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DER challenges utilities to provide reliable renewable energy

July 24, 2019

By Greg Clark
Senior Project Manager, Power Delivery

U.S. utilities are declaring their intention to replace carbon-based fuel sources such as coal with renewable energy sources such as wind and solar at a rapid clip. Consider these recent examples:

Some of the renewable energy coming onto the grid is generated by large commercial operations, such as wind and solar farms. But power generated from a variety of small devices, such as a rooftop solar system connected to the grid, also is playing an increasingly important part in generation.

These decentralized or distributed energy resources (DER) are changing the way power is generated and delivered to the electric grid. Solar arrays, wind turbines, microgrids, energy storage and other DER technologies also bring plenty of challenges.

Electricity users in California have adopted residential rooftop solar in a huge way, putting pressure on the grid and making it work in ways it never has. San Diego Gas and Electric already has days when renewable energy sources make up more than 85% of its power generation.

Ted Reguly of SDG&E discusses distributed energy trends in his service area as John Gibson of Avista Utilities (left) and William Rambo from POWER Engineers (right) listen in at the 2019 Power Delivery Design Conference

At Avista Utilities, meanwhile, its customers are pushing for more and more solar and other non-conventional generation. John Gibson, chief research and development engineer with Avista, said his utility is working to get ahead of customer demand by exploring the latest renewable technology before it is adopted on a mass scale. Speaking at the 2019 Power Delivery Design Conference, John said Avista needs to “capture opportunity from the changing electric utility business model. If we don’t do it, someone else will.”

The electric grid, however, is not quite ready for 100% renewables. Far more storage will need to come online. “California is looking at 100% renewables,” said Ted Reguly, director of portfolio and project management at SDG&E and another PDDC participant. “But you can’t get there with four hours of storage. Even in San Diego, the sun doesn’t shine from six to nine in the evening.”

The period he was referring to is SDG&E’s peak demand, when customers go home and begin plugging in electric devices, cooking dinner, doing laundry and placing increased demand on the grid. Peak loads for SDG&E clock in at 4,000 MW, but its existing energy storage needs can’t meet that demand.

There are measures customers can take to help even out demand and supply, such as installing workplace vehicle chargers and charging electrical devices late at night. Ted said he charges his electric car at work to help do his part to ease the demand on the grid. An electric vehicle in charging mode is essentially the same as adding a household’s worth of demand onto the distribution system.

Without utility-scale energy storage systems, there’s no way to capture the excess energy produced during the day and use it to meet peak demand in the evening. John and Ted agreed that full-scale DER and renewables will require a more robust back-up. If the price of lithium, an element used in batteries, continues to drop, large-scale battery energy storage systems (BESS) will continue to become more affordable.

Distributed energy resources are disrupting the traditional business of investor-owned utilities and municipal utilities. For those grappling with the tremendous changes taking place, the path ahead isn’t always clear.

SDG&E has worked hard to adapt to customer needs, but Ted said he’s not sure what role the utility will play for customers in the future. “The majority of our customers will no longer be buying energy from us,” he said, adding that the utility will likely shift its focus to making the grid more reliable and resilient, improving the “pipes and wires.”

John sees a possible different path for Avista. He said the utility sees the disruption as an opportunity to guide its customers as they face more and more energy choices. “Rather than try to catch up with [our customers], we can lead them through the process” by applying Avista’s knowledge and experience to become aggregators of energy choice, he said.

Another major concern for both was how to fairly allocate the cost of maintaining a grid even as more customers switch to residential solar. Ted mentioned he hadn’t had a power bill in more than five years, thanks to his solar system. But John pointed out that Ted’s solar system was likely putting excess power back into the distribution grid, putting stress on the feeders. Those feeders require maintenance, which ratepayers who can’t afford residential solar would be subsidizing, while those who can afford alternative energy are benefitting from the grid without paying for it.

Ted agreed that is a challenge SDG&E definitely will face as DER becomes more prominent. John said it will be a top priority for Avista to figure out how to fairly allocate costs.

Greg Clark of POWER Engineers and John Gibson of Avista Utilities contemplate the future of DER during a panel discussion at the 2019 Power Delivery Design Conference

Despite the uncertainties and challenges DER, it is possible to blaze a trail ahead. At POWER, we’ve been providing DER services for decades, beginning in 1994 when we designed a BESS for Golden Valley Electric Association. That system kept GVE operational after the 2017 Alaska earthquake.

If you’re facing DER challenges, we’d be pleased to talk with you about how we can work together to find solutions that fit your unique issues. Just email me at Greg.Clark@powereng.com.

About the author

Greg Clark is an experienced engineer and senior project manager for POWER Engineers, Inc. He is skilled in the design and implementation of SCADA and communications systems, energy management and automation systems and has successfully managed projects worldwide. He also has experience managing renewable energy projects and has served as owner’s engineer for various greenfield and plant modernization projects for wind energy, solar PV and geothermal power generation facilities.