EPRI, Entergy validate voltage stability monitoring

Solar Plus Storage is accelerating across utilities and microgrids, pairing rooftop solar with lithium-ion batteries to enhance grid resilience, reduce peak costs, prevent blackouts, and leverage tax credits amid falling prices and decarbonization goals.

Key Points

Solar Plus Storage combines solar generation with batteries to shift load, boost reliability, and cut energy costs.

✅ Cuts peak demand charges and enhances blackout resilience

✅ Falling battery and solar costs drive nationwide utility adoption

✅ Enables microgrids and grid services like frequency regulation

Todd Karin was prepared when California’s largest utility shut off power to millions of people to avoid the risk of wildfires last month. He’s got rooftop solar panels connected to a single Tesla Powerwall in his rural home near Fairfield, California. “We had backup power the whole time,” Karin says. “We ran the fridge and watched movies.”

Californians worried about an insecure energy future are increasingly looking to this kind of solution. Karin, a 31-year-old postdoctoral fellow at Lawrence Berkeley National Laboratory, spent just under $4,000 for his battery by taking advantage of tax credits. He's also saving money by discharging the battery on weekday evenings, when energy is more expensive during peak demand periods. He expects to save around $1,500 over the 10 years the battery is under warranty.

The economics don’t yet work for every household, but the green-power combo of solar panels plus batteries is popping up on a much bigger scale in some unexpected places. Owners of a rice processing plant in Arkansas are building a system to generate 26 megawatts of solar power and store another 40 MW. The plant will cut its power bill by a third, and owners say they will pass the savings to local rice growers. New York’s JFK Airport is installing solar plus storage to reduce its power load by 10 percent, while Pittsburgh International Airport is building a 20-MW solar and natural gas microgrid to keep it independent from the local utility. Officials at both airports are worried about recent power shutdowns due to weather and overload-related blackouts.

And residents of the tiny northern Missouri town of Green City (pop. 608) are getting 2.5 MW of solar plus four hours of battery storage from the state’s public utility next year. The solar power won’t go directly to townspeople, but instead will back up the town’s substation, reducing the risk of a potential shutdown. It’s part of a $68 million project to improve the reliability of remote substations far from electric generating stations.

“It’s a pretty big deal for us,” says Chad Raley, who manages technology and renewables at Ameren, a Missouri utility that is building three rural solar-plus-storage projects to better manage the flow of electricity across the local grid. “It gives us so much flexibility with renewable generation. We can’t control the sun or clouds or wind, but we can have battery storage.”

The first solar-plus-storage installations started about a decade ago on a small scale in sunny states like California, Hawaii, and Arizona. Now they’re spreading across the country, driven by falling prices of both solar panels and lithium-ion batteries the size of a shipping container imported from both China and South Korea, with wind, solar, and batteries making up most of the utility-scale pipeline nationwide. These countries have ramped up production efficiencies and lowered labor costs, leaving many US manufacturers in the dust. In fact, the price of building a comparable solar-plus-storage generating facility is now cheaper than operating a coal-fired power plant, industry officials say. In certain circumstances, the cost is equal to some natural gas plants.

“This is not just a California, New York, Massachusetts thing,” says Kelly Speakes-Backman, CEO of the Energy Storage Association, an industry group in Washington. She says more than 30 states have renewable storage on the grid. Utilities have proposed and states have approved 7 gigawatts to be installed by 2030, and most new storage will be paired with solar across the US.

Speakes-Backman estimates the unit cost of electricity produced from a solar-plus-storage system will drop 10 to 15 percent each year through 2024, supporting record growth in solar and storage investments. “If you have the option of putting out a polluting or non-polluting generating source at the same price, what are you going to pick?” says Speakes-Backman.

She notes that PJM, a large Mid-Atlantic wholesale grid operator, announced it will deploy battery storage to help smooth out fluctuating power from two wind farms it operates. “When the grid fluctuates, storage can react to it quickly and can level out the supply,” she says. In the Midwest, grid-level battery storage is also being used to absorb extra wind power. Batteries hold onto the wind and put it back onto the grid when people need it.

While the solar-plus-storage trend isn’t yet putting a huge dent in our fossil fuel use, according to Paul Denholm, an energy analyst at the National Renewable Energy Laboratory in Golden, Colorado, it is a good beginning and has the side effect of cutting air pollution. By 2021, solar and other renewable energy sources will overtake coal as a source of energy, and the US is moving toward 30% electricity from wind and solar, according to a new report by the Institute for Energy Economics and Financial Analysis, a nonprofit think tank based in Cleveland.

That’s a glimmer of hope in a somewhat dreary week of news on carbon emissions. A new United Nations report released this week finds that the planet is on track to warm by 3.9 degrees Celsius (7 Fahrenheit) by 2100 unless drastic cuts are made by phasing out gas-powered cars, eliminating new coal-fired power plants, and changing how we grow and manage land, and scientists are working to improve solar and wind power to limit climate change as well.

Energy-related greenhouse gas emissions in the US rose 2.7 percent in 2018 after several years of decline. The Trump administration has rolled back climate policies from the Obama years, including withdrawing from the Paris climate accords.

There may be hope from green power initiatives outside the Beltway, though, and from federal proposals like a tenfold increase in US solar that could remake the electricity system. Arizona plans to boost solar-plus-storage from today’s 6 MW to a whopping 850 MW by 2025, more than the entire capacity of large-scale batteries in the US today. And some folks might be cheering the closing of the West’s biggest coal-fired power plant, the 2.25-gigawatt Navajo Generating Station, in Arizona, which had spewed soot and carbon dioxide over the region for 45 years until last week. The closure might help the planet and clear the hazy smog over the Grand Canyon.

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Rio Tinto Off-Grid Solar Power Plant showcases renewable energy at the Diavik Diamond Mine in Canada's Northwest Territories, cutting diesel use, lowering carbon emissions, and boosting remote mining resilience with advanced photovoltaic technology.

Key Points

A remote solar PV plant at Diavik mine supplying clean power while cutting diesel use, carbon emissions, and costs.

✅ Largest off-grid solar in Northwest Territories

✅ Replaces diesel generators during peak solar hours

✅ Enhances sustainability and lowers operating costs

In a significant step towards sustainable mining practices, Rio Tinto has completed the largest off-grid solar power plant in Canada’s Northwest Territories. This groundbreaking achievement not only highlights the company's commitment to renewable energy, as Canada nears 5 GW of solar capacity nationwide, but also sets a new standard for the mining industry in remote and off-grid locations.

Located in the remote Diavik Diamond Mine, approximately 220 kilometers south of the Arctic Circle, Rio Tinto's off-grid solar power plant represents a technological feat in harnessing renewable energy in challenging environments. The plant is designed to reduce reliance on diesel fuel, traditionally used to power the mine's operations, and mitigate carbon emissions associated with mining activities.

The decision to build the solar power plant aligns with Rio Tinto's broader sustainability goals and commitment to reducing its environmental footprint. By integrating renewable energy sources like solar power, a strategy that renewable developers say leads to better, more resilient projects, the company aims to enhance energy efficiency, lower operational costs, and contribute to global efforts to combat climate change.

The Diavik Diamond Mine, jointly owned by Rio Tinto and Dominion Diamond Mines, operates in a remote region where access to traditional energy infrastructure is limited, and where, despite lagging solar demand in Canada, off-grid solutions are increasingly vital for reliability. Historically, diesel generators have been the primary source of power for the mine's operations, posing logistical challenges and environmental impacts due to fuel transportation and combustion.

Rio Tinto's investment in the off-grid solar power plant addresses these challenges by leveraging abundant sunlight in the Northwest Territories to generate clean electricity directly at the mine site. The solar array, equipped with advanced photovoltaic technology, which mirrors deployments such as Arvato's first solar plant in other sectors, is capable of producing a significant portion of the mine's electricity needs during peak solar hours, reducing reliance on diesel generators and lowering overall carbon emissions.

Moreover, the completion of the largest off-grid solar power plant in Canada's Northwest Territories underscores the feasibility and scalability of renewable energy solutions, from rooftop arrays like Edmonton's largest rooftop solar to off-grid systems in remote and resource-intensive industries like mining. The success of this project serves as a model for other mining companies seeking to enhance sustainability practices and operational resilience in challenging geographical locations.

Beyond environmental benefits, Rio Tinto's initiative is expected to have positive economic and social impacts on the local community. By reducing diesel consumption, the company mitigates air pollution and noise levels associated with mining operations, improving environmental quality and contributing to the well-being of nearby residents and wildlife.

Looking ahead, Rio Tinto's investment in renewable energy at the Diavik Diamond Mine sets a precedent for responsible resource development and sustainable mining practices in Canada, where solar growth in Alberta is accelerating, and globally. As the mining industry continues to evolve, integrating renewable energy solutions like off-grid solar power plants will play a crucial role in achieving long-term environmental sustainability and operational efficiency.

In conclusion, Rio Tinto's completion of the largest off-grid solar power plant in Canada's Northwest Territories marks a significant milestone in the mining industry's transition towards renewable energy. By harnessing solar power to reduce reliance on diesel generators, the company not only improves operational efficiency and environmental stewardship but also adds to momentum from corporate power purchase agreements like RBC's Alberta solar deal, setting a positive example for sustainable development in remote regions. As global demand for responsible mining practices grows, initiatives like Rio Tinto's off-grid solar project demonstrate the potential of renewable energy to drive positive change in resource-intensive industries.

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Alberta NDP Net-Zero Electricity Plan targets a 2035 clean grid, expands renewable energy, cuts emissions, creates jobs, and boosts economic diversification and rural connectivity, aligning Alberta with Canada's 2050 climate goals.

Key Points

A policy to achieve a net-zero electricity grid by 2035, advance renewable energy, cut emissions, and grow jobs.

✅ Net-zero electricity grid target set for 2035

✅ Scales renewable energy and emissions reductions

✅ Focus on jobs, rural connectivity, and diversification

Ahead of the NDP’s weekend convention, Alberta’s Opposition leader has committed to transforming the province’s energy sector and moving the province’s electricity grid to net-zero by 2035, despite debate over the federal 2035 net-zero electricity grid target in other provinces, should an orange crush wash over Alberta in the next election.

NDP Leader Rachel Notley said they would achieve this as part of the path towards Canada’s 2050 net-zero emissions goal, aligning with broader clean grids trends, which will help preserve and create jobs in the province.

“I think it’s an important goal. It’s a way of framing the work that we’re going to do within our energy industry and our energy sector, including how Alberta produces and pays for electricity going forward,” said Notley. “We know the world is moving toward different objectives and we still have the ability to lead on that front, but we need to lay down the markers early and focus on reaching those goals.”

Premier Jason Kenney has previously called the 2050 target “aspirational,” and, as the electricity sector faces profound change in Alberta, Notley said, once the work begins, it’s likely they would meet the objective earlier than proposed to reduce greenhouse gas emissions that contribute to global warming.

This is just one key issue that will be addressed at the party’s online convention, which is the first since the NDP’s defeat by the UCP in the last provincial election. Notley said other key issues will address economic diversification, economic recovery, job creation and social issues, as Alberta’s electricity market is headed for a reshuffle too. The focus, as she puts it, is “jobs, jobs, jobs.”

Attendees will also debate more than 140 policy resolutions over the weekend, including the development of a safe supply drug policy, banning coal mining in the Rocky Mountains and providing paid sick leave for workers.

Outside the formal agenda, debate over electricity market competition continues in Alberta as stakeholders weigh options.

Notley said an area of growing focus for the NDP will be rural Alberta, which is typically a conservative stronghold. One panel presentation during the convention will focus on connecting and building relationships with rural Albertans and growing the NDP profile in those areas.

“We think that we have a lot to offer rural Alberta and that, quite frankly, the UCP and (Kenney), in particular, have profoundly taken rural Alberta for granted,” she said. “Because of that, we think with a renewed energy amongst our membership to go out to parts of the province where we haven’t been previously as active, and talk about what they have been subjected to in the last two years, that we have huge opportunities there.”

Delegates will be asked to support a call for high-speed internet coverage across Alberta, which would remove barriers to access in rural Alberta and Indigenous communities, said the convention guidebook.

The convention comes as the NDP has a wide lead on the UCP, according to the latest polls. A Leger online survey of 1,001 Albertans conducted between March 5 to 8 found 40 per cent of respondents support the NDP, compared to just 20 per cent for the UCP.

Notley said it’s “encouraging” to see, but they aren’t taking anything for granted.

“I’ve always believed that Alberta Democrats have to work twice as hard as anybody else in the political spectrum, or the political arena,” she said. “So what we’re going to do is continue to do exactly what we have been, not only being a strong and I would argue fearless Opposition, but also trying to match every oppositional position with something that is propositional — offering Albertans a different vision, including an Alberta path to clean electricity where possible.”

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California Battery Storage is transforming grid reliability as distributed energy, solar-plus-storage, and demand response mitigate rolling blackouts, replace peaker plants, and supply flexible capacity during heat waves and evening peaks across utilities and homes.

Key Points

California Battery Storage uses distributed and utility batteries to stabilize power, shift solar, and curb blackouts.

✅ Supplies flexible capacity during peak demand and heat waves

✅ Enables demand response and replaces gas peaker plants

✅ Aggregated assets form virtual power plants for grid support

Last month as a heat wave slammed California, state regulators sent an email to a group of energy executives pleading for help to keep the lights on statewide. “Please consider this an urgent inquiry on behalf of the state,” the message said.

The manager of the state’s grid was struggling to increase the supply of electricity because power plants had unexpectedly shut down and demand was surging. The imbalance was forcing officials to order rolling blackouts across the state for the first time in nearly two decades.

What was unusual about the emails was whom they were sent to: people who managed thousands of batteries installed at utilities, businesses, government facilities and even homes. California officials were seeking the energy stored in those machines to help bail out a poorly managed grid and reduce the need for blackouts.

Many energy experts have predicted that batteries could turn homes and businesses into mini-power plants that are able to play a critical role in the electricity system. They could soak up excess power from solar panels and wind turbines and provide electricity in the evenings when the sun went down or after wildfires and hurricanes, which have grown more devastating because of climate change in recent years. Over the next decade, the argument went, large rows of batteries owned by utilities could start replacing power plants fueled by natural gas.

But that day appears to be closer than earlier thought, at least in California, which leads the country in energy storage. During the state’s recent electricity crisis, more than 30,000 batteries supplied as much power as a midsize natural gas plant. And experts say the machines, which range in size from large wall-mounted televisions to shipping containers, will become even more important because utilities, businesses and homeowners are investing billions of dollars in such devices.

“People are starting to realize energy storage isn’t just a project or two here or there, it’s a whole new approach to managing power,” said John Zahurancik, chief operating officer at Fluence, which makes large energy storage systems bought by utilities and large businesses. That’s a big difference from a few years ago, he said, when electricity storage was seen as a holy grail — “perfect, but unattainable.”

On Friday, Aug. 14, the first day California ordered rolling blackouts, Stem, an energy company based in the San Francisco Bay Area, delivered 50 megawatts — enough to power 20,000 homes — from batteries it had installed at businesses, local governments and other customers. Some of those devices were at the Orange County Sanitation District, which installed the batteries to reduce emissions by making it less reliant on natural gas when energy use peaks.

John Carrington, Stem’s chief executive, said his company would have provided even more electricity to the grid had it not been for state regulations that, among other things, prevent businesses from selling power from their batteries directly to other companies.

“We could have done two or three times more,” he said.

The California Independent System Operator, which manages about 80 percent of the state’s grid, has blamed the rolling blackouts on a confluence of unfortunate events, including extreme weather impacts on the grid that limited supply: A gas plant abruptly went offline, a lack of wind stilled thousands of turbines, and power plants in other states couldn’t export enough electricity. (On Thursday, the grid manager urged Californians to reduce electricity use over Labor Day weekend because temperatures are expected to be 10 to 20 degrees above normal.)

But in recent weeks it has become clear that California’s grid managers also made mistakes last month, highlighting the challenge of fixing California’s electric grid in real time, that were reminiscent of an energy crisis in 2000 and 2001 when millions of homes went dark and wholesale electricity prices soared.

Grid managers did not contact Gov. Gavin Newsom’s office until moments before it ordered a blackout on Aug. 14. Had it acted sooner, the governor could have called on homeowners and businesses to reduce electricity use, something he did two days later. He could have also called on the State Department of Water Resources to provide electricity from its hydroelectric plants.

Weather forecasters had warned about the heat wave for days. The agency could have developed a plan to harness the electricity in numerous batteries across the state that largely sat idle while grid managers and large utilities such as Pacific Gas & Electric scrounged around for more electricity.

That search culminated in frantic last-minute pleas from the California Public Utilities Commission to the California Solar and Storage Association. The commission asked the group to get its members to discharge batteries they managed for customers like the sanitation department into the grid. (Businesses and homeowners typically buy batteries with solar panels from companies like Stem and Sunrun, which manage the systems for their customers.)

“They were texting and emailing and calling us: ‘We need all of your battery customers giving us power,’” said Bernadette Del Chiaro, executive director of the solar and storage association. “It was in a very last-minute, herky-jerky way.”

At the time of blackouts on Aug. 14, battery power to the electric grid climbed to a peak of about 147 megawatts, illustrating how virtual power plants can rapidly scale, according to data from California I.S.O. After officials asked for more power the next day, that supply shot up to as much as 310 megawatts.

Had grid managers and regulators done a better job coordinating with battery managers, the devices could have supplied as much as 530 megawatts, Ms. Del Chiaro said. That supply would have exceeded the amount of electricity the grid lost when the natural gas plant, which grid managers have refused to identify, went offline.

Officials at California I.S.O. and the public utilities commission said they were working to determine the “root causes” of the crisis after the governor requested an investigation.

Grid managers and state officials have previously endorsed the use of batteries, using AI to adapt as they integrate them at scale. The utilities commission last week approved a proposal by Southern California Edison, which serves five million customers, to add 770 megawatts of energy storage in the second half of 2021, more than doubling its battery capacity.

And Mr. Zahurancik’s company, Fluence, is building a 400 megawatt-hour battery system at the site of an older natural gas power plant at the Alamitos Energy Center in Long Beach. Regulators this week also approved a plan to extend the life of the power plant, which was scheduled to close at the end of the year, to support the grid.

But regulations have been slow to catch up with the rapidly developing battery technology.

Regulators and utilities have not answered many of the legal and logistical questions that have limited how batteries owned by homeowners and businesses are used. How should battery owners be compensated for the electricity they provide to the grid? Can grid managers or utilities force batteries to discharge even if homeowners or businesses want to keep them charged up for their own use during blackouts?

During the recent blackouts, Ms. Del Chiaro said, commercial and industrial battery owners like Stem’s customers were compensated at the rates similar to those that are paid to businesses to not use power during periods of high electricity demand. But residential customers were not paid and acted “altruistically,” she said.

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Asia Electricity Consumption 2025 highlights an IEA forecast of surging global power demand led by China, lagging access in Africa, rising renewables and nuclear output, stable emissions, and weather-dependent grids needing flexibility and electrification.

Key Points

An IEA forecast that Asia will use half of global power by 2025, led by China, as renewables and nuclear drive supply.

✅ Asia to use half of global electricity; China leads growth

✅ Africa just 3% consumption despite rapid population growth

✅ Renewables, nuclear expand; grids must boost flexibility

Asia will for the first time use half of the world’s electricity by 2025, even as global power demand keeps rising and Africa continues to consume far less than its share of the global population, according to a new forecast released Wednesday by the International Energy Agency.

Much of Asia’s electricity use will be in China, a nation of 1.4 billion people whose China's electricity sector is seeing shifts as its share of global consumption will rise from a quarter in 2015 to a third by the middle of this decade, the Paris-based body said.

“China will be consuming more electricity than the European Union, United States and India combined,” said Keisuke Sadamori, the IEA’s director of energy markets and security.

By contrast, Africa — home to almost a fifth of world’s nearly 8 billion inhabitants — will account for just 3% of global electricity consumption in 2025.

“This and the rapidly growing population mean there is still a massive need for increased electrification in Africa,” said Sadamori.

The IEA’s annual report predicts that low-emissions sources will account for much of the growth in global electricity supply over the coming three years, including nuclear power and renewables such as wind and solar. This will prevent a significant rise in greenhouse gas emissions from the power sector, it said.

Scientists say sharp cuts in all sources of emissions are needed as soon as possible to keep average global temperatures from rising 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial levels. That target, laid down in the 2015 Paris climate accord, appears increasingly doubtful as temperatures have already increased by more than 1.1 C since the reference period.

One hope for meeting the goal is a wholesale shift away from fossil fuels such as coal, gas and oil toward low-carbon sources of energy. But while some regions are reducing their use of coal and gas for electricity production, in others, soaring electricity and coal use are increasing, the IEA said.

The 134-page also report warned that surging electricity demand and supply are becoming increasingly weather dependent, a problem it urged policymakers to address.

“In addition to drought in Europe, there were heat waves in India (last year),” said Sadamori. “Similarly, central and eastern China were hit by heatwaves and drought. The United States, where electricity sales projections continue to fall, also saw severe winter storms in December, and all those events put massive strain on the power systems of these regions.”

“As the clean energy transition gathers pace, the impact of weather events on electricity demand will intensify due to the increased electrification of heating, while the share of weather-dependent renewables poised to eclipse coal will continue to grow in the generation mix,” the IEA said. “In such a world, increasing the flexibility of power systems while ensuring security of supply and resilience of networks will be crucial.”

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Utility Battery Storage Rankings measure grid-connected capacity, not ownership, highlighting MW, MWh, and watts per customer across PJM, MISO, and California IOUs, featuring Duke Energy, IPL, ancillary services, and frequency regulation benefits.

Key Points

Rankings that track energy storage connected to utility grids, comparing MW, MWh, and W/customer rather than ownership.

✅ Ranks by MW, MWh, and watts per customer, not asset ownership

✅ Highlights PJM, MISO cases and California IOUs' deployments

✅ Examples: Duke Energy, IPL, IID; ancillary services, frequency response

The rankings do not tally how much energy storage a utility built or owns, but how much was connected to their system. So while IPL built and owns the storage facility in its territory, Duke does not own the 16 MW of storage that connected to its system in 2016. Similarly, while California’s utilities are permitted to own some energy storage assets, they do not necessarily own all the storage facilities connected to their systems.

Measured by energy (MWh), IPL ranked fourth with 20 MWh, and Duke Energy Ohio ranked eighth with 6.1 MWh.

Ranked by energy storage watts per customer, IPL and Duke actually beat the California utilities, ranking fifth and sixth with 42 W/customer and 23 W/customer, respectively.

Duke ready for next step

Given Duke’s plans, including projects in Florida that are moving ahead, the utility is likely to stay high in the rankings and be more of a driving force in development. “Battery technology has matured, and we are ready to take the next step,” Duke spokesman Randy Wheeless told Utility Dive. “We can go to regulators and say this makes economic sense.”

Duke began exploring energy storage in 2012, and until now most of its energy storage efforts were focused on commercial projects in competitive markets where it was possible to earn revenues. Those included its 36 MW Notrees battery storage project developed in partnership with the Department of Energy in 2012 that provides frequency regulation for the Electric Reliability Council of Texas market and two 2 MW storage projects at its retired W.C. Beckjord plant in New Richmond, Ohio, that sells ancillary services into the PJM Interconnection market.

On the regulated side, most of Duke’s storage projects have had “an R&D slant to them,” Wheeless said, but “we are moving beyond the R&D concept in our regulated territory and are looking at storage more as a regulated asset.”

“We have done the demos, and they have proved out,” Wheeless said. Storage may not be ready for prime time everywhere, he said, but in certain locations, especially where it can it can be used to do more than one thing, it can make sense.

Wheeless said Duke would be making “a number of energy storage announcements in the next few months in our regulated states.” He could not provide details on those projects.

More flexible resources
Location can be a determining factor when building a storage facility. For IPL, serving the wholesale market was a driving factor in the rationale to build its 20 MW, 20 MWh storage facility in Indianapolis.

IPL built the project to address a need for more flexible resources in light of “recent changes in our resource mix,” including decreasing coal-fired generation and increasing renewables and natural gas-fired generation, as other regions plan to rely on battery storage to meet rising demand, Joan Soller, IPL’s director of resource planning, told Utility Dive in an email. The storage facility is used to provide primary frequency response necessary for grid stability.

The Harding Street storage facility in May. It was the first energy storage project in the Midcontinent ISO. But the regulatory path in MISO is not as clear as it is in PJM, whereas initiatives such as Ontario storage framework are clarifying participation. In November, IPL with the Federal Energy Regulatory Commission, asking the regulator to find that MISO’s rules for energy storage are deficient and should be revised.

Soller said IPL has “no imminent plans to install energy storage in the future but will continue to monitor battery costs and capabilities as potential resources in future Integrated Resource Plans.”

California legislative and regulatory push

In California, energy storage did not have to wait for regulations to catch up with technology. With legislative and regulatory mandates, including CEC long-duration storage funding announced recently, as a push, California’s IOUs took high places in SEPA’s rankings.

Southern California Edison and San Diego Gas & Electric were first and fourth (63.2 MW and 17.2 MW), respectively, in terms of capacity. SoCal Ed and SDG&E were first and second (104 MWh and 28.4 MWh), respectively, and Pacific Gas and Electric was fifth (17 MWh) in terms of energy.

But a public power utility, the Imperial Irrigation District (IID), ended up high in the rankings – second in capacity (30 MW) and third  in energy (20 MWh) – even though as a public power entity it is not subject to the state’s energy storage mandates.

But while IID was not under state mandate, it had a compelling regulatory reason to build the storage project. It was part of a settlement reached with FERC over a September 2011 outage, IID spokeswoman Marion Champion said.

IID agreed to a $12 million fine as part of the settlement, of which $9 million was applied to physical improvements of IID’s system.

IID ended up building a 30 MW, 20 MWh lithium-ion battery storage system at its El Centro generating station. The system went into service in October 2016 and in May, IID used the system’s 44 MW combined-cycle natural gas turbine at the generating station.

Passing savings to customers
The cost of the storage system was about $31 million, and based on its experience with the El Centro project, Champion said IID plans to add to the existing batteries. “We are continuing to see real savings and are passing those savings on to our customers,” she said.

Champion said the battery system gives IID the ability to provide ancillary services without having to run its larger generation units, such as El Centro Unit 4, at its minimum output. With gas prices at $3.59 per million British thermal units, it costs about $26,880 a day to run Unit 4, she said.

IID’s territory is in southeastern California, an area with a lot of renewable resources. IID is also not part of the California ISO and acts as its own balancing authority. The battery system gives the utility greater operational flexibility, in addition to the ability to use more of the surrounding renewable resources, Champion said.

In May, IID’s board gave the utility’s staff approval to enter into contract negotiations for a 7 MW, 4 MWh expansion of its El Centro storage facility. The negotiations are ongoing, but approval could come in the next couple months, Champion said.

The heart of the issue, though, is “the ability of the battery system to lower costs for our ratepayers,” Champion said. “Our planning section will continue to utilize the battery, and we are looking forward to its expansion,” she said.” I expect it will play an even more important role as we continue to increase our percentage of renewables.”

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