|Range of technologies to pre-treat coal to reduce emissions, burn it more efficiently, or capture and store carbon emissions.
||Most abundant and widely distributed fossil fuel. Preserves existing industry and makes use of existing infrastructure.
||Uses more coal per kWh than normal coal power. Produces some pollutants, such as heavy metals. Coal is a finite resource.
||Small-scale trials under way. Huge investment(c $3trn) needed by 2050. Estimated cost: 5-13 cents/kWh (double normal coal).
|Uses naturally hot rocks, or temperature differences, beneath Earth's surface to heat water directly or drive turbines.
||Constant renewable energy source in some locations. Highly efficient for heating living spaces. Long hardware lifetime.
||Underground heat only available in some locations. Energy can "dry up" for years. Can in some locations release toxic gases.
||Currently less than 1% of global capacity. US and Australia investing in new technologies. Estimated cost: 5-11 cents/kWh.
|Harnesses energy from the controlled splitting of atoms, releasing heat that is harvested to drive turbines.
||Significant historical experience and technology developed. Can provide heat and electricity. Plentiful fuel supplies.
||Perceived as risky. Strong opposition from green campaigners. Creates radioactive waste. Fuel can be weapons security risk.
||Set for a comeback after years in shadow. New reactors behind schedule. Disputed cost. One estimate: 4-8 cents/kWh.
|Exploits energy of shifting tides, underwater currents, or shoreline and offshore waves.
||Large and infinitely renewable resource. Tidal energy very regular. Can be exploited on small or large scale.
||No consensus on best means to capture energy. Large projects may disrupt natural water flow, tides and ecosystems.
||Little expected before 2030. Technology uncertain, so wide cost range: 15-30 cents/KWh (double or triple coal).
|Using the wind, on land or at sea, to drive turbines.
||Significant experience and mature industry and infrastructure. Infinitely renewable resource. Can be deployed in range of project sizes.
||Intermittent resource. Not efficient for all locations. Windfarms interrupt radar signals, can be noisy and regarded by some as unsightly.
||Currently about 1% of global supply. Onshore cheaper than offshore. High energy storage costs are handicap. Quite low cost: 7-14 cents/kWh.
|Gathers energy from sunlight, using light to generate electricity directly (photovoltaic) or to heat liquids to drive a turbine.
||Infinitely renewable and most abundant zero-carbon resource. Silent and no effects on local environment.
||Like wind and marine, intermittent. Current photovoltaic designs complex; if widely used, chemicals could become scarce.
||US investing heavily, EU planning plant in Africa. Cost still high (13-35 cents/kWh) but expected to fall. Price of solar panels falling.
|Generates electricity by damming water and constraining flow through turbines. Most widely deployed renewable strategy.
||Well-established as a large-scale energy source. Can also be used for energy storage if run in reverse.
||Dams disrupt ecosystems and are a public health risk if they burst. Can trap decaying matter that creates pollution.
||One of the cheapest forms of electricity. Development focusing on small hydro-electric power. Estimated cost: 2-6 cents/kWh.