The National Renewable Energy Laboratory plans Friday to issue a report on how renewable resources could contribute 80% of US power generation by 2050, an NREL spokesman said Thursday.
The study has been requested by the Department of Energy's Office of Energy Efficiency and Renewable Energy, and it follows previous NREL reports about wind power and solar power integration by 2030, said NREL spokesman George Douglas.
DOE requested the economic and engineering analysis using more renewable resources "to help understand how much renewable generation can be effectively integrated into the grid and what the impacts on grid operations would be," Douglas said Thursday.
The NREL report will consider biomass, geothermal, hydropower, onshore wind and solar — both photovoltaic and concentrating solar power as renewable resources, Douglas said. Only commercially available technologies, as of 2010, were considered, because the focus of the effort is on grid integration and not potential technology advances, he said. Wave and tidal energy systems, offshore wind and other technologies under development were not included in the 80% figure, he said.
While the 80% figure may seem monumental and difficult to achieve, the size of the task depends on what is counted as a renewable resource and the time frame covered in the study, said Revis James, director of generation research development with the Electric Power Research Institute.
"My first reaction, as an engineer," was that 80% renewable power on the grid would be "very, very challenging. A lot of questions come to mind" about how that could be done, James said in an interview.
Those questions include addressing the intermittent nature of renewable resources, the need for back-up generation or storage technologies to aid grid integration, and maintaining frequency and voltage control on the transmission system to move power among different regions, he said.
COMPARING WITH EIA OUTLOOK
Even with a number of challenges associated with a high penetration level of renewables, EPRI often takes an approach to its research that "very few things are impossible," but achieving them at what cost and at what scale are important elements, James said.
Among the scenarios where 80% renewables could be feasible, James said, would be with wide-scale deployment of storage technologies to store power produced during off-peak periods for use during peak demand periods, though "that is a model that's never been worked out as far as I know."
Another scenario is adding a lot more transmission to move power where it is needed, which presents a slew of challenges, he added.
Comparing the NREL report with projections from the Energy Information Administration's reference case in its 2012 Annual Energy Outlook, released early this year, can show the gains needed to boost integration of renewable resources. The EIA outlook said a growth in renewables and natural gas-fired generation will shift the generation fuel mix lower-carbon options by 2035, but at much lower levels.
Gas-fired generation's share was projected to increase to 27% in 2035 from its current 24%, with the renewables share growing to 16% from 10% in the same time period. Coal is projected to be 39% of the mix in 2035, down from the 2010 level of 45%. Nuclear will be at 18% in 2035, with oil and other liquids representing 1% as they did in 2010, EIA said.
The NREL report has been years in the making, various sources said this week, noting that they have not seen a preview of the document.
The North American Electric Reliability Corp. provided input to NREL on the effort, but it has not seen anything from the lab, NERC spokeswoman Kimberly Mielcarek said Thursday. She had no comment on the upcoming report without having a chance to see it, she said.
Representatives from several renewable energy trade groups also had no comment without seeing the report.
