Maine could be a prime location for a pilot project that converts surplus electricity from wind farms and other renewable generators into a gas that can be stored in underground pipelines.
Such a project would help solve a growing problem, a top gas company executive told lawmakers this month.
The transmission lines connecting Maine’s far-flung renewable generators to the regional electric grid sometimes are too weak to carry all their power. When that happens, grid operators order generators to reduce output or even stop running, to prevent overloading and jeopardizing reliable service. The practice is called curtailment.
At one substation in northern Maine, there’s a bottleneck that forced grid operators to curtail 75,000 megawatt hours of renewable power last year, according to a recent legislative presentation. That’s enough electricity to run 10,000 homes.
Upgrading the transmission system is very expensive. It could be better if there was some way to soak up the wasted energy potential, not just for a few hours in huge batteries, but for days or even months.
There are ways, according to Kurt Adams, president and chief executive at Summit Natural Gas, one of the state’s gas distribution companies.
Plants that demonstrate these technologies are running in Colorado, and in California, which already produces more solar power than its grid can handle. And in Europe, where electricity is more expensive, plants like this are starting to be built at commercial scale. Two Summit managers just returned from touring plants in Germany, Denmark and Switzerland to get a first-hand look at the power-to-gas process or P2G, as it’s often called.
“The conclusion they came to,” Adams said, “is that this technology is where solar was in 2005 or so. The cost is starting to come down, the technology is becoming commercial, and its role in the energy mix is becoming clearer.”
POTENTIAL POWER SOURCES
That’s where Maine could play a leadership role in the evolving development of power-to-gas, Adams told a special legislative committee studying ways to attract energy storage projects to Maine. He cited the Keene Road substation in Lincoln, where power from area wind farms, hydro-electric dams and biomass plants converges on its way south. Congestion there forces ISO-New England, the grid operator, to curtail 75,000 megawatt hours a year.
This situation will worsen and will force curtailments at other choke points in Maine and southern New England, Adams said. That’s because policies in Maine and other states to fight climate change and reduce carbon emissions are encouraging developers to bring on big slugs of solar energy in the 2020s.
One evolving solution is to store excess generation in giant, lithium-ion battery banks. Maine’s Commission to Study the Economic, Environmental and Energy Benefits of Energy Storage has been learning about existing projects and policies in other states that create incentives for developers. On Dec. 2, it plans to finalize its recommendations for the full Legislature to consider next year.
Asked if Summit is positioning itself to develop a project in Maine, Adams said it’s too soon to say. Summit’s primary motivation, he said, is to make the Legislature aware of P2G options and to lobby for policies that level the playing field with battery storage, as a way to attract private investors.
P2G is getting attention because today’s grid-scale battery banks can only absorb enough electricity for a few hours of discharge. For now, their chief roles seem to be in balancing output on the grid and providing bursts of power during periods of peak demand.
That’s why Summit is highlighting the potential for a pilot P2G plant near the substation in Lincoln. From there, gas could be injected into the nearby Maritimes & Northeast Pipeline system. By raising and lowering pressure on the system, pipeline operators could make room for the gas and keep it at the ready until demand is high.
“What power-to-gas does,” Adams said, “is allows you to store the energy indefinitely.”
To do this, power-to-gas technology uses surplus renewable electricity to create hydrogen and natural gas, or methane.
For instance: During the winter, wind farms in eastern Maine may produce more power than they can feed into the grid. The pilot plant could use surplus electricity and equipment called an electrolyzer to extract hydrogen and oxygen from water, capture the hydrogen and mix it with natural gas in the pipeline system.
A further step could turn the hydrogen into natural gas through a process using carbon dioxide. In Colorado, the federal National Renewable Energy Laboratory has partnered with California gas utility SoCalGas to build the nation’s first biomethanation reactor.
In Germany, methane gas derived from wind power and created through the methanation process is now being fed into gas pipeline networks.
RENEWABLE GAS OPTIONS
Besides surplus wind and solar energy, Maine has other significant resources that could be used to generate renewable natural gas, according to Brad Bradshaw, president of the Velerity management and consulting firm, as well as the Portland-based Hydrogen Energy Center. In a presentation to the study group, Bradshaw outlined the potential from landfills, which emit methane as waste decomposes, as well as dairy farms and municipal wastewater treatment plants.
In Maine, a couple of landfills already tap methane for onsite generation.
Summit is partnering with some central Maine dairy farms on a project to turn cow manure into renewable natural gas and inject it into its distribution system. The facility is due to be online in 2021.
At the Brunswick Landing business park, an anaerobic digester system uses municipal and other organic waste to create methane gas and generate electricity. A second digester is in the planning stages, according to the Midcoast Regional Redevelopment Authority, which operates the business park. A manager with the digester’s owner, New York-based Genesis Industrial Group, couldn’t be reached by phone or email to ask about the company’s latest plans.
These and other ventures form a backdrop for recommendations that will be finalized in the coming days at the study commission.
Rep. Tina Riley, D-Jay, who’s on the commission as well as the standing legislative committee that handles energy issues, said she expects the group to recommend storage targets and incentives – but not mandates – some that could be folded into the state’s Renewable Portfolio Standard. That law mandates increasing levels of solar, wind and other non-fossil generation.
“Setting a goal gives a clear signal to developers that we are serious about moving forward, and that is key to encouraging growth,” she said.
Riley also is preparing a bill that would encourage a few pilot projects. She said the combination of natural gas pipeline capacity shortfalls in the winter, the trend away from oil heat and growing transmission congestion suggest Maine should offer limited support to emerging P2G technologies that offer solutions.
“It is my intention that we allow the market, rather than the government, to decide what direction our clean energy economy takes, to the greatest degree feasible,” she said.
When Riley’s bill does come up for a hearing, chances are it won’t be universally embraced.
For one thing, some environmental groups are opposed to any incentives that prop up the natural gas industry. In southern California, where renewable natural gas has become an issue for debate, groups such as the Sierra Club label it “greenwashing,” more of a public relations campaign than an earth-friendly solution. Some critics point out that the pipeline system is mostly filled with natural gas and contains only a minor proportion of renewable gas.
Adams, a former Maine PUC chair and a chief development officer at now-defunct wind farm developer First Wind, said he’s aware of that criticism. But to combat climate change, he said, it’s a mistake to write off the role of a nationwide energy pipeline system, in the belief that renewables alone can do the job.
Riley said she, too, has heard these arguments. But in her view, power-to-gas can make a positive contribution in Maine.
“There’s plenty to pick apart,” Riley said. “But the takeaway is, it’s far better to be using a renewable resource. Any amount of fossil fuel we can replace with renewables is a step in the right direction.”