The much-watched microgrid at Marine Corps Air Station (MCAS) Miramar took another big step this week with an expansion that will demonstrate landfill gas as a reliable fuel for an islanded microgrid.
Initially funded by $20 million from Congress, the San Diego, California microgrid is considered one of the most sophisticated under development with five distributed energy resources, including solar, energy storage, landfill gas, diesel and natural gas plant, and EV charging.
The first phase of the demonstration project paired solar and fossil fuels. Its second phase, announced this week, will demonstrate the interplay between landfill gas and energy storage, said Mark Feasel, vice president, electric utilities & microgrid at Schneider Electric, which is developing the microgrid in conjunction with Black & Veatch.
Out of waste comes power
This step is significant because it demonstrates a way to make landfill gas more useful in generating electricity — and swap it out for fossil fuels.
Given the worldwide need to manage waste — especially in light of rapid urbanization — the search is on for ways to make productive use of gases emitted from landfills. The world generates about 2.01 billion tons of municipal waste, a figure expected to grow 70 percent over the next 30 years, according to World Bank.
Often characterized as a renewable fuel, landfill gas brings with it the same problem of other renewables — it may not always be available when you need it.
“One of the challenges associated with landfill gas is the uncertain nature of its output,” said Feasel in an interview. “It’s not like burning natural gas that has been provided by a utility, filtered and cleaned and the same pressure at all times.”
Like solar energy, landfill gas is an intermittent fuel source, but even more so, he said. “We can predict [solar] radiance based on weather. With landfill gas we cannot predict precisely what’s going to happen.”
Its unreliable nature becomes a particular problem when the microgrid islands from the main grid and relies solely on its own generators.
“If you cannot deal with that intermittency, you can’t treat it [the landfill gas] as a fuel source during outages when you do not have the main grid,” he said. “So in a microgrid scenario, absent the ability to make up for that intermittency, you simply can’t use it.”
So in some cases, projects are forced to shut down the landfill gas generation while islanded.
The Miramar microgrid intends to demonstrate how to solve the probem with a battery energy storage system, which “stiffens” the output of landfill gas.
‘This allows us to maintain stable bus, frequency and voltage, even isolated from the grid,” he said. “It adds a big, new generation source that we frankly couldn’t have counted on in an island model.”
The battery, provided by Schneider, also will be used for other means, such as peak shaving and demand response.
The Miramar microgrid tour is sold out for Microgrid 2019. Space is still available to attend a special presentation on Miramar at the San Diego event, May 14-16.
“The microgrid is critical in allowing operations to continue if the utility power grid is compromised, and this expansion will enable enhanced capability to enable financial benefit and power assurance,” said Mick Wasco, installation energy manager, MCAS Miramar.
The California Energy Commission is funding the energy storage, and its integration and testing, through a $3.9 million grant from the Electric Program Investment Charge program.
Resources within the Miramar microgrid
- 1.3 MW solar photovoltaics
- 3.2 MW landfill gas
- 6.45 MW diesel and natural gas power plant
- 1.6 MW HVAC demand response
- 157 kW thermal energy storage
- EV charging station control
- 3 MW energy storage (microgrid system level)
- 390 kW building level energy storage (Lithium Ion and zinc flow batteries and vehicle-to-grid bi-directional hybrid vans)
- SCADA system upgrades
- Advanced microgrid control system
- Energy and Water Operations center (EWOC)
To be complete in 2019
The MCAS Miramar microgrid is scheduled to be complete this year. The project was contracted through the Naval Facilities Engineering Command (NAVFAC), Southwest.
“Because of their paramount need for critical power resilience, military bases are one of the types of facilities that demand microgrid implementation for islanding capabilities and integration of renewable DER,” Feasel said. “For the many facilities hoping to boost power resilience with renewable energy generation like the Marine Corps Air Station Miramar, microgrids are a sensible solution to boost power resilience and long-term sustainability efforts.”
Upon completion, the microgrid will have the ability to electrify the base’s 100 mission critical buildings, including its entire flight line, even during a power outage.
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