Can Batteries Make Solar Work for Local Government?

Going solar is hard. It took 40 years to reach 1 million solar array installations in the U.S., and the technology still makes up less than 1 percent of the country’s power supply.

But maybe there’s a way to make solar work more easily, in small towns and counties that own their own utilities. Take Minster, Ohio — a tiny village of fewer than 3,000 people that may have figured it out.

The village recently grabbed national attention when the Smart Electric Power Alliance reported that it provided more watts of solar power per customer than any other utility in the nation, whether private, investor-owned or public. And a few other towns and counties are looking into whether they can follow Minster’s lead.

So how did Minster do it?

Batteries, says Village Administrator Don Harrod. The village built a system of lithium-ion batteries with more storage capacity than the solar array’s peak capacity, and are using that system to sell services to the area’s power grid.

“I’d encourage [other public utilities] to look at not only the solar, but the energy storage system. There are so many benefits from the storage system,” Harrod said. “Pairing them together just seems like the best opportunity to get all the benefits that you can from renewable energy.”

Though many are examining batteries as a solution for flattening out the power generation curve inherent in solar power — which could turn it into a clean power source during peak usage hours — Harrod emphasized that the village primarily turned to batteries for economic reasons.

Minster, Ohio's battery-backed photovoltaic solar array. Photo courtesy of the village of Minster.

See, the original plan was to help pay back the up-front cost involved in setting up the solar array by selling renewable energy credits for the zero-emission power the system would generate. Then in the middle of Minster’s planning process, state legislation froze Ohio’s market for those credits and the investors backing the solar array began to sour on the project.

But as organizations like the Electric Power Research Institute (EPRI) and the Rocky Mountain Institute (RMI) have pointed out in studies and white papers in recent years, there is revenue-generating potential in batteries. Aside from simply storing power, the systems can provide services that grid operators are willing to pay for. In Minster, PJM Interconnection is paying to use the battery to “shave” off some of the demand during peak hours — a time when it’s typically more expensive and more polluting to generate enough electricity to meet demand.

EPRI and RMI note a variety of other services. Batteries can be used to regulate voltage, to help bring infrastructure back online after a blackout, or avoid congestion along transmission lines. Big-picture, batteries can offer an alternative to some other types of power infrastructure — meaning that if power companies are able to tap into batteries for those services, they can avoid paying millions of dollars to build that infrastructure.

Is it a trend?

It’s difficult to say whether small towns and public utilities are warming up to the idea of stored energy, according to EPRI Engineer Scientist Brittany Westlake. There’s no doubt that there’s momentum on a global scale — according to Sandia National Lab’s Energy Storage Database, global energy storage capacity has risen almost from about 1 gigawatt in 2005 to nearly 4 gigawatts in 2016. The database shows more than 3.5 gigawatts in announced projects coming down the pipeline through 2020.

But that involves all manner of grid-connected storage projects aside from pumped hydro storage. When it comes to tracking small-town projects specifically, Westlake said, the best resource is probably press releases.

William Spratley, executive director of Green Energy Ohio, said he’s not sure whether storage is a trend among small public utilities. He sees potential there, though — big power companies in Ohio have started looking at battery projects, including possible partnerships with small public utilities.

“If a little village can do this, why can’t the big guys do it?” Spratley said.

There are more towns than just Minster looking at energy storage as a means of achieving their goals. Elected officials in the town of Snowflake, Ariz., are considering a grid takeover that would involve building a lot of solar backed up with energy storage systems.

And then there’s the strange case of Los Alamos County, N.M. Of the roughly 18,000 people who live there, more than 10,000 are involved with the Los Alamos National Lab in some way. The lab accounts for about 80 percent of the county’s electricity consumption.

With the national lab involved in all kinds of climate-change-related work, from renewable energy to battery materials to carbon dioxide sequestration, Los Alamos County Public Utilities Deputy Manager for Power Production Steve Cummins said there’s a lot of public will to go green.

“Our community, just as a community that’s got a lot of scientists in it, they want to see the community go carbon neutral and [release] no greenhouse gases,” he said.

So with the help of 17 Japanese companies, the county collaborated on a trial project in 2012. They hooked up a 1-megawatt solar array to two batteries, one lead-acid and one sodium, hooked them up to a microgrid and watched what happened. 

“What they did is get a real smooth bell curve,” Cummins said.

A bell curve in solar power production, that is. Where typical solar output involves a steep bell curve spiking at midday and falling to zero at night, Los Alamos was able to flatten out the spikes and put the sun to work for longer than usual.

That allowed the utility to make solar a bigger piece of the electric portfolio on the microgrid.

“Between the 1-megawatt solar [array] and the 1.8-megawatt battery [system], my understanding is they got somewhere between 50 and 75 percent [solar penetration] at times on that feeder,” Cummins said.

What are the puzzle pieces?

Los Alamos County has every intention of taking the idea further in the future. And yet, Cummins said, batteries are not necessarily the solution the county will turn to.

Right now that’s mostly because of the cost of batteries. The 1-megawatt sulfur battery used in the Los Alamos trial cost about $4.5 million. For that price, Cummins said, the county could simply buy shares in a carbon-free nuclear power plant.

But the cost of batteries has come down, and it looks to continue doing so. That’s partially due to continuing research on improving batteries, and partially because Tesla Motors is working on an enormous battery factory in Nevada that could achieve economies of scale for energy storage production.

Still, Los Alamos County needs some sort of solution for managing the variability of renewables as it continues to make up more of its power mix. Specifically, Cummins said, the county is under a contractual obligation to provide power within a 2-megawatt band of current demand. That is, it needs to have the means to supply 2 more megawatts of power than its users are drawing at any given time.

One solution could be demand response. The concept, which has been gaining some steam itself around the country, involves finding users who are willing to reduce their power use at a moment’s notice. For example, a utility might install a switch on a water heater that allows it to reduce power flow to the appliance if a cloud suddenly passes above a large solar array and power production dips.

It acts as a kind of substitute for storage, providing some of the same key services like helping avoid supply-demand mismatches.

Another solution would be to have natural gas-fired generators that would likely sit idle most of the time, coming online when needed to prevent problems.

In the future, he said, perhaps the price of batteries will come down far enough to make it an easy choice for a small public utility. The goal, he said, is to be able to “firm up” the intermittent so that the grid could continue operating for two hours even with generation loss from renewable supplies.

“You can’t control enough to back up if you lose your entire [photovoltaic] array if you’ve got 50 megawatts from solar,” he said.

Some wrenches in the works

Today, Westlake said, the closest one get to a definitive answer when trying to determine whether batteries can make solar worth it for a small utility is “it depends.”

“It’s hard to make a blanket statement that solar with all this storage is the solution,” she said. “It still needs to be [considered] on a case-by-case basis.”

That’s because both the value and cost of a storage project can vary considerably based on individual circumstances. Some types of storage, hooked up with different kinds of solar arrays, in different parts of the country, with different types of electricity consumers, might provide more value than others. And when it comes to cost, Westlake likened the quest to find a hard-set number for dollars per kilowatt-hour to a quest to always pay the same amount for coffee.

“[Let’s] say coffee costs a dollar. You go into Starbucks and give them a dollar for your latte — it’s not going to go well,” she said.

EPRI does offer some help in that area. In April it launched an online tool for calculating the total cost of storage — not just the up-front cost of different types of storage, but the costs of installation, insurance and more.

As costs come down, demonstration projects continue to add examples of how grid-scale storage might work and research continues on new materials, batteries may yet become a mainstay for small-town solar projects. Spratley said he thinks there’s big potential for the industry because it could create jobs — usually a goal government can get behind.

“It’s a matter of public policy, and frankly, the more little towns that adopt this, the more political value I think is created because it shows that this is a technology that works at a local level,” he said.

For now, perhaps the best place to look for whether energy storage is the solution that can get solar off the ground is whether more towns follow the lead of Minster.

“I think it’ll be interesting to see if other munis adopt the model of the battery,” Spratley said.