Researchers in the US have been taking a fresh look at the challenges of building a power grid based entirely on renewable energy, but have found a number of unanswered questions.
The team of 17 power systems experts from the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) and DOE's Office of Energy Efficiency and Renewable Energy (EERE) developed an analysis, published in the journal Joule, that looks at the technical challenges achieving 100 percent renewable energy across the country.
"Our paper offers perspective drawn from real-world experience in deploying variable renewables, the literature, and our team’s experience studying these issues in detail over the past two decades at a variety of scales—from our 2012 national-scale Renewable Electricity Futures Study to our 2021 work," said Paul Denholm, NREL principal energy analyst and lead author of the paper. "While our focus here is on the US power system, many of the issues addressed and lessons learned apply more generally to other regions—and these are complex, multidisciplinary challenges that will require a lot of collaboration among the research community to solve."
"Technology type essentially establishes the definition of the word renewable—which can vary based on the parameters of a research study or the priorities of a community setting a renewable target or policy," said Denholm. "Here, we distinguish between two general types of technologies: what we call variable technologies that depend on short-term weather conditions and typically use inverters, like wind and solar photovoltaics [PV]; and those that are less—or not at all—variable and typically use traditional synchronous generators, including hydro, biomass, geothermal, and concentrating solar power."
"Our emphasis is on questions we think can be addressed through technology development and engineering, but we recognize that other topics are critically important—from siting considerations, to energy equity concerns, to policy, regulatory, and market design challenges," he said. "We want to clear a path for resolving the technical and