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Revision as of 13:59, 18 December 2004
Future energy development face great challenges due to an increasing world population, demands for higher standards of living, demands for less pollution and a much discussed end to fossil fuels. Failure would result in overpopulation and a Malthusian catastrophe.
Most energy sources use energy from sunlight, either directly like solar cells or in stored forms like fossil fuels. The exceptions being nuclear power, geothermal power and tidal power. Once the stored forms are used up and assuming no contribution from the three previous energy sources and no energy from space exploration, then the long-term energy usage of humanity is limited to that from the sunlight falling on earth. The total energy consumption of humanity today is equivalent to about 0.1-0.01% of that. But humanity cannot self use most this energy since it also provides the energy for almost all other lifeforms and drive the weather.
The Kardashev scale theory is a general method of classifying how technologically advanced a civilization is, based on the amount of usable energy a civilization has at its disposal
Fossil Fuels
Most energy production in the world today is from fossil fuels. Energy production by source: Oil 40%, natural gas 22.5%, coal 23.3%, nuclear 6.5%, hydroelectric 7.0%, biomass and other 0.7%. But fossil fuels have great problems with pollution, including contributing to global warming and mainly coal causing tens of thousands of deaths each year in the US alone. They are also finite. See Hubbert peak for a discussion about the peaking of oil and other fossil fuels.
Oil
- Main article: Petroleum
Non-conventional oil
- Main article: Non-conventional oil
Non-conventional oil is another source of oil separate from conventional or traditional oil. Non-conventional sources include: tar sands, oil shale and bitumen. Potentially significant deposits of non-conventional oil include the Athabasca Tar Sands site in northwestern Canada and the Venezuelan Orinoco tar sands. Oil companies estimate that the Athabasca and Orinoco sites (both of similar size) have as much as two-thirds of total global oil deposits, but they are not yet considered proven reserves of oil. Extracting a significant percentage of world oil production from tar sands may not be feasible. The extraction process takes a great deal of energy for heat and electrical power, presently coming from natural gas (itself in short supply). There are proposals to build a series of nuclear reactors to supply this energy. Non-conventional oil production is currently less efficient, and has a larger environmental impact than conventional oil production.
Other fossil fuels
Geologists expect that natural gas will peak 5-15 years after oil does. There are large unconventional gas resources, like methane clathrate or geopressurized zones, that could increase the amount of gas by a factor of ten or more, if recoverable. There are large but finite coal reserves which may increasingly be used as a fuel source during oil depletion. There are 200 years of proven reserves of coal at the current consumption. Reserves have increased by over 50% in the last 22 years and are expected to continue to increase.
Nuclear power
- Main article: Nuclear power
The U.S. would require at least an elevenfold increase in nuclear power production to replace both the current amount of electricity generated from fossil fuels and gasoline usage. This may involve using hydrogen as transportation fuel, which adds inefficiency (perhaps increasing this ratio). Or it could be used together with for example biodiesel as transportation fuel.
There are about 50 years of today explored and economical uranium reserves in the ground. Instead using thorium as fuel, which is more common than uranium, could increase this.
Fast breeder reactors are another possibility. As opposed to current LWR (light water reactors) which burn the rare isotope of uranium U-235, fast breeder reactors produce plutonium from U-238, and then fission that to produce electricity and thermal heat. It has been estimated that there is anywhere from 10,000 to five billion years' worth of U-238 for use in these power plants. Breeder technology have been in use in dozen reactors already. There are also research projects working to develop the technology. Lawrence Livermore National Laboratory being one, currently working on the small, sealed, transportable, autonomous reactor (SSTAR).
The possibility of nuclear accidents like Three Mile Island and Chernobyl have caused much public fear. Research are being done to lessen these problems of current reactor technology by developing reactors automated and passively safe.
The long-term radioactive waste storage problems of nuclear power have not been solved. One possible solution several countries are considering is using underground repositories. The U.S nuclear waste from various locations is planned to be entombed inside Yucca Mountain, Nevada. Nuclear waste take up little space, compared to say wastes from coal or other industry wastes toxical indefinitely. It could be greatly reduced with reprocessing. More far off, fusion or ADS system could eliminate waste.
Those advocating nuclear power point out that it is a cost competitive way to produce energy, including all costs such as decommissioning of the plants. . Using life cycle analysis, it takes 4-5 months of energy production from the nuclear plant to fully pay back the initial energy investment. Nuclear energy give more energy per input energy than many other energy sources. If energy would be scarce, this could be important.
Developing countries like India and China are rapidly building out their nuclear energy.
Renewable energy
- Main article: Renewable energy
Another possible solution to an energy shortage or predicted future shortage would be to use some of the world's remaining fossil fuel reserves as an investment in renewable energy infrastructure such as wind power, solar power, tidal power, geothermal power, hydropower, thermal depolymerization and biodiesel which do not suffer from a finite energy reserves, but do have a finite energy flow. The construction of a sufficiently large renewable energy infrastructure might avoid the economic consequences of an extended period of dramatically shrinking energy use per capita.
Hydropower is one of the most promising renewable energy sources, but there is increasingly little damable river left. Dams produce electricity more cheaply than natural-gas turbines, and have reasonable capital costs. As a result, nearly every river in North America that can be dammed has been. Gigantic hydropower projects have recently been built all around the world (see Itaipu and Three Gorges Dam). Another promising renewable energy source may be wind power (currently over four times as efficient as solar PV power systems.
Solar trough concentrating power systems are economic in arid and semiarid regions today. This is particularly true if these solar power plants are designed to take full advantage of the combined heat and power potential outputs. These solar facilities can produce not only electricity, but also steam, hot water, chilled water, and ice using absorption refrigeration cycle equipment.
Thermal depolymerization and biodiesel are potential candidates to make up for oil depletion since they provide energy in a form that is both easily transportable and storable, like oil.
One factor potentially in renewable energy's favor is its much smaller environmental impact. Renewable energy sources may have a significantly smaller total "cost" compared with fossil fuel production after factoring in pollution, in other words, oil production is likely more expensive than the initial price seems to indicate and relative to renewable energy if you factor in the "cost" of pollution.
More efficiency in using available energy
New technology may use already available energy better, examples being more efficient lightbulbs or engines. Better insulation another one. It is possible to recover some of the energy in waste warm water and air, for example to preheat incoming fresh water. Thermal depolymerization could also be in this category, allowing recovery of some of the energy in hydrocarbon waste. Note that none of these methods allows perpetual motion, some energy is always lost to heat.
Energy storage and transportation fuel
There is a widely held misconception that hydrogen is an alternative to crude, oil-based liquid fuels. As there are no uncombined hydrogen reserves in nature, hydrogen is itself not a source of chemical energy. Hydrogen-based energy always involves conversion of an upstream energy source. Typically, this energy source is natural gas, in the case of the steam-reformed methane process, or electricity (generated by fossil fuels, nuclear, solar or wind), in the case of water electrolysis. Genetically modified organisms have also been proposed as a way to generate hydrogen.
Many of the potential power sources sometimes produce no power, and cannot increase production when demanded. For example, solar power produce no power during the night and during the winter, when demand is greater. The role of such power sources will be greatly limited, unless there is way to store large amounts of energy. Another potential role for hydrogen is as a transportable fuel for vehicles, taking the place of gasoline. It is as a means of storage and transportation of energy that hydrogen may play a very important role. (See Hydrogen economy) However, the idea is currently impractical: hydrogen is inefficient to produce, and expensive to store, transport, and convert back to electricity. Research is underway to ameliorate these problems; the outcome is at best uncertain.
The Fischer-Tropsch process converts coal, natural gas, and low-value refinery products into a high-value, clean-burning fuel. This process was developed and used extensively in World War II by the Germans, who had limited access to crude oil supplies. It is today used in South Africa to produce most of country's diesel from coal. This technology could be used as an interim transportation fuel if conventional oil were to disappear.
Methanol can be used in internal combustion engines with minor modifications. It usually is made from natural gas, sometimes from coal and could be made from any carbon source including CO2.
Diesel from the Fischer-Tropsch process, biodiesel, methanol and oil from thermal depolymerization have the advantage of already existing technology for diesel and gasoline engines and in place distribution infrastructure.
Speculative
Solar power satellite, abiogenic petroleum origin, and helium on the moon have been proposed as very speculative future sources of energy. More long-term, proposed future technologies include hydrocarbons on other planets and a Dyson sphere.