See the first article in this series on geothermal values “Is Geothermal the Only Baseload Power Replacement that Makes Sense?” here.
Geothermal’s dispatching benefits are being used optimally today at Ormat’s Puna geothermal facility in Hawaii. The facility was recently expanded with a contract that dedicates eight of its 38 MW to providing flexible capacity for grid support.
“To expand our facility, Hawaii Electric Light Company, the utility, needed to be able to dispatch us to follow electric load,” says Sullivan. “Though it turns out that we’re not dispatched down all that much, and that’s because we’re a low cost provider.”
“This is the only geothermal plant we know of that uses AGC,” adds Sullivan — that’s Automatic Generation Control. “To visualize it, there’s a control room at their operation center, so they basically have control of our 8-MW unit remotely and they can turn it up and turn it down based on the grid’s needs,” he explains. “It’s fully completely dispatchable; this is the highest bar when it comes to flexibility values.”
Sullivan explains that unexpected changes in the load such as those caused by intermittency can be more dramatic on an island than on a bigger grid, so the Puna facility can be considered “a case study on a micro scale.” Puna is the only plant that has dedicated ancillary services, but the capability exists for most binary geothermal plants built in the past decade; sooner or later, developers hope, more markets will catch up to the benefits.
It may just take time to see ramping valued, especially in valuing renewable energy technologies. “With most modern gas turbines, there is a marketing push for fast ramping turbines because that’s what everyone wants; well, geothermal is already there, and we come with the added benefit of being able to be flexible without the CO2,” says Sullivan.
Recently a Wisconsin geologist with a career in the oil and gas and portland cement industries approached the GEA explaining his interest in geothermal energy: “Arguing for renewables, particularly geothermal, is justifiable in itself when carbon-based fuels are the primary cause of the Earth's present climatic imbalance.”
The worsening consequences of climate change are manifesting in extreme weather events that have devastated communities as diverse as the Eastern Shore of the United States and the Leyte geothermal area of the Philippines. Carbon reductions will need to reach as much as 80%, leaving little room to spare; the Union of Concerned Scientists and the U.S. Environmental Protection Agency (EPA) show that the natural gas share of electric sector CO2 emissions grew from 15 percent in 2008 to 24 percent in 2012.
So, natural gas is often viewed as a bridge fuel, but when geothermal is used optimally in the places where it’s available now, it provides environmental savings at zero or near-zero emissions (see Table 2 below from GEA’s report, “The Values of Geothermal Energy”).
In some of those places, the problem remains that systems aren’t set up to take advantage of the technology benefits.
“In California, for example, the contracts right now are not set up correctly; that’s not to say it won’t be fixed in the future,” says Sullivan. California’s system ignores geothermal flexibility as well as other positive values it can offer to the grid, including its role as a non-intermittent baseload power source and its other significant ancillary benefits including frequency control.
Yet California’s Salton Sea Known Geothermal Resource Area represents one of the greatest opportunities for new geothermal energy development in the U.S. The state’s Renewable Energy Credit (REC) program and geothermal governance will be further explored in an upcoming article in this series on the values of geothermal energy. See also a new report on the state of geothermal energy in California.
This article was originally published on GEA's Geothermal Energy Weekly and was republished with permission.
Lead image: Geothermal plant steam via Shutterstock