Connecting renewable generation to the grid faces technological and regulatory challenges
A wave of renewable energy generation construction has swept the nation, accounting for the majority of new capacity over the last two years, and that has led to a new challenge—getting it all on the grid in the most efficient way.
“The competitiveness of wind and solar has made them a go-to option,” said Aaron Bloom, project manager for the National Renewable Energy Laboratory’s energy modeling and forecasting group. “It is creating a period of transition.”
“There are a lot of different ways to integrate renewables,” Bloom said. “The first question was can we do this, and now we are transitioning into how can we do this the most efficient way.”
While there have been big strides in residential rooftop solar, the biggest current growth and projected future growth is in utility-scale solar and wind projects. That is where there has been a big focus by operators and regulators on interconnection issues.
The wholesale power markets of multi-state regional transmission organization (RTOs) or independent system operators (ISOs) are where a lot of questions of renewable generation grid optimization are being hashed out.
“The RTOs are leading the way in this. They have fast markets, and they are large,” Bloom said. “They have a lot of buyers, and they have a lot of transparency, and they are doing a better job of coordinating with their neighbors.”
An RTO such as the Midcontinent Independent System Operator, whose territory stretches from Canada to Louisiana, can more easily balance intermittent renewable energy. “If the wind isn’t blowing in one place, in such a large area, it is blowing someplace else,” said Drake Bartlett, a senior trading analyst with Xcel Energy, and in such a large market, there are almost always buyers for excess solar or wind power.
There are, however, problems with which the RTOs are wrestling. ISO New England has revised its application requirements for interconnections. “There was a feeling they were getting delayed by inaccurate or insufficient information from developers,” said Steve Garwood, a principal and senior consultant at PowerGrid Strategies LLC. “They don’t want half-baked projects in the queue.”
Before connecting a project to the grid, the operator has to assess if the addition would create any reliability criteria violations, such as thermal overloads, voltage violations, and stability and short circuit problems. The ISO also has be able to able to determine what would be necessary to resolve the problems.
Under the new rules, inverter-based resources need to provide a minimum amount of information including models on system impact, Garwood said. “It is going to require more time on the part of the developer, but should prevent the starts and restarts and delays.”
Still, Garwood said, “When you make changes it helps someone and hurts someone . . . There hasn’t yet been a perfect design for interconnection.”
More and better data will be increasingly important, said Bloom. “People are going to ask for a lot of data going forward because they want to understand what is happening on the system and have ability to plan and integrate better,” he said.
A rule on new project interconnections in the PJM, the electric grid operator serving 13 Mid-Atlantic and Midwest states and the District of Columbia, has drawn a legal challenge from four environmental groups. Under the rule, all generation in the PJM market has to be deliverable year-round.
PJM said the rule will provide greater grid reliability and the Federal Energy Regulatory Commission (FERC), which regulates wholesale power markets, approved the new rules. In September, the Natural Resources Defense Council (NRDC), the Sierra Club, Earthjustice and the Union of Concerned Scientists filed suit seeking to overturn the FERC approval.
“PJM requires year-round delivery that presents a challenge for some renewable,” said Jennifer Chen, an attorney with the NRDC’s Sustainable FERC Project. “These are rules that are favorable to traditional generation. We are trying to make the rules for flexible.”
The issue is that while solar and wind resources may not be available at all times, when they are, they are often among the cheapest generation. “Not all generation needs to be available all the time,” Chen said.
“We have capacity markets which are supposed to be competitive markets, but that depends on how the rules are written,” Chen said.
Bill Babcock, a consultant at PA Consulting Group, however, maintains that a rule like PJM’s makes sense. “If you are going to get credit for capacity, you need to perform when you are needed,” he said. “I as a consumer want to buy something that I can depend upon.”
And it isn’t just an issue for renewable generation, he said. During the polar vortex of 2104, when temperatures plunged in New England, natural gas supplies became tight due to increased demand and pipeline constraints. Only 27 percent of the natural gas-fired 11,000 megawatts was in operation. In the wake of that incident, Babcock said there has been an effort to “incent operators to ante up for firmed gas.”
Many of the battles and decisions on the future of interconnection and integration for wholesale power are begin hashed out at FERC. In 2015, the American Wind Energy Association, an industry trade group, petitioned the commission to amend the Large Generator Interconnection Procedures (GIP) and Large Generator Interconnection Agreements (GIA), contending they are “unduly discriminatory and unreasonable barriers to generator market access.”
“In May, FERC had a technical conference on the petition and asked a lot of good questions,” Chen said. “The aim is to update large generator and small generator interconnection agreements looking to make it less onerous.”
That, however, is only the beginning. New technologies, such as battery storage are also set to change the way the grid operates.
“There have been regulatory hurdles to storage participating” in markets, Chen said. “The rules don’t contemplate a category for resources that can absorb energy at times and inject energy into the system at other times,” she said.
On Nov. 17, FERC issued a proposed notice of rulemaking to amend the Federal Power Act “to remove barriers to the participation of electric storage resources and distributed energy resource aggregations in the capacity, energy, and ancillary service markets operated by regional transmission organizations and independent system operators.”
At the same time, the commission issued another notice of proposed rulemaking to modify the regulations aimed at ensuring grid stability, accounting for technological improvements in renewable generation.
The proposed changes, FERC said, will “ensure fair and consistent treatment for all types of generating facilities, helping balancing authorities meet their frequency response obligations.”
“There is a lot more potential if we remove the barriers to renewable energy, which occur every step of the way,” Chen said. “We’ve been making progress, but we haven’t gotten to fully competitive equality.”