Micro Grid Sets Stage for Reliable Renewable Energy Network

The State of California is transitioning its electric power grid from hydro- and carbon-based central power generation to an equal blend of central power generation and distributed generation from renewable energy sources.

However, major issues must be resolved before the 50/50 split between central plant and renewable energy generation can be achieved – from the management of the intermittent nature of renewable energy sources such as solar and wind power, to the best methods of coordinating and controlling large-scale distribution of renewable energy resources.

WSP is designing a project to demonstrate a micro grid that combines solar generation and two forms of energy storage – large-scale battery for electrical energy storage, and large-scale thermal energy storage. Currently in the final design stage, the micro grid will be integrated into the electrical grid of Las Positas College, a community college in Livermore, California.

“The Las Positas College grid provides a unique opportunity to study and evaluate means and methods to manage impacts to the grid from high-density renewable energy generation sources,” said Bruce Rich, area construction manager and program manager for WSP.

Using this combination for micro grid control technology, he said, is “an innovative combination of multiple energy storage and generation sources.”

He estimates the immediate benefit to the college will be $100,000 in annual cost savings, adding that the local utilities will benefit from a reduction in power surges, plus a reduction in longer-term peak energy usage.

“This is an exciting innovation with multiple reapplication,” Rich said. “Energy storage and the micro grid software are key to effective use of renewable energy sources.”

Funding for the project included a $1.5 million grant from the California Energy Commission (CEC). WSP developed the proposal that demonstrated the benefits of a micro grid system, which led to the project winning the grant. The project is also co-funded with $300,000 from Las Positas College and $150,000 from the battery vendor.

WSP has worked with Las Positas College over the last eight years to develop on-site sustainable energy, reduce overall energy use and reduce the cost of utility charges.

“As the amount of energy purchased was reduced, the charges for peak energy use became a significant part of the energy bill,” Rich said. “When the CEC demonstration grant was announced, it provided us with an opportunity to solve the problem with these demand peaks and reduce energy expenses.”

Work on the project began in June 2015, with completion expected by December 2017. With its ability to decrease power demand charges, schedule energy purchases more efficiently, and use solar energy more effectively, Rich anticipates that the micro grid system will serve as a blueprint for evaluating, planning and installing energy storage and energy management micro grids at the hundreds of California educational facilities with solar photovoltaic systems.

“Every project that includes renewable energy, sets a net zero energy goal, or wants to reduce peak demands can use this technology,” he said.

The Las Positas micro grid project uses an energy operating system and energy management applications developed by Growing Energy Labs, Inc (Geli) as the micro grid controller. The Geli system combines historical patterns with real-time data to manage the storage and discharge cycles.

“The system will direct storage of excess PV generation to charge the battery and run mechanical chillers to make ice and release that energy at night by discharging the batteries and cooling buildings using the ice rather than chillers,” Rich said. The GELI system will also communicate with local utilities to absorb excess energy or release stored energy.

“The Geli energy management system is based on the concepts of internet connectivity,” Rich said. “Communicating with a standard protocol using a standard operating system allows equipment vendors and utility companies to develop applications that interface their equipment, programs or applications with all other devices on the ‘internet of energy’ allowing coordination of assets and moving energy effectively.