Renewable energy sources, including solar power, wind power, tidal power and hydroelectric power are often referred to as zero emission power, since their operation produce very few, or zero, emissions. On the other hand, the construction of such plants may involve emissions if the materials are created or assembled using equipment that produces emissions. For example, the production of high purity silicon for photovoltaic cells consumes large quantities of carbon, contributing to CO2 emissions, and this is also true for the production of steel and concrete for wind turbines and hydroelectric dams.

Similarly, Nuclear power plants do not emit significant amounts of pollutants during their operation, but the extraction of Uranium ore and construction of waste repositories usually involves machinery powered by gasoline. The construction of the plant itself also requires materials similar to those for renewable energy sources, though because of nuclear power-plants large output per station, less so per amount of energy produced. All in all, emissions due to the operation, fuel production and waste management from nuclear power-plants are similar in magnitude to those of the renewables. However, though nuclear power-plants do not emit large amounts of pollution during normal operation, they do produce large quantities of radioactive waste, which has to be stored for several centuries before it's radioactivity has decreased to that of the uranium ore. There is also concern that flawed designs or operation can lead to nuclear accidents, emitting radioactive pollutants, as happened during the Chernobyl disaster.

Many technological improvements have been suggested to reduce emissions from various energy sources. Carbon dioxide could be captured from fossil plants and stored underground rather than released into the atmosphere ( a technology known as carbon capture and storage ). Improved efficiency for solar cells, or cells made from novel materials, could offset the emissions associated with silicon production. New reactor technology could enable nuclear reactors to produce orders of magnitude more energy without increased emissions, and recycled or new materials could reduce the emissions associated with construction of wind turbines and hydroelectric dams. Additionally, many new energy sources with low emissions are being researched, including among others: wave power, nuclear fusion and bio fuel.