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On this page I look at most common fuels and methods used for generating electricity (and a few novel methods) and give an objective listing of the good and bad points of each. Advantages and disadvantages are not quantified.Electricity generation fuels and methods discussed include: coal, gas, oil, oil shale, biogas, biomass (which includes firewood), conventional nuclear, proposed 'fast' nuclear, wind, solar thermal, solar photovoltaic, bio-voltaic, and hot dry rock. I want to make this site useful, informative, and correct. If you believe I've missed anything significant, been ambiguous or unfair, or if you think I'm wrong on some point, I'd be very pleased to have your comments. My email address is daveclarkecb@yahoo.com. |
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Methods are listed alphabetically within each group.
This page uses several technical units.
Energy units, definitions and conversions
are available on an additional page.
Some notesCarbon dioxideAn advantage of almost any method of power production that does not consume fossil fuels is that it need not result in a net addition of the important greenhouse gas carbon dioxide to the atmosphere.No level playing fieldEconomists and politicians often make statements such as "Sustainable methods of power generation cannot yet compete financially on a level playing field with fossil fuel fired power stations". There is no level playing field!Fossil fuel electricity is only cheaper than the more economically viable of the environmentally friendly options (for example wind power) because the fossil fuel power station operators are allowed to dump their waste (carbon dioxide) into the atmosphere at no cost to themselves. Of course this same waste is the main cause of man-made greenhouse warming, and that is the greatest environmental threat to the world today. Nuclear powered electricity would be much cheaper if the power station operators were allowed to dump their radioactive wastes in the sea. The petrochemical industry would make bigger profits if it could dump its wastes in the most convenient place. If fossil fuel electricity generators were made to dispose of their carbon dioxide responsibly, their costs would increase enormously. The wholesale price of black coal generated electricity is around (Australian) 3 cents per kilowatt hour (kWhr) at present (2008). Estimates of the cost of black coal electricity with disposal of carbon dioxide by geosequestration vary from 6.4 to 13 cents per kWhr. (Geosequestration is the deep burial of carbon dioxide.) Wind farm electricity wholesales for around 7 to 8 cents per kWhr (without any subsidies), and one prominent developer of hot dry rock electricity estimates that it will be able to wholesale at 4 cents per kWhr. For comparison, domestic electricity users typically pay about 17 cents per kWhr at the retail end. Even worse for fossil-fuelled electricity: no one has yet demonstrated that carbon geosequestration is viable at any price, and at best, geosequestration is more a land-fill style of disposal than it is an environmentally friendly method.
Comparative costs of power generationThe estimates in the table below are from California Energy Commission (CEC, 2007) and Scientific American (SA, March 2009)
Note that fossil fuel powered stations dump their waste gasses into the atmosphere at no cost to themselves and great cost to the environment; see No level playing field. Nuclear power is very difficult to cost because, if the figure is to be meaningful, it must cover mining, building the power station, running costs for the full life of the power station, protecting the nuclear material from possible theft by terrorists, decommissioning costs, and costs of disposing of the radioactive wastes and protecting them from disturbance for many years.
Nuclear fusionNuclear fusion is, in a way, the opposite of nuclear fission, the reaction that is currently used in all nuclear power stations. While nuclear fission gets its energy from the breaking apart of very large atomic nuclei, fusion releases energy by making very small nuclei join together.Unlike nuclear fission, nuclear fusion would produce little radioactive waste. Unfortunately, no-one has ever built a nuclear fusion power station that is anything near profitable, in spite of many billions of dollars being spent on the effort over the last several decades. War timeIn the tables below, notes relating to the advantages and disadvantages of power generating methods in war time are indicated by the words 'war time' in red as in this sentence. Large power stations are major targets for enemy attack in war time. Numerous small power stations, or distributed generators like wind turbines and solar photovoltaic panels, would be more difficult to put out of action. Nuclear power stations would be hugely polluting if bombed; they could produce disasters on a par with Chernobyl. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
LinksThere is an extensive article on renewable energy in Wikipedia. |
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| Fuel | Advantages | Disadvantages | Comments |
| Coal |
Low cost
Apparently plentiful: we will probably not run out of easily mined coal in the next few decades. It has been believed that the world's coal reserves would last a century or more, but some recent research has indicated that this was optimistic. |
Not sustainable
Requires around 1.7 million litres of fresh water for each gigawatt-hour of electricity generated. Produces more carbon dioxide (CO2) per Watt-hour of energy than any other generation method. The methods of mining coal can be very destructive, although responsible coal miners do a remarkably good job of restoring the land after the coal has been mined out. Very large quantities of ash have to be disposed of and a lot of smoke is produced, although in modern power stations most of the latter is separated from the waste gas stream and disposed of with the ash. Coal contains substances such as sulfur, arsenic, selenium, mercury and the radioactive elements uranium, thorium, radium and radon (see USGS). When the coal is mined and burned these substances can be released into the environment. Burned sulfur is one of the main causes of acid rain, but most modern coal-fired power stations remove most of the sulfur oxides from the released gasses. War time - For maximum efficiency coal fired power stations must be big. They therefore present a desirable target for enemy attack. |
Coal has an 'unfair' advantage over 'cleaner' forms of power generation in
that the power station operators do not have to pay for the damage that they
are doing to the atmosphere. See:
No level playing field.
A coal-fired power station generates a large amount of energy in a relatively small area compared to most renewable methods. However, when all the land required for mining and disposal of ash is taken into account coal does not have any space advantage over several sustainable methods. The misleading term 'clean coal' is sometimes used to refer to coal-fired power stations that efficiently extract substances like sulfur from the coal, either before or after burning. It is impossible to burn coal without producing carbon dioxide, so all coal-fired power stations are dirty in this sense. However, it is possible to dispose of (sequestrate) the carbon dioxide so that it is not released into the atmosphere for a long time. As of the time of writing (Feb. 2006) this has not been done for a commercial scale power station. |
| Fuel | Advantages | Disadvantages | Comments |
| Natural gas |
Low cost
Generators are very compact Produces less CO2 than oil and much less than coal Requires much less water than coal fired power stations |
Not sustainable
Produces carbon dioxide. (CO2), which is an important greenhouse gas. The world's natural gas reserves are limited, but not so limited as oil reserves. | At the rate we are using natural gas our children will see the price rise so much that it will no longer be economical as a fuel. In a more far sighted world natural gas would be reserved for more valuable uses than burning as fuel. We are consuming our children's heritage. Also see: No level playing field. |
| Fuel | Advantages | Disadvantages | Comments |
| Oil |
Low cost
Generators are very compact. Produces less CO2 than coal and requires much less water than coal |
Not sustainable
Produces carbon dioxide (CO2), which is an important greenhouse gas. Requires a substantial amount of cooling water. The world's oil reserves are limited. Oil spills, especially at sea, cause severe pollution. Some oils contain high levels of sulfur. See the note on sulfur under coal, above. The world's supply of oil is limited; see Peak Oil. |
At the rate we are using oil our children will see the price rise so
much that it will no longer be economical as a fuel.
In a more far sighted world oil would be reserved for more valuable
uses than burning as fuel.
We are consuming our children's heritage.
Also see: No level playing field.
Shale oil is oil that can be extracted from shale by mining a shale that is saturated with oil, and roasting it at about 500 degrees Celsius to extract the oil. For more detail see Shale oil in 'Notes' on my page Heating Efficiencies and Greenhouse. |
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| Fuel | Advantages | Disadvantages | Comments | |
| Biogas |
Uses a renewable fuel.
Non-polluting Waste is disposed of at the same time and in the same operation. Consumes methane that might otherwise leak into the atmosphere and increase the greenhouse effect. Biogas can also be used on a small scale, eg. a pig farm. |
Very limited in the quantity of electricity it can produce on
the global scale.
There is little or no control on the rate of gas production, although the gas can, to some extent, be stored and used as required. | The biogas that I am considering here is that produced from buried organic waste or from sewerage. It is also possible to produce flamable gas from materials such as wood. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Biomass (including firewood) |
Uses a renewable fuel.
Non-polluting (so long as smoke is either not produced, or captured). |
A large area of land is required for the production of the
fuel (eg. wood lot or cane field) per MW of power generated.
Because of the above point, this method can never generate enough power to satisfy a major part of current demands. Burns organic matter that might be better returned to the land for soil improvement |
Biomass includes firewood; see environmental aspects of burning
firewood on this site.
So long as the biomass that is burned is continually being replaced by the next crop there is no net increase to atmospheric carbon dioxide. My page, Energy Calculator calculates the relative costs of firewood and several other fuels in terms of energy per dollar. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Geothermal |
Sustainable
Relatively low cost for renewable energy, US$0.06 to $0.08/kWh. Non-polluting; little environmental impact since the steam would be released to the atmosphere with or without the power generation. | It can only be developed in selected volcanic areas, so it can never be a major contributor to the world energy supply | I have used 'geothermal' in relation to the capture and use of more-or-less natural steam in volcanic areas; distinct from 'hot dry rock', which is discussed elsewhere. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Hot dry rock |
Compact; a large amount of electrical power can be produced by
a moderately sized station.
There are huge volumes of very hot rocks at depths of 5km or so. The resource could not be significantly depleted in decades. In human terms it is close to sustainable. It could provide a large part of the worlds base-level electricity supply. Non-polluting | While there have been some trial operations, the technology remains unproven. The costs and technical problems with drilling to great depths in very hot rocks are considerable. |
Also see geothermal above
A hot dry rock company in Australia: Geodynamics. | |
| Fuel | Advantages | Disadvantages | Comments | |
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Hydro (falling water) |
Compact; a large amount of electrical power can be produced by
a moderately sized station.
Sustainable Once established it is fairly environmentally benign. |
The building of dams is usually environmentally destructive –
river valleys are important ecosystems;
it often requires great changes in many peoples' life styles; river valleys
are often fertile and densely populated.
Fermenting vegetation in hydro dams releases the greenhouse gas methane to the atmosphere. The water released from a hydro-power station often comes from the bottom of a dam. If so, it is cold and may not suit species native to the region. Water is often released from a hydro-power dam at times that depend on power consumption (or possibly to suit down-stream irrigators). The natural occasional high-flows or floods that the river's ecosystem has adapted to is disrupted. |
There is a trend toward modifying dams to produce hydro-power where
they were not originally designed for that purpose. This is
sometimes called mini-hydro power.
There is of course a continuous range of hydro-power stations from multi-megawatt down to a few hundred Watts or even less, see: micro hydro. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Conventional nuclear |
Compact; a large amount of electrical power can be produced by
a moderately sized station.
Low fuel costs. Small number of accidents. Normally does not produce any significant atmospheric pollutants. Quantity of waste produced is small. |
About 99.3% of natural uranium is in the form of U238 which
cannot be used as a fuel in a simple nuclear power station.
To use 0.7% of the uranium and dump the remainder, as is currently done,
is terribly wasteful.
(Fast neutron reactors can use the U238, see
below.).
Requires substantial amounts of cooling water. It is expensive, especially in capital costs, maintenance costs, and due to the long lead time in planning and construction; see footnote. Large amounts of fossil fuels are used in mining and processing the uranium fuel; with consequent release of greenhouse gasses. There is a danger of radiation release. While there are few accidents the consequences of some accidents may be catastrophic. Decommissioning a nuclear power station at the end of its useful life is very difficult and expensive. Safe long-term disposal of nuclear waste is difficult. (It must be kept away from the biosphere for several tens of thousands of years). The lead time in building a nuclear power station is around ten years. A tempting target for terrorist attack. War time - Nuclear power stations would produce a huge amount of radioactive contamination if bombed. |
There is insufficient U235 (0.7% of natural uranium) to provide a major part of the current world electrical consumption for a long period. | |
| Fuel | Advantages | Disadvantages | Comments | |
| 'Fast' neutron nuclear (combined with pyrometallurgical recycling of fuel) |
Compact; a large amount of electrical power can be produced by
a moderately sized station.
Abundant fuel is available from existing stored 'waste' nuclear fuel. Conventional reactors only use about 1% of the potential power in uranium, the Fast reactor system could utilise most of the other 99%. Should not produce any significant atmospheric pollutants. Quantity of waste produced should be much smaller than for conventional nuclear. Nuclear waste from a fast reactor system will need to be isolated from the biosphere for several hundred years, compared to the tens of thousands for conventional nuclear. Thorium, which is about three times as abundant as uranium, can be used as fuel in a fast neutron reactor. |
The system is not proven on a commercial scale.
Just as expensive as conventional nuclear? See footnote. Requires substantial amounts of cooling water. There is a danger of radiation release. While the system seems to be sound, the consequences of accidents may be catastrophic. Decommissioning a nuclear power station at the end of its useful life is very difficult and expensive. The lead time in building a nuclear power station is around ten years, since this system is 'new' its lead time will be more like fifteen years. A tempting target for terrorist attack. War time - Nuclear power stations would produce a huge amount of radioactive contamination if bombed. |
Since this system could make use of most of the energy available from
uranium, unlike conventional nuclear, in theory a major part of the current
world electrical consumption could be generated for a long period.
It is claimed that the transuranic elements recovered in the pyroprocessing are "unsuited for weapons" because they include several isotopes of plutonium, not just the plutonium 239 favoured for bomb making, some uranium 238, and fission products. Bad news for uranium miners. If Fast nuclear takes over from conventional then no uranium need be mined for several hundred years; the waste of the old power stations becomes the fuel for the new. | |
Footnote on nuclear powerIt is very difficult to obtain reliable figures on the true monitory cost of nuclear power because of government subsidies.From New Matilda...
The information on the proposed Fast neutron nuclear power combined with pyrometallurgical recycling of fuel was obtained from Scientific American, Dec. 2005. 'Fast' nuclear reactors would use reactions involving fast neutrons rather than moderated neutrons, and probably a low pressure liquid sodium primary coolant rather than the high pressure water that is used in almost all conventional reactors.
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| Fuel | Advantages | Disadvantages | Comments | |
| Solar thermal |
Sustainable, non-polluting
Heat can be stored and used to generate electricity when the sun is not shining. This gives solar thermal an advantage over wind which can only generate electricity when the wind is blowing. |
Solar energy is spread relatively thinly.
If a solar thermal generator is to produce much electricity it has to cover
a large area.
Some forms of solar power require substantial amounts of cooling water. The sun's position in the sky is continually changing so most solar thermal generators have to include expensive machinery to keep them pointed in the right direction. Solar thermal electricity is expensive, US$0.20 to $0.28/kWh. |
Solar thermal energy has been most highly developed in the United States
South West where clear skies are common.
While the technology has great promise it has not yet been proven to be cost-competitive on a large industrial scale. Solar power is most effectively built on flat land. I have written on Australian solar energy at Sun on the Bush. | |
| Fuel | Advantages | Disadvantages | Comments | |
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Solar chimney (A type of solar thermal) |
Sustainable, non-polluting
Requires little water Unlike some other forms of solar energy this can produce electricity at night and for limited periods under clouds due to the heat stored in the 'greenhouse'. |
Must cover a very large area
While a small (50KW) trial station has run in Spain for some years, the technology has never been proven on a commercial scale. War time - To maximise efficiency solar chimneys must be very tall. They would present conspicuous and desirable targets for enemy attack. |
The solar chimney concept uses a large 'greenhouse' to convert
solar radiation into warm air. The air is then allowed to rise
up a very tall (around 1km to be highly effective) chimney, turning turbines
and generating power as it rises.
I have written on Australian solar energy at Sun on the Bush. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Wave |
Sustainable, non-polluting
War time - Spread over a large area, and some types completely under water, so they would be difficult to destroy |
Not proven on a commercial scale
Installation would damage the sea-bed locally |
One type (CETO) has been estimated by its designers to be capable of
producing electricity at around Aus$80/MWh (US$70/MWh), similar to the
cost of wind-power.
This type can either produce electricity or desalinated water (at a claimed cost of around Aus$1.50-$2 per kilolitre (US$1.35-$1.80/kL). | |
| Fuel | Advantages | Disadvantages | Comments | |
| Wind, large turbines |
Sustainable, non-polluting
A well proven technology and low-priced for a sustainable energy, US$0.06 to US$0.08/kWh. Wind farms can be built by moderately sized local or regional businesses. Requires little water, no cooling water. War time - The scattered layout of turbines in wind farms would make it difficult for enemies to destroy more than a few at any one time. |
Does not produce power when the wind isn't blowing.
If a large proportion of a power system's electricity is wind power then there may be a need for a large 'spinning reserve' backup power supply. (See Sustainable Electricity). |
There are many misconceptions about wind farms.
I have notes on problems, alleged problems and objections at
Wind Problems.
An excellent wind power Internet site is that of the Danish Wind Industry Association. I have written on Australian wind energy at Wind in the Bush. | |
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War time - Scattered, numerous, and small power stations would be more difficult for an enemy to put out of action than a few large power stations.
| Fuel | Advantages | Disadvantages | Comments | |
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Bio-voltaic or bio-electricity |
Sustainable
Can combine sewerage disposal with power generation. Non-polluting | Unproven on anything other than a laboratory scale |
Some bacteria have the ability to produce an electrical potential.
These can be fed on something convenient, perhaps sewerage or sugar, and
produce electrical power.
A little more about bio-electricity can be read at ZDNet, in the news section. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Micro hydro |
Sustainable
Can be used in such a way as to minimise disruption of aquatic life and stream ecosystems. Does not necessarily require damming a stream. Non-polluting | If poorly designed and/or operated, it can have similar disadvantages to large hydro-power, but on a smaller scale. |
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| Fuel | Advantages | Disadvantages | Comments | |
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Solar photovoltaic (Solar electrical panels) |
Sustainable
It is a well proven technology. Well suited to providing power in home or single building applications. Roof-top installations are well suited to high-consumption urban areas where it has the additional advantage of saving on the cost of building new transmission lines. Peak generation matches peak consumption fairly well. |
While the panels are environmentally benign once they are built,
the manufacturing process requires large amounts of energy.
One less common, expensive, but highly efficient type of solar panel, gallium arsenide, contains toxins that need to be disposed of carefully at the end of the life of the panel. Solar energy is spread relatively thinly. If a photovoltaic generator is to produce much electricity (ie. several megawatts) it has to cover a large area. Does not produce much power when the sun isn't shining. Electricity generated by solar panels is quite expensive, US$0.47 to US$0.70/kWh. |
A solar photovoltaic panel must operate for a considerable time before it
produces more power than was required in its manufacture.
The US National Renewable Energy Labaratory
states on its
energy payback
page that "Paybacks for multicrystalline modules are 4 years for systems
using recent technology and 2 years for anticipated technology. For
thin-film modules, paybacks are 3 years using recent technology, and just
1 year for anticipated thin-film technology".
Can be combined with small-scale wind-generated electricity or with mains power. Alternatively, batteries can be charged when more electricity is being generated than is being consumed. Excess electricity can be sold to the grid in some cases. In the past photovoltaic panels have predominantly been based on silicon. It is possible that in future a larger proportion will use alternatives such as gallium arsenide (GaAs) or copper indium gallium selenide (CIGS). While these elements are much rarer than silicon, they can be used as a thin film; this makes the cost competative. One wonders if there are pollution implications in their eventual disposal. I have written on Australian solar energy at Sun on the Bush. | |
| Fuel | Advantages | Disadvantages | Comments | |
| Wind, small turbines |
Sustainable, non-polluting
A well proven technology. | Does not produce power when the wind isn't blowing so a back-up electrical supply is also needed. If batteries provide the backup they have the disadvantage of being expensive and needing to be replaced every few years | Units are available to suit single houses or several houses. Small scale wind turbines grade into large scale; turbines are available in a great range of generating capacities. Can usefully be combined with photovoltaic electricity, so that power will be generated when either the wind is blowing or the sun is shining. |
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| Fuel | Advantages | Disadvantages | Comments |
| Diesel and petrol powered generators |
Small.
Relatively low cost. The smaller units are easily portable. |
Consume fossil fuels - therefore not sustainable.
Are net producers of the greenhouse gas carbon dioxide. Produce varying amounts of noise. Some petrol powered units are remarkably well muffled for internal combustion engines. | Petrol engine powered generators are generally small; up to 5 or 10kW. Diesel powered units tend to be larger, heavier, and less portable. |
| Fuel | Advantages | Disadvantages | Comments |
| Fuel cells | Can be a highly efficient way of converting a fuel to useful energy, 45% or even better |
Not yet available at commercially competative costs
At present they (indirectly) consume fossil fuels - therefore they are not sustainable and are net producers of the greenhouse gas carbon dioxide. | If fuel cells were used for powering homes, and the 'waste' heat then used for tasks such as heating water or space heating, the effeciency could be even higher than 45% |
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