Low-carbon power comes from sources that produce more greenhouse gases but fewer than usual, in than do traditional means of power generation. It includes zero carbon power generation sources, such as wind power, solar power, geothermal power and (except for fuel preparation) nuclear power, as well as sources with lower-level emissions such as natural gas. These power-generation techniques emit significantly less carbon dioxide than a traditional fossil fuel power plant.
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Over the past 30 years, significant findings regarding global warming highlighted the need to curb carbon emissions. From this, the idea for low carbon power was born. The Intergovernmental Panel on Climate Change (IPCC), established by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP) in 1988, set the scientific precedence for the introduction of low carbon power. The IPCC has continued to provide scientific, technical and socio-economic advice to the world community, through its periodic assessment reports and special reports.[1]
Internationally, the most prominent early step in the direction of low carbon power was the signing of the Kyoto Protocol, which came into force on February 16, 2005, under which most industrialized countries committed to reduce their carbon emissions. The historical event set the political precedence for introduction of low carbon power technology.[2]
On a social level, perhaps the biggest factor contributing to the general public’s awareness of climate change and the need for new technologies, including low carbon power, came from the documentary An Inconvenient Truth, which clarified and highlighted the problem of global warming.
The Swedish utility Vattenfall did a study of full life cycle emissions of nuclear, hydro, coal, gas, solar cell, peat and wind which the utility uses to produce electricity. The net result of the study was that nuclear power produced 3.3 grams of carbon dioxide per kW-hr of produced power. This compares to 400 for natural gas and 700 for coal (according to this study). The study also concluded that nuclear power produced the smallest amount of CO2 of any of their electricity sources.[3]
A 2008 meta analysis, "Valuing the use Gas Emissions from Nuclear Power: A Critical Survey,"[4] by Benjamin K. Sovacool, analysed 103 life cycle studies of greenhouse gas-equivalent emissions for nuclear power plants. The studies surveyed included the 1997 Vattenfall comparative emissions study, among others. Sovacool's analysis calculated that the mean value of emissions over the lifetime of a nuclear power plant is 66 g/kWh. Comparative results for wind power, hydroelectricity, solar thermal power, and solar photovoltaic, were 9-10 g/kWh, 10-13 g/kWh, 13 g/kWh and 32 g/kWh respectively.[5]
There are many options for lowering current levels of carbon emissions. Some options, such as wind power and solar power, produce no carbon emissions, using entirely renewable sources. Other options, such as nuclear power, produce no carbon emissions during operation, but come from non-renewable sources (uranium). The term low carbon power can also include power that continues to utilize the world’s natural resources, such as natural gas and coal, but employs techniques that reduce carbon emissions from these sources when burning them for fuel.
As the single largest emitter of carbon dioxide in the United States, the electric-power industry accounted for 39% of CO2 emissions in 2004, a 27% increase since 1990.[6] Because the cost of reducing emissions in the electricity sector appears to be lower than in other sectors such as transportation, the electricity sector may deliver the largest proportional carbon reductions under an economically efficient climate policy.[7]
Technologies to produce electric power with low-carbon emissions are already in use at various scales. Together, they account for roughly 28% of all U.S. electric-power production, with nuclear power representing the majority (20%), followed by hydroelectric power (7%).[7] However, demand for power is increasing, driven by increased population and per capita demand, and low carbon power can supplement the supply needed.[8]
While it may seem counter-intuitive that natural gas is a source of low carbon power, of all the fossil fuels used in power generation, it emits the least carbon dioxide.[9]
Through the combined cycle process, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine; this last step enhances the efficiency of electricity generation.
Hydroelectric plants have the advantage of being long-lived and many existing plants have operated for more than 100 years. Hydropower is also an extremely flexible technology from the perspective of power grid operation. Large hydropower provides one of the lowest cost options in today’s energy market, even compared to fossil fuels and there are no harmful emissions associated with plant operation.[10]
Hydroelectric power is currently the world’s largest installed renewable source of electricity, supplying about 17% of total electricity in 2005.[11] China is the world's largest producer of hydroelectricity in the world, followed by Canada.
However, there are several significant social and environmental disadvantages of large-scale hydroelectric power systems: dislocation of people living where the reservoirs are planned, release of significant amounts of carbon dioxide and methane during construction and flooding of the reservoir, and disruption of aquatic ecosystems and birdlife.[12] There is a strong consensus now that countries should adopt an integrated approach towards managing water resources, which would involve planning hydropower development in co-operation with other water-using sectors.[10]
At the end of 2009, worldwide wind farm capacity was 157,900 MW, representing an increase of 31 percent during the year,[14] and wind power supplied some 1.3% of global electricity consumption.[15] Wind power accounts for approximately 19% of electricity use in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland.[16] The United States is an important growth area and installed U.S. wind power capacity reached 25,170 MW at the end of 2008.[17] As of November 2010, the Roscoe Wind Farm (781 MW) is the world's largest wind farm.[18]
As of September 2010, the Thanet Offshore Wind Project in United Kingdom is the largest offshore wind farm in the world at 300 MW, followed by Horns Rev II (209 MW) in Denmark. The United Kingdom is the world's leading generator of offshore wind power, followed by Denmark.[19]
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSP systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. PV converts light into electric current using the photoelectric effect.
Commercial CSP plants were first developed in the 1980s, and the 354 MW SEGS CSP installation is the largest solar power plant in the world and is located in the Mojave Desert of California. Other large CSP plants include the Solnova Solar Power Station (150 MW) and the Andasol solar power station (100 MW), both in Spain. The 97 MW Sarnia Photovoltaic Power Plant in Canada, is the world’s largest photovoltaic plant.
Nuclear power's capability to add significantly to future low carbon power depends strongly on several factors, including new plant designs (see Nuclear reactor technology), national and regional politics, fuel availability (see Uranium depletion), etc.
Nuclear power, with as of 2007 a 20% share of U.S. electricity production, is the largest deployed technology among current low-carbon energy sources[7]. However, the over-one-hundred currently employed U.S. plants are ageing (see Plant life extension). Also, the Economics of new nuclear power plants are still evolving and plans to add to those plants are mostly in flux [20]. Nuclear power's capability to add significantly to future low carbon power in the U.S. therefore remains uncertain.
Nuclear power brings with it important waste disposal, safety, and security risks which are unique among low-carbon energy sources.[21] Amory Lovins has said:
Nuclear power is the only energy source where mishap or malice can kill so many people so far away; the only one whose ingredients can help make and hide nuclear bombs; the only climate solution that substitutes proliferation, accident, and high-level radioactive waste dangers. Indeed, nuclear plants are so slow and costly to build that they reduce and retard climate protection.[22]
Geothermal electricity is electricity generated from geothermal energy. Technologies in use include dry steam power plants, flash steam power plants and binary cycle power plants. Geothermal electricity generation is currently used in 24 countries[23] while geothermal heating is in use in 70 countries.[24]
Current worldwide installed capacity is 10,715 megawatts (MW), with the largest capacity in the United States (3,086 MW),[25] Philippines, and Indonesia. Estimates of the electricity generating potential of geothermal energy vary from 35 to 2000 GW.[24]
Geothermal power is considered to be sustainable because the heat extraction is small compared to the Earth's heat content.[26] The emission intensity of existing geothermal electric plants is on average 122 kg of CO2 per megawatt-hour (MW·h) of electricity, a small fraction of that of conventional fossil fuel plants.[27]
Tidal power is a form of hydropower that converts the energy of tides into electricity or other useful forms of power. The first large-scale tidal power plant (the Rance Tidal Power Station) started operation in 1966. Although not yet widely used, tidal power has potential for future electricity generation. Tides are more predictable than wind energy and solar power.
The Intergovernmental Panel on Climate Change stated in its first working group report that “most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations, contribute to climate change.[28]
As a percentage of all anthropogenic greenhouse gas emissions, carbon dioxide (CO2) accounts for 72 percent,[29] and has increased in concentration in the atmosphere from 315 parts per million (ppm) in 1958 to more than 375 ppm in 2005.[30]
Emissions from energy make up more than 61.4 percent of all greenhouse gas emissions.[31] Power generation from traditional coal fuel sources accounts for 18.8 percent of all world greenhouse gas emissions, nearly double that emitted by road transportation.[31]
Estimates state that by 2020 the world will be producing around twice as much carbon emissions as it was in 2000.[32]
World energy consumption is predicted to increase from 421 quadrillion British Thermal Units (BTU) in 2003 to 722 quadrillion BTU in 2030.[33] Coal consumption is predicted to nearly double in that same time.[34] The fastest growth is seen in non-OECD Asian countries, especially China and India, where economic growth drives increased energy use.[35] By implementing low carbon power options, world electricity demand could continue to grow while maintaining stable carbon emission levels.
By 2015, one-third of the 2007 U.S. coal plants will be more than 50 years old.[36] Nearly two-thirds of the generation capacity required to meet power demand in 2030 is yet to be built.[36] There are currently 151 new coal-fired power plants planned for the U.S., providing 90GW of power.[37]
Improvements to current carbon capture technologies could reduce CO2 capture costs by at least 20-30% over approximately the next decade, while new technologies under development promise more substantial cost reduction.[37]
Investment in low carbon power sources and technologies is increasing at a rapid rate. Zero-carbon power sources produce about 2% of the world's energy, but account for about 18% of world investment in power generation, attracting $100 billion of investment capital in 2006.[38]
