The U.S. is surging ahead in terms of adopting battery storage. In 2013-2014, U.S. companies installed, or were in the process of installing more than 300 MW of energy storage capacity. The largest is Southern California Edison’s Tehachapi Energy Storage Project. It is a 8-MW system capable of supplying 32 megawatt-hours of electricity to the grid.
“One of the shots that was heard around the world was AB 2514, which is a California mandate for the minimum amount of energy storage the utilities have to install by 2020. That minimum allocated across the three major IOUs in California — Southern California Edison (SCE), Pacific Gas & Electric (PG&E) and San Diego Gas and Electric (SDG&E) — totals 1.325 gigawatts,” according to John Jung, CEO of the energy storage software, services & systems company GreenSmith.
GreenSmith is battery agnostic. It develops the software used in battery storage facilities. By the end of this year, it will have integrated a dozen battery storage units to the grid. That represents 23 MW of installed capacity deployed in four states.
Philip Hiersemenzel of Younicos believes that Germany could be using 60 percent renewable energy if the right technology were in place. Credit: Roy L Hales.
“We are seeing major procurement — RFPs, RFOs and RFIs — happening in places like Hawaii, Ontario (Canada), the North East of the United States and Texas,” said Jung.
Adding Renewables to the Aging US Infrastructure
The aging U.S. infrastructure is a problem when it comes to grid stability. Many of the distribution feeders are nearing the end of their expected useful life. They are fairly weak and not equipped to handle a large influx of intermittent energy.
“A Southern California utility that we’ve delivered five different projects for, including about 6 MWh of grid stability and deferral applications this year, has reported in excess of 35 percent grid penetration of PV alone,” Jung said.
A lot of GreenSmith’s applications are 3-5 hours in length, which gives utilities more control over when electrons hit the grid.
One of Greensmith’s energy storage projects in California. Credit: Greensmith.
“We’ve got what you call ‘peak shaving’ that allows you to take those electrons generated by renewable (and other intermittent) resources and store them until the peak hours when they are needed,” said Jung. “The issue is really about smoothing out the intermittency so that it mitigates the effect on distribution feeders.”
Jung said the U.S. usually uses only about half of its electrical generation capacity. The peak times only amount to 2 or 3 percent of the year. Very expensive equipment is being purchased to meet that peak demand and it is not used very often.
Illustration showing how the battery agnostic Greensmith system works. Credit: Greensmith.
Instead of simply replacing the old grid with a new one, U.S. utilities should ask questions like: Where will we get the most value for our investments? What value do we place on getting a more resilient, more reliable grid? How important is it to have a grid that utilizes more renewable resources? Do we want to lengthen the life of existing resources?
Jung added, “We think all of these things can be done better. Not by spending another dollar on hardware equipment, but by spending another 10 cents on software and algorithms.”
Battery Storage for Ramp-up Speed
Like the US-based GreenSmith, Germany-based Younicos’ real contribution is software. Its battery plant focuses on 15-minute applications, the maximum allowed under “regulations/market design.”
“Batteries use all of their power (positive and negative) and because they are much faster and much more precise, our 5-MW unit replaces 50 MW of conventional generation capacity that would be AT THE VERY least required for the same +/- 5 MW,” said Hiersemenzel.
Landis D. Kannberg, Manager of Energy Storage and Renewable Integration at Pacific Northwest National Laboratory, agrees that batteries have a superior ramp rate.
The demonstration grid at the Younicos facility in Berlin, Germany. Credit: Roy L. Hales.
“A coal-fired power plant might have (if modified for such) a ramp rate of 5 percent/minute,” he said. “Batteries can literally go to 100 percent (and in some cases higher for short periods of time) of rated power, in seconds Flywheels also have extremely fast response.”
“Energy storage is by far one of the fastest resources, capable of handling the increase or decrease of the required frequency almost instantaneously,” echoed Jung.
Their weakness is duration. They become energy limited if forced to carry loads over an extended time. Utilities use a progression of plants for providing spinning reserve, primary and secondary reserves.
Younicos’ solution replaces a large number of those first line plants with battery packs.
Hiersemenzel explained, “To be able to adjust their power just a little up and down, these plants have to run at something like 70 percent of capacity. In fact a typical coal fired power plant runs at 90 percent in order to adjust 2 percent up and down. The remainder of the power thus produced has to be absorbed by the grid and thus blocks space for renewable generation. In Germany we have about 25 gigawatts of such so-called “must-run” capacity. With an average load of 60 and a low of 45 GW that means that in times of low load everything above 20 GW of renewable generation has to be powered down or exported.”
It is not economically feasible to insert more than 75 percent of renewable content into the grid, using battery packs. Younico’s goal is 60 percent annually. This means some conventional plants will have to remain online until a new technology is developed.
Kannberg is not convinced that it is necessary for Germany to replace quite so many conventional plants.
“If you rule out conventional generation (which will by definition be what happens at very high penetration of wind and solar) then all you have is storage (assuming load reduction is not an option). At very high penetration of renewables, the relative expense for any technology becomes high because of the very low capacity factor (you don’t want to use it, but it has to be there in case you need it). Biofuels may become an acceptable carbon-neutral fuel for thermal power production for limited use. Another aspect of the future potential approaches for enabling very high renewables is the use of vehicular storage (e.g. EV’s), which should become a viable grid resource in the future, under the right conditions.”
Can the US Build a Green Grid?
Regardless of whether Younicos’ solution works in Germany, or not, it is not applicable to the U.S.
“We couldn’t do that right now because we are not generating enough renewable energy to store, even if we had the storage available,” said Allan Hoffman, a former senior executive with the U.S. Department of Energy.
Hoffman believes the U.S. will eventually use 80 percent renewable energy, and referred to the National Renewable Energy Laboratory’s Renewable Electricity Futures Study:
Renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80 percent of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country.
Jung has seen projections that call for anywhere between 50 percent and 100 percent renewable content.
“There’s an interplay around what assumptions you are making about what investments you are making into the grid infrastructure,” said Jung. “Without those, even targets like 33 percent renewable content in California appear challenging.”
Kannberg said 80 percent “is technically feasible. Costs are non-trivial, perhaps under all scenarios, but particularly if we want to get there quickly. Perhaps the largest barriers, at least in the U.S., are institutional. Having the collective will and enduring commitment to achieving such a goal, that is the biggest challenge.”
“What we lack is a national energy policy,” Hoffman said. “That’s going to create an environment in which people will be willing to invest and know that 10 to 20 years down the road they can count on a rate of return. Nobody in their right mind, whether they are liberal or conservative or anything, is going to put up that kind of money unless they know it is safe and they are going to get a return on their investment.”
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