Further information: Outline of energy development
World total primary energy production
Note the different y-axis for total (left) and regional curves (right)
US Energy Use/Flow in 2011
Energy flow charts show the relative size of primary energy resources and end uses in the United States, with fuels compared on a common energy unit basis (2011: 97.3 quads).
Energy development is the field of activities focused on obtaining sources of energy from natural resources. These activities include production of conventional, alternative and renewable sources of energy, and for the recovery and reuse of energy that would otherwise be wasted. Energy conservation and efficiency measures reduce the demand for energy development, and can have benefits to society with improvements to environmental issues.
Societies use energy for transportation, manufacturing, illumination, heating and air conditioning, and communication, for industrial, commercial, and domestic purposes. Energy resources may be classified as primary resources, where the resource can be used in substantially its original form, or as secondary resources, where the energy source must be converted into a more conveniently usable form. Non-renewable resources are significantly depleted by human use, whereas renewable resources are produced by ongoing processes that can sustain indefinite human exploitation.
Thousands of people are employed in the energy industry. The conventional industry comprises the petroleum industry, the natural gas industry, the electrical power industry, and the nuclear industry. New energy industries include the renewable energy industry, comprising alternative and sustainable manufacture, distribution, and sale of alternative fuels.
Classification of resources
Further information: World energy resources and consumption
See also: Worldwide energy supply, Energy and society, Energy planning, and Energy policy
Energy resources may be classified as primary resources, suitable for end use without conversion to another form, or secondary resources, where the usable form of energy required substantial conversion from a primary source. Examples of primary energy resources are wind power, solar power, wood fuel, fossil fuels such as coal, oil and natural gas, and uranium. Secondary resources are those such as electricity, hydrogen, or other synthetic fuels.
Another important classification is based on the time required to regenerate an energy resource. "Renewable" resources are those that recover their capacity in a time significant by human needs. Examples are hydroelectric power or wind power, when the natural phenomena that are the primary source of energy are ongoing and not depleted by human demands. Non-renewable resources are those that are significantly depleted by human usage and that will not recover their potential significantly during human lifetimes. An example of a non-renewable energy source is coal, which does not form naturally at a rate that would support human use.
Main articles: Fossil fuel and Peak oil
Fossil fuel (primary non-renewable fossil) sources burn 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. These fossil fuels are part of the carbon cycle and thus allow stored solar energy to be used today.
The use of fossil fuels in the 18th and 19th Century set the stage for the Industrial Revolution.
Fossil fuels make up the bulk of the world's current primary energy sources. In 2005, 81% of the world's energy needs was met from fossil sources. The technology and infrastructure already exist for the use of fossil fuels. Liquid fuels derived from petroleum deliver a great deal of usable energy per unit of weight or volume, which is advantageous when compared with lower energy density sources such as a battery. Fossil fuels are currently economical for decentralised energy use.
Energy dependence on imported fossil fuels creates energy security risks for dependent countries. Oil dependence in particular has led to war, funding of radicals, monopolization, and socio-political instability.
Fossil fuels are non-renewable resources, which will eventually decline in production  and become exhausted. While the processes that created fossil fuels are ongoing, fuels are consumed far more quickly than the natural rate of replenishment. Extracting fuels becomes increasingly costly as society consumes the most accessible fuel deposits. Extraction of fossil fuels results in environmental degradation, such as the strip mining and mountaintop removal of coal.
Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. The fuel economy is the energy efficiency of a particular vehicle, is given as a ratio of distance travelled per unit of fuel consumed. Weight-specific efficiency (efficiency per unit weight) may be stated for freight, and passenger-specific efficiency (vehicle efficiency per passenger). The inefficient atmospheric combustion (burning) of fossil fuels in vehicles, buildings, and power plants contributes to urban heat islands.
Conventional production of oil has peaked, conservatively, between 2007 and 2010. In 2010, it was estimated that an investment in non-renewable resources of $8 trillion would be required to maintain current levels of production for 25 years. In 2010, governments subsidized fossil fuels by an estimated $500 billion a year. Fossil fuels are also a source of greenhouse gas emissions, leading to concerns about global warming if consumption is not reduced.
The combustion of fossil fuels leads to the release of pollution into the atmosphere. The fossil fuels are mainly carbon compounds. During combustion, carbon dioxide is released, and also nitrogen oxides, soot and other fine particulates. Man-made carbon dioxide according to the IPCC contributes to global warming. Other emissions from fossil fuel power station include sulfur dioxide, carbon monoxide (CO), hydrocarbons, volatile organic compounds (VOC), mercury, arsenic, lead, cadmium, and other heavy metals including traces of uranium.
A typical coal plant generates billions of kilowatt hours per year.
Nuclear power is the use of nuclear fission to generate useful heat and electricity. Fission of uranium produces nearly all economically significant nuclear power. Radioisotope thermoelectric generators form a very small component of energy generation, mostly in specialized applications such as deep space vehicles.
Nuclear power plants, excluding naval reactors, provided about 5.7% of the world's energy and 13% of the world's electricity in 2012.
In 2013, the IAEA report that there are 437 operational nuclear power reactors, in 31 countries, although not every reactor is producing electricity. In addition, there are approximately 140 naval vessels using nuclear propulsion in operation, powered by some 180 reactors. As of 2013, attaining a net energy gain from sustained nuclear fusion reactions, excluding natural fusion power sources such as the Sun, remains an ongoing area of international physics and engineering research. More than 60 years after the first attempts, commercial fusion power production remains unlikely before 2050.
There is an ongoing debate about nuclear power. Proponents, such as the World Nuclear Association, the IAEA and Environmentalists for Nuclear Energy contend that nuclear power is a safe, sustainable energy source that reduces carbon emissions.Opponents, such as Greenpeace International and NIRS, contend that nuclear power poses many threats to people and the environment.
Nuclear power plant accidents include the Chernobyl disaster (1986), Fukushima Daiichi nuclear disaster (2011), and the Three Mile Island accident (1979). There have also been some nuclear submarine accidents. In terms of lives lost per unit of energy generated, analysis has determined that nuclear power has caused less fatalities per unit of energy generated than the other major sources of energy generation. Energy production from coal, petroleum, natural gas and hydropower has caused a greater number of fatalities per unit of energy generated due to air pollution and energy accident effects. However, the economic costs of nuclear power accidents is high, and meltdowns can take decades to clean up. The human costs of evacuations of affected populations and lost livelihoods is also significant.
Comparing Nuclear's latent cancer deaths, such as cancer with other energy sources immediate deaths per unit of energy generated(GWeyr). This study does not include fossil fuel related cancer and other indirect deaths created by the use of fossil fuel consumption in its "severe accident" classification, which would be an accident with more than 5 fatalities.
Nuclear power is a low carbon power generation method of producing electricity, with an analysis of the literature on its total life cycleemission intensity finding that it is similar to renewable sources in a comparison of greenhouse gas(GHG) emissions per unit of energy generated. Since the 1970s, nuclear fuel has displaced about 64 gigatonnes of carbon dioxide equivalent(GtCO2-eq) greenhouse gases, that would have otherwise resulted from the burning of oil, coal or natural gas in fossil-fuel power stations.
As of 2012, according to the IAEA, worldwide there were 68 civil nuclear power reactors under construction in 15 countries, approximately 28 of which in the Peoples Republic of China (PRC), with the most recent nuclear power reactor, as of May 2013, to be connected to the electrical grid, occurring on February 17, 2013 in Hongyanhe Nuclear Power Plant in the PRC. In the United States, two new Generation III reactors are under construction at Vogtle. U.S. nuclear industry officials expect five new reactors to enter service by 2020, all at existing plants. In 2013, four aging, uncompetitive, reactors were permanently closed.
Japan's 2011 Fukushima Daiichi nuclear accident, which occurred in a reactor design from the 1960s, prompted a rethink of nuclear safety and nuclear energy policy in many countries. Germany decided to close all its reactors by 2022, and Italy has banned nuclear power. Following Fukushima, in 2011 the International Energy Agency halved its estimate of additional nuclear generating capacity to be built by 2035.
Recent experiments in extraction of uranium use polymer ropes that are coated with a substance that selectively absorbs uranium from seawater. This process could make the considerable volume of uranium dissolved in seawater exploitable for energy production. Since ongoing geologic processes carry uranium to the sea in amounts comparable to the amount that would be extracted by this process, in a sense the sea-borne uranium becomes a sustainable resource.
Main article: Economics of new nuclear power plants
The economics of new nuclear power plants is a controversial subject, since there are diverging views on this topic, and multibillion-dollar investments ride on the choice of an energy source. Nuclear power plants typically have high capital costs for building the plant, but low direct fuel costs.
In recent years there has been a slowdown of electricity demand growth and financing has become more difficult, which affects large projects such as nuclear reactors, with very large upfront costs and long project cycles which carry a large variety of risks. In Eastern Europe, a number of long-established projects are struggling to find finance, notably Belene in Bulgaria and the additional reactors at Cernavoda in Romania, and some potential backers have pulled out. Where cheap gas is available and its future supply relatively secure, this also poses a major problem for nuclear projects.
Analysis of the economics of nuclear power must take into account who bears the risks of future uncertainties. To date all operating nuclear power plants were developed by state-owned or regulatedutility monopolies where many of the risks associated with construction costs, operating performance, fuel price, and other factors were borne by consumers rather than suppliers. Many countries have now liberalized the electricity market where these risks, and the risk of cheaper competitors emerging before capital costs are recovered, are borne by plant suppliers and operators rather than consumers, which leads to a significantly different evaluation of the economics of new nuclear power plants.
Two of the four EPRs under construction (in Finland and France) are significantly behind schedule and substantially over cost. Following the 2011 Fukushima Daiichi nuclear disaster, costs are likely to go up for currently operating and new nuclear power plants, due to increased requirements for on-site spent fuel management and elevated design basis threats. While first of their kind designs, such as the EPRs under construction are behind schedule and over-budget, of the seven South Korean APR-1400s presently under construction worldwide, two are in S.Korea at the Hanul Nuclear Power Plant and four are at the largest nuclear station construction project in the world as of 2016, in the United Arab Emirates at the planned Barakah nuclear power plant. The first reactor, Barakah-1 is 85% completed and on schedule for grid-connection during 2017.
Main article: Renewable energy commercialization
Renewable energy is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as sunlight, wind, rain, tides, waves and geothermal heat. Renewable energy replaces conventional fuels in four distinct areas: electricity generation, hot water/space heating, motor fuels, and rural (off-grid) energy services.
About 16% of global final energy consumption presently comes from renewable resources, with 10%  of all energy from traditional biomass, mainly used for heating, and 3.4% from hydroelectricity. New renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) account for another 3% and are growing rapidly. At the national level, at least 30 nations around the world already have renewable energy contributing more than 20% of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond.Wind power, for example, is growing at the rate of 30% annually, with a worldwide installed capacity of 282,482 megawatts (MW) at the end of 2012.
Renewable energy resources exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency is resulting in significant energy security, climate change mitigation, and economic benefits. In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power.
While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas and developing countries, where energy is often crucial in human development.United Nations' Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity.
Hydroelectricity is electric power generated by hydropower; the force of falling or flowing water. In 2015 hydropower generated 16.6% of the world's total electricity and 70% of all renewable electricity [page needed] and is expected to increase about 3.1% each year for the next 25 years.
Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. There are now three hydroelectricity plants larger than 10 GW: the Three Gorges Dam in China, Itaipu Dam across the Brazil/Paraguay border, and Guri Dam in Venezuela.
The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. The average cost of electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatt-hour. Hydro is also a flexible source of electricity since plants can be ramped up and down very quickly to adapt to changing energy demands. However, damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gascarbon dioxide than fossil fuel powered energy plants.
Wind power 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. There are offshore and onshore wind farms. Global wind power capacity has expanded rapidly to 336 GW in June 2014, and wind energy production was around 4% of total worldwide electricity usage, and growing rapidly.
Wind power is widely used in Europe, Asia, and the United States. Several countries have achieved relatively high levels of wind power penetration, such as 21% of stationary electricity production in Denmark, 18% in Portugal, 16% in Spain, 14% in Ireland, and 9% in Germany in 2010.:11 By 2011, at times over 50% of electricity in Germany and Spain came from wind and solar power. As of 2011, 83 countries around the world are using wind power on a commercial basis.:11
Many of the world's largest onshore wind farms are located in the United States, China, and India. Most of the world's largest offshore wind farms are located in Denmark, Germany and the United Kingdom. The two largest offshore wind farm are currently the 630 MWLondon Array and Gwynt y Môr.
Main articles: Solar PV systems and Concentrated solar power
Solar energy, radiant light and heat from the sun, is harnessed using a range of ever-evolving technologies such as solar heating, solar photovoltaics, solar thermal electricity, solar architecture and artificial photosynthesis.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared". More than 100 countries use solar PV.
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct currentelectricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material. Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium gallium selenide/sulfide. Due to the increased demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.
Solar photovoltaics is a sustainable energy source. By the end of 2011, a total of 71.1 GW had been installed, sufficient to generate 85 TWh/year. And by end of 2012, the 100 GW installed capacity milestone was achieved. Solar photovoltaics is now, after hydro and wind power, the third most important renewable energy source in terms of globally installed capacity. In 2016, after another year of rapid growth, solar generated 1.3% of global power.
Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics has declined steadily since the first solar cells were manufactured, and the levelised cost of electricity (LCOE) from PV is competitive with conventional electricity sources in an expanding list of geographic regions. Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have supported solar PV installations in many countries. The Energy Payback Time (EPBT), also known as energy amortization, depends on the location's annual solar insolation and temperature profile, as well as on the used type of PV-technology. For conventional crystalline silicon photovoltaics, the EPBT is higher than for thin-film technologies such as CdTe-PV or CPV-systems. Moreover, the payback time decreased in the recent years due to a number of improvements such as solar cell efficiency and more economic manufacturing processes. As of 2014, photovoltaics recoup on average the energy needed to manufacture them in 0.7 to 2 years. This results in about 95% of net-clean energy produced by a solar rooftop PV system over a 30-year life-time.:30 Installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building (either building-integrated photovoltaics or simply rooftop).
Main articles: Biofuel and Sustainable biofuel
A biofuel is a fuel that contains energy from geologically recent carbon fixation. These fuels are produced from living organisms. Examples of this carbon fixation occur in plants and microalgae. These fuels are made by a biomass conversion (biomass refers to recently living organisms, most often referring to plants or plant-derived materials). This biomass can be converted to convenient energy containing substances in three different ways: thermal conversion, chemical conversion, and biochemical conversion. This biomass conversion can result in fuel in solid, liquid, or gas
Solar Power: The Future Of Energy
I am certain that all have heard of the terms green house gases, fossil fuels, and global warming. Have you ever questioned what will happen if nothing is done about the environmental problems facing the world today? What if I answer you that, we can merely use the power from the sun to power up our entire planet without the use of harmful energy sources, which affect our atmosphere? The power from the sun is what we call solar power. Solar power is the energy that comes from the sun as light and heat energy, and then it is later converted into electrical energy through solar panels (Nelson, 2008). This kind of power is completely free, right? Why should we put a lot of expense on other sources of energy, when there is a complete free and healthy power? It is evident that solar energy is a healthy source of energy, which will help stop global warming all together, but it is economically efficient to switch everything to solar energy. Solar energy is capable of becoming the world's future power supply because, it is renewable, eco-friendly, and extremely efficient when strategically placed.
Solar energy is clean energy that does not affect our environment. Solar power utilizes the sun’s energy to produce electricity, unlike other sources of energy, which rely on continual mining for raw materials. Consequently, producing solar energy from the heat from the sun does not result into the annihilation of the ecosystem, compared to the extraction of fossil fuels (Bode, 2005). Therefore, with the use of solar energy, it will help keep the environment clean, thus help to combat the issue of global warming, which is a threat to the world’s ecosystem worldwide. The use of solar energy will help save the worlds vegetation, and help prevent the effects of global warming in future. Therefore, solar energy is capable of becoming the world's future power supply as a clean energy source. If we choose to switch to solar energy in future, it will greatly save our environment because, it does not pollute our air and it is reasonably efficient. It will help reduce global warming, and thus a future green environment with no pollution from fossil fuels, and other conventional sources of energy. To add on that, it will also help in conserving our remaining fossil fuels so that it may not run out in the coming 100-500 years, as it has been predicted.
In addition, solar energy operational costs are manageable. It is free from monthly charges compared to conventional sources of energy. Solar energy does not require raw materials such as oil and coal, and once the panels are built, there will be no monthly charges. In addition, the prices of fossil fuels are increasing day by day, and this means conventional energy will be very expensive. Solar energy will remain the most capable world’s future power supply because, it is cost effective once the plants are built, and there will be no transport costs like for conventional energy sources. Therefore, solar energy is...
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