Study outlines five thermal energy grand challenges for decarbonization

Green dreamland

Only five ‘grand’ challenges? Better be quick — we keep hearing there’s supposed to be a climate emergency on. Yes, throw out existing successful energy solutions when there’s nothing of equivalence to replace them with. Then wonder what to do next, while muttering about climate change. Great plan! Or maybe not.
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Solar and wind power are an important part of solving the problem of climate change, but these renewable technologies on their own probably will never provide the energy for many industrial processes, like making steel, reports TechXplore.

Approximately 90 percent of the world’s energy use involves generation or manipulation of heat, including the cooling of buildings and food.

Maintaining modern economies and improving life in developing economies while mitigating climate change will require five major advances in how we convert, store and transmit thermal energy, according to a new paper in Nature Energy from Stanford University, Massachusetts Institute of Technology and Lawrence Berkeley National Laboratory.

“Modern renewable technologies are the most inexpensive source of electricity we have today, but solar and wind power are intermittent and account for a small percentage of the world’s energy,” said Arun Majumdar, one of three co-authors and a Stanford professor of mechanical engineering. “We need to increase this percentage, but we also must decarbonize heat and use heat to store electricity from solar and wind.”

The analysis underscores the urgent need to research and develop thermal technology breakthroughs that potentially could reduce greenhouse gas emissions by at least one gigaton, which is about 3 percent of annual energy-related GHG emissions globally.

“We as a species are endangering ourselves with the infrastructure we have erected to improve our quality of life,” said co-author Asegun Henry, associate professor of mechanical engineering at MIT. “There are a few instances in history when scientists and engineers have come together and achieved something very remarkable in very short timeframes. This must be one of those times.”

Heat as energy storage

One major challenge in thermal engineering is to store excess wind and solar power as heat energy over multiple days and then convert it back into electricity when needed.

The full decarbonization of electricity would reduce man-made, global GHG emissions by about a fourth. Getting 70 percent or more of our electricity from intermittent renewables will require massive additions of electricity storage.

Expanding the most common current technology, pumped hydroelectric storage, is limited by geography, and lithium-ion batteries are too expensive for storing excess renewable power over multiple days.

“The key advantage for thermal energy storage is its potential for low cost at large scale,” said co-author Ravi Prasher, associate laboratory director for energy technologies at Lawrence Berkeley National Laboratory.

“While it is relatively easy to convert electricity to heat,” Prasher explained, “the key challenge for thermal energy storage is the large efficiency penalty when converting heat back to electricity.”

Full report here.