Sempra Energy may be one of California’s three biggest utilities. But just like any other business, it wants to reduce its electricity consumption during peak periods and to cut its energy overhead. Its headquarters is located in San Diego. It is a 16 story building with 400,000 square feet — a complex that now utilizes a microgrid that integrates battery storage charged by solar panels. The building can rely entirely on the microgrid if the power goes out.
Any building or company could install a similar configuration. As for Sempra, the battery stores energy and releases that power during peak hours when electricity is priced at its highest levels. Energy consumption during high demand is falling dramatically, saving the utility thousand dollars.
“The microgrid controls the load at the meter,” says Chuck Wells, chief technology officer and founder of PXiSE Energy Solutions in San Diego, in an interview with Environmental Leader. “This means we can calculate what the load and flow should be to minimize their cost.
“The electric grid is being operated similar to 100 years ago,” he adds. “Power flows from large facilities to distribution networks to end-users. Utilities have no control over how much flow goes through their circuits. With microgrids, we can reverse that paradigm. We can control the loads — with energy storage and local energy generation behind the meter. Now we have the ability to control the flow at the metering point.”
Onsite generation, battery storage, and microgrids are becoming increasingly relevant as the green economy evolves. The global community is committed to solving the climate crisis and adding more wind and solar to the electricity mix. And commercial and industrial users are standing up and buying more renewable power. But those sustainable sources are intermittent.
The more traditional way of dealing with such weather-dependent energy sources is by creating “spinning reserves” — to keep fossil-fired generation running or to use units that can fire up in less than a minute. Electricity customers will not see the lights flicker on and off. It is seamless. But Wells says that microgrids are a more effective way to address intermittency. They can start up in “milliseconds” and have “thousands of shock absorbers.”
“A microgrid is a better proposition,” Wells says. The electricity feedstock is wide-ranging — and can come from solar panels, battery storage, or electric vehicle batteries that are accessible to the microgrid.
Virtual Power Plants
A microgrid is a system with one interconnection point to the primary grid. It can operate in “island mode” or connected to the network. And the flow — at the point of the interconnection — can be directed by a controller. A utility or independent system operator could remotely control electricity flow.
Think of it this way: an airliner is coasting on autopilot from New York to Los Angeles. When the wing dips, the autopilot levels the aircraft. Ditto for the nose of the plane that is dropping. That type of control drives the microgrid — an autopilot system for the primary network. Wells says that the system's brains are spinning at 60-times per second.
But some features allow commercial and industrial customers to offset their costs and recoup their investments. That is, their distributed energy resources — the assets behind the meter — can function as a virtual power plant. Simply, the utility could curtail services and save companies money. The business could also return power to the primary grid and get paid for it. Or, the enterprise could provide needed services to utilities, such as smoothing out blips in their frequency and voltage — things that won’t make the lights blink on and off.
Consider Santa Rosa Junior College: it is seeking to attain 100% renewable power by 2030 while also reducing its costs and increasing its resiliency — the ability to bounce back after an outage. To do this, it is building a microgrid to cover its 100-acre campus with funding from the California Energy Commission Electric Program Investment Charge. The purpose of the microgrid is to keep critical facilities operating if there is a wildfire or a planned outage. The mini-grid will reduce peak demand and overall energy consumption.
“The solution calculates what loads inside the microgrid can be shed,” says Wells. “It calculates this based on the constraints the user gives,” For example, the hospital and campus police may be assigned the highest priority for available power. Or, the physics department may take precedence over the athletic facilities. “The university can run as an island if it goes black. Or it may want to recoup its investment on batteries while it is connected” by selling power or curtailing it.
Microgrids enable companies to improve reliability — to keep their operations purring during an outage. But they have added benefits, including the ability to reduce costs and cut their CO2 releases — all evidenced by their effectiveness at Sempra’s headquarters and the Santa Rosa Jr. College.
