Reprinted from Energywire with permission from E&E News. Copyright 2019. E&E provides essential news for energy and environment professionals at www.eenews.net. For the original story and more news click here
The usefulness of energy storage for states seeking to accelerate a renewable transition and decarbonize their grid might depend on where the technology is deployed, according to a study published today in Nature Communications.
Researchers from three U.S. universities assessed what would happen if power grids in California and Texas were to take on a massive amount of new wind and solar and combine it with storage technologies, all while governments imposed huge new taxes on carbon.
In California, they found, those three policies could help the state cut as much as 90% of its carbon dioxide emissions from the power sector, compared with 72% if energy storage were excluded.
But in Texas, leaving out storage from that mass renewable deployment wouldn't make that much of a difference: CO2 emissions would fall 54% without it, compared with 57% with it.
That's because in Texas, renewable power sources don't do much "curtailing" — generating power but failing to deliver it — because the power mix operates more flexibly there than in California, where power from nuclear, hydro and biomass sources is often generated or imported into the state on a fixed schedule.
"As such, energy storage has a more limited role in increasing the use of renewable energy in Texas relative to California," wrote the team, which included sustainability engineers from the University of Michigan, Ohio State University and North Carolina State University.
The range of policies contemplated by the team, while assessing energy storage's utility in a "deep decarbonization," would go beyond anything pursued by state or even national governments to date.
The 90% emissions reduction estimated in California, for instance, would occur if a $200-per-ton carbon tax were enacted. That's larger than taxes imposed in Europe — where they tend not to exceed a few dozen dollars per ton — although the figures are on the lower end of what U.N. scientists have said should be imposed in order to keep global warming within 1.5 degrees Celsius.
A 'hot topic'
Lithium-ion batteries, a storage technology that has gotten much attention for its applications in electric vehicles, also would have "a limited role to play" in decarbonization, unless the technology's upfront cost comes down, according to the research.
Pumped hydro and compressed-air technologies, which use water or air to drive a turbine, would generally be the most cost-effective, assuming any carbon tax remained small.
"But then, we know that there are other issues" with those technologies, said Maryam Arbabzadeh, lead author of the study and a postdoctoral fellow at the University of Michigan's School for Environment and Sustainability. "It's not very easy to develop a pumped-hydro storage system."
"A small reduction in the cost of lithium-ion could make these batteries cost-effective," she said.
In Texas, energy storage would mostly be useful under the largest carbon taxes, when it would shift the grid from coal power to natural gas, the study found.
The team's policy analysis also included renewable deployments that would dwarf those currently in place: 20 gigawatts of wind and 40 GW of solar.
As of this year's first quarter, Texas had just under 3 GW of solar installed, although it had almost 25 GW of wind. California had about 25 GW of solar and less than 6 GW of wind.
The researchers based their case studies on the two states' grids during the 2010-12 period, the latest years for which the National Renewable Energy Laboratory had data available when the team began work, said Arbabzadeh.
Only a handful of states have enacted mandates for energy storage development, including California, which was the first to do so in 2013. But some renewable analysts expect more to follow.
For sustainability experts, "it's a hot topic," said Arbabzadeh.