Getting to 100% renewable energy

Expanded markets, better storage, and finessed demand needed, say Colorado utility executives

by Allen Best

To get to 100% renewables for electrical production won’t be as simple as going to the wind and solar shelf and stocking up. That can get utilities to 50% easily enough, perhaps even 70% or 80%, conceivably even 90%.

Chief executives at several Colorado utilities say the last 10 to 30% will also require sharing of electricity across broad areas, possibly from the West Coast to the Great Plains, to balance supplies with demands. They also see need for new and cost-effective bulk storage, technology that is neither affordable nor achievable yet at the scale needed. A third challenge will be to finesse supplies and demands at the very local, even neighborhood level.

Emissions-free electricity may ultimately come at higher cost. But In the shorter term—roughly the next decade— costs of electricity may well decline even as demand expands for electricity for transportation and home heating, both sectors now largely supplied by fossil fuels.

“It’s really an exciting time,” said Bryan Hannegan, of Holy Cross Energy, the electrical cooperative that serves the Vail, Aspen, and Rifle areas.

Hannegan spoke on a webinar sponsored by the Payne Institute of Public Policy at the Colorado School of Mines and the Colorado Energy Research Collaboratory along with representatives of two wholesale suppliers in Colorado.

The way to solve the first challenge, creating greater connectivity from the clustering of utilities, is basically understood. The arrival of renewables at scale made the need abundantly clear. And it is starting to happen. Last year, both Tri-State Generation and Transmission and Platte River Power Authority, along with partnering utilities, committed to two different energy imbalance markets, or EIMs.

Such markets, or EIMs, should best be understood as the first step toward broader regional transmission organizations, or RTOs. RTOs can advance the necessary transmission planning and coordinate services such as day-ahead markets. Both are needed to move electrons around the grid to accommodate the greater variability of renewables.

Duane Highley

Duane Highley, chief executive of Tri-State, was asked whether utilities really wanted the centralized planning that comes with an RTO. “Yes, and we shouldn’t view it as a problem but as an enormous opportunity,” he replied.

He pointed to the example of the Southwest Power Pool, an Arkansas-based organization that manages the grid on behalf of 14 Midwestern states. It has been able to achieve 78% percent renewable penetration with a peak demand of 48 gigawatts.

“No single utility, no matter how big they are that I am aware of, can do that by themselves within just their balancing area. I don’t think any one state is big enough to do that. It takes multiple states and regions to coordinate that across many, many balancing areas and many megawatts of load,” he said, using the word used by utilities to describe demand or consumption.

When in Arkansas, his prior posting before taking the helm at Tri-State in April 2019, HIghley was running a utility that joined an organized energy market. In doing so, his utility was able to avoid operating its coal-fired power plants during winter because as a participant in the market, it could then draw electricity generated by wind farms in Iowa, a resource previously unavailable.

Massing the available renewable supplies to meet demand expands the benefits, he said. But that mass scale also reduces the need for what utilities call their reserve margins. Operating individually or even in small groups, utilities need large amounts of reserves because—well, you never know. With much greater diversity across a far larger geographic footprint, utilities need narrower margins.

“A lot of benefit will come if we are willing to give up a small amount of control and cede it to a centralized organization that can better coordinate across a region on behalf of everyone,” he said.

At Holy Cross, Hannegan sees the same benefit. “Everybody from NREL to the Department of Energy and others have said that it’s an absolute key to getting clean energy on a regional basis,” he said.

Bryan Hannegan

Hannegan sees the need to bring together the wind of the Great Plains and the sunshine of Western states. “You really do need that geographic diversity,” he said.

The two are on separate electrical grids, roughly in line with Colorado’s border with Kansas. Think of these grids as being like two big pastures divided by a tall fence. This fence between the Western and the Eastern interconnection grids has just a few, narrow gates.

Asked after the webinar how he sees this fence being penetrated, he said one way is high-voltage direct-current or DC lines from one side to the other. Another would be to upgrade and expand these gates, or DC interties.

NREL is conducting a study https://www.nrel.gov/analysis/naris.html about how to better integrate renewables across America. An NREL spokesman said the study is being peer-reviewed and the results will be released later this year.

To completely shed coal and natural gas, though, utilities need improved storage.

“We need some kind of extremely large bulk storage system, to replace the equivalent reliability of the coal stockpile,” said Highley. “The value of the coal stockpile is that it can carry you through the week when the wind turbines are frozen up or the solar is producing at just partial capacity because of snow and ice.”

Lithium-ion batteries will unlikely be able to provide the answer, because of their limitations, combined with cost. Other battery technology might surface, he suggested, or hydrogen, even ammonia.

“We can convert energy to hydrogen, even ship it. If you take a further step, to convert hydrogen to ammonia, you can store it in conventional storage tanks and transport it and then actually burn the ammonia in internal-combustion engines and create electricity.

He suggested that Craig, the site of Tri-State’s largest generating resource at present, could be adapted for storage. Extensive high-voltage transmission lines emanate from that plant.

Fort Collins-based Platte River Power Authority also sees storage being crucial to achieving 100% non-carbon energy by 2030 for its four members: Estes Park, Fort Collins, Longmont, and Loveland. It is installing 2-megawatts of battery storage next to a 22-megawatt solar farm now being completed north of Fort Collins, adjacent to the Rawhide power station.

Allyssa Clemsen-Roberts

“We know battery prices are going to have to come down, and we are going to have to see some technology improvements,” said Alyssa Clemsen Roberts, the chief strategy officer.

Utilities also see the need to finesse demand and supplies at the micro level. One component in this will be the charging of electric vehicles, or EVS, during times when power is abundant.

“That’s an absolute must, particularly for the last 10% to 15% of that getting to a 100% challenge,” said Hannegan. He described the need for “fast twitch responses” of resources to the varying needs of every node of the grid for every second of every day.”

Holy Cross has provided the charging stations in housing units at a new project called Basalt Vista. One reason for doing so “is to get some experience with that fast-twitch muscle, so that when it comes time for us to go to 80, 90 or 100% we have the flexibility we need in our grid to continue to match that supply and demand and meet that reliability objective, which is our No. 1A objective, along with working safely and keeping electric power affordable for everyone.”

Basalt Vista provides a living laboratory for many components that Holy Cross sees as necessary. The affordable-housing project in the town of Basalt was designed to avoid need for any natural gas. Four of the units have five basic components of energy that can interplay and be managed remotely: rooftop solar photovoltaics, battery storage, the level-2 EV chargers, heat-pump water heaters, and air-source heat pumps. Taken together, the units can, if necessary, be operated as a microgrid, providing both power as well as posing demand.

“We manage these 20 devices, either collectively or one at a time, just as we would (the electricity) from a conventional power plant,” Hannegan explained.

“The other thing that is really cool about this is that we could say, ‘Hey houses, for the next 4 or 5 hours we don’t want you to use any power from us, function as a microgrid and take care of your own needs, because we’ve got other needs for power somewhere else,’” he explained.

The houses could actually serve as mini powerhouses, their batteries delivering power to other uses beyond Basalt Vista.

That idea is not an academic exercise. Two years ago, Holy Cross came perilously close—one power pole—from being unable to supply power to Aspen during the Fourth of July weekend because of a wildfire – and that remaining power pole was on fire when firefighters arrived. The experience convinced Holy Cross of the need for microgrids to be built within the broader fabric. This design optimizes power flows to maximize reliability and also affordability.

“That is a huge tool in our arsenal as we go to a clean energy future,” said Hannegan. A dozen more projects in the service territory of Holy Cross are now eager to follow down this same path.

This has caused Holy Cross to begin rethinking its business model, moving away from being a commodity seller to kilowatt-hours to maybe being one of a service provider with a flat monthly fee.

Beyond 70%, he added, some more costly technologies may be needed. “But as I like to say, before getting to 100% you first have to get to 70%, so let’s get that squared away as soon as possible.”

And Xcel Energy’s plans…

Xcel Energy believe it knows how to get to 80% renewables by 2030. But emissions-free energy by 2050?

Alice Jackson, president of Xcel’s subsidiary in Colorado, said recently that the company has been tracking development of modular nuclear reactors as well as carbon capture and storage technology.

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Allen Best