09/10/2013
Gaps in the Flow of Renewable Energy
The biggest problem with solar panels and wind turbines is that they do not produce energy all the time.
So what is the solution?
Batteries. And other technologies that store energy to be released when it is needed.
As renewable energy becomes increasingly commonplace, interest in energy storage technologies is growing around the world. Researchers in Germany, Japan, the United States and elsewhere are finding governments increasingly willing to support their ideas, although many projects are in the early stages. Cheap, large-scale energy storage is considered the holy grail of renewable power because it would allow wind and solar farms to provide constant energy to the electric grid.
Energy storage “was a kind of Cinderella topic until a few years ago — no one really paid much attention to it,” said Peter Bruce, a chemistry professor at the University of St. Andrews in Scotland. Now, “there is a huge interest in this across the world.”
A big focus of the research is on advanced batteries. Traditionally, a chief limitation of batteries and supercapacitors — electrical systems that charge and discharge power quickly — has been that they do not last long enough, just as a laptop battery may degrade over time, according to Valeria Nicolosi, a research professor at Trinity College in Dublin. Today, tiny substances called nanomaterials are emerging that “can hold mechanical distress much much better,” she said. Dr. Nicolosi is working on such technologies with a grant from the European Research Council.
Britain just connected its first large-scale battery, rated at 2 megawatts, to the grid in August, in the Orkney Islands. The system resembles several cargo containers and can store more than 10,000 times as much energy as an iPad battery. In Texas, the utility company Duke Energy recently began using an even more powerful battery, rated at 36 megawatts, at a remote wind farm.
Stranger-sounding ways to store energy are also getting a fresh look. Air that is compressed and stored in places like caverns during times of excess electricity production can be released to create power when it is needed, via turbines. Projects using this technology are moving forward in New Hampshire and Germany.
The energy storage method most widely used today on power grids involves huge hydropower systems, in which water gets pumped uphill with extra electricity and then released through turbines when the energy is needed. Such projects are hard to build because they are so large, but a new system of this kind is under consideration in Wales.
Governments are putting up money. In Germany, where nuclear power is gradually yielding to renewables, the government is devoting €200 million, or $270 million, to energy storage research, according to Eicke Weber, who directs the Fraunhofer Institute for Solar Energy Systems ISE in Germany.
The German government also announced this year that €50 million would be available in subsidies for systems that pair batteries with solar panels, so that residents could use both at their homes. However, only a modest amount has been spent so far, said Dr. Weber, who recently founded the German Energy Storage Association.
“We have done a good job in developing the renewable energies,” he said. “We have not done an equally good job in making sure we have enough storage.”
Japan, which is also eager to use more renewable energy in the aftermath of the Fukushima nuclear crisis, made money available last year to support small-scale energy storage systems that can be paired with solar panels, according to Abigail Ward, a market analyst at IHS, a global research group.
In California, regulators are expected on Thursday to require electric utilities to add energy storage capacity, in the first policy of its kind in the United States. In July, U.S. electricity regulators approved a rule that supports energy storage by addressing some accounting issues.
But finding an energy storage technology capable of revolutionizing the power grid will take time, experts caution. Batteries have been around a long while, but progress has been relatively limited when it comes to inexpensive, large-scale, durable applications.
“There’s got to be a recognition that there is no quick fix — that it is going to be a longer haul, partly because, yes, we should have done more before in this area,” said Dr. Bruce, of the University of St. Andrews. “You can only accelerate so fast.”
Dr. Nicolosi, of Trinity College, said that advances in storage technologies like batteries may not be obvious for several years. “We are in that sort of time frame where research has been productive but has not yet been developed and implemented in a commercial project,” she said.
Some say that the recent investments are baby steps and that governments should be doing much more.
“In the last 10 to 15 years, the total amount of money that goes into really cutting-edge energy-related research is far too low,” said Donald Sadoway, a professor of materials chemistry at the Massachusetts Institute of Technology. “That means you don’t have a large enough community of scientists working on the problem.”
Dr. Sadoway and his team invented a liquid metal battery, which sandwiches molten salt between two common molten metals that serve as electrodes. They are working to commercialize it, but the project will need considerably more than the $15 million acquired in a round of funding last year. He hopes to have an industrial prototype ready in about a year and envisions running tests with the military or in remote places like Alaska or the Caribbean Islands, where high prices for diesel-generated electricity make renewable energy attractive.
“The whole field of electrochemistry is ripe for discovery still,” Dr. Sadoway said. “We just haven’t made the investment.”
