What is a microgrid?
A microgrid is a local energy grid with control capability, meaning it can disconnect from the traditional grid and operate autonomously. In comparison to the larger, traditional grid, the localized microgrid can reduce costs, increase reliability, and scale up renewables through combining local energy production and storage.
A microgrid generally operates while connected to the grid, but, through the flip of an automated switch, it can break off and operate independently using local energy generation. This capability is important when there are storms or power outages, when repairs need to happen to the grid, as a cost saving measure, or to connect to a local resource that is too small or unreliable for traditional grid use. A microgrid allows communities to be more energy independent and, in many cases, more environmentally friendly.
The localized microgrid can be powered by distributed generators, batteries, and/or renewable resources like solar panels.
Microgrids in Action
A microgrid comes in a variety of designs and sizes. A microgrid can power a single facility like the Santa Rita Jail microgrid in Dublin, California. Or a microgrid can power a larger area. For example, in Fort Collins, Colorado, a microgrid is part of a larger goal to create an entire district that produces the same amount of energy it consumes.
Another example of a microgrid in action is UC San Diego. A reliable power supply is essential for sensitive electronic equipment on campus; the microgrid helps to ensure that power is available always through on-site power generation and energy storage.
The UC San Diego microgrid, which covers over 92% of campus electricity needs and 95% of heating and cooling, includes renewable and conventional power sources such as:
• 2.2 MW of solar
• 2.8 MW from a methane-powered fuel-cell (methane from landfill gas)
• Two 13.5 MW combined-heat-and-power gas turbines
• A 3 MW steam turbine
• Several hundred kW of battery storage
• Steam and electric chillers to store cool water at night for building cooling during daytime
UC San Diego is a model for microgrid design, especially cost effectiveness; the microgrid saves UC San Diego an estimated $850,000 a month on its electricity bill,”largely due to the economics of generating their own power at high efficiencies with combined-heat-and-power.