Earlier this year, thousands of residents in the Porter Ranch neighborhood of Los Angeles had to evacuate their homes and schools after a natural gas leak — the worst on record in the United States. For over 10 weeks, a damaged well in Aliso Canyon oozed methane and ethane, leaving residents with nosebleeds, nausea and headaches.
As a safety precaution, regulators drastically reduced the natural gas reserves in Alison Canyon, taking them from 86 billion cubic feet of stored gas to 15 billion. The leak hit just as LA was heading into a sweltering summer season when energy demand typically peaks. Officials worried that the reduced levels of gas reserves would mean rolling blackouts for LA residents.
So California Governor Jerry Brown put out an urgent call for new ideas that would make the gas remaining in the storage facility go further.
Engineers at Current, GE’s energy startup, which works on new ways to reduce, use and store energy, realized they could offer a solution to Southern California Edison, a longtime GE customer. They were already working with GE’s Power Services and Wellhead Power Solutions businesses on a hybrid electric gas turbine (Hybrid EGT) to reduce fuel burn. The technology could also help at Aliso Canyon.
The GE Hybrid EGT is the world’s first gas turbine and battery storage hybrid, coupling a 10-megawatt battery with a 50-megawatt (MW) GE LM6000 Gas Turbine. The whole thing is operated by an integrated digital turbine control system.
Under normal conditions, some gas turbines must run at minimum loads in order to provide reserves to the grid. This maintains the reliability of the grid but forces the turbines to run at inefficient minimum loads and burn gas even when they’re not really needed
The new hybrid system uses excess power from the turbine to charge the battery. The battery then responds quickly to any changes in power demand and allows the gas turbine to operate at a smoother rate. This increases efficiency and reduces maintenance costs.
A hybrid car is a good analogy for the new system. The engine charges the battery when it’s running, and when the engine isn’t really needed, say at a stoplight, it can turn off and let the battery take over.
There are other benefits to the hybrid solution. The Hybrid EGT can provide voltage support to the grid and get turbines up and running quickly to return the grid to normal operation after an outage.
“The EGT solution allows GE to unlock 50 MW of gas turbine response capability with the addition of only a 10-MW battery,” Heinzmann says. “As battery systems have become more standardized and costs have dropped, we can now economically create this hybrid solution.” Naturally, the hybrid system also helps lower greenhouse gas emissions.
The hybrid design (which uses the GE OpFlex turbine controls software) will be deployed at two Southern California Edison sites later this year.