Charlie Riedel / AP
In this file photo, a group of 260-foot-high wind towers are silhouetted against a bright orange sky at the Elk River Wind farm near Beaumont, Kan. Massive integration of wind power to the electric grid will take breakthroughs in energy storage technologies.
Breakthroughs in energy storage technologies are on the horizon that could turn vast swathes of the world's sun-soaked deserts and windy plains into sources of clean, renewable energy, according to experts focused on our energy future.
No one technology — ranging from storing a portion of the sun's energy collected during the day in molten salt to run solar thermal generators at night to banks of lithium-ion batteries scattered around neighborhoods — will be the solution.
Rather, "there is going to be a portfolio of energy storage" options, Bruce Dunn, a professor of materials science and engineering at the University of California at Los Angeles, told me Thursday.
Dunn is the lead author of a review paper in this week's issue of the journal Science that explores the prospects for three battery technologies to become cheap, reliable and efficient enough for wide-scale deployment on the electric power grid.
Lithium-ion battery technology, for example, is enjoying a boost in research and development for the electrical vehicle market that is driving down manufacturing costs. Utilities will piggyback on those improvements and may even be able to use EVs to store excess wind and solar energy, he noted.
Other technologies such as redox-flow batteries are relatively new and unproven. "On paper it looks to be very inexpensive," he said, but there's very little experience using them at the scale utilities need.
The batteries are based on the use of liquid electrolytes stored in tanks and pumped through a reactor to produce energy.
As it stands now, there's plenty known about how the batteries work on the small scale, but not much about how they work on large scale. Will they maintain the right power levels? Will there be corrosion problems?
Answers to such questions should start to come within three or four years with preliminary results from demonstration projects supported by the Advanced Research Projects Agency-Energy and the Department of Energy.
"It's an experiential thing, there's no way around it. You've got to build big stuff," Dunn said. "And those things are built and they are being tested. That's the good news."
Sodium-sulfur batteries, the third technology in the Science review, are already in limited use by utilities around the world, including Japan where they are sold commercially, but the technology is costly, Dunn said. Manufacturing prices have to fall before they can be embraced.
In time, he said, prices will fall, just as they have for technologies such as personal computers. And as prices for big, utility-scale batteries fall, they'll be incorporated onto the electric grid, allowing the integration of renewable sources of power such as wind and solar.
The use of batteries on the grid will also reduce the need to construct generation capacity that sits idle most of the time but puts off excess emissions of greenhouse gases as they are cycled up and down to meet peak demands, the researchers note.
Another way to store energy is in the form of hydrogen, which has long been eyed for the fuel cells that some believe will power most cars in the future. A hurdle is how to cheaply and efficiently get hydrogen, which is abundant but almost always bound to something else.
One solution may come from researchers at the Massachusetts Institute of Technology who are working on so-called artificial leaf technology that splits water into bubbles of oxygen and hydrogen. The hydrogen can be stored and used to power fuel cells.
Questions remain about how efficient the system is and how inexpensively they can generate hydrogen, notes Robert Service in a news story about the technology in Science.
One study, he noted, found that hydrogen can be produced from natural gas about half as cheaply using a mature technology called steam reforming than the best-case scenarios envisioned for the artificial leaf technologies.
"That's not saying artificial photosynthesis isn't worth pursuing – only that fossil fuels are the leading energy source for a reason and they won't be easy to dethrone," he writes.
More bang for the fossil fuel buck
Eric Wachsman, a sustainable energy researcher at the University of Maryland, argues that technological improvements are making fuel cells that run on all types of fuels, including conventional fuels such as gasoline, in addition to hydrogen, a viable option everywhere from power grids to transportation.
In separate Science review article, he explains that the breakthrough comes from new electrolyte materials that allow solid oxide fuel cells to be operated at lower temperatures.
Solid oxide fuel cells such as Bloom Energy's device that was rolled out last year, he told me, have a power density of about 0.2 watts per square centimeter while operating at about 950 degrees Celsius. His team has developed a solid oxide fuel cell that gets 2 watts per square centimeter at 650 degrees Celsius.
"It is an order of magnitude higher power density at a much lower temperature," he said, adding that his team has also developed electrolytes that make operation at 350 degrees Celsius viable.
And if solid oxide fuel cells can operate at lower temperatures, they become attractive for use in transportation where using a fuel cell to power a car is two and a half to three times more efficient than using fuel to run an internal combustion engine, he noted.
Wachsman is hoping the government will continue to support research in solid oxide fuel cell technology to help bring down the costs and scale up the technology, though noted the prospects are grim.
"There is no funding for solid oxide fuel cells in the current DOE budget," he said.
The dearth of government funding for energy innovation is taken up by Bill Gates, Microsoft chairman and co-chair of the Bill and Melinda Gates Foundation, in a Science editorial that plugs his call to increase R&D spending from $5 billion to $16 billion a year.
"History has repeatedly proven that federal investments in research return huge payoffs with incredible associated benefits for U.S. industries and the economy," he writes. "Yet over the past three decades, U.S. government investment in energy innovation has dropped by more than 75 percent."
Without further government investment, will the needed breakthroughs in energy storage remain on the horizon?
More stories about energy technology:
- Battery tech improving as demand soars
- Artificial leaf makes real fuel
- Sever for cleaner energy unveiled
- Can fuel cells power the future?
- Eight hurdles on a track to a green energy future
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