploiting such resources on a large scale is likely to require considerable investment in transmission and distribution networks as well as in the technology itself.
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Solar Power is light and heat that is derived from the sun and collected through solar panels. It can be used to generate electricity for a variety of useful applications.
  
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If renewable and [[distributed generation]] were to become widespread, [[electric power transmission]] and [[electricity distribution]] systems would no longer be the main distributors of electrical energy but would operate to balance the electricity needs of local communities.  Those with surplus energy would sell to areas needing "top ups". That is, network operation would require a shift from 'passive management' - where generators are hooked up and the system is operated to get electricity 'downstream' to the consumer - to 'active management', wherein generators are spread across a network and inputs and outputs need to be constantly monitored to ensure proper balancing occurs within the system. This will require significant changes in the way that such networks are operated.
 
  
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However, on a small scale, use of renewable energy that can often be produced "on the spot" lowers the requirements [[electricity distribution]] systems have to fulfill. Current systems, while rarely economically efficient, have proven an average household with a solar panel array and energy storage system of the right size needs electricity from outside sources for only a few hours every week. Hence, advocates of renewable energy believe electricity distribution systems will become smaller and easier to manage, rather than the opposite.
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<!-- 4. Individually or as a group, discuss some of the earliest forms of renewable energy. Are there energy forms that might have been used before sin? By Noah? By the patriarchs? -->
  
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==Renewable energy history==
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The earliest form of renewable energy was probably the burning of biomass in the form of wood and dried animal dung. The fuel could be stored, and energy was available for immediate use, but the energy could not be kept in storage for afterwards.
  
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The original energy source for all human activity was the [[sun]] via growing [[plant]]s.   [[Solar power | Solar energy]]'s main human application throughout most of history has thus been in [[agriculture]] and [[forestry]], via photosynthesis.
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Some people believe that the pre-flood culture had advanced technologies. Out of place artifacts like machined balls and gold chains inside coal suggest this. Consider how much knowledge a person living hundreds of years and so close to God's perfect creation of Adam and Eve could amass and what they could create with that knowledge. The world had one language as well, and many overlapping generations, facilitating communication.
  
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===Wood===
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Additional references are available from the Bible which can provide further insight into this. For example, the sun, the movement of water through rivers, etc.
  
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[[Firewood]] was the earliest manipulated energy source in human history, being used as a thermal energy source through burning, and it is still important in this context today. Burning wood was important for both [[cooking]] and providing heat, enabling human presence in cold climates. Special types of wood cooking, [[drying (food)|food dehydration]] and [[smoking (food)|smoke curing]], also enabled human societies to safely store perishable foodstuffs through the year.  Eventually, it was discovered that partial combustion in the relative absence of oxygen could produce [[charcoal]], which provided a hotter and more compact and portable energy source.  However, this was not a more efficient energy source, because it required a large input in wood to create the charcoal.
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For this requirement, you will need to research the history of renewable energy, and then present your findings using one of the techniques listed in the requirement.
  
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===Animal traction===
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Prior to the development of coal in the mid 19th century, nearly all energy used was renewable. Almost without a doubt the oldest known use of renewable energy, in the form of traditional biomass to fuel fires, dates from the beginning of history.
  
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Motive power for vehicles and mechanical devices was originally produced through [[animal traction]].  Animals such as horses and oxen not only provided transportation but also powered mills. Animals are still extensively in use in many parts of the world for these purposes.
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Probably the second oldest usage of renewable energy is harnessing the wind in order to drive ships over water. This practice can be traced back to ships on the Nile.
  
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===Water power===
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The primary sources of traditional renewable energy were human labor, animal power, water power, wind, in grain crushing windmills, and firewood, a traditional biomass. A graph of energy use in the United States up until 1900 shows oil and natural gas with about the same importance in 1900 as wind and solar played in 2010.
  
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Animal power for mills was eventually supplanted by water power, the power of falling water in rivers, wherever it was exploitable.  Direct use of water power for mechanical purposes is today fairly uncommon, but still in use.
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By 1873, concerns of running out of coal prompted experiments with using solar energy. Development of solar engines continued until the outbreak of World War I. The importance of solar energy was recognized in a 1911 Scientific American article: "in the far distant future, natural fuels having been exhausted [solar power] will remain as the only means of existence of the human race".
  
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Originally, water power through [[hydroelectricity]] was the most important source of electrical generation throughout society, and is still an important source today.  Throughout most of the history of human technology, hydroelectricity has been the only renewable source of electricity generation significantly tapped for the generation of electricity.
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The theory of peak oil was published in 1956. In the 1970s environmentalists promoted the development of renewable energy both as a replacement for the eventual depletion of oil, as well as for an escape from dependence on oil, and the first electricity generating wind turbines appeared. Solar had long been used for heating and cooling, but solar panels were too costly to build solar farms until 1980.
  
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===Wind power===
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The source of most renewable energy comes from the sun.
  
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[[Wind power]] has been used for several hundred years. It was originally used via large sail-blade windmills with slow-moving blades, such as those seen in the [[Netherlands]] and mentioned in [[Don Quixote]].  These large mills usually either pumped water or powered small mills.  Newer windmills featured smaller, faster-turning, more compact units with more blades, such as those seen throughout the [[Great Plains]]. These were mostly used for pumping water from wells.  Recent years have seen the rapid development of wind generation farms by mainstream power companies, using a new generation of large, high wind turbines with two or three immense and relatively slow-moving blades.
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Renewable energy such as solar energy can be used to supply power larger communities through a solar power station. Tanks of molten salt can be used to store the energy harnessed from the sun for the purpose of generating electricity during cloud cover, or through the night. Renewable energy can also be used for agricultural purposes, providing social services, education, and health care.
  
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===Solar power===
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Fuel made from bio sources like corn is now a common ingredient in automotive fuel.
  
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[[Solar power]] as a direct energy source has been not been captured by mechanical systems until recent human history, but was captured as an energy source through architecture in certain societies for many centuries.  Not until the twentieth century was direct solar input extensively explored via more carefully planned architecture (passive solar) or via heat capture in mechanical systems (active solar) or electrical conversion (photovoltaic).  Increasingly today the sun is harnessed for heat and electricity.
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Hydro electric power (electricity) is a renewable energy used everywhere the grid goes.
  
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<!-- 8. Why have many governments invested in renewable energy sources? Be able to cite at least two examples. -->
  
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There are positive incentives for governments to invest in renewable energy sources.
  
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===The renewable energy movement===
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===The Overall Impact on the Planet=== <!--T:27-->
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Most sources of renewable energy pose no noxious by-products (the main exception being the burning of biomass). As a result, there is less pollution, waste, and less of a threat concerning extremely destructive natural disasters.
  
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Renewable energy as an issue was virtually unheard-of before the middle of the twentieth century.  There were experimentations with passive solar energy, including daylighting, in the early part of the twentieth century, but little beyond what had actually been practiced as a matter of course in some locales for hundreds of years. The renewable energy movement gained awareness, credence and strength with the great burgeoning of interest in environmental affairs in the mid-1900s, which in turn was largely due to [[Rachel Carson]]'s 'Silent Spring'.
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The reality of global warming has also become a considerable factor with regard to the harmful effects of carbon dioxide (CO2) on the balance of the planet’s ecosystem. The less CO2, the better of our planet would be.
  
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The first US politician to focus significantly on solar energy was [[Jimmy Carter]], in response to the long term consequences of the [[1973 energy crisis]].
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===The Failure of its Technology More Minimized=== <!--T:29-->
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The technology used to harness energy from renewable resources is essentially stable. As a result, insurance companies are more inclined to issue warranties for performance of panels and turbines for 20 years or more. Once these items are installed, they can be relied upon to start working straight away and not stop for years.
  
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==Renewable energy today==
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<!-- 9. What are some of the issues facing the use of renewable energy? What are some of the advantages and potential disadvantages of moving away from fossil fuel energy sources to renewable energy? -->
  
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Around 80% of energy requirements in western industrial societies are focused around heating or cooling buildings and powering the vehicles that ensure mobility (cars, trains, airplanes). However, most uses of renewable power focus on electricity generation.
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Although renewable energy has many advantages with regard to its environmental impact, there are concerns that must be considered as well. The ability to supply energy to meet the demand may pose a problem. Providing renewable energy requires designing and building equipment that will harness and extract it once found. The entire manufacturing process must be considered as well.
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The general population has grown accustomed to current resources such as oil for heating. As such, although the development of an cleaner, alternative means that present less of an environmental impact may not gain the momentum desired. Some renewable resources have not been around long and tested long enough for individuals to give up what they are comfortable with for something that may be cleaner.
  
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[[Geothermal exchange heat pump|Geothermal heat pumps]] (also called ground-source heat pumps) are a means of extracting heat in the winter or cold in the summer from the earth to heat or cool buildings.
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<!-- 10. Individually or as a group, build, not from a kit, a device to harness some form of renewable energy. These devices may include:<br>a. Potato clock<br>b. Solar or wind powered motor<br>c. Hydropower lift<br>d. Your choice. -->
  
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==Modern sources of renewable energy==
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Note: Internet search engines provide tons of information when you type one of the sources of renewable power and “science experiment.” Thus for hydropower you would search for “hydropower science experiment.”
  
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There are several types of renewable energy, including the following:  
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* [[Solar power]].
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* [[Geothermal]] energy.
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* Energy from [[biomass]], also called biomatter energy
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===Smaller-scale sources===
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===Wind - to move ships through the waters.=== <!--T:34-->
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“But the Lord sent out a great wind into the sea, and there was a mighty tempest in the sea, so that the ship was like to be broken.”
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}}
  
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Of course there are some smaller-scale applications as well:
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===In Job, Satan used a wind power for evil.=== <!--T:35-->
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* [[piezoelectricity|Piezo electric]] crystals embedded in the sole of a shoe can yield a small amount of energy with each step. Vibration from [[internal combustion engine|engines]] can stimulate piezo electric crystals.
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{{Bible verse
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* Some watches are already powered by movement of the arm.
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|book=Job
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* Special [[antenna (electronics)|antennae]] can collect energy from stray radiowaves or even light ([[Electromagnetic radiation|EM radiation]]).
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|chapter=1
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“And, behold, there came a great wind from the wilderness, and smote the four corners of the house, and it fell upon the young men, and they are dead; and I only am escaped alone to tell thee.”
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}}
  
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===Renewables as solar energy===
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===Biomass - from firewood=== <!--T:36-->
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{{Bible verse
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|book=Leviticus
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|chapter=1
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“And the sons of Aaron the priest shall put fire upon the altar, and lay the wood in order upon the fire: And the priests, Aaron's sons, shall lay the parts, the head, and the fat, in order upon the wood that is on the fire which is upon the altar.”
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}}
  
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Most renewable energy sources can trace their roots to solar energy, with the exception of [[geothermal energy|geothermal]] and [[tidal power]] -- yet even these can be attributed to the sun's gravity.  For example, wind is caused by the sun heating the earth unevenly. Hot air is less dense, so it rises, causing cooler air to move in to replace it. Hydroelectric power can be ultimately traced to the sun too.  When the [[sun]] evaporates water in the ocean, the vapor forms clouds which later fall on mountains as rain which is routed through turbines to generate electricity.  The transformation goes from solar energy to potential energy to kinetic energy to electric energy.
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{{Bible verse
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|book=1 Kings
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|chapter=17
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|verse=10-12
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|version=KJV
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|text=
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“And when he came to the gate of the city, indeed a widow was there gathering sticks. And he called to her and said, “Please bring me a little water in a cup, that I may drink.” And as she was going to get it, he called to her and said, “Please bring me a morsel of bread in your hand.”
  
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===Solar energy per se===
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So she said, “As the Lord your God lives, I do not have bread, only a handful of flour in a bin, and a little oil in a jar; and see, I am gathering a couple of sticks that I may go in and prepare it for myself and my son, that we may eat it, and die.”
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}}
  
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Since most renewable energy is "Solar Energy" this term is slightly confusing and used in two different ways: firstly as a synonym for "renewable energies" as a whole (like in the [[political slogan]] "Solar not nuclear") and secondly for the energy that is directly collected from solar radiation. In this section it is used in the latter category.
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{{Bible verse
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|book=2 Kings
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|chapter=1
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|verse=12
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|version=KJV
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|text=
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“And Elijah answered and said unto them, If I be a man of God, let fire come down from heaven, and consume thee and thy fifty. And the fire of God came down from heaven, and consumed him and his fifty.”
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}}
  
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There are actually two separate approaches to solar energy, termed [[active solar]] and [[passive solar]].
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====Solar electrical energy====
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For electricity generation, ground-based solar power has serious limitations because of its diffuse and intermittent nature. First, ground-based solar input is interrupted by night and by cloud cover, which means that solar electric generation inevitably has a low capacity factor, typically less than 20%. Also, there is a low intensity of incoming radiation, and converting this to high grade electricity is still relatively inefficient (14% - 18%), though increased efficiency or lower production costs have been the subject of much research over several decades.
 
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Two methods of converting the Sun's radiant energy to electricity are the focus of attention. The better-known method uses sunlight acting on [[photovoltaic]] (PV) cells to produce electricity. This has many applications in [[satellite]]s, small devices and lights, grid-free applications, earthbound signaling and communication equipment, such as remote area [[telecommunications]] equipment. Sales of solar PV modules are increasing strongly as their efficiency increases and price diminishes. But the high cost per unit of electricity still rules out most uses.
 
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Several experimental PV power plants mostly of 300 - 500 kW capacity are connected to electricity grids in [[Europe]] and the [[United States|USA]]. [[Japan]] has 150 MWe installed. A large solar PV plant was planned for [[Crete]]. In 2001 the world total for PV electricity was less than 1000 MWe with Japan as the world's leading producer. Research continues into ways to make the actual solar collecting cells less expensive and more efficient. Other major research is investigating economic ways to store the energy which is collected from the Sun's rays during the day.
 
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Alternatively, many individuals have installed small-scale PV arrays for domestic consumption.  Some, particularly in isolated areas, are totally disconnected from the main power grid, and rely on a surplus of generation capacity combined with [[Battery (electricity)|batteries]] and/or a fossil fuel generator to cover periods when the cells are not operating.  Others in more settled areas remain connected to the grid, using the grid to obtain electricity when solar cells are not providing power, and selling their surplus back to the grid.  This works reasonably well in many climates, as the peak time for energy consumption is on hot, sunny days where air conditioners are running and solar cells produce their maximum power output.  Many U.S. states have passed "net metering" laws, requiring electrical utilities to buy the locally-generated electricity for price comparable to that sold to the household.  Photovoltaic generation is still considerably more expensive for the consumer than grid electricity unless the usage site is sufficiently isolated, in which case photovoltaics become the less expensive.
 
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====System problems with solar electric====
 
−
 
 
−
Frequently renewable electricity sources are disadvantaged by regulation of the electricity supply industry which favors 'traditional' large-scale generators over smaller-scale and more distributed generating sources. If renewable and [[distributed generation]] were to become widespread, [[electric power transmission]] and [[electricity distribution]] systems would no longer be the main distributors of electrical energy but would operate to balance the electricity needs of local communities. Those with surplus energy would sell to areas needing "top ups". Some Governments and regulators are moving to address this, though much remains to be done. One potential solution is the increased use of active management of electricity transmission and distribution networks.
 
−
 
 
−
====Solar thermal electric energy====
 
−
 
 
−
The second method for utilizing solar energy is solar thermal. A solar thermal power plant has a system of [[mirror]]s to concentrate the sunlight on to an absorber, the resulting heat then being used to drive turbines. The concentrator is usually a long mirrored [[parabolic trough]] oriented north-south, which tilts, tracking the Sun's path through the day. A black absorber tube is located at the focal point and converts the solar radiation to heat (about 400°C) which is transferred into a fluid such as synthetic oil. The oil can be used to heat buildings or water, or it can be used to drive a conventional turbine and generator. Several such installations in modules of 80 MW are now operating. Each module requires about 50 hectares of land and needs very precise engineering and control. These plants are supplemented by a gas-fired boiler which ensures full-time energy output. The gas generates about a quarter of the overall power output and keeps the system warm overnight. Over 800 MWe capacity worldwide has supplied about 80% of the total solar electricity to the mid-[[1990s]].
 
−
 
 
−
One proposal for a solar electrical plant is the [[solar tower]], in which a large area of land would be covered by a greenhouse made of something as simple as transparent foil, with a tall lightweight tower in the centre, which could also be composed largely of foil.  The heated air would rush to and up the centre tower, spinning a turbine.  A system of water pipes placed throughout the greenhouse would allow the capture of excess thermal energy, to be released throughout the night and thus providing 24-hour power production.  A 200 MWe tower is proposed near [[Mildura, Australia]].
 
−
 
 
−
====Solar thermal energy====
 
−
 
 
−
Solar energy need not be converted to electricity for use.  Many of the world's energy needs are simply for heat; space heating, water heating, process water heating, oven heating, and so forth.  The main role of solar energy in the future may be that of direct heating. Much of society's energy need is for heat below 60°C (140°F) - e.g. in hot water systems. A lot more, particularly in industry, is for heat in the range 60 - 110°C. Together these may account for a significant proportion of primary energy use in industrialized nations. The first need can readily be supplied by solar power much of the time in some places, and the second application commercially is probably not far off. Such uses will diminish to some extent both the demand for electricity and the consumption of fossil fuels, particularly if coupled with [[energy conservation]] measures such as [[insulation]].
 
−
 
 
−
=====Solar water heating=====
 
−
 
 
−
Domestic solar hot water systems were once common in [[Florida]] until they were displaced by highly-advertised natural gas.  Such systems are today common in the hotter areas of
 
−
[[Australia]], and simply consist of a network of dark-colored pipes
 
−
running beneath a window of heat-trapping [[glass]].  They typically have
 
−
a backup electric or gas heating unit for cloudy days.  Such systems
 
−
can actually be justified purely on economic grounds, particularly in
 
−
some remoter areas of Australia where electricity is expensive.
 
−
 
 
−
=====Solar heat pumps=====
 
−
 
 
−
With adequate insulation, [[heat pump]]s utilizing the conventional refrigeration cycle can be used to warm and cool buildings, with very little energy input other than energy needed to run a compressor. Eventually, up to ten percent of the total primary energy need in industrialized countries may be supplied by direct solar thermal techniques, and to some extent this will substitute for base-load electrical energy.
 
−
 
 
−
=====Solar ovens=====
 
−
 
 
−
Large scale solar thermal powerplants, as mentioned before, can be used to heat buildings, but on a smaller scale [[solar oven]]s can be used on sunny days. Such an oven or solar furnace uses mirrors or a large lens to focus the [[Sun]]'s rays onto a baking tray or black pot which heats up as it would in a standard [[oven]].
 
−
 
 
−
===Wind energy===
 
−
 
 
−
[[Wind generator|Wind turbines]] have been used for household electricity generation in conjunction with [[battery (electricity)|battery]] storage over many decades in remote areas. Generator units of more than 1 MWe are now functioning in several countries. The power output is a function of the cube of the wind speed, so such turbines require a wind in the range 3 to 25 m/s (11 - 90 km/h), and in practice relatively few land areas have significant prevailing winds. Like solar, wind power requires alternative power sources to cope with calmer periods.
 
−
 
 
−
There are now many thousands of wind turbines operating in various parts of the world, with utility companies having a total capacity of over 39,000 MWe of which [[Europe]] accounts for 75% (ultimo [[2003]]). Additional windpower is generated by private windmills both on-grid and off-grid. Germany is the leading producer of wind generated electricity with over 14,600 MWe in 2003. In 2003 the U.S.A. produced over 6,300 Mwe of wind energy, second only to Germany.
 
−
 
 
−
New wind farms and offshore wind parks are being planned and built all over the world. This has been the most rapidly-growing means of electricity generation at the turn of the [[21st century]] and provides a complement to large-scale base-load power stations. [[Denmark]] generates over 10% of its electricity with wind [[turbine]]s, whereas wind turbines account for 0.4% of the total electricity production on a global scale (ultimo [[2002]]). The most economical and practical size of commercial wind turbines seems to be around 600 kWe to 1 MWe, grouped into large wind farms. Most turbines operate at about 25% load factor over the course of a year, but some reach 35%.
 
−
 
 
−
===Geothermal energy===
 
−
 
 
−
Geothermal electricity is created by hot gases vented from the fissures in the earth's crust. A wheel is turned by the pressure of the gases. The wheel turns the [[dynamo]] on the generator, which makes electricity.
 
−
 
 
−
Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such [[geothermal power]] sources have potential in certain parts of the world such as [[New Zealand]], [[United States]], [[Philippines]] and [[Italy]]. The two most prominent areas for this in the United States are in the [[Yellowstone National Park|Yellowstone]] basin and in northern [[California]]. [[Iceland]] produced 170 MWe geothermal power and heated 86% of all houses in the year 2000. Some 8000 MWe of capacity is operating over all.
 
−
 
 
−
There are also prospects in certain other areas for pumping water underground to very hot regions of the Earth's crust and using the steam thus produced for electricity generation. An Australian startup company, Geodynamics, proposes to build a commercial plant in the Cooper Basin region of [[South Australia]] using this technology by [[2004]].
 
−
 
 
−
===Water power===
 
−
 
 
−
Energy inherent in water can be harnessed and used, in the forms of kinetic energy or temperature differences.
 
−
 
 
−
====Electrokinetic energy====
 
−
 
 
−
This type of energy harnesses what happens to water when it is pumped through tiny channels. See [[electrokinetics]] (water).
 
−
 
 
−
====Hydroelectric energy====
 
−
 
 
−
[[Hydroelectric]] energy produces essentially no [[carbon dioxide]], in contrast to burning [[fossil fuel]]s or gas, and so is not a significant contributor to global warming. Hydroelectric power from potential energy of rivers, now supplies about 715,000 [[MWe]] or 19% of world electricity. Apart from a few countries with an abundance of it, hydro capacity is normally applied to peak-load demand, because it is so readily stopped and started. It is not a major option for the future in the developed countries because most major sites in these countries having potential for harnessing gravity in this way are either being exploited already or are unavailable for other reasons such as environmental considerations.
 
−
 
 
−
The chief advantage of hydrosystems is their capacity to handle seasonal (as well as daily) high peak loads. In practice the utilization of stored water is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.
 
−
 
 
−
====Tidal power====
 
−
 
 
−
Harnessing the tides in a bay or estuary has been achieved in [[France]] (since [[1966]]), [[Canada]] and [[Russia]], and could be achieved in certain other areas where there is a large tidal range. The trapped water can be used to turn [[turbine]]s as it is released through the tidal barrage in either direction. Worldwide this technology appears to have little potential, largely due to environmental constraints. See: [[tidal power]].
 
−
 
 
−
====Tidal stream power====
 
−
 
 
−
A relatively new technology development, tidal stream generators draw energy from underwater currents in much the same way that wind generators are powered by the wind. The much higher density of water means that there is the potential for a single generator to provide significant levels of power. Tidal stream technology is at the very early stages of development though and will require significantly more research before it becomes a significant contributor to electrical generation needs.
 
−
 
 
−
====Wave power====
 
−
 
 
−
Harnessing power from wave motion is a possibility which might yield much more energy than tides. The feasibility of this has been investigated, particularly in the UK. Generators either coupled to floating devices or turned by air displaced by waves in a hollow concrete structure would produce electricity for delivery to shore. Numerous practical problems have frustrated progress.
 
−
 
 
−
A 100-400 kW prototype shore based wave power generator is being constructed at Port Kembla in Australia, due for completion in January, 2005. The energy of waves crashing against the shore is absorbed by an air driven generator and converted to electricity. For countries with large coastlines and rough sea conditions the energy density of breaking waves offers the possibility of generating electricty in utility volumes. Excess capacity in periods of rough sea could be used to generate renewable Hydrogen.
 
−
 
 
−
====Ocean thermal energy conversion====
 
−
 
 
−
[[Ocean thermal energy conversion]] is a relatively unproven technology, though it was first used by the French engineer [[Jacques Arsene d'Arsonval]] in [[1881]]. The difference in temperature between water near the surface and deeper water can be as much as 20°C. The warm water is used to make a liquid such as [[ammonia]] evaporate, causing it to expand. The expanding gas forces its way through turbines, after which it is condensed using the colder water and the cycle can begin again.
 
−
 
 
−
====Deep lake water cooling====
 
−
 
 
−
[[Deep lake water cooling]] is the use of cold water piped from a lake bottom and used for cooling. [[Energy]] measures [[mechanical work| work]] or [[heat]] exchange; although this technology doesn't ''generate'' energy that can do work, water-cooling is a form of heat exchange. That is, this technology is an efficient, renewable [[substitute good|substitute]] for expensive [[air conditioning]] which requires expensive, [[peak demand]] electrical generation which, typically uses [[fossil fuel]]s. Like geothermal energy and unlike many other forms of renewable energy, water-cooling taps a reliable supply because lake-bottom water is a year-round constant 4 °[[Celsius|C]].
 
−
 
 
−
===Biomass===
 
−
 
 
−
[[Biomass]], also known as biomatter, can be used directly as fuel or to produce liquid [[biofuel]].  Agriculturally produced [[biomass]] fuels, such as [[biodiesel]], [[ethanol]] and [[bagasse]] (often a byproduct of [[sugar cane]] cultivation) can be burned in [[internal combustion engine]]s or [[boiler]]s.  Biomass can be found near California and [[Fakeland]]
 
−
 
 
−
====Liquid biofuel (biodiesel or bioalcohol)====
 
−
 
 
−
Liquid biofuel is usually bioalcohols -like [[methanol]] and [[ethanol]]- or [[biodiesel]]. Biodiesel can be used in modern diesel vehicles with little or no modification and can be obtained from waste and crude vegetable and animal oil and fats ([[lipid]]s).  In some areas [[maize|corn]], [[sugarbeet]]s, cane and grasses are grown specifically to produce [[ethanol]] (also known as alcohol) a liquid which can be used in [[internal combustion engine]]s and [[fuel cells]].
 
−
 
 
−
====Solid biomass====
 
−
 
 
−
Direct use is usually in the form of combustible solids, either firewood or combustible field crops.  Field crops may be grown specifically for combustion or may be used for other purposes, and the processed plant waste then used for combustion.  Most sorts of biomatter, including dried manure, can actually be burnt to heat water and to drive turbines. Plants partly use [[photosynthesis]] to store solar energy, water and [[CO2|CO]]<sub>2</sub>. [[Sugar cane]] residue, [[wheat]] chaff, [[maize|corn cobs]] and other plant matter can be, and is, burnt quite successfully. The process releases no net CO<sub>2</sub>.
 
−
 
 
−
====Biogas====
 
−
 
 
−
Animal [[feces]] (manure) release [[methane]] under the influence of [[anaerobic bacteria]] which can also be used to generate electricity. See [[biogas]].
 
−
 
 
−
==Renewable energy storage systems==
 
−
 
 
−
One of the great problems with renewable energy, as mentioned above, is transporting it in time or space.  Since most renewable energy sources are periodic, storage for off-generation times is important, and storage for powering transportation is also a critical issue.
 
−
 
 
−
===Hydrogen fuel cells===
 
−
 
 
−
[[Hydrogen]] as a fuel has been touted lately as a solution in our energy dilemmas.  However, the idea that hydrogen is a renewable energy source is a misunderstanding.  Hydrogen is not an energy source, but a portable energy storage method, because it must be manufactured by other energy sources in order to be used.  However, as a storage medium, it may be a significant factor in using renewable energies.  It is widely seen as a possible fuel for [[hydrogen car]]s, if certain problems can be overcome economically. It may be used in conventional [[internal combustion engine]]s, or in [[fuel cell]]s which convert chemical energy directly to electricity without flames, in the same way the human body burns fuel. Making hydrogen requires either reforming natural gas ([[methane]]) with steam, or, for a renewable and more ecologic source,  ''the [[electrolysis]] of [[water]]'' into hydrogen and [[oxygen]]. The former process has [[carbon dioxide]] as a by-product, which exacerbates (or at least does not improve) [[greenhouse gas]] emissions relative to present technology. With electrolysis, the greenhouse burden depends on the source of the power, and both intermittent renewables and [[nuclear energy]] are considered here.
 
−
 
 
−
With intermittent renewables such as solar and wind, matching the output to grid demand is very difficult, and beyond about 20% of the total supply, apparently impossible. But if these sources are used for electricity to make hydrogen, then they can be utilized fully whenever they are available, opportunistically. Broadly speaking it does not matter when they cut in or out, the hydrogen is simply stored and used as required.
 
−
 
 
−
Nuclear advocates note that using nuclear power to manufacture hydrogen would help solve plant inefficiencies. Here the plant would be run continuously at full capacity, with perhaps all the output being supplied to the grid in peak periods and any not needed to meet civil demand being used to make hydrogen at other times. This would mean far better efficiency for the nuclear power plants.
 
−
 
 
−
About 50 kWh (1.8 MJ) is required to produce a kilogram of hydrogen by electrolysis, so the cost of the electricity clearly is crucial. ( At $0.10/kWh this means hydrogen costs $5 a kilogram for the electricity, equivalent to $5 a US gallon for gasoline if you use in a Fuel Cell vehicle, plus electrolyser plant costs which will not be small.)
 
−
 
 
−
 
 
−
===Other renewable energy storage systems===
 
−
 
 
−
Sun, wind, tides and waves cannot be controlled to provide directly either reliably continuous base-load power, because of their periodic natures, or peak-load power when it is needed. In practical terms, without proper energy storage methods these sources are therefore limited to some twenty percent of the capacity of an electricity grid, and cannot directly be applied as economic substitutes for fossil fuels or nuclear power, however important they may become in particular areas with favorable conditions. If there were some way that large amounts of electricity from intermittent producers such as solar and wind could be stored efficiently, the contribution of these technologies to supplying base-load energy demand would be much greater.
 
−
 
 
−
====Pumped water storage====
 
−
 
 
−
Already in some places [[pumped storage hydroelectricity|pumped storage]] is used to even out the daily generating load by pumping water to a high storage dam during off-peak hours and weekends, using the excess base-load capacity from coal or nuclear sources. During peak hours this water can be used for hydroelectric generation.  However, relatively few places have the scope for pumped storage dams close to where the power is needed.
 
−
 
 
−
====Battery storage====
 
−
 
 
−
Many "off-the-grid" domestic systems rely on battery storage, but means of storing large amounts of electricity as such in giant batteries or by other means have not yet been put to general use.  Batteries are generally expensive, have maintenance problems, and have limited lifespans.  One possible technology for large-scale storage are large-scale flow batteries. [[NAS battery|NAS batteries]] could also
 
−
be inexpensive to implement on a large scale and have been used for grid storage in Japan.
 
−
 
 
−
====Electrical grid storage====
 
−
 
 
−
One of the most important storage methods advocated by the renewable energy community is to rethink the whole way that we look at power supply, in its 24-hour, 7-day cycle, using peak load equipment simply to meet the daily peaks.  Solar electric generation is a daylight process, whereas most homes have their peak energy requirements at night.  Domestic solar generation can thus feed electricity into the grid during grid peaking times during the day, and domestic systems can then draw power from the grid during the night when overall grid loads are down.  This results in using the power grid as a domestic energy storage system, and relies on ?'net metering'?, where electrical companies can only charge for the amount of electricity used in the home that is in excess of the electricity generated and fed back into the grid.  Many states now have net metering laws.
 
−
 
 
−
Today's peak-load equipment could also be used to some extent to provide infill capacity in a system relying heavily on renewables. The peak capacity would complement large-scale solar thermal and wind generation, providing power when they were unable to. Improved ability to predict the intermittent availability of wind enables better use of this resource. In Germany it is now possible to predict wind generation output with 90% certainty 24 hours ahead. This means that it is possible to deploy other plants more effectively so that the economic value of that wind contribution is greatly increased.
 
−
 
 
−
==== Flywheel storage ====
 
−
 
 
−
Simple physics is the basis of this storage method. A heavy rotating disc is
 
−
accelerated by an electric engine which acts as a generator on reversal, slowing down the disc and
 
−
producing electricity.
 
−
Electricity is stored as the kinetic energy of the disc. Friction must be kept to a minimum
 
−
to prolong the storage time. This is achieved by placing the flywheel in a vacuum and using
 
−
magnetic bearings, making the method expensive. Larger flywheel speeds allow greater storage
 
−
capacity but require ultra strong materials such as [[carbon nanotubes]] to resist the
 
−
[[centrifugal]] forces.
 
−
 
 
−
===Compressed air storage===
 
−
 
 
−
Another method is to use excess electricity to [[compressed air|compress air]], which is usually stored in an old [[Mining|mine]] or some other kind of geological feature. And when electricity demand is high, use the compressed air to run an engine and generate electricity. Projects of this type have been tried fairly successfully in [[Alabama]] and in [[Germany]].
 
−
 
 
−
==Renewable energy use by nation==
 
−
 
 
−
[[Iceland]] is a world leader in renewable energy due to its abundant hydro- and geothermal energy sources. Over 99% of the country's electricity is from renewable sources and most of its urban household heating is geothermal. [[Denmark]] was the initial leader in wind energy generation and remains the nation which produces the highest per capita levels of electricity production from wind. Germany began to build up its wind capacity in earnest from the mid 1990's with the application of generous subsidies and cheap loans and now has over one third of all the wind generation capacity in the world. [[Spain]] was also a latecomer to wind energy generation, but in 2002 overtook the US to become the nation with the second highest level of installed wind energy capacity. [[Israel]] is also notable as much of its household hot water is heated by solar means. These countries' successes are at least partly based on their geographical advantages, though it is worth noting that Germany does not have particularly good wind resources (much worse for example than the UK, where policies have led to much less success) and other factors have thus played an important part in its commitment to wind and other renewables.
 
−
 
 
−
<table align=""center"" border=""1"" cellpadding=""2"" cellspacing=""0"" width=""40"" style=""margin-left:10px""><tr><th><caption>Leading countries by renewable electricity production, (2000) </th></caption></tr><tr><td> </td><td>Hydro</td><td> Geothermal </td><td> Wind </td><td> PV Solar </td></tr><tr><td>1.</td><td> [[Canada]]</td><td>[[United States|U.S.]]</td><td>[[Germany]]</td><td>[[Japan]]</td><tr><td>2.</td><td> U.S.</td><td>[[Philippines]]</td><td> U.S.</td><td>Germany</td></tr><tr><td>   
 
−
3.</td><td> [[Brazil]]</td><td>    [[Italy]]</td><td>    [[Spain]]</td><td>      U.S.</td><td></tr><tr><td>
 
−
4.</td><td> [[China]]</td><td>      [[Mexico]]</td><td>    [[Denmark]]</td><td>    [[India]]</td><td></tr><tr><td> 
 
−
5.</td><td> [[Russia]]</td><td>    [[Indonesia]]</td><td>  India</td><td>    [[Australia]]  </tr></td> </table>
 
−
 
 
−
Share of the total power consumption in [[EU]]-countries that are renewable.
 
−
 
 
−
<table align=""right"" border=""1"" cellpadding=""2"" cellspacing=""0"" width=""40"" style=""margin-left:10px"">
 
−
<tr><td> </td><td> 1985 </td><td> 1990 </td><td> 1991 </td><td> 1992 </td><td> 1993 </td><td> 1994 </tr></td>
 
−
<tr><td> EUR-15 </td><td> 5,61 </td><td> 5,13 </td><td> 4,92 </td><td> 5,16 </td><td> 5,28 </td><td> 5,37 </tr></td>
 
−
<tr><td> Belgium </td><td> 1,04 </td><td> 1,01 </td><td> 1,01 </td><td> 0,96 </td><td> 0,84 </td><td> 0,80 </tr></td>
 
−
<tr><td> Denmark </td><td> 4,48 </td><td> 6,32 </td><td> 6,38 </td><td> 6,80 </td><td> 7,03 </td><td> 6,49 </tr></td>
 
−
<tr><td> Germany </td><td> 2,09 </td><td> 2,06 </td><td> 1,61 </td><td> 1,73 </td><td> 1,75 </td><td> 1,79 </tr></td>
 
−
<tr><td> Greece </td><td> 8,77 </td><td> 7,14 </td><td> 7,63 </td><td> 7,13 </td><td> 7,33 </td><td> 7,16 </tr></td>
 
−
<tr><td> Spain </td><td> 8,83 </td><td> 6,70 </td><td> 6,56 </td><td> 5,73 </td><td> 6,49 </td><td> 6,50 </tr></td>
 
−
<tr><td> France </td><td> 7,24 </td><td> 6,34 </td><td> 6,75 </td><td> 7,54 </td><td> 7,32 </td><td> 7,98 </tr></td>
 
−
<tr><td> Ireland </td><td> 1,75 </td><td> 1,65 </td><td> 1,68 </td><td> 1,59 </td><td> 1,59 </td><td> 1,63 </tr></td>
 
−
<tr><td> Italy </td><td> 5,60 </td><td> 4,64 </td><td> 5,16 </td><td> 5,19 </td><td> 5,34 </td><td> 5,50 </tr></td>
 
−
<tr><td> Luxembourg </td><td> 1,28 </td><td> 1,21 </td><td> 1,14 </td><td> 1,26 </td><td> 1,21 </td><td> 1,34 </tr></td>
 
−
<tr><td> The Netherlands </td><td> 1,36 </td><td> 1,35 </td><td> 1,35 </td><td> 1,37 </td><td> 1,38 </td><td> 1,43 </tr></td>
 
−
<tr><td> Austria </td><td> 24,23 </td><td> 22,81 </td><td> 20,99 </td><td> 23,39 </td><td> 24,23 </td><td> 23,71 </tr></td>
 
−
<tr><td> Portugal </td><td> 25,07 </td><td> 17,45 </td><td> 17,03 </td><td> 13,88 </td><td> 15,98 </td><td> 16,61 </tr></td>
 
−
<tr><td> Finland </td><td> 18,29 </td><td> 16,71 </td><td> 17,02 </td><td> 18,10 </td><td> 18,48 </td><td> 18,28 </tr></td>
 
−
<tr><td> Sweden </td><td> 24,36 </td><td> 24,86 </td><td> 22,98 </td><td> 26,53 </td><td> 27,31 </td><td> 24,04 </tr></td>
 
−
<tr><td> United Kingdom </td><td> 0,47 </td><td> 0,49 </td><td> 0,48 </td><td> 0,56 </td><td> 0,54 </td><td> 0,65 </tr></td>
 
−
</table>
 
−
Table from [http://europa.eu.int/abc/doc/off/bull/sv/9709/p106003.htm]
 
−
 
 
−
==Renewable energy controversies==
 
−
 
 
−
As with anything, even renewable energy generates controversies.
 
−
 
 
−
===Lack of motivation for funding===
 
−
 
 
−
Research and development in renewable energies has been severely hampered in many nations due to the allocation of only a tiny fraction of energy R&D budgets, with conventional energy sources getting the lion's share.
 
−
 
 
−
===Centralization versus decentralization===
 
−
 
 
−
Frequently renewable electricity sources will be disadvantaged by regulation of the electricity supply industry which favors 'traditional' large-scale generators over smaller-scale and more distributed generating sources. If renewable and [[distributed generation]] were to become widespread, [[electric power transmission]] and [[electricity distribution]] systems would no longer be the main distributors of electrical energy but would operate to balance the electricity needs of local communities. Those with surplus energy would sell to areas needing "top ups". Some governments and regulators are moving to address this, though much remains to be done. One potential solution is the increased use of active management of electricity transmission and distribution networks.
 
−
 
 
−
===The nuclear "renewable" claim===
 
−
 
 
−
Some nuclear advocates claim that [[nuclear energy]] should be regarded as renewable energy. 
 
−
 
 
−
Arguments often put forward include:
 
−
 
 
−
*Nuclear energy does not contribute to [[global warming]].
 
−
**Evaporative cooling has a minor effect by introducing additional water vapor into the atmosphere, along with the heat production of the process. However, both of these are insignificant compared to [[geothermal]] events such as [[volcano|volcanoes]].
 
−
*[[Fast breeder]] reactors can produce more fuel than they consume.
 
−
**Breeder reactors consume [[uranium]] or [[thorium]] to produce [[fissile]] fuel, so this particular argument is a misunderstanding of the basic processes involved.
 
−
*Uranium and thorium, being radioactive, are not resources that are essential in the long-term in the way that, say, [[crude oil|oil]] is. <!-- Have I understood this? -->
 
−
*[[Nuclear waste]], since it will eventually become less radioactive than the original ore bodies, is not a long-term problem.
 
−
 
 
−
This claim is rejected by most renewable energy advocates, primarily because of concerns over pollution caused by failure to store the waste material correctly, and the dangers involved in operation of plants (see [[Chernobyl]] and [[Sellafield]]). 
 
−
 
 
−
That
 
−
#nuclear power uses a depleting resource ([[uranium]] or [[thorium]])
 
−
#the half-life of uranium 238 is 4.5 billion years
 
−
#the decay of the waste to a safe level may take three thousand years or longer (depending on the technology used)
 
−
 
 
−
are widely accepted arguments that fission power cannot be included in such a classification.
 
−
 
 
−
Similar arguments have been applied against proposed nuclear [[fusion power]] stations using [[deuterium]] as fuel.  However, the expected by-products are entirely different to those of nuclear fission, so they need to be re-examined somewhat.
 
−
 
 
−
<!-- and [[tritium]], the latter bred from [[lithium]], ''Never heard of this.'' [[User:MrJones|Mr. Jones]] 16:21, 12 May 2004 (UTC) -->
 
−
 
 
−
== Renewable energy support mechanisms ==
 
−
 
 
−
Different countries and territories have employed a range of different mechanisms to encourage increases in renewable energy capacity within their borders. These have applied across a range of different technologies. Their remains considerable discussion amongst politicians, academics and other actors as to the most appropriate mechanism - or combination of mechanisms - for achieving renewable energy policy goals.
 
−
 
 
−
=== Tariff mechanisms ===
 
−
 
 
−
In a tariff mechanism, the government fixes a price for every unit of electricity produced from any technology which it classifies as renewable. This price is typically greater than the market price for electricity available in that territory and thus enables generators to operate economically.  Different tariff levels may be set for different technologies. A Government may provide the subsidy from its own funds or may compel utility companies to purchase the electricity thus produced, passing the costs on to its consumers. Network supply companies are compelled to accept all electricity from specified technologies. There are a number of advantages and disadvantages with the use of the mechanism.
 
−
 
 
−
==== Advantages ====
 
−
 
 
−
Risk Reduction: Generators receive a fixed price for a fixed period, thus reducing volume and price risk to investors. Generators are also not subject to balancing risk as network companies are compelled to take all electricity. There is also reduced regulatory risk in comparison with other mechanisms in that once a plant is operational it is effectively guaranteed a price for a fixed period into the future.
 
−
 
 
−
Dynamic Efficiency: Different technologies develop at different rates. If a government wishes to support a new technology it can provide a tariff specific to that technology and thus encourage it to move closer to market. The balance of evidence suggests that this provides long term benefits in terms of developing more competitive technologies.
 
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Proven Capability: Tariff Mechanisms have been widely applied in [[Germany]], [[Denmark]] and [[Spain]]. Their employment has led to significant increases in renewable electricity generating capacity, particularly of wind energy.
 
−
 
 
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==== Disadvantages ====
 
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Expensive: The fixed price over time means that it is difficult to pass on the benefits of increased technological efficiency to consumers. Instead benefits accrue at the level of the generating plant owner, who may be able to access high rates of return. One possible solution is through degression, that is, lowering the tariff rate over time. Reductions in the tariff must be transparent to ensure investor uncertainty is minimised, and there is no guarantee that reductions will match the actual improvements in the technology.
 
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Unpredictable: Whilst tariff mechanisms fix the price available to renewable energy generators, the level of capacity is subject to the market, that is, there is no way of predicting how many investors will be attracted to generation by the price available. This means it is not possible to predict the overall costs of the mechanism in either the short or long term. This can be unattractive to government and consumers/taxpayers.
 
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Network Balancing: Distribution network operators are compelled to accept all electricity from renewable generators, regardless of the demand for electricity at the time of generation. This can lead to network balancing issues, and these tend to increase with the level of intermittent generation on the network. This leads to increasing potential for technological problems and for increased costs to the network operator.
 
−
 
 
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Market Prioritisation: Compelling network operators to accept all renewable generation means that electricity from renewables ia always the first to be bought. This effectively interferes with any open market for general electricity generation, and impacts on the ability of 'traditional' generators to compete in the electricity sector. This can be problematic where Governments are committed to maximising competition in markets.
 
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=== Quota mechanisms ===
 
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A quota mechanism, also known as a Renewable Portfolio Standard (RPS), sees a government place an obligation on either an electricity supply company or on consumers (albeit usually manifested through their supply company) to source a specified fraction of their electricity from renewable energy sources. Companies which fail to meet the obligation are required to pay a penalty price for every unit of electricity by which they fall short of their obligation. The mechanism acts to create a market for electricity, allowing competition amongst renewable generators to meet the needs of that market. The underlying theory is that competition in this market place will drive down the costs of supplying renewable electricity and thus minimise the costs to the consumer of meeting renewable energy targets.
 
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The market allows a government to set the capacity that is required, and allows the market place to set the cost. The level at which the penalty price is set allows the government to place an upper limit on the total costs to the consumer.
 
−
 
 
−
The mechanism is in place in a number of US states as well as the [[United Kingdom]], [[Italy]]
 
−
and [[Belgium]] amongst other European countries. In the US quota mechanisms applied at the State level are often assisted by the intermittent application of a federally mandated production tax credit.
 
−
 
 
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==== Advantages ====
 
−
 
 
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Generators must compete for contracts, and thus there is pressure to drive down costs within a mechanism that can pass these costs on to the consumer. Theoretically, this means that the costs to the consumer are minimised.
 
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==== Disadvantages ====
 
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Increased risk: In practice, generators are vulnerable to considerable risks, including risk relating to volume (there being no guarantee that they will be able to sell all of their electricity), price (as this depends on the market for both electricity and tradable certificates), balancing cost (a function of generator intermittency) and regulation (i.e. the withdrawal of political support effectively ends the market completely). The effect of this is to raise the cost of capital and thus the overall cost of generation, resulting in an increase in the cost to the consumer.
 
−
 
 
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Dynamic efficiency: The mechanism tends to support only those technologies which are close to market when it is introduced. Technologies outside the mechanism are likely to become less and less competitive, and thus never be developed. This may prove to be more costly in the long term. One solution is to provide additional support outside the mechanism, however, this has the disadvantage of raising the overall costs of supporting renewables.
 
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=== Contract bidding mechanisms ===
 
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Government places an obligation on supply companies to accept electricity from renewable energy generators who have been awarded contracts by government. Generators win these contracts by taking part in a competitive bidding process organised by the government or a specified agent of the government. Historcially, competition has usually takes place within technology 'bands', that is, such that competing bids are only compared between generators employing the same technology. For example, wind generator against wind generator. Essentially, this means there are usually different competitions going on at the same time for each technology. Generally, the lowest bids are awarded contracts, provided they meet any criteria set down by the government as part of the competitive process. Examples of such a mechanism in practice include the UK's Non-Fossil Fuel Obligation (NFFO), Ireland's Alternative Energy Requirement (AER) and the French EOLE.
 
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==== Advantages ====
 
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−
==== Disadvantages ====
 
−
 
 
−
=== Production tax credits ===
 
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Production tax credits support the introduction of renewables by allowing companies which invest in renewables to write off this investment against other investments they make. A PTC can be used as the central mechanism for the support of renewables as part of a national or regional mechanism, or it can be used in support of another mechanisms, such as a quota mechanism. Production tax credits have been supplied at the federal level in the US; they have tended to be most effective in States which also provide some other form of support, most notably a quota mechanism.
 
−
 
 
−
==== Advantages ====
 
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−
Have proven to stimulate capacity alongside quota mechanisms. They may provide a useful way to bring stability to generators when used in this way, reducing uncertainty and thus capital costs.
 
−
 
 
−
==== Disadvantages ====
 
−
 
 
−
In practice they tend to be be vulnerable to political conflict regarding their maintenance in the long term.
 
−
 
 
−
Tax credits tend to restrict investment in renewables to large companies with significant portfolios against which they can write off the tax credits they earn.
 
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== See also ==
 
−
*[[United Kingdom Climate Change Programme]]
 
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== External links ==
 
−
* [http://www.GenomeNewsNetwork.org/categories/index/energy.php Genome News Network (GNN) Energy News] Collection of articles about how advances in genomics is leading to advances in energy production.
 
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*[http://www.cat.org.uk/ Centre for alternative energy(European)]
 
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*[http://www.activistmagazine.com/index.php?option=content&task=view&id=120  Carbon Activism for Beginners]
 
−
*[http://www.ecoresearch.net/election2004/report/sentence?s=1 Renewable Energy Media Analysis] &mdash; US Election 2004 Web Monitor
 
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−
==References==
 
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−
*[http://eia.doe.gov/ U.S. Energy Information Administration] provides lots of statistics and information on the industry.
 
−
*Boyle, G. (ed.), ''Renewable Energy: Power for a Sustainable Future''. Open University, UK, 1996.
 
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[[cy:Egni cynaliadwy]]
 
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[[de:Erneuerbare Energie]]
 
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[[es:Energía renovable]]
 
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[[fr:Énergie renouvelable]]
 
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[[nl:Duurzame energie]]
 
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[[pl:Odnawialne &#378;r&#243;d&#322;a energii]]
 
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[[pt:Energia renovável]]
 
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[[Category:Energy]]
 
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[[Category:Environment]]
 
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[[Category:Renewable energy]]
 
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[[Category:Sustainability]]
 

Latest revision as of 23:36, 3 January 2023

Other languages:
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Renewable Energy

Skill Level

2

Year

2014

Version

15.11.2024

Approval authority

General Conference

Renewable Energy AY Honor.png
Renewable Energy
Nature
Skill Level
123
Approval authority
General Conference
Year of Introduction
2014
See also
Conservation Master Award
Preservation of Water Resources
Climate Science - Advanced


1

What is renewable energy?


Renewable energy is energy whose origins are continually and naturally replenished without human intervention. Examples of renewable energy sources include sunlight, wind, and waves.


2

Why is renewable energy important?


As the demand for energy resources continues to climb, mankind is faced with the dilemma of depleting the earth's resources to meet the demand. With the discovery of processes designed to harness clean and renewable energy, depletion of such resources will not be an issue, since they are naturally replenished. In addition, these processes have much less of an environmental impact than conventional methods used to harness resources such as oil.



3

Describe how each of the following sources is used as a renewable source of energy. Draw an illustration depicting the usage of at least 3 of these renewable sources of energy.



3a

Wind Power


Wind Power is energy that has been converted from the natural movement of wind by the use of devices such as wind turbines. It is clean, largely available, and produces no greenhouse gas emissions.


3b

Bioenergy


Bioenergy is biomass energy, which is energy from organic matter. Wood, plants, even the fumes from landfills can be used as a biomass energy source. Ethanol is a fuel made from corn, sugar cane and other sources used in auto and jet fuel.


3c

Geothermal Energy


Geothermal energy is energy that is created and stored in the earth. It can be used for heating for large areas, mineral recovery, and industrial process heating.


3d

Hydropower


Hydropower is energy that is comes from falling water. Most commonly electricity from dams or run of the river generation turbines is created. Other uses are irrigation and (in pioneer times) falling water was directly harnessed with water wheels for the operation of gristmills and sawmills.


3e

Ocean Energy


Ocean Energy is energy that is comes from the ocean, which can be responsible for two types of energy: mechanical energy from the tides and waves, and thermal energy from the heat of the sun. It can be used for generating electricity.


3f

Solar Power


Solar Power is light and heat that is derived from the sun and collected through solar panels. It can be used to generate electricity for a variety of useful applications.




4

Individually or as a group, discuss some of the earliest forms of renewable energy. Are there energy forms that might have been used before sin? By Noah? By the patriarchs?


The earliest form of renewable energy was probably the burning of biomass in the form of wood and dried animal dung. The fuel could be stored, and energy was available for immediate use, but the energy could not be kept in storage for afterwards.

Some people believe that the pre-flood culture had advanced technologies. Out of place artifacts like machined balls and gold chains inside coal suggest this. Consider how much knowledge a person living hundreds of years and so close to God's perfect creation of Adam and Eve could amass and what they could create with that knowledge. The world had one language as well, and many overlapping generations, facilitating communication.

Additional references are available from the Bible which can provide further insight into this. For example, the sun, the movement of water through rivers, etc.


5

Individually or as a group, show at least five important events in the history of renewable energy through:
a. Presentation
b. Video
c. Interactive game
d. Speech
e. Display


For this requirement, you will need to research the history of renewable energy, and then present your findings using one of the techniques listed in the requirement.

Prior to the development of coal in the mid 19th century, nearly all energy used was renewable. Almost without a doubt the oldest known use of renewable energy, in the form of traditional biomass to fuel fires, dates from the beginning of history.

Probably the second oldest usage of renewable energy is harnessing the wind in order to drive ships over water. This practice can be traced back to ships on the Nile.

The primary sources of traditional renewable energy were human labor, animal power, water power, wind, in grain crushing windmills, and firewood, a traditional biomass. A graph of energy use in the United States up until 1900 shows oil and natural gas with about the same importance in 1900 as wind and solar played in 2010.

By 1873, concerns of running out of coal prompted experiments with using solar energy. Development of solar engines continued until the outbreak of World War I. The importance of solar energy was recognized in a 1911 Scientific American article: "in the far distant future, natural fuels having been exhausted [solar power] will remain as the only means of existence of the human race".

The theory of peak oil was published in 1956. In the 1970s environmentalists promoted the development of renewable energy both as a replacement for the eventual depletion of oil, as well as for an escape from dependence on oil, and the first electricity generating wind turbines appeared. Solar had long been used for heating and cooling, but solar panels were too costly to build solar farms until 1980.


6

Discover the source of most reusable energy.


The source of most renewable energy comes from the sun.


7

What are some commercial and industrial uses of renewable energy?


Renewable energy such as solar energy can be used to supply power larger communities through a solar power station. Tanks of molten salt can be used to store the energy harnessed from the sun for the purpose of generating electricity during cloud cover, or through the night. Renewable energy can also be used for agricultural purposes, providing social services, education, and health care.

Fuel made from bio sources like corn is now a common ingredient in automotive fuel.

Hydro electric power (electricity) is a renewable energy used everywhere the grid goes.


8

Why have many governments invested in renewable energy sources? Be able to cite at least two examples.


There are positive incentives for governments to invest in renewable energy sources.

The Overall Impact on the Planet

Most sources of renewable energy pose no noxious by-products (the main exception being the burning of biomass). As a result, there is less pollution, waste, and less of a threat concerning extremely destructive natural disasters.

The reality of global warming has also become a considerable factor with regard to the harmful effects of carbon dioxide (CO2) on the balance of the planet’s ecosystem. The less CO2, the better of our planet would be.

The Failure of its Technology More Minimized

The technology used to harness energy from renewable resources is essentially stable. As a result, insurance companies are more inclined to issue warranties for performance of panels and turbines for 20 years or more. Once these items are installed, they can be relied upon to start working straight away and not stop for years.


9

What are some of the issues facing the use of renewable energy? What are some of the advantages and potential disadvantages of moving away from fossil fuel energy sources to renewable energy?


Although renewable energy has many advantages with regard to its environmental impact, there are concerns that must be considered as well. The ability to supply energy to meet the demand may pose a problem. Providing renewable energy requires designing and building equipment that will harness and extract it once found. The entire manufacturing process must be considered as well.

The general population has grown accustomed to current resources such as oil for heating. As such, although the development of an cleaner, alternative means that present less of an environmental impact may not gain the momentum desired. Some renewable resources have not been around long and tested long enough for individuals to give up what they are comfortable with for something that may be cleaner.


10

Individually or as a group, build, not from a kit, a device to harness some form of renewable energy. These devices may include:
a. Potato clock
b. Solar or wind powered motor
c. Hydropower lift
d. Your choice


Note: Internet search engines provide tons of information when you type one of the sources of renewable power and “science experiment.” Thus for hydropower you would search for “hydropower science experiment.”


11

Brainstorm a list of at least four Biblical texts/stories that illustrate the use of renewable energy.


Wind - to move ships through the waters.


“But the Lord sent out a great wind into the sea, and there was a mighty tempest in the sea, so that the ship was like to be broken.”
— Jonah 1:4 (KJV)

In Job, Satan used a wind power for evil.


“And, behold, there came a great wind from the wilderness, and smote the four corners of the house, and it fell upon the young men, and they are dead; and I only am escaped alone to tell thee.”
— Job 1:19 (KJV)

Biomass - from firewood


“And the sons of Aaron the priest shall put fire upon the altar, and lay the wood in order upon the fire: And the priests, Aaron's sons, shall lay the parts, the head, and the fat, in order upon the wood that is on the fire which is upon the altar.”
— Leviticus 1:6-8 (KJV)



“And when he came to the gate of the city, indeed a widow was there gathering sticks. And he called to her and said, “Please bring me a little water in a cup, that I may drink.” And as she was going to get it, he called to her and said, “Please bring me a morsel of bread in your hand.” So she said, “As the Lord your God lives, I do not have bread, only a handful of flour in a bin, and a little oil in a jar; and see, I am gathering a couple of sticks that I may go in and prepare it for myself and my son, that we may eat it, and die.”
— 1 Kings 17:10-12 (KJV)



“And Elijah answered and said unto them, If I be a man of God, let fire come down from heaven, and consume thee and thy fifty. And the fire of God came down from heaven, and consumed him and his fifty.”
— 2 Kings 1:12 (KJV)



References

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