Energy development is the ongoing effort to provide sufficient primary energy sources and secondary energy forms to fulfill civilization's needs. It involves both installation of established technologies and research and development to create new energy-related technologies. Major considerations in energy planning include resource depletion, supply production peaks, security of supply, cost, impact on air pollution and water pollution, and whether or not the source is renewable.

Technologically advanced societies have become increasingly dependent on external energy sources for transportation, the production of many manufactured goods, and the delivery of energy services. This energy allows people who can afford the cost to live under otherwise unfavorable climatic conditions through the use of heating, ventilation, and/or air conditioning. Level of use of external energy sources differs across societies, as do the climate, convenience, levels of obesity, traffic congestion, pollution, production, and greenhouse gas emissions of each society.

Increased levels of human comfort generally induce increased dependence on external energy sources, although the application of energy efficiency and conservation approaches allows a certain degree of mitigation of the dependence. Wise energy use therefore embodies the idea of balancing human comfort with reasonable energy consumption levels by researching and implementing effective and sustainable energy harvesting and utilization measures.

Primary energy sources

Primary energy sources are substances or processes with concentrations of energy at a high enough potential to be feasibly encouraged to convert to lower energy forms under human control for human benefit. Except for nuclear fuels, tidal energy and geothermal energy, all terrestrial energy sources are from current solar insolation or from fossil remains of plant and animal life that relied directly and indirectly upon sunlight, respectively. And ultimately, solar energy itself is the result of the Sun's nuclear fusion. Geothermal power from hot, hardened rock above the magma of the earth's core is the result of the decay of radioactive materials present beneath the earth's crust; which was the byproduct of a previous supernova event.

Fossil fuels

Fossil fuels, in terms of energy, involve the burning of coal or hydrocarbon fuels, which are the remains of the decomposition of plants and animals. There are three main types of fossil fuels: coal, petroleum, and natural gas. Another fossil fuel, liquefied petroleum gas (LPG), is principally derived from the production of natural gas. Heat from burning fossil fuel is used either directly for space heating and process heating, or converted to mechanical energy for vehicles, industrial processes, or electrical power generation.

Pros

• The technology and infrastructure already exist for the use of fossil fuels.
• Petroleum energy density in terms of volume (cubic space) and mass (weight) is superior to some alternative energy sources (or energy storage devices, like a battery (electricity)).

Cons

• Petroleum-powered vehicles are very inefficient. Only about 15% of the energy from the fuel they consume is converted into useful motion.^[1] The rest of the fuel-source energy is inefficiently expended as waste heat. The heat and gaseous pollution emissions harm our environment.
• The inefficient atmospheric combustion (burning) of fossil fuels in vehicles, buildings, and power plants contributes to urban heat islands.^[2]
• The combustion of fossil fuels leads to the release of pollution into the atmosphere. According to the Union of Concerned Scientists, a typical coal plant produces in one year:^[3]
  • 3,700,000 tons of carbon dioxide (CO₂), could be the primary cause of global warming.
  • 10,000 tons of sulfur dioxide (SO₂), the leading cause of acid rain.
  • 500 tons of small airborne particles, which result in chronic bronchitis, aggravated asthma, and premature death, in addition to haze-obstructed visibility.
  • 10,200 tons of nitrogen oxides (NOx), (from high-temperature atmospheric combustion), leading to formation of ozone (smog) which inflames the lungs, burning lung tissue making people more susceptible to respiratory illness.
  • 720 tons of carbon monoxide (CO), resulting in headaches and additional stress on people with heart disease.
  • 220 tons of hydrocarbons, toxic volatile organic compounds (VOC), which form ozone.
  • of mercury, where just 1/70th of a teaspoon deposited on a lake can make the fish unsafe to eat.
  • of arsenic, which will cause cancer in one out of 100 people who drink water containing 50 parts per billion.
  • of lead, of cadmium, other toxic heavy metals, and trace amounts of uranium.
• Dependence on fossil fuels from volatile regions or countries creates energy security risks for dependent countries. Oil dependence in particular has led to war, major funding of radical terrorists, monopolization, and socio-political instability.
• Fossil fuels are non-renewable, un-sustainable resources, which will eventually decline in production^[4] and become exhausted, with dire consequences to societies that remain highly dependent on them. (Fossil fuels are actually slowly forming continuously, but we are using them up at a rate approximately 100,000 times faster than they are formed.)

The Moss Landing Power Plant burns natural gas to produce electricity in California.

• Extracting fossil fuels is becoming more difficult as we consume the most accessible fuel deposits. Extraction of fossil fuels is becoming more expensive and more dangerous as mines get deeper and oil rigs must drill deeper, and go further out to sea.^[5]
• Extraction of fossil fuels results in extensive environmental degradation, such as the strip mining and mountaintop removal of coal.

Gas flare from an oil refinery.

Nuclear energy

California's Diablo Canyon Power Plant.

The status of nuclear power globally. Nations in dark green have reactors and are constructing new reactors, those in light green are constructing their first reactor, those in dark yellow are considering new reactors, those in light yellow are considering their first reactor, those in blue have reactors but are not constructing or decommissioning, those in light blue are considering decommissioning and those in red have decommissioned all their commercial reactors. Brown indicates that the country has declared itself free of nuclear power and weapons.

History of the use of nuclear power (top) and the number of active nuclear power plants (bottom).

Nuclear power stations use nuclear fission to generate energy by the reaction of uranium-235 inside a nuclear reactor. The reactor uses uranium (and sometimes plutonium) in fuel rods, the atoms of which are split in the process of fission, releasing a large amount of energy. The process continues as a chain reaction with other nuclei. The heat released, heats water to create steam, which spins a turbine generator, producing electricity.

Availability of uranium

Depending on the type of fission fuel considered, estimates for existing supply at known usage rates varies from several decades for the currently popular uranium-235 to thousands of years for uranium-238. At the present use rate, there are (as of 2007) about 70 years left of known reserves economically recoverable at a uranium price of US$ 130/kg.^[6] In peak uranium, it is stated (and referenced) that "a doubling of price from price levels in 2007 could be expected to create about a tenfold increase in measured resources, over time."

One method for extending the nuclear fuel supply would be to use breeder reactors and nuclear reprocessing. Nuclear reprocessing is already being done in several nations. Current light water reactors consume ("burn up") only a small fraction of the nuclear fuel, wasting much of the energy put into refinement and enrichment. Nuclear reprocessing alone^[7], or burning the fuel better using different reactor designs, would both significantly reduce the amount of waste material generated and allow greatly improved use of the available resources.

Another alternative would be to use thorium as fission fuel. Thorium is three times more abundant in Earth's crust than uranium,^[8] and much more of the thorium can be used (or, more precisely, bred into Uranium-233, reprocessed and then used as fuel). India has around 32 percent of the world?s reserves of thorium and intends on using it for itself because the country has run out of uranium.^[9]

Energy return on investment (EROI)

Depending on the source, different energy returns on energy investment (EROI) are claimed. Advocates (using life cycle analysis) calculate that it takes 4 to 5 months of energy production from the nuclear plant to fully pay back the initial energy investment.^[10] Opponents claim that it depends on the grades of the ores the fuel came from, so a full payback can vary from 10 to 18 years, and that the advocates' claim was based on the assumption of high grade ores (the yields are getting worse, as the ores are leaner, for less than 0.02% ores, the yield is less then 50%).^[11]

Pros and Cons

Proponents of nuclear energy aver that nuclear power is a sustainable energy source that reduces carbon emissions and increases energy security by decreasing dependence on foreign oil.^[12] Proponents also claim that the risks of storing waste are small and can be further reduced by the technology in the new reactors and the operational safety record is already good when compared to the other major kinds of power plants.

Critics believe that nuclear power is a potentially dangerous and declining^[13] energy source, with decreasing proportion of nuclear energy in power production, and dispute whether the risks can be reduced through new technology. Critics also point to the problem of storing radioactive waste, the potential for possibly severe radioactive contamination by accident or sabotage, the possibility of nuclear proliferation and the disadvantages of centralized electrical production.

Arguments of economics and safety are used by both sides of the debate.

Nuclear fusion

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.^[14] Many technical problems remain unsolved. Proposed fusion reactors commonly use deuterium, an isotope of hydrogen, as fuel and in most current designs also lithium. Assuming a fusion energy output equal to the current global output and that this does not increase in the future, then the known current lithium reserves would last 3000 years, lithium from sea water would last 60 million years, and a more complicated fusion process using only deuterium from sea water would have fuel for 150 billion years.^[15]

Renewable sources

Renewable energy is the alternative to fossil fuels and nuclear power.

Biomass, biofuels, and vegetable oil

Sugar cane residue can be used as a biofuel

Main articles: Alcohol fuel, Biomass, Vegetable oil economy, vegetable oil as fuel, biodiesel, Ethanol fuel

Biomass production involves using garbage or other renewable resources such as corn or other vegetation to generate electricity. When garbage decomposes, the methane produced is captured in pipes and later burned to produce electricity. Vegetation and wood can be burned directly to generate energy, like fossil fuels, or processed to form alcohols.

Vegetable oil is generated from sunlight and CO₂ by plants. It is safer to use and store than gasoline or diesel as it has a higher flash point. Straight vegetable oil works in diesel engines if it is heated first. Vegetable oil can also be transesterified to make biodiesel, which burns like normal diesel.

Pros

• Biomass production can be used to burn organic waste products resulting from agriculture. This type of recycling encourages the philosophy that nothing on this Earth should be wasted. The result is less demand on the Earth's resources, and a higher carrying capacity for Earth because non-renewable fossil fuels are not consumed.
• Biomass is abundant on Earth and is generally renewable. In theory, we will never run out of organic waste products as fuel, because we are continuously producing them. In addition, biomass is found throughout the world, a fact that should alleviate energy pressures in third world nations.
• When methods of biomass production other than direct combustion of plant mass are used, such as fermentation and pyrolysis, there is little effect on the environment. Alcohols and other fuels produced by these alternative methods are clean burning and are feasible replacements to fossil fuels.
• Since CO₂ is first taken out of the atmosphere to make the vegetable oil and then put back after it is burned in the engine, there is no net increase in CO₂.
• Vegetable oil has a higher flash point and therefore is safer than most fossil fuels.
• Transitioning to vegetable oil could be relatively easy as biodiesel works where diesel works, and straight vegetable oil takes relatively minor modifications.
• The World already produces more than 100 billion gallons a year for food industry, so we have experience making it.
• Algaculture has the potential to produce far more vegetable oil per acre than current plants.
• Infrastructure for biodiesel around the World is significant and growing.

Cons

• Direct combustion of any carbon-based fuel leads to air pollution similar to that from fossil fuels.
• Some researchers claim that when biomass crops are the product of intensive farming, ethanol fuel production results in a net loss of energy after one accounts for the fuel costs of petroleum and natural-gas fertilizer production, farm equipment, and the distillation process.^[16]
• There is a long list of reasons why even non-food based cellulosic ethanol cannot solve our energy crisis or global warming problems.^[17]
• Direct competition with land use for food production and water use.
• Current production methods would require enormous amounts of land to replace all gasoline and diesel. With current technology, it is not feasible for biofuels to replace the demand for petroleum.
• Even with the most-optimistic current energy return on investment claims, in order to use 100% solar energy to grow corn and produce ethanol (fueling machinery with ethanol, distilling with heat from burning crop residues, using NO fossil fuels at all), the consumption of ethanol to replace only the current U.S. petroleum use would require three quarters of all the cultivated land on the face of the Earth.^[18]

Geothermal energy

Geothermal energy harnesses the heat energy present underneath the Earth. Two wells are drilled. One well injects water into the ground to provide water. The hot rocks heat the water to produce steam. The steam that shoots back up the other hole(s) is purified and is used to drive turbines, which power electric generators. When the water temperature is below the boiling point of water a binary system is used. A low boiling point liquid is used to drive a turbine and generator in a closed system similar to a refrigeration unit running in reverse.

Pros

• Geothermal energy is base load power.^[19]
• Economically feasible in high grade areas now.^[19]
• Low deployment costs.^[19]
• Geothermal power plants have a high capacity factor; they run continuously day and night with an uptime typically exceeding 95%.
• Once a geothermal power station is implemented, the energy produced from the station is practically free. A small amount of energy is required in order to run a pump, although this pump can be powered by excess energy generated at the plant.
• Geothermal power stations are relatively small, and have a lesser impact on the environment than tidal or hydroelectric plants. Because geothermal technology does not rely on large bodies of water, but rather, small, but powerful jets of water, like geysers, large generating stations can be avoided without losing functionality.
• Geothermal is now feasible in areas where the earth's crust is thicker. Using enhanced geothermal technology, it's possible to drill deeper and inject water to generate geothermal power.^[20]
• Geothermal energy does not produce air or water pollution if performed correctly.

Cons

• Geothermal power extracts small amounts of minerals such as sulfur that are removed prior to feeding the turbine and re-injecting the water back into the injection well.

• Geothermal power requires locations that have suitable subterranean temperatures within 5km of surface.

• Some geothermal stations have created geological instability, even causing earthquakes strong enough to damage buildings. ^[21]

Hydroelectric energy

In hydro energy, the gravitational descent of a river is compressed from a long run to a single location with a dam or a flume. This creates a location where concentrated pressure and flow can be used to turn turbines or water wheels, which drive a mechanical mill or an electric generator.

Pros

• Hydroelectric power stations can promptly increase to full capacity, unlike other types of power stations. This is because water can be accumulated above the dam and released to coincide with peak demand.
• Electricity can be generated constantly, so long as sufficient water is available.
• Hydroelectric power produces no primary waste or pollution.
• Hydropower is a renewable resource.
• Hydroelectricity assists in securing a country's access to energy supplies.
• Much hydroelectric capacity is still undeveloped, such as in Africa.

Cons

• The construction of a dam can have a serious environmental impact on the surrounding areas. The amount and the quality of water downstream can be affected, which affects plant life both aquatic, and land-based. Because a river valley is being flooded, the local habitat of many species are destroyed, while people living nearby may have to relocate their homes.
• Hydroelectricity can only be used in areas where there is a sufficient and continuing supply of water.
• Flooding submerges large forests (if they have not been harvested). The resulting anaerobic decomposition of the carboniferous materials releases methane, a greenhouse gas.
• Dams can contain huge amounts of water. As with every energy storage system, failure of containment can lead to catastrophic results, e.g. flooding.
• Hydroelectric plants rarely can be erected near load centers, requiring long transmission lines.

Solar power

The CIS Tower, Manchester, England, was clad in PV panels at a cost of £5.5 million. It started feeding electricity to the national grid in November 2005.

Main articles: Solar energy, Photovoltaics

Solar power involves using solar cells to convert sunlight into electricity, using sunlight hitting solar thermal panels to convert sunlight to heat water or air, using sunlight hitting a parabolic mirror to heat water (producing steam), or using sunlight entering windows for passive solar heating of a building. It would be advantageous to place solar panels in the regions of highest solar radiation. In the Phoenix, Arizona area, for example, the average annual solar radiation is 5.7 kWh/m²/day,^[22] or 2080.5 kWh/m²/year. Electricity demand in the continental U.S. is 3.7*10¹² kW·h per year. Thus, at 100% efficiency, an area of 1.8x10^9 sq. m (around 700 square miles) would need to be covered with solar panels to replace all current electricity production in the US with solar power, and at 20% efficiency, an area of approximately 3500 square miles (3% of Arizona's land area). The average solar radiation in the United States is 4.8 kwh/m²/day,^[23] but reaches 8?9 kWh/m²/day in parts of Southwest.

The cost, assuming $500/meter², would be about $5-10 trillion dollars.

China is increasing worldwide silicon wafer capacity for photovoltaics to 2,000 metric tons by July 2008, and over 6,000 metric tons by the end of 2010.^[24] Significant international investment capital is flowing into China to support this opportunity. China is building large subsidized off-the-grid solar-powered cities in Huangbaiyu and Dongtan Eco City. Much of the design was done by Americans such as William McDonough.

Pros

• Solar power imparts no fuel costs.
• Solar power is a renewable resource. As long as the Sun exists, its energy will reach Earth.
• Solar power generation releases no water or air pollution, because there is no combustion of fuels.
• In sunny countries, solar power can be used in remote locations, like a wind turbine. This way, isolated places can receive electricity, when there is no way to connect to the power lines from a plant.
• Solar energy can be used very efficiently for heating (solar ovens, solar water and home heaters) and daylighting.
• Coincidentally, solar energy is abundant in regions that have the largest number of people living off grid ? in developing regions of Africa, Indian subcontinent and Latin America. Hence cheap solar, when available, opens the opportunity to enhance global electricity access considerably, and possibly in a relatively short time period.^[25]
• Photovoltaic systems are subsidized, up to $5 USD per watt in some American states.^[26]
• Passive solar building design and zero energy buildings are demonstrating significant energy bill reduction, and some are cost-effectively off the grid.
• Photovoltaic equipment cost has been steadily falling, the production capacity is rapidly rising, and the U.S. Administration expects its Solar America Initiative to help make amortized PV electricity price competitive for the new generation of zero energy buildings.^[27]
• Distributed point-of-use photovoltaic systems eliminate expensive long-distance electric power transmission losses.
• Photovoltaics are much more efficient in their conversion of solar energy to usable energy than biofuel from plant materials.^[28]

Cons

• Solar electricity is currently more expensive than grid electricity.
• Solar heat and electricity are not available at night and may be unavailable due to weather conditions; therefore, a storage or complementary power system is required for off-the-grid applications.
• Solar cells produce DC which must be converted to AC (using a grid tie inverter) when used in currently existing distribution grids. This incurs an energy loss of 4?12%.^[29]
• The energy payback time ? the time necessary for producing the same amount of energy as needed for building the power device ? for photovoltaic cells is about 1?5 years, depending primarily on location.^[30]

Tidal Power Generation

Tidal power can be extracted from Moon-gravity-powered tides by locating a water turbine in a tidal current, or by building impoundment pond dams that admit-or-release water through a turbine. The turbine can turn an electrical generator, or a gas compressor, that can then store energy until needed. Coastal tides are a source of clean, free, renewable, and sustainable energy.

Wind power

Wind power: worldwide installed capacity and prediction 1997-2010, Source: [http://www.wwindea.org/ WWEA

This type of energy harnesses the power of the wind to propel the blades of wind turbines. These turbines cause the rotation of magnets, which creates electricity. Wind towers are usually built together on wind farms.

Pros

• Wind power produces no water or air pollution that can contaminate the environment, because there are no chemical processes involved in wind power generation. Hence, there are no waste by-products, such as carbon dioxide.
• Power from the wind does not contribute to global warming because it does not generate greenhouse gases.
• Wind generation is a renewable source of energy, which means that we will never run out of it.
• Wind towers can be beneficial for people living permanently, or temporarily, in remote areas. It may be difficult to transport electricity through wires from a power plant to a far-away location and thus, wind towers can be set up at the remote setting.
• Farming and grazing can still take place on land occupied by wind turbines.
• Those utilizing wind power in a grid-tie configuration will have backup power in the event of a power outage.
• Due to the ability of wind turbines to coexist within agricultural fields, siting costs are frequently low.

Cons

• Wind is unpredictable; therefore, wind power is not predictably available. When the wind speed decreases less electricity is generated. This makes wind power unsuitable for base load generation.
• Wind farms may be challenged in communities that consider them an eyesore or view obstructor.^[31]
• Wind farms, depending on the location and type of turbine, may negatively affect bird migration patterns and may pose a danger to the birds themselves. Newer, larger wind turbines have slower moving blades which are visible to birds.

Increased efficiency in energy use

Efficiency is increasing by about 2% a year, and absorbs most of the requirements for energy development. New technology makes better use of already available energy through improved efficiency, such as more efficient fluorescent lamps, 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. 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. New power plants may become more efficient with technology like cogeneration. New designs for buildings may incorporate techniques like passive solar. Light-emitting diodes are gradually replacing the remaining uses of light bulbs. Note that none of these methods allows perpetual motion, as some energy is always lost to heat.

Mass transportation increases energy efficiency compared to widespread conventional automobile use while air travel is regarded as inefficient. Conventional combustion engine automobiles have continually improved their efficiency and may continue to do so in the future, for example by reducing weight with new materials. Hybrid vehicles can save energy by allowing the engine to run more efficiently, regaining energy from braking, turning off the motor when idling in traffic, etc. More efficient ceramic or diesel engines can improve mileage. Electric vehicles such as Maglev, trolleybuses, and PHEVs are more efficient during use (but maybe not if doing a life cycle analysis) than similar current combustion based vehicles, reducing their energy consumption during use by 1/2 to 1/4. Microcars or motorcycles may replace automobiles carrying only one or two people. Transportation efficiency may also be improved by in other ways, see automated highway system.

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 or improved power factor correction 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 transportation

While new sources of energy are only rarely discovered or made possible by new technology, distribution technology continually evolves. The use of fuel cells in cars, for example, is an anticipated delivery technology. This section presents some of the more common delivery technologies that have been important to historic energy development. They all rely in some way on the energy sources listed in the previous section.

An elevated section of the Alaska Pipeline.

• Fuels

Shipping is a flexible delivery technology that is used in the whole range of energy development regimes from primitive to highly advanced. Currently, coal, petroleum and their derivatives are delivered by shipping via boat, rail, or road. Petroleum and natural gas may also be delivered via pipeline and coal via a Slurry pipeline. Refined hydrocarbon fuels such as gasoline and LPG may also be delivered via aircraft. Natural gas pipelines must maintain a certain minimum pressure to function correctly. Ethanol's corrosive properties prevent it from being transported via pipeline. The higher costs of ethanol transportation and storage are often prohibitive.^[32]

• Electric grids

Electricity grids are the networks used to transmit and distribute power from production source to end user, when the two may be hundreds of kilometres away. Sources include electrical generation plants such as a nuclear reactor, coal burning power plant, etc. A combination of sub-stations, transformers, towers, cables, and piping are used to maintain a constant flow of electricity.

Electric Grid: Pilons and cables distribute power

Grids may suffer from transient blackouts and brownouts, often due to weather damage. During certain extreme space weather events solar wind can interfere with transmissions.

Grids also have a predefined carrying capacity or load that cannot safely be exceeded. When power requirements exceed what's available, failures are inevitable. To prevent problems, power is then rationed.

Industrialised countries such as Canada, the US, and Australia are among the highest per capita consumers of electricity in the world, which is possible thanks to a widespread electrical distribution network. The US grid is one of the most advanced, although infrastructure maintenance is becoming a problem.

CurrentEnergy provides a realtime overview of the electricity supply and demand for California, Texas, and the Northeast of the US. African countries with small scale electrical grids have a correspondingly low annual per capita usage of electricity. One of the most powerful power grids in the world supplies power to the state of Queensland, Australia.

Energy consumption from 1989 to 1999

Energy production from 1989 to 1999

Energy consumption per capita (2001). Red hues indicate increase, green hues decrease of consumption during the 1990s.

Energy storage

Main articles: Energy storage, grid energy storage

Methods of energy storage have been developed, which transform electrical energy into forms of potential energy. A method of energy storage may be chosen based on stability, ease of transport, ease of energy release, or ease of converting free energy from the natural form to the stable form.

Compressed air vehicles

Main articles: Compressed air vehicle, Air car

The Indian company, Tata, is planning to release a compressed air powered car in 2008.

Battery-powered vehicles

Main articles: battery, battery electric vehicle

Batteries are used to store energy in a chemical form. As an alternative energy, batteries can be used to store energy in battery electric vehicles. Battery electric vehicles can be charged from the grid when the vehicle is not in use. Because the energy is derived from electricity, battery electric vehicles make it possible to use other forms of alternative energy such as wind, solar, geothermal, nuclear, or hydroelectric.

Pros

• Produces zero emissions to help counteract the effects of global warming, as long as the electricity comes from a source which produces no greenhouse gases.
• Batteries are a mature technology, no new expensive research and development is needed to implement technology.
• Current lead acid battery technology offers 50+ miles range on one charge.^[33]
• The Tesla Roadster has a range on one charge.
• Batteries make it possible for stationary alternative energy generation such as solar, wind, hydroelectric, or nuclear
• Electric motors are 90% efficient compared to about 20% efficiency of an internal combustion engine.^[34]
• Battery electric vehicles have fewer moving parts than internal combustion engines, thus improving the reliability of the vehicle.
• Battery electric vehicles are quiet compared to internal combustion engines.
• Multiple electric vehicles sold out including the General Motors EV1 and the Tesla Roadster proving the demand for battery electric vehicles.
• Operation of a battery electric vehicle is approximately 2 to 4 cents per mile, about a sixth the price of operating a gasoline vehicle.^[35]
• The use of battery electric vehicles may reduce the dependency on fossil fuels, depending on the source of the electricity.

Cons

• Current battery technology is expensive.
• Battery electric vehicles have a relative short range compared to internal combustion engine vehicles.
• Some batteries (like the Gel battery and the Lead-acid battery) are highly toxic. Spent vehicle batteries present a potential environmental hazard. They are all best recycled at end of life.
• Grid infrastructure and output would need to be improved significantly to accommodate a mass-adoption of grid-charged electric vehicles.

Hydrogen economy

Hydrogen can be manufactured at roughly 77 percent thermal efficiency by the method of steam reforming of natural gas.^[36] When manufactured by this method it is a derivative fuel like gasoline; when produced by electrolysis of water, it is a form of chemical energy storage as are storage batteries, though hydrogen is the more versatile storage mode since there are two options for its conversion to useful work: (1) a fuel cell can convert the chemicals hydrogen and oxygen into water, and in the process, produce electricity, or (2) hydrogen can be burned (less efficiently than in a fuel cell) in an internal combustion engine.

Pros

• Hydrogen is colorless, odorless and entirely non-polluting, yielding pure water vapor (with minimal NOx) as exhaust when combusted in air. This eliminates the direct production of exhaust gases that lead to smog, and carbon dioxide emissions that enhance the effect of global warming.
• Hydrogen is the lightest chemical element and has the best energy-to-weight ratio of any fuel (not counting tank mass).
• Hydrogen can be produced anywhere; it can be produced domestically from the decomposition of water. Hydrogen can be produced from domestic sources and the price can be established within the country.

Cons

• Other than some volcanic emanations, hydrogen does not exist in its pure form in the environment, because it reacts so strongly with oxygen and other elements.
• It is impossible to obtain hydrogen gas without expending energy in the process. There are three ways to manufacture hydrogen;
  • By breaking down hydrocarbons ? mainly methane (steam reforming}. If oil or gases are used to provide this energy, fossil fuels are consumed, forming pollution and nullifying the value of using a fuel cell. It would be more efficient to use fossil fuel directly.
  • By electrolysis of water ? The process of splitting water into oxygen and hydrogen using electrolysis consumes large amounts of energy. It has been calculated that it takes 1.4 joules of electricity to produce 1 joule of hydrogen (Pimentel, 2002).
  • By reacting water with a metal such as sodium, potassium, or boron. Chemical by-products would be sodium oxide, potassium oxide, and boron oxide. Processes exist which could recycle these elements back into their metal form for re-use with additional energy input, further eroding the energy return on energy invested.
• There is currently modest fixed infastructure for distribution of hydrogen that is centrally produced,^[37] amounting to several hundred kilometers of pipeline. An alternative would be transmission of electricity over the existing electrical network to small-scale electrolyzers to support the widespread use of hydrogen as a fuel.
• Hydrogen is difficult to handle, store, and transport. It requires heavy, cumbersome tanks when stored as compressed hydrogen, and complex insulating bottles if stored as a cryogenic liquid hydrogen. If it is needed at a moderate temperature and pressure, a metal hydride absorber may be needed. The transportation of hydrogen is also a problem because hydrogen leaks effortlessly from containers.
• Some current fuel cell designs, such as proton exchange membrane fuel cells, use platinum as a catalyst. Widescale deployment of such fuel cells could place a strain on available platinum resources.^[38] Reducing the platinum loading, per fuel cell stack, is the focus of R&D.
• Electricity transmission and battery electric vehicles are far more efficient for storage, transmission and use of energy for transportation, neglecting the energy conversion at the electric power plant. As with distributed production of hydrogen via electrolysis, battery electric vehicles could utilize the existing electricity grid until widespread use dictated an expansion of the grid.

Energy storage types

• Chemical

Some natural forms of energy are found in stable chemical compounds such as fossil fuels. Most systems of chemical energy storage result from biological activity, which store energy in chemical bonds. Man-made forms of chemical energy storage include hydrogen fuel, synthetic hydrocarbon fuel, batteries and explosives such as cordite and dynamite.

• Gravitational

Dams can be used to store energy, by using excess energy to pump water into the reservoir. When electrical energy is required, the process is reversed. The water then turns a turbine, generating electricity. Hydroelectric power is currently an important part of the world's energy supply, generating one-fifth of the world's electricity.^[39]

• Electrical capacitance

Electrical energy may be stored in capacitors. Capacitors are often used to produce high intensity releases of energy (such as a camera's flash).

• Mechanical

• Pressure:

Energy may also be stored pressurized gases or alternatively in a vacuum. Compressed air, for example, may be used to operate vehicles and power tools. Large scale compressed air energy storage facilities are used to smooth out demands on electricity generation by providing energy during peak hours and storing energy during off-peak hours. Such systems save on expensive generating capacity since it only needs to meet average consumption rather than peak consumption.^[40]

• Flywheels and springs

Energy can also be stored in mechanical systems such as springs or flywheels. Flywheel energy storage is currently being used for uninterruptible power supplies.

Sustainability

The environmental movement emphasizes sustainability of energy use and development. Renewable energy is sustainable in its production; the available supply will not be diminished for the foreseeable future - millions or billions of years. "Sustainability" also refers to the ability of the environment to cope with waste products, especially air pollution. Sources which have no direct waste products (such as wind, solar, and hydropower) are seen as ideal in this regard.

The status of nuclear power is controversial. The uranium supply might last a very long time with nuclear reprocessing, with an almost-unlimited supply from sea water available once ground based mining is exhausted.

Fossil fuels such as petroleum, coal, and natural gas are not renewable. For example, the timing of worldwide peak oil production is being actively debated but it has already happened in some countries. Fossil fuels also make up the bulk of the world's current primary energy sources. With global demand for energy growing, the need to adopt alternative energy sources is also growing. Fossil fuels are also a major source of greenhouse gas emissions, leading to concerns about global warming if consumption is not reduced.

Energy conservation is an alternative or complementary process to energy development. It reduces the demand for energy by using it more efficiently.

Energy resilience

Andy Grove argues that energy independence is a flawed and infeasible objective, particularly in a network of integrated global exchange. He suggests instead that the objective should be energy resilience: resilience goes hand in hand with adaptability, and it also is reflected in important market ideas like substitutability. In fact, resilience is one of the best features of market processes; the information transmission function of prices means that individual buyers and sellers can adapt to changes in supply and demand conditions in a decentralized way. His suggestion for how to increase the resilience of the U.S. energy economy is to shift use from petroleum to electricity (electrification), that is sticky and can be produced using multiple sources of energy, including renewables. ^[41].

On the other hand, the Pembina Institute and WWF-Canada aver in their "Renewable is Doable" plan that resilience is a feature of renewable energy ^[42].

Future energy development

World energy consumption.

An increasing share of world energy consumption is predicted to be used by developing nations. Source: EIA.

Extrapolations from current knowledge to the future offer a choice of energy futures. Some predictions parallel the Malthusian catastrophe hypothesis. Numerous are complex models based scenarios as pioneered by Limits to Growth. Modeling approaches offer ways to analyze diverse strategies, and hopefully find a road to rapid and sustainable development of humanity. Short term energy crises are also a concern of energy development. Some extrapolations lack plausibility, particularly when they predict a continual increase in oil consumption.

Existing technologies for new energy sources, such as renewable energy technologies, particularly wind power and solar power, are promising. Nuclear fission is also promoted, and each need sustained research and development, including consideration of possible harmful side effects. Jacques Cousteau spoke of using the salinization of water at river estuaries as an energy source, which would not have any consequences for a million years, and then stopped to point out that since we are going to be on the planet for a billion years we had to be looking that far into the future. Nuclear fusion and artificial photosynthesis are other energy technologies being researched and developed.

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 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, although ultimately basic physics sets limits that cannot be exceeded.

It should be noted that between 1950 and 1984, as the Green Revolution transformed agriculture around the globe, world grain production increased by 250%. The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon fueled irrigation.^[43] The peaking of world hydrocarbon production (Peak oil) may test Malthus critics.^[44]

History of predictions about future energy development

Ever since the beginning of the Industrial Revolution, the question of the future of energy supplies has occupied economists.

• 1865 ? William Stanley Jevons published The Coal Question in which he claimed that reserves of coal would soon be exhausted and that there was no prospect of oil being an effective replacement.
• 1885 ? U.S. Geological Survey: Little or no chance of oil in California.
• 1891 ? U.S. Geological Survey: Little or no chance of oil in Kansas or Texas.
• 1914 ? U.S. Bureau of Mines: Total future production of .
• 1939 ? U.S. Department of the Interior: Reserves to last only 13 years.
• 1951 ? U.S. Department of the Interior, Oil and Gas Division: Reserves to last 13 years.

(Data from Kahn et al. (1976) pp.94?5 infra)

• 1956 ? Geophysicist M. King Hubbert predicts U.S. oil production will peak between 1965 and 1970 (peaked in 1971). Also predicts world oil production will peak "within half a century" based on 1956 data. This is Hubbert peak theory.
• 1989 ? Predicted peak by Colin Campbell ("Oil Price Leap in the Early Nineties," Noroil, December 1989, pages 35-38.)
• 2004 ? OPEC estimates it will nearly double oil output by 2025 (Opec Oil Outlook to 2025 Table 4, Page 12)

The history of perpetual motion machines is a long list of failed and sometimes fraudulent inventions of machines which produce useful energy "from nowhere" ? that is, without requiring additional energy input.

See also

Main list: List of basic energy development topics

Notes

References

Relevant journals

• ''Energy Sources, Part A: Recovery, Utilization and Environmental Effects''
• ''Energy Sources, Part B: Economics, Planning and Policy''
• ''International Journal of Green Energy''

External links

• RECaBS REcalculator Interactive Renewable Energy Calculator ? compare renewable energy to conventional energy sources
• Free access to view over 300 U.S. Department of Energy Workshop Slides Online: Alternative Future Energy

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