By Robert Mullin

California must significantly upgrade its transmission system in order to meet its 2030 target of generating 50% of its electricity from renewable resources, according to an interagency study.

“We have either the seventh or eighth largest economy in the world — we need a grid to match that,” state Secretary for Natural Resources John Laird said during an Aug. 15 workshop to discuss the second iteration of the state’s Renewable Energy Transmission Initiative (RETI 2.0). The first initiative focused on helping the state meet a 33% renewable portfolio standard.

But there is uncertainty about the amount of new renewables needed to fulfill the 50% RPS — as well as the most cost-effective transmission solutions required to reach whatever resources are selected.

“It’s very difficult to predict what load will be” in the future, said California Energy Commission Chair Robert Weisenmiller, pointing out that demand for renewables — like other types of generation — will ultimately be driven by economic growth, the penetration of vehicle electrification and the success of the state’s “very aggressive” energy efficiency goals.

State officials conceived RETI 2.0 to determine what combination of renewable resources could meet their environmental goals most cost-effectively and what transmission will be needed to deliver their output. The initiative also seeks to identify the land use and environmental issues that could constrain development and access to resources.

The intended result: an “accelerated, agency-driven, high-level assessment to inform future planning and regulatory proceedings,” according to project director Brian Turner, of the state’s Natural Resources Agency.

Two Policy Developments

Two major policy developments last year drove the development of the initiative.

The first was Gov. Jerry Brown’s executive order directing California agencies to reduce the state’s greenhouse gas emissions to 40% below 1990 levels by 2030. That goal has so far failed to win legislative backing to become codified into law.

The second development was passage of SB 350, which not only increased the state’s RPS to 50% by 2030, but also set higher standards for energy efficiency in buildings, ensured utility progress toward GHG reductions, expressed intent to expand CAISO into other areas of the West and encouraged electrification of the state’s transportation fleet.

Those overlapping objectives are creating challenges for resource planners.

“How do you translate the high-level goals for SB 350 and the executive order into quantifiable objectives?” Turner asked. “How much [renewable resources] might we need to meet the 50% [RPS] by 2030?”

The initiative’s findings indicate that an additional 25 to 108 TWh of renewables will be needed, depending on growth in vehicle electrification, adoption of behind-the-meter solar and the success of energy efficiency programs.

That translates into 7,000 to 31,000 MW of new capacity, assuming a 40% average capacity factor — or 9,000 to 41,000 MW assuming a 30% capacity factor.

Adding to the uncertainty is that a 40% economy-wide GHG reduction could require the equivalent of a 55 to 60% RPS for the state.

Planners working on the initiative found that “environmental and land use constraints tend to favor in-state solar and out-of-state wind” for meeting mandates, but “determining the environmental and transmission access feasibility for in-state wind may [also] be a priority,” according to Turner.

He also said that while low-cost solar is “ubiquitous” in California, a focus on resource and technology diversity would be more cost-effective because of the “long-term integration challenges” posed by an overreliance on solar. Geothermal may offer “important benefits” by 2030, but more investigation is needed into the costs, benefits and transmission access to those resources.

‘Broad Support’

The planners also found “broad support” among industry participants for further assessing procurement of out-of-state resources, with a focus on high-quality, low-cost options that would be complementary to in-state resources. That task is made difficult by a lack of information about the potential for developing the resources themselves and the transmission options for reaching them absent a broader study in cooperation with other Western states, an issue the initiative is seeking to address.

The subject of transmission access fell to the RETI 2.0 Transmission Technical Input Group (TTIG), led by Neil Millar, CAISO’s executive director of infrastructure development.

Fully Deliverable

Millar said that California has sufficient transmission capacity to fulfill the state’s 33% by 2020 RPS, but more will be needed to meet the 50% RPS with “full deliverability” for additional renewable resources. While the TTIG estimates that there is “significant transmission available to accommodate resources beyond 33% on an ‘energy only’ basis” — which would allow for quicker and less costly interconnection — those resources would be subject to curtailment.

Under California regulations, a generating resource is considered “fully deliverable” if its output can reach its intended load sink without hitting constraints — which typically requires a contracted path from a generator to a utility service area. The state’s rules also allow a utility to count those resources toward its resource adequacy requirement. “Energy-only” resources have no such requirements for deliverability and cannot be counted as capacity.

“The sufficiency of [energy-only resources] from a policy perspective is yet to be determined,” the group found.

To explore potential transmission solutions, the group evaluated seven internal and four transmission assessment focus areas to determine what transmission upgrades would be necessary to make new renewables fully deliverable into each area’s load centers.

For example, the San Joaquin focus area can currently handle 1,823 MW of deliverable and 3,131 MW of energy-only capacity, but developing another 5,000 MW of deliverable capacity to accommodate new resources would require upgrades costing about $440 million. Some areas — like the Tehachapi — would require few upgrades, while other areas require much more to open up renewable development.

Sushant Barave, a lead transmission engineer with CAISO, pointed out that transmission capacity is dynamic.

“Resource additions in one area may impact availability in other areas,” Barave said, adding that mitigating a constraint that limits flows through multiple focus areas would be the most cost-effective approach to planning.

Barave noted that energy-only resources might require less extensive upgrades, prompting CAISO CEO Steve Berberich to ask that a comparison between energy-only and fully deliverable requirements be made explicit in the group’s final report, to be published later this year.

The group also concluded that any out-of-state resources being delivered into California will be injected into one of the focus areas, subjecting new imports to the same transmission constraints as those faced by internal resources.

The potential for renewable imports from other areas of the West is still something of a blind spot for California grid planners. To remedy that, RETI 2.0 created the Western Outreach Project to “gather stakeholder input from across the Western Interconnection regarding the availability of renewable energy and transmission that could contribute to meeting California’s renewable goals,” according to Keegan Moyer, an Energy Strategies consultant working on the project — a collaboration with the Western Interstate Energy Board.

Key Questions

The project is looking to answer a number of key questions, including:

• How much additional renewable development is likely in the West?
• Where — and in which technologies — is development of renewables likely to occur over the next 15 years?
• How will the future mix of renewables affect daily and seasonal power flows in the Western Interconnection?
• What load centers could potentially import surpluses from California?

The project also seeks to determine the existing load capacity to deliver power from high-quality renewable areas into California — and what constraints limit additional deliveries.

“How would different expansion options affect deliverability to and from California?” Moyer said.

Another project task is to gain insight into generation fleet trends, including coal plant closures that could free up transmission capacity in the interior West and possible changes to hydroelectric utilization in the Northwest.

The project will also seek to answer the question of how increased use of dynamic scheduling, conditional firm and energy-only resources, and other renewable procurement arrangements will impact transmission availability and needs.

“It’s pretty clear that we have a lot of options,” Weisenmiller said. “We have to do it in a way that minimizes environmental and economic impacts.”

“I think significant progress is being made,” said Michael Picker, president of the California Public Utilities Commission. “The goal here, I think, is to reuse as much as we can, so we don’t have to go new.”

“In the old paradigm we were looking at renewables. Now we’re looking at greenhouse gases,” Weisenmiller said. “We’re in a brave new world that will require a lot of new thinking about how the pieces fit together.”