Second of a two-part series on new battery technologies. To read the first part, click here.
In the push for a better battery, many in the industry are finding that the biggest challenges aren’t in chemistry and physics, but in regulations and market forces.
Currently, the opportunities for a cheaper, more efficient way to store electricity are booming. Market research firm IHS Inc. reported that grid-level energy storage is on track to reach 40 gigawatts in capacity by 2022, a hundredfold increase from 2013 (ClimateWire, Feb. 27).
Meanwhile, global light-duty electric vehicle sales are expected to increase from 2.1 million in 2014 to 6.3 million in 2020, according to Navigant Research.
Energy storage offers many new opportunities for improving efficiency and cutting greenhouse gas emissions, but using it effectively requires rethinking how we drive and how we use electricity, challenges that may be more difficult to clear than getting the price down or the capacity up.
Though battery innovations will help, there is plenty of room for improvement in policy, engineering and economies of scale.
"About one-third of the price of the [electric] vehicle is the battery," said Claire Curry, an advanced transportation analyst at Bloomberg New Energy Finance. "The big technology barrier is energy density."
In a car, there isn’t much space, so you have to do as much as you can with what little you have. That means packing electrons into as small a container as possible. The container also has to be light, since added weight eats into performance. Safety and durability are also critical, since vehicles move around and occasionally crash.
Manufacturers have made big strides over the years in all of these frontiers. Battery costs in vehicles now dip below $300 per kilowatt-hour, down from $750 per kWh in 2010, a performance trend that’s faster than most analysts predicted (ClimateWire, Mar. 24).
The best lithium-ion batteries now have energy densities above 400 watt-hours per kilogram.
On the cusp of a new generation
Yet a $20,000 electric car that gets 400 miles of range is still a dream. Engineers are approaching diminishing returns in the current crop of lithium-ion batteries, leaving new development to manufacturers with deep pockets like LG, Toshiba and Panasonic, which are racing to produce the $100-per-kWh battery that many analysts think will tip the scales away from internal combustion.
"They are mainly selling at cost or at a loss," Curry said. "They are hoping they can bid everyone else out of the market."
In addition, gasoline’s energy density is more than 12,000 watt-hours per kilogram and its prices are very low, moving the goal posts away from electric cars even with government subsidies and tax breaks.
Still, while waiting for the next new battery chemistry, manufacturers are still working to optimize the current generation. About 60 percent of a battery’s cost is tied up in materials, so doing more with less is helping drop the price, Curry said. Power electronics and better heat management to increase battery life are other areas that are helping drive costs down.
Automakers are also feeling the government’s push from corporate average fuel economy standards to improve mileage across their offerings. Some car companies have introduced electric cars to their lineups as a result, but whether they become more than token offerings depends on buyers wanting them.
"You need to have a real incentive to buy the vehicles first before you can change the market," Curry said. "Basically, improvements have not been what we thought they could be."
On the electric grid, utilities are findings that batteries can do a lot more than compensate for wavering renewables.
Energy storage can provide frequency regulation. Storage can shift and shave peak energy demands, allowing utilities to buy up electricity when it’s cheap and abundant and use it when it’s desperately needed and expensive. These devices can also provide emergency power and the startup power to get a power plant fired up.
‘Transformational’ opportunities in grid storage
Deployed widely, energy storage means that operators can redesign the grid for average energy consumption rather than bracing for peak consumption on hot days when air conditioners crank up across an entire power market.
At a conference earlier this year, Massachusetts Institute of Technology materials science and engineering professor Donald Sadoway likened the current grid strategy to building a 60-lane highway so that no one who is driving would ever have to touch his or her brakes or overtake someone.
Energy storage enables a much more sensible two-lane highway by allowing energy demand and supply to move around.
"The ability to go up and down, accept and inject power on the grid is absolutely transformational," said Dean Frankel, an analyst at Lux Research, a market research firm.
Matt Roberts, executive director of the Energy Storage Association, observed that grid batteries are already online in the United States across many transmission networks and many more are going up.
But as with electric cars, the biggest hurdle for grid batteries may not be the technology.
As batteries are a resource that doesn’t generate electricity but soaks it up and releases it on demand, many grid operators aren’t sure how to attach a price tag to them. When they absorb electricity, energy storage systems appear as a load. When they release it, they appear as producers.
"It really is incredibly flexible for all the things it can perform," he added. "The challenge is you cannot always get remuneration for these services.
"The primary opportunity is in restructuring markets so energy storage could be valued properly," he added.
Breakthrough or slow advance?
As for technology, Roberts said that different strategies would have to fill different roles. Over short time frames, between a few minutes and a couple hours, flywheels could be a viable option. Between two and four hours, some form of lithium battery might win out. Longer than that, flow batteries would excel.
However, grid battery customers are not wedded to any particular strategy so long as it meets cost and reliability benchmarks. "They don’t really care what’s inside the box; they want the service," Roberts said. "They want to see that it’s going to work."
While intermittent wind and solar capacity continues to grow, energy storage systems haven’t caught on at the same pace. Other power sources, like generators running on cheap natural gas, are already filling the gaps, leading some researchers to question whether energy storage is really the gatekeeper for clean energy on the grid (ClimateWire, Sep. 28).
The question, then, is which approach will tip the balance toward electric cars and grid storage, whether it’s a slow advance across the finish line or a breakthrough new chemistry.
Claus Daniel, a researcher at the Oak Ridge National Laboratory, said that it’s likely that no single energy storage strategy will claim the crown that lithium-ion wears today. "It’s a variety of different decision points, and it’s really up to the private industry on how to capitalize on it," he said.
Though it may be years before improvements in batteries make their mark on our everyday lives, the main frontiers for energy storage — energy density and cost — are making rapid progress. "For both of those, I see the research community moving forward quite dramatically," Daniel said.