100% Renewables Increasingly Looks Possible

Research may be toppling one of the strongest objections to renewable energy: that wind and solar are not reliable enough to support the grid 24-7-365, so they need fossil and nuclear backup.
Scientists seem to be finding solutions to the variability and uncertainty of wind and solar that are, in some cases, relatively simple and cheap.
"I think the landscape has really changed in terms of whether or not the world community understands the transition to 100 percent non-emitting energy as something we can accomplish," said Chris Field, founding director of Stanford's Carnegie Department of Global Ecology. "I think the answer only a few years ago was maybe, and now the answer is clearly yes."
Non-emitting energy includes nuclear power, but in a video released this week, Field goes on to argue that a system of 100 percent renewables is technically possible, though not presently affordable.
"With a really ambitious commitment to building out the storage and load-balancing and demand-balancing components, it looks like it's technically feasible to build an energy system with a high amount of renewables," Field said. "It may be too expensive—and an energy system that's got fossil with CCS (carbon capture and storage) and has some nuclear is likely to be a lot more robust and cheaper and more reliable. But we could do it."
The National Renewable Energy Laboratory has been working on those load-balancing and demand-balancing components. Last week, NREL researcher Michael Milligan briefed energy executives on ways they could improve reliability without turning power plants on and off, much less building new ones.
"Numerous options for increasing flexibility are available in any power system," Milligan said in a webinar hosted by the Clean Energy Solutions Center. Among the simplest and cheapest options are better coordination between grid operators, the use of larger geographic areas to balance load and demand, and the use of shorter intervals of time to decide how much power to dispatch to different areas—dispatching in 5-minute increments, for example, instead of hourly.
"Size matters: larger is better," he said. "And speed matters: faster is better."
Size matters in part because the variability of wind and solar smooths itself out when more windmills or panels are feeding the system. Speed matters because system operators can respond to variability more quickly, reducing its threat.
"And that’s true no matter how large or how small you are and how fast you're dispatching. If you can get larger that’s going to be more efficient, and if you can get faster that’s also going to be more efficient."
If the United States were to pursue a size and speed agenda, it would be following India, which established a synchronized national grid, with 15-minute dispatch intervals, in anticipation of development that will rely on renewable energy.
Back at Stanford, Field based his comments on research led by Mark Z. Jacobsen from the Dept. of Civil and Environmental Engineering. Jacobsen and University of California Berkeley transportation Prof. Mark A. Delucchi simulated conditions on the electrical grid with 100 percent penetration of water, wind, and solar power across the continental United States between 2050 and 2055. Then they sought the cheapest ways to resolve reliability issues that arose.
"No natural gas, biofuels, nuclear power, or stationary batteries are needed," Jacobsen wrote in the study published last year.
They used a variety of energy storage techniques deemed cheaper than the current cost of battery storage, including pumped hydro and underground thermal energy storage.
Their work was not without its critics, both in academia and the blogosphere. But the study highlighted energy-storage options that prior studies had overlooked, as well as ill-considered costs of nuclear power and carbon capture. They found that an electrical system based on water, wind and solar (WWS) had roughly the same "business cost" as a conventional system, but its social cost, considering health and climate effects, was 40 percent lower.
"Because WWS requires zero fuel cost, whereas conventional fuel costs rise over time, long-term WWS costs should stay less than conventional fuel costs."