Clean Line Energy: HVDC makes sense in Western Interconnection

Long-distance transmission, and particularly HVDC, makes sense in the Western Interconnection as it allows access to the best and most cost-effective renewable resources, including high-capacity factor wind energy, David Berry, vice president of strategy and finance with Clean Line Energy, said Aug. 7.

“HVDC is the lowest cost, most efficient transmission solution,” he said, speaking on TransmissionHub’s webcast, “Reshaping the Western grid: Integrating wind power into the Western grid.”

He noted, however, that that is not true in all applications, such as when moving power short distances.

Berry also said DC lines are controllable, “so when you’re dealing with renewable energy, you can actually move the variability of that renewable energy to the place where you deliver,” he said. “This is important because if you think about a very small state that is home to a lot of wind…, the variability of that wind could overwhelm that small system, but if it’s integrated as part of a big system…then that wind is much easier to manage.”

Other advantages of DC transmission include that it uses less right-of-way than a similar alternating current solution, and it helps with diversity in renewable energy resources, he said.

While a disadvantage with DC is the need to build a converter station, which is an expensive undertaking, “wherever the challenge has been to move a lot of energy a long distance, DC always comes out as the right answer,” he said.

The single biggest driver of renewable demand in the Western Interconnection is California’s 33% by 2020 renewable portfolio standard (RPS), he said.

Berry noted that 75% of the ultimate RPS target has to come from “category 1” resources, which are in-state resources or energy that is delivered directly into a California balancing authority without substituting any electricity from another source.

While 2020 may seem like a long time from now, “given the timeframe of developing, permitting and constructing these transmission lines, you always have to be thinking about many years ahead,” he said, adding, “[O]ne of the challenges in transmission development…is maintaining focus and making project progress when the needs you’re meeting are far out in the future.”

One of the huge advantages of renewable resources is cost certainty, Berry said, noting that it is not subject to such fluctuations in gas or coal prices. In places like New Mexico, for instance, “we’re seeing really remarkably low prices for wind energy,” he said. “[T]his is a long-term power purchase agreement price, so it’s an energy price that’s fixed.”

Various factors have driven the cost decrease in wind over the past couple of years, including better turbine technology and increased competition among turbine manufacturers, he said.

Thinking outside the box

Also participating in the webcast was Lisa Szot, head of transmission and land management North America with Enel Green Power North America.

Enel has had to think “outside the box and [try] to figure out within the realm that we have, and the confines of the transmission,” she said, adding, “[E]verything is sort of in the state of change in the transmission world concerning any of the interconnection.”

One thing that Enel has done is turn some of its projects into hybrid projects in order to use the interconnection capacity to the maximum of what is available. 

For instance, she added, Enel built a solar PV project on the same site as its geothermal project, which then generated an additional 24 MW of peak energy. “[I]t doesn’t only improve the production profile of our project, but it also allows us to make use of the same infrastructure and that also reduces the environmental impact,” she said. “The one thing that Enel has at its benefit is its very diverse and unique portfolio of technologies that we can present together.”

The company has taken the diversity of its portfolio and combined the resources to present to offtakers a firmer product by mixing the different renewable resources, she said.

“We’ve mixed solar with hydro…[and] we’re mixing [concentrated solar power] with geothermal…to provide a better output for the offtakers, so many of these things that we’re doing are sort of our way of trying to work around some of the transmission constraints that we’re seeing,” Szot said.

Among other things, she said Enel is also working on scenarios where it will use existing interconnection rights and come up with displacement agreements in order to work with gas plants or other types of fossil fuels to displace their power output in order to allow Enel’s plant to operate and not overuse any of the interconnection lines that exist in the system.

“[T]his way, we better utilize the transmission grid without having to incur costs and deal with the long timeframes that we’re seeing now, primarily in California,” she said.


About Corina Rivera-Linares 3286 Articles
Corina Rivera-Linares was TransmissionHub’s chief editor until August 2021, as well as part of the team that established TransmissionHub in 2011. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial from 2005 to 2011. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines.