If we want to limit air pollution and reduce greenhouse gas emissions while meeting unmet demand in developing countries, renewable electricity is a promising option, as our new research shows.

By Edgar Hertwich, Thomas Gibon and Anders Arvesen, NTNU

The use of fossil energy sources has made it possible for cities, population and prosperity to grow. It has also led to the pollution of air, water and soil. The main product of the combustion of fossil fuels is carbon dioxide, a gas that holds back the Earth’s heat radiation so that the surface and ocean temperature increases. To prevent dangerous anthropogenic warming, we have to either switch to non-fossil energy sources or adopt clean technologies that prevent carbon dioxide from reaching the atmosphere. Fossil energy is not only the main cause of climate change, but is also the most significant source of air pollution and an important cause of several other environmental problems. As many people die from air pollution every year as in battlefields of World War II: 7 million per year, according to the World Health Organization. About half of these deaths are caused by fossil fuels; a tenth by fossil power plants. In a new study, we investigate how the replacement of normal coal and gas power with climate friendly alternatives affects the pollution and hence damage to humans and ecosystems.
The production of electricity from renewable sources causes little or no emissions directly, but the construction, maintenance and scrapping of plants such as wind farms requires materials, electricity, and transport. These activities lead to emissions, which can be quantified using life cycle analysis. In our study, we analyzed solar, wind, geothermal and hydropower plants and compared them to different types of coal and gas fired power plants. Technology experts in several countries have contributed data and assessments. We have both compared the environmental impact of producing a single kilowatt hour and assessed the global environmental effects of a reorganization of the entire global energy supply.
Our study calculates the amount of materials necessary to produce power. We conclude that wind power and solar thermal energy demand up to ten times more steel and concrete than coal and twenty times more than gas. Solar cells need much copper for wires and aluminum for frames.

It’s not just the final production of these materials results in emissions, but also the extraction of raw materials, processing and transport. In spite of the large quantity of materials and equipment required, renewable energy causes much less pollution than fossil fuels. Thermal solar energy, PV, onshore and offshore wind turbines are clearly better than coal on all environmental indicators we have examined, and beat gas power on several indicators. Many hydroelectric and geothermal power plants are also environmental champions, although not all such projects are good. The use of carbon capture and storage to clean fossil fuel power plants results in a moderate increase of emissions other than carbon dioxide, compared to plants without capture. Even though the demand of space for renewables is often emphasized, the increase deployment of renewables would lead to lower space requirements than a continued expansion of fossil based power due to the large land use of coal mining.
The comparison of our various global future scenarios shows that a further development of fossil power production to meet a growing demand, as foreseen in the IEA Baseline scenario, will lead to a doubling of air pollution to 2050, even the use of modern and more efficient fossil power plants. It will also lead to a doubling or tripling of various types of pollution to water and soil that are harmful to ecosystems. A global adoption of low carbon power generation, as foreseen in the IEA 2 degree scenario, will however stabilize air pollution and reduce emissions of other pollutants, although the power production almost doubled. Further reductions in emissions are possible if we use more renewable energy and less carbon capture to meet emission targets. Our study shows that a global transition from fossil to renewable electricity will reduce not only global warming but also limit damage to human health and ecosystems. While some challenges remain on the way to power systems that rely on a large degree of variable renewable energy sources, technologies such as compressed air or thermal energy storage offer part of the solution.

Hertwich, E. G.; Gibon, T.; Bouman, E. A.; Arvesen, A.; Suh, S.; Heath, G. A.; Bergesen, J. D.; Ramirez, A.; Vega, M. I.; Shi, L. Integrated life cycle assessment of electricity supply scenarios confirms global environmental benefit of low-carbon technologies. Proceedings of the National Academy of Sciences, 2014. www.pnas.org/cgi/doi/10.1073/pnas.1312753111

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