With emerging microgrid technologies, utility companies are beginning to see microgrids pop up on their electric systems which could vastly change utility rates and procedures.
In an effort to learn more about microgrids both technically and socially, City Utilities of Springfield, Missouri, a municipal utility; Ameren, an investor-owned utility; and the Missouri University of Science & Technology, teamed up to answer pending microgrid questions.
Housed on the Missouri S&T campus are four student-built, student-occupied solar homes which run entirely on renewable resources. This small community of solar homes created a perfect environment to research, educate and demonstrate microgrid technologies and also to discover any problems that may arise when utilized in a residential setting.
The research was conducted using funding from a federal Demonstration of Energy & Efficiency Developments grant, along with funding from Ameren and several other partners. The intent of the research was to explore the connection of the four solar homes to a centrally-managed microgrid.
The central point of the microgrid is maintained by a lithium-ion battery bank. Within the central point of the microgrid is an intelligent switchgear and a 5 kilowatt natural gas fuel cell. The lithium-ion battery bank serves as the repository for all energy generated from the solar homes and is backed up by the fuel cell.
The intelligent switchgear monitors the feeds of all energy sources and loads and then delivers this data in real time. If electricity produced by the solar homes were to be inadequate, the natural gas fuel cell would provide uninterruptible power as long as natural gas is obtainable. If energy is not available within the batteries to feed the homes, power from the local utility company, Rolla Municipal Utilities, is used.
A total of 24 kilowatts of solar photovoltaic power is generated by the four-home community. As a way to test all possibilities, the microgrid was comprised of different components. In addition to the homes being a source for energy consumption, an electric car charging port was installed in the solar home community to increase the energy demand and create a more realistic example of energy usage.
The Missouri S&T microgrid research was unique because residents were able to actively receive feedback of their energy usage on energy monitors throughout the homes. For residents, the intelligent switchgear provided a way to observe the fluctuation of their energy usage. This could be an attractive feature to residents who are considering using energy funneled through a microgrid.
As with any research, the conclusion of a project often means there are questions left unanswered. Microgrids would provide residents with first-hand knowledge of their energy production and consumption, which is a great thing; however, this may not be such a great thing for municipal utilities. Why?
The use of microgrids could dramatically affect utilities that use time-of-use rates. Microgrids have the potential to use energy at low rate times and then produce and sell back energy to the utility company at higher rate times. If overall consumption is less than the amount generated, it seems that microgrids would result in neutral revenue for the utility company.
Over the past year, City Utilities, Ameren and Missouri S&T have continued their research in microgrid technologies to try to answer outstanding questions. A Grid Engineering for Accelerated Renewable Energy Deployment grant of $5 million has been awarded to the team to create a renewable energy curriculum to educate those interested in utilizing microgrid technologies.
Hallie Heinzler is Electric Line Operations Analyst at City Utilities of Springfield, Missouri.