Energy development is the ongoing effort to provide sustainable energy resources through knowledge, skills, and constructions. When harnessing energy from primary energy sources and converting them into more convenient secondary energy forms, such as electrical energy and cleaner fuel, both emissions (reducing pollution) and quality (more efficient use) are important.



Wind power: worldwide installed capacity and prediction 1997-2010, Source: WWEA


Wind power: worldwide installed capacity and prediction 1997-2010

Source: WWEA



Dependence on external energy sources


Technologically advanced societies have become increasingly vulnerable in their dependence on external energy sources for transportation, the production of many manufactured goods, and the delivery of energy services. This energy allows people, in general, to live under otherwise unfavorable climatic conditions through the use of heating, ventilation, and/or air conditioning. Level of dependence of human societies on external energy sources differs, as does the climate, convenience,, 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. Conversely, comfort can also be realized with lowered energy consumption by the application of energy efficiency and conservation approaches. 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.


As an example of external energy dependence, U.S. President George W. Bush has stated that "America is addicted to oil, which is often imported from unstable parts of the world." Another example is the growing reliance on energy supplies to Europe from Russia.



Limitations to energy development


Use of any given energy source in human societies encounters limits to quantitative expansion. At the beginning of the 21st century some issues have achieved global dimension. Principal fossil energy sources, such as oil and natural gas are approaching production declines that may occur within the span of a generation. Closely linked to energy development are concerns about the environmental effects of energy use, such as climate changes. Energy development issues are part of the much debated sustainable development problem.



Energy sources


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 is the result of the accumulation of radioactive materials during the formation of Earth that 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. Steam power plant combustion heats water to create steam, which turns a turbine, which, in turn, generates electricity, waste heat, and pollution. There are three main types of fossil fuels: coal, petroleum, and natural gas.




  • Because it is based on the simple process of combustion, the burning of fossil fuels can generate large amounts of electricity with a small amount of fuel. Gas-fired power plants are more efficient than coal fired power plants.

  • Fossil fuels such as coal are readily available and are currently plentiful. Excluding external costs, coal is less expensive than most other sources of energy because there are large deposits of coal in the world.

  • The technology already exists for the use of fossil fuels, though oil and natural gas are approaching peak production and will require a transition to other fuels and/or other measures.

  • Commonly used fossil fuels in liquid form such as light crude oil, gasoline, and liquefied propane gas are easy to distribute.




  • The combustion of fossil fuels leads to the release of pollution into the atmosphere. A typical coal plant produces:

    • 3,700,000 tons of carbon dioxide (CO2), the primary human 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), 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, volatile organic compounds (VOC), which form ozone.

    • 170 pounds of mercury, where just 1/70th of a teaspoon deposited on a 25-acre lake can make the fish unsafe to eat.

    • 225 pounds of arsenic, which will cause cancer in one out of 100 people who drink water containing 50 parts per billion.

    • 114 pounds of lead, 4 pounds 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 lead to monopolization, war, and socio-political instability.

  • They are considered non-renewable resources, which will eventually decline in production 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.

  • 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 go further out to sea.

  • Extraction of fossil fuels can result in extensive environmental degradation, such as the strip mining and mountaintop removal of coal.

  • The drilling and transportation of petroleum can result in accidents that result in the despoilation of hundreds of kilometers of beaches and the death or elimination of many forms of wildlife in the area.

  • The storage of these fuels can result in accidents with explosions and poisoning of the atmosphere and groundwater.



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. An electric generator, when there is excess energy available, can be run backwards as a motor to pump water back up for later use.




  • 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 peaks in demand.

  • Electricity can be generated constantly, because there are no outside forces, which affect the availability of water. This is in contrast to wind, solar or tidal power, all of which are far less reliable.

  • Hydroelectric power produces no waste or pollution.

  • Hydropower is a renewable resource; oil, natural gas, and coal reserves will be depleted over time.

  • Hydroelectricity secures a country's access to energy supplies.




  • 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 delicate 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 supply of water.

  • Flooding submerges large forests (if they have not been harvested). If such vegetation decayed, it could release 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, i.e. flooding.



Nuclear energy


Nuclear power stations work similar to fossil fuel power plants, except for the fact that the heat is produced by the reaction of uranium inside a nuclear reactor. The reactor uses uranium 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 takes place. The heat released heats water to create steam, which spins a turbine, producing electricity.




  • The energy content of a kilogram of uranium or thorium, if spent nuclear fuel is reprocessed and fully utilized, is equivalent to about 3.5 million kilograms of coal.

  • The cost of making nuclear power, with current legislation, is about the same as making coal power, which is considered very inexpensive (see Economics of new nuclear power plants). If a carbon tax is applied, nuclear does not have to pay anything.

  • Nuclear power plants are guarded with the nuclear reactor inside a reinforced containment building, and thus are relatively impervious to terrorist attack or adverse weather conditions.

  • Nuclear power does not produce any air pollution (except for slight radioactivity from the (filtered and delayed) ventilation system) or release carbon dioxide and sulfur dioxide into the atmosphere. Therefore, it does not contribute to global warming or acid rain.




  • Members of the public are unsure of and concerned about the overall safety of nuclear power plants.

  • The operation of an uncontained nuclear reactor near human settlements can be catastrophic, as shown by the Chernobyl disaster in the Ukraine (former USSR), where large areas of land were affected by radioactive contamination.

  • Waste produced from nuclear fission of uranium is both poisonous and highly radioactive, requiring maintenance and monitoring at the storage sites. Moreover, the long-term disposal of the long-lived nuclear waste causes serious problems, since (unless the spent fuel is reprocessed) it takes from one to three thousand years for the spent fuel to come back to the natural radioactivity of the uranium ore body that was mined to produce it.

  • There can be connections between nuclear power and nuclear weapon proliferation, since both require large-scale uranium enrichment facilities. While civilian nuclear facilities are normally overseen internationally by the IAEA, a couple of countries with such facilities refuse oversight.

  • Large capital cost. Building a nuclear power plant requires a huge investment and the costs of safe disassembling (called decommissioning) after it reaches end of usable life must be factored into the full lifecycle budget.

  • Nuclear fuels are a non-renewable energy source, with unknown high concentration ore reserves. There is a large amount of trace concentration nuclear material in seawater and most rocks; however, extraction from these is not currently economically competitive.

  • Uranium mining activities produce greenhouse gases which contribute to global warming. For the same amount of electricity, there is approximately 4% as much mining as for coal.

  • The limited liability for the owners of a nuclear power plant in case of a nuclear accident can be seen as an indirect subsidy by national governments.

  • The limited liability for the owner of a nuclear power plant in case of a nuclear accident differs per nation while nuclear installations are sometimes built close to national borders.



Wind power


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.




  • 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.

  • 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 grid outage.

  • Due to the ability of wind turbines to coexist within agricultural fields, siting costs are frequently low.




  • Wind power is intermittent in many locations, because consistent wind is needed to ensure continuous power generation. When the wind speed decreases, the turbine lingers and less electricity is generated, thus the production at any time in these places is not fully predictable. In some areas, however, winds are highly reliable, or seasonably predictable.

  • Wind farms may be challenged in communities that consider them an eyesore or view obstructor.

  • Wind farms, depending on the location and type of turbine, can negatively affect bird migration patterns and pose a danger to the birds themselves. Newer, larger wind turbines have slower moving blades which are visible to birds.

  • The effect of large scale wind farms on the climate is unknown, just as the effect of buildings, other manmade structures, and agricultural windbreaks have unknown effects on the climate through the extraction of energy from the prevailing wind.



Pelamis machine pointing into the waves: it attenuates the waves, gathering more energy than its narrow profile suggests.  See Pelamis Wave Energy Converter


Pelamis wave energy converter pointing into the waves: it attenuates

the waves, gathering more energy than narrow profile suggests



Wave power


Wave power is the extraction of energy from waves in large bodies of water such as oceans and large lakes. Wave power is a form of renewable energy that is on the rise. It should not be confused with Tidal power, which involves construction of a dam or "power tower" (which is basically a large tube which waves push air through to create power with turbines), which are both structures connected to the land. Wave power is harnessed by other means, including floating objects or machines on the floor of the body of water.




  • Potentially highly abundant for countries with large coastlines.

  • Potentially minimal effect on the environment.

  • Wave power is a renewable resource.




  • Requires further research, development and investment in infrastructure.


Sugar cane residue can be used as a biofuel


Sugar cane residue can be used as a biofuel





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, like fossil fuels, to generate energy, or processed to form alcohols.





  • 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, such as fermentation and pyrolysis, are used, 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.





  • Direct combustion without emissions filtering generally leads to air pollution similar to that from fossil fuels.

  • Producing liquid fuels from biomass is generally less cost effective than from petroleum, since the production of biomass and its subsequent conversion to alcohols is particularly expensive.

  • 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 fertilizer production, farm equipment, and the distillation process. [3]

  • Direct competition with land use for food production.



Hydrogen fuel


Unlike the other energy sources in this article, hydrogen fuel must be manufactured with a net loss of energy. When manufactured from natural gas it is, like gasoline, a derivative fuel; when produced using electricity, it is a form chemical energy storage as in storage batteries. In using hydrogen as a fuel, there are two basic alternatives: (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.




  • 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. Because of this, hydrogen can be economically competitive with gasoline or diesel as a transportation fuel.

  • Hydrogen can be produced anywhere; it can be produced domestically from the decomposition of the most abundant chemical on earth: water. Consequently, countries do not have to rely on OPEC countries for fossil fuels. Hydrogen can be produced from domestic sources and the price can be established within the country.

  • Electrolysis combined with fuel-cell regeneration [4] is more than 50% efficient; more efficient than pumped hydro and many other forms of mechanical storage.

  • Stationary storage with double-walled tanks is stable over long periods of time; hydrogen which outgases from the interior can be pumped back in.




  • Other than some volcanic emanations, hydrogen does not exist in its pure form in the environment, as a gas, because Earth's gravity is not strong enough to hold it at bay at the existing temperature (temperature provides the escape velocity. Helium also isn't retained.) There is concern that a hydrogen economy based on nonhydrocarbon or unreacted hydrogen sources would negatively affect Earth's overall hydrogen budget due to leaks into the atmosphere, and then from the atmosphere into outer space.

  • It is impossible to obtain hydrogen gas without expending energy in the process. There are three ways to manufacture hydrogen;

    • By electrolysis from 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 breaking down hydrocarbons - mainly methane. 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 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 a lack of infrastructure and distribution network required to support the widespread use of hydrogen as a fuel. It would cost a lot of money and energy to build hydrogen plants and to replace every car and bus with a hydrogen engine and fuel tank.

  • Hydrogen is complicated to handle, store, and transport. It requires heavy, cumbersome tanks when stored as a gas, and complex insulating bottles if stored as a cryogenic liquid. If it is needed at a moderate temperature and pressure, a metal hydride absorber may be needed. Transport is also a problem, because hydrogen leaks effortlessly from containers, reducing the efficiency of the fuel. These hassles make hydrogen power very expensive.

  • Current efficient fuel cell designs are expensive since they need Platinum as a catalyst. If we were to replace every Internal combustion engine with a Fuel cell then we could potentially use all the Earth's Platinum reserves in two years.



Vegetable oil


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.




  • 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. So vegetable oil does not contribute to the problem of greenhouse gas.

  • It has a high flash point and is safer than most 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.




  • Current production methods would require enormous amounts of land to replace all gasoline and diesel.

  • Growth in vegetable oil production is already resulting in deforestation.

  • Converting forest land to vegetable oil production can result in a net increase in CO2.

  • Prices of vegetable oils (and vegetation used to make it) will increase dramatically.



Tidal power


Tidal energy involves building a dam across the opening to a tidal basin, called an estuary. The dam, called a barrage, is composed of turbines, located within tunnels in the dam that rotate when a tide comes in, generating electricity.




  • Tidal power is free once the dam is built. This is because tidal power harnesses the natural power of tides and does not consume fuel. In addition, the maintenance costs associated with running a tidal station are relatively low.

  • Tides are very reliable because it is easy to predict when high and low tides will occur. The tide goes in and out twice a day usually at the predicted times. This makes tidal energy easy to maintain, and positive and negative spikes in energy can be managed.




  • Tidal energy is not strictly "renewable": because all energy produced from tidal generation results in an equal loss of the earth's rotational energy it consumes the earth's rotational inertia, very slightly slowing it down. Tidal power relies on the gravitational pull of the Moon and the earth's rotation, which pull the sea backwards and forwards, generating tides.

  • It provides power only for around 10 hours each day, when the tide is moving in or out of the basin.

  • The barrage construction can affect the transportation system in water. Boats may not be able to cross the barrage outside of a lock system.

  • The erection of a barrage may affect the aquatic ecosystems surrounding it. The environment affected by the dam is very wide, altering areas numerous miles upstream and downstream. For example, many birds rely on low tides to unearth mud flats, which are used as feeding areas.

  • Maximum energy production is limited to 2.5 terawatts. This is the total amount of tidal dissipation or the friction measured by the slowing of the lunar orbit.


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.


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



Solar power


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. In one minute if harnessed, enough solar energy falls on the earth to provide all humanity enough energy need for a year.




  • 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.

  • It is free to produce but panels can be costly.




  • Solar power is not always completely predictable because it depends on the amount of sunlight that reaches the Earth at any given time. This precludes solar power generation during the night when sunlight does not reach the part of the Earth in which the cell is located and limits solar power generation when cloud cover scatters portions of the electromagnetic spectrum. To solve this deficiency solar generators can be coupled to a hydroelectric power plant through the power grid. Excess power generated by solar cells during the day can be used to pump water above the dam. The hydroelctric power plant then supplies the power at night.

  • Some forms of solar power are not currently cost competitive. A photovoltaic power station is expensive to build, about 10% efficient, and the energy payback time - the time necessary for producing the same amount of energy than needed for building the power device - for photovoltaic cells is between 1.8 and 3.3 years, depending primarily on location.



Geothermal energy


Geothermal energy harnesses the heat energy present underneath the Earth. The hot rocks heat water to produce steam. When holes are drilled in the region, the steam that shoots up is purified and is used to drive turbines, which power electric generators.




  • Geothermal energy does not produce air or water pollution if performed correctly

  • 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 energy is only sufficient as source of power in certain areas of the world. These regions require the presence of hot rocks near the surface to warm the water. The depth of these rocks must be shallow enough that one can drill down to them, and the type of rock also plays a role as it must be easy to drill through.

  • Some geothermal sites are prone to running out of steam, when their water is not heated at a high enough temperature to generate steam pressure. This can render the site useless in terms of energy production for decades.

  • Drilling holes underground may release hazardous gases and minerals from deep inside the Earth. It can be problematic to dispose of these subsidiary products in a safe manner.

  • Drilling deep holes and pumping water into them may cause unexpected seismic events, such as earthquakes, in the surrounding area.



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.


  • 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. 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


Electric Grid: towers and cables distribute power

Electric Grid: towers and cables distribute power


  • 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.


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. The electrical power industry is one of the most heavily subsidized.


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 storage


While most fuels can be stored, electricity in itself cannot. For that reason, many methods of energy storage have been developed, which transform electrical energy into other forms of 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.


  • 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, 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. :[5].

Another example of gravitational energy storage is the counter-weight on elevators.

  • Electrical capacitance

Electrical energy may be stored in capacitors. These 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.

  • 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.


Energy consumption from 1989 to 1999


Energy consumption from 1989 to 1999



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



Future energy development


Extrapolations from current knowledge to future energy development 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. Modelling 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.


Existing technologies for new energy sources, such as new renewable energy technologies, nuclear fission and fusion are promising, but need sustained research and development, including consideration of possible harmful side effects. Artificial Photosynthesis is another energy technology being researched and developed.







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