Strategies for decarbonizing the energy infrastructure are a hot topic as the United Nations COP26 climate conference in Glasgow, Scotland is being watched by the entire world. But renewables critics are skeptical of the reliability of systems that depend on intermittent resources. Researchers at the University of California Irvine have tackled the reliability issue head-on in a recent study.
Recent Nature Communications paper by the authors includes experts from China's Tsinghua University and the Carnegie Institution for Science and Caltech. They found that wind and solar power can meet most of the electricity needs of advanced industrialized countries. However, this positive conclusion comes with the caveat of additional efforts required to fully satisfy the country's needs.
According to the study, the most reliable systems that are dominated and powered by wind power are capable of meeting the electricity needs of the countries they are studying 72 to 91 per cent of the time. This is even with no energy storage. Systems can be dominated by solar power with 12 hours of energy storage and can meet demand for 83 to 94% of the hours.
Steve Davis, UCI professor in Earth system science, said that wind and solar could meet more then 80 percent of the demand in many locations without excessive storage capacity or excess generating power. This is the critical point. "But, depending on where you live, there might be multiple days throughout the year when energy storage or other non-fossil sources of energy in a zero carbon future.
To assess the availability of solar and wind power resources to meet their energy needs, the team analysed 39 years worth of hourly demand data from 42 countries. It was easier to convert to sustainable power resources for countries with higher latitudes, as they can rely on the availability of solar power throughout the year.
Researchers highlighted Germany as an example for a smaller country in terms of its land mass at higher latitudes, which will make it harder to supply electricity with solar and wind resources.
"Historic data shows that countries farther from the Equator can sometimes experience periods of 'dark dondrums' when there is very little solar and wind power availability," said Dan Tong, an assistant professor Earth system science at Tsinghua University. "A recent German occurrence of this phenomenon lasted two weeks. This forced Germans to resort in dispatchable generation, which is often provided by fossil fuel-burning power plants.
The researchers recommended several approaches to address this problem: building generating capacity beyond annual demand, long-term storage capabilities, and pooling resources from multiple countries on a continent.
Tong said that Europe is a good example. She began her research on this topic as a postdoctoral scholar at UCI's Department of Earth System Science. A system that incorporates solar resources from Spain and Italy, as well as wind energy available in the Netherlands, Denmark, and the Baltic regions, could provide a lot of reliability and consistency.
Researchers found that wind and solar power systems could supply about 85 percent of America's electricity needs. This could be increased by capacity overbuilding, adding batteries, or connecting to other countries on the North American continent.
Davis stated that there are definite geophysical limitations on the ability to produce net zero carbon electricity around the globe. It comes down to the distinction between the possible and impossible. Although it will be difficult to eliminate all fossil fuels from our power plant mix, we can make that happen if technology, economics, and socio-political will align.
