Energy development is the ongoing effort to provide abundant and accessible energy, through knowledge, skills and constructions. When harnessing energy from primary energy sources and converting them into ever more convenient secondary energy forms, such as electrical energy and cleaner fuels, both quantity (harnessing more energy) and quality (more efficient use) are important.
Future energy development faces 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.
Without energy, the entire infrastructure would collapse; agriculture, transportation, waste collection. In that scenario, the resulting mass famine could lead to a Malthusian catastrophe, in which humanity will need to move out of the cities and rely on foraging and basic survival again.
General considerations
All the energy we consume is generated by using the four fundamental forces of nature: gravity, electromagnetism (commonly known as solar radiation or solar energy), the weak nuclear force and the strong nuclear force to create work. Fission energy and fusion energy are generated by the strong nuclear force. Most forms of terrestrial energy can be traced back to fusion reaction inside the sun, with the exception of tidal power, geothermal energy and nuclear power. Geothermal energy is generated by nuclear reactions inside the Earth. Radioactive decay energy is generated by the weak nuclear force. Tidal energy comes from the gravity energy of the Earth/Moon system.
Most human energy sources today use energy from sunlight, either directly like solar cells or in stored forms like fossil fuels. Once the stored forms are used up (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 exploit most of this energy since it also provides the energy for almost all other lifeforms and drives the weather cycle [2][3].
World energy production by source: Oil 40%, natural gas 22.5%, coal 23.3%, nuclear 6.5%, hydroelectric 7.0%, biomass and other 0.7% [4]. In the U.S., transportation accounted for 28% of all energy use and 70% of petroleum use in 2001; 97% of transportation fuel was petroleum [5].
The United Nations projects that world population will stabilize in 2075 at nine billion due to the demographic transition. Birth rates are now falling in most developing nations and the population would decrease in several developed nations if there was no immigration [6]. Still, economic growth probably requires a continued increase in energy consumption. Since 1970, each 1% increase in world GDP has yielded a 0.64% increase in energy consumption [7].
In geology, resources refer to the amount of a specific substance that may be present in a deposit. This definition does not take into account the economic feasibility of exploitation or the fact that resources may not be recoverable using current technology. Reserves constitute those resources that are recoverable using current technology. They can be recovered economically under current market conditions. This definition takes into account current mining technology and the economics of recovery, including mining and transport costs, government royalties and current market prices. Reserves decrease when prices are too low for some of the substance to be recovered economically, and increase when higher prices make more of the substance economically recoverable. Neither of these terms consider the energy required for exploitation (except as reflected in economic costs) or whether there is a net energy gain or loss.
Energy production usually requires an energy investment. Drilling for oil or building a wind power plant requires energy. The fossil fuel resources (see above) that are left are often increasingly more difficult to extract and convert. They may thus require increasingly higher energy investments. If the investment is greater than the energy produced, then the fossil resource is no longer an energy source. This means that a large part of the fossil fuel resources and especially the non-conventional ones cannot be used for energy production today. Such resources may still be exploited economically in order to produce raw materials for plastics, fertilizers or even transportation fuel but now more energy is consumed than produced. (They then become similar to ordinary mining reserves, economically recoverable but not net positive energy sources.) New technology may ameliorate this problem if it can lower the energy investment required to extract and convert the resources. One example being that the use of lasers may revolutionize oil drilling [8].
The classification of energy sources into renewables and non-renewables is not without problems. Geothermal power and hydroelectric power are classified as renewable energy but geothermal sites eventually cool down and hydroelectric dams gradually become filled with silt which is be very expensive to remove. Although it can be argued that while a specific ___location may be depleted, the total amount of potential geothermal and hydroelectric power is not and a new power plant may sometimes be built on a different ___location. Nuclear power is not classified as a renewable but the amount of uranium in the seas may continue to be replenished by rivers through erosion of underground resources for as long as the remaining life of the Sun. Fossil fuels are finite but hydrocarbon fuel may be produced in several ways as described below.
Fossil fuels
Fossil fuels supply most of the energy consumed today. They are relatively concentrated and pure energy sources and technically easy to exploit, and provide cheap energy if the costs of pollution are ignored. Petroleum products provide almost all of the world's transportation fuel.
Pollution is a large problem. The fossil fuels contribute to global warming and acid rains. The use of fossil fuels, mainly coal, causes tens of thousands of deaths each year in the US alone from diseases like respiratory disease, cardiovascular disease, and cancer [9]. Both derivatives from the hydrocarbon fuel itself like carbon dioxide and impurities like heavy metals, sulfur, and uranium contribute to the pollution. Natural gas is generally considered the least polluting of the fossil fuels with coal being the most polluting. Some of the non-conventional forms like oil shale may be significantly more polluting than the conventional ones. These problems may be lessened by new ways of burning the fuels and cleaning up the exhaust. The storage of the ashes and the pollutants recovered from the cleaning processes may also be a problem. To ameliorate the greenhouse gas emissions from burning hydrocarbons and coal, various techniques have been proposed for CO2 sequestration.
Fossil fuels are also finite. See Hubbert peak for a discussion about the projected production peak of oil and other fossil fuels.
Oil
Conventional oil
Main article: Hubbert peak
The pessimists predict that conventional oil production will peak in 2007. There are many other predictions, one example is that the world conventional oil production will peak somewhere between 2020 and 2050, but that the output is likely to increase at a substantially slower rate after 2020 (Greene, 2003).
Non-conventional oil
Main article: Non-conventional oil
Non-conventional types of production include: tar sands, oil shale and bitumen. These resources are estimated to contain three times as much oil as the remaining conventional oil resources but few are economically recoverable with current technology [10].
Natural gas
Conventional natural gas
The turning point for conventional natural gas will probably be somewhat later than for oil [11]. The pessimists predict a peak for conventional gas production between 2010 and 2020.
Non-conventional natural gas
There are large unconventional gas resources, like methane hydrate or geopressurized zones, that could increase the amount of gas by a factor of ten or more, if recoverable [12][13].
Vast quantities of methane hydrate are inferred from the actual finds. Methane hydrate is a clathrate; a crystalline form in which methane molecules are trapped. The form is stable at low temperature and high pressure, conditions that exist at ocean depth of 500 meters or more, or under permafrost. Inferred quantities of methane hydrates exceed those of all other fossil fuels combined, including oil, conventional natural gas and coal [14].Technology for extracting methane gas from the hydrate deposits in commercial quantities has not yet been developed. A research and development project in Japan is targeting commercial-scale technology by 2016 [15].
There are several companies developing the Fischer-Tropsch process to enable practical exploitation of so-called stranded gas reserves.
Coal
There are large but finite coal reserves which may increasingly be used as an energy source during oil depletion. There are today 200 years of economically exploitable reserves at the current rate of consumption. Reserves have increased by over 50% in the last 22 years and are expected to continue to increase [16]. Coal resources are estimated to be 10 times larger. [17] Large amounts of coal waste that has been produced during coal mining and stored near the mines could become exploitable with new technology [18].
Nuclear power
Main article: Nuclear power
At the present use rate, there are 50 years left of low cost known uranium reserves [19]. Given that the cost of fuel is a minor cost factor for fission power, more expensive, lower grade, sources of uranium could be used in the future. For example: extraction from seawater or granite. Another alternative would be to use thorium as fission fuel. Thorium is three times more abundant in the Earth crust than uranium [20].
Current light water reactors burn the nuclear fuel poorly, leading to energy waste. Nuclear reprocessing [21] or burning the fuel better using different reactor designs would reduce the amount of waste material generated and allow better use the available resources. As opposed to current light water reactors which use Uranium-235 (0.7% of all natural uranium), fast breeder reactors use Uranium-238 (99.3% of all natural uranium). It has been estimated that there is anywhere from 10,000 to five billion years worth of Uranium-238 for use in these power plants [22]. Breeder technology has been used in several reactors [23].
The possibility of reactor accidents, like the Three Mile Island and Chernobyl meltdowns, have caused much public fear. Research is being done to lessen the known problems of current reactor technology by developing automated and passively safe reactors. Coal and hydropower has caused many more deaths per energy unit produced than nuclear [24]. Various kinds of energy infrastructure might be attacked by terrorists, including nuclear power plants, hydropower plants, and liquified natural gas tankers.
Nuclear proliferation is the spread from nation to nation of nuclear technology, including nuclear power plants but especially nuclear weapons. New technology like SSTAR may lessen this risk.
The long-term radioactive waste storage problems of nuclear power have not been fully solved. Several countries have considered using underground repositories. U.S nuclear waste from various locations is planned to be entombed inside Yucca Mountain, Nevada. Nuclear waste takes up little space compared to wastes from the chemical industry which remain toxic indefinitely [25]. In the future, fusion or ADS systems could eliminate waste [26]. In the meantime, spent fuel rods are stored in concrete casks close to the nuclear reactors [27].
Advocates of nuclear power point out that it is a cost competitive way to produce energy versus fossil fuels, especially if you take into account fossil fuel externalities, the same way nuclear reactors have to pay for their pollution and plant decommissioning costs [28]. 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 gives more energy per input energy than many other energy sources. If energy becomes scarce, this could be important [29]. It is possible to relatively rapidly increase the number of plants. New reactor designs have a construction time of 3-4 years.[30]. 43 plants were being built in 1983, before an unexpected fall in fossil fuel prices stopped most new construction. Developing countries like India and China are rapidly increasing their nuclear energy use [31][32].
Fusion power could solve many of the problems of fission power (the technology mentioned above) but, despite research having started in the 1950s, no commercial fusion reactor is expected before 2050 [33]. Many technical problems remain unsolved.
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. Before the industrial revolution, they were the only energy source used by humanity. Solid biofuel like wood is still the main power source for many poor people in developing countries, where overuse may lead to deforestation and desertification
Hydroelectricity is the only renewable today making a large contribution to world energy production. The long-term technical potential is believed to be 9 to 12 times current hydropower production, but increasingly, environmental concerns block new dams [34].
Solar cells can convert around 17% of the energy of incident sunlight to electrical energy. Solar thermal collectors can capture 70-80% as usable heat. Researchers have estimated that algae farms could convert 10% into biodiesel energy. If built out as solar collectors, 1% of the land today used for crops and pasture could supply the world's total energy consumption. A similar area is used today for hydropower, as the electricity yield per unit area of a solar collector is 50-100 times that of an average hydro scheme. [35]
Wind power is one of the most cost competitive renewables today. Its long-term technical potential is believed to be up to 1.4 times total current world energy use [36]. This number could increase if using high altitude airborne wind turbines [37].
Geothermal power and tidal power are the only renewables not dependent on the sun but are today limited to special locations. All available tidal energy is equivalent to 1/4 of total human energy consumption today [38]. Geothermal power has a very large potential if considering all the heat generated inside Earth.
Ocean thermal energy conversion and wave power are other renewables with large potential. Several other variations of utilizing energy from the sun also exist, see renewable energy.
Most renewable sources are diffuse and require large land areas and great quantities of construction material for significant energy production. There is some doubt that they can be built out rapidly enough to replace fossil fuels [39]. The large and sometimes remote areas may also increase energy loss and cost from distribution. On the other hand, some forms allow small-scale production and may placed very close to consumers which reduce distribution problems.
The large areas affected also means that renewables may have a negative environmental impact. Hydroelectricity dams, like the Aswan Dam, have adverse consequences both upstream and downstream. The flooded areas also contain decaying organic material that release gases contributing to global warming. The mining and refining of large amounts of construction material may also affect the environment.
Aside from hydropower and geothermal power, which are site-specific, renewable supplies generally have higher costs than fossil fuels if the externalized costs of pollution are ignored, as is common. Renewables like wind and solar are cost effective in remote areas that are off grid because the cost of a grid connection is high, as is the cost of transporting diesel fuel. The fact that small diesel generators are not hugely efficient and the fact that they consume fuel and make noise even when offload also makes renewables seem more desirable in this situation.
There is some hope that further investment in R&D might bring down the cost of some renewable energy sources. Nuclear power has been subsidized by 0.5-1 trillion dollars since the 1950s. No comparable investment has yet been made in renewable energy. Even so, the technology is improving rapidly. For example, solar cells are a hundred times less expensive today than the 1970s. Larger scale production of renewable sources might also decrease unit costs.
Renewable sources currently make most sense in less developed areas of the world, where the population density cannot economically support the construction of an electrical grid or petroleum supply network. Without these investments, fossil fuel energy sources do not enjoy large economies of scale, and distributed, small-scale electrical generation from renewables is often cheaper.
Increased efficiency in current energy use
New technology may make better use of already available energy, examples being more efficient lightbulbs, engines and insulation. Using heat exchangers, it is possible to recover some of the energy in waste warm water and air, for example to preheat incoming fresh water. Mass transportation increases energy efficiency compared to widespread automobile use while air travel in its current form is regarded as inefficient. Hydrocarbon fuel production from pyrolysis could also be in this category, allowing recovery of some of the energy in hydrocarbon waste. Meat production is energy inefficient compared to the production of protein sources like soybean or Quorn. Already existing power plants often can and usually are made more efficient with minor modifications due to new technology. Note that none of these methods allows perpetual motion, some energy is always lost to heat.
Electricity distribution may change in the future. New small scale energy sources may be placed closer to the consumers so that less energy is lost during electricity distribution. New technology like superconductivity may also decrease the energy lost. Distributed generation permits electricity "consumers", who are generating electricity for their own needs, to send their surplus electrical power back into the power grid.
Energy storage and transportation fuel
There is a widely held misconception that hydrogen is an alternative energy source. There are no uncombined hydrogen reserves on Earth that could provide energy like fossil fuels or uranium. Uncombined hydrogen is instead produced with the help of other energy sources. It may play an important role in a future hydrogen economy as a general energy storage system, used both to smooth power output by intermittent power sources, like solar power, and as transportation fuel for vehicles. However, the idea is currently impractical: hydrogen is inefficient to produce, and expensive to store, transport, and convert back to electricity. New technology may change this in the future.
Many renewable energy systems produce intermittent power. Other generators on the grid can be throttled to match varying production from renewable sources, but most of this throttling capacity is already committed to handling variations in load. Further development of intermittent renewable power will require simultaneous development of storage systems such as hydrogen. See grid energy storage for other alternatives. Intermittent energy sources may be limited to at most 20-30% of the electricity produced for the grid without such storage systems. Some energy will be lost when converting to and from storage and the storage systems will also add to the cost of the intermittent energy sources requiring them. If electricity distribution loss and costs could be greatly reduced, then intermittent power production from many different sources could be averaged into smooth output. Renewables that are not intermittent include hydroelectric power, geothermal power, solar chimney, ocean thermal energy conversion, high altitude airborne wind turbines, biofuel, and solar power satellites.
There are also other alternatives for transportation fuel. The Fischer-Tropsch process converts coal, natural gas, and low-value refinery products into diesel. 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. [40] This technology could be used as an interim transportation fuel if conventional oil were to disappear. Coal itself has historically been used directly for transportation purposes in vehicles and boats using steam engines. Compressed natural gas is another alternative.
Liquid hydrocarbon fuels can also be produced by pyrolysis of organic wastes, by photosynthesis from carbon dioxide which produces biofuels like biodiesel or alcohol fuels, or by industrial processes [41]. Although the last possibility requires energy from some other source. Compared to hydrogen, these fuels have the advantage of reusing existing engine technology and existing fuel distribution infrastructure.
Nuclear power has been used in large ships [42]. High technology sails could provide some of the power for ships [43]. Electric vehicles and electric boats not using hydrogen are other alternatives. Several companies are proposing vehicles using compressed air as fuel. [44] [45]. Airships require less onboard fuel than a traditional aircraft and combining airship technology with glider technology may eliminate onboard fuel completely [46]. Some mass transportation systems, like trolleybus or metro, can use electricity directly from the grid and do not need a liquid fuel or battery.
Boron [47] or silicon [48] have also been proposed as energy storage solutions.
Speculative
Abiogenic petroleum origin and cold fusion has been proposed as very controversial future sources of energy. Space exploration could yield energy sources from satellites (see solar power satellite), from the moon (see helium-3), from other planets (see abiogenic petroleum origin for a list of planets with hydrocarbons), and from a Dyson sphere. The accretion disc of a black hole can convert about 50% of the mass energy of an object into radiation, as opposed to nuclear fusion which can only convert a few percent of the mass to energy.
See also
External links
Organizations
- IEA Energy Information Centre
- WEC Survey of Energy Resources
- U.S. Energy Information Agency
- Rocky Mountain Institute articles on energy
- Electricity Storage Association on articles on energy storage
- Information Network on the Technology of Utilisation and Sustainability of Energy Resources
Articles
- Order of Magnitude Morality
- Do we need nuclear power?
- Progress and its sustainability
- Alternatives to Oil: Fuels of the Future or Cruel Hoaxes?
- Nine Critical Questions to Ask About Alternative Energy
- Alternative Energy Sources
- World energy beyond 2050
Blogs
References
- Greene, D.L. & J.L. Hopson. (2003). Running Out of and Into Oil: Analyzing Global Depletion and Transition Through 2050 ORNL/TM-2003/259, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Octobe