Enhancing Minnesota Power Grids with Battery Technology

By Joel Tallaksen, Renewable Energy Scientist

July 2017

Over the last decade, the percentage of renewable energy being used on the Minnesota power grid has begun to approach 28%. Much of this is due to solar and wind power production, which are beginning to replace the fossil fuel energy that Minnesota must import from other states. However, one very significant challenge remains as we increase the amount of renewable energy in our power production mix- the fact that both solar and wind energy are intermittent and depend on the sun or wind.  Coal-based electricity production is difficult to quickly increase or decrease to balance out the load as solar and wind production change. One way that Minnesota-based power companies have responded to the issue is to introduce the use of natural gas peaking plants. These plants can quickly increase or decrease their production to match customer demand for power. However, they still rely on fossil-based electricity or fuels purchased from other states.  

I recently had the opportunity to see new battery technology being installed in California that is helping to overcome this problem. As part of a multidisciplinary team organized by the University of Minnesota Energy Transition Lab, I visited several battery installations in California and Washington State.  Each of the batteries we saw used a different technology and was installed with a slightly different purpose.  All of these large batteries are capable of storing megawatts of electricity in shipping container size systems. 

Battery storage at the U of CA, San Diego

Storage Battery at the University of California, San Diego. This 1 megawatt battery can deliver up to 500 kWhr output. More of these battery modules, each in a shipping container, could be added to the system to increase capacity.

Using the latest generation of lithium-ion and flow cell battery technology, each of the battery installations solved unique power grid related problems in the locations they were at. For example, the lithium-ion batteries installed by San Diego Gas and Electric are specifically for late-in-the-day use when California’s power grid is stressed by the reduction in solar power production, there is added demand for cooling, and household electricity increases when residents arrive home. The Marine Corps Air Station Miramar uses a flow cell battery as part of their system to store solar energy, provide power during regional power outages, and help with redundant backup for a more resilient power source on the base.  At Washington State University- Pullman, the battery system helps stabilize the power grid. The battery helps maintain proper voltage and frequency at the end of the power grid, where electrical fluctuations could cause problems.  At a California farm, an iron flow cell battery is used to store solar energy for the computerized control systems and other electronic equipment used on the farm.  By integrating electric storage batteries into their grids or micro-grids, all of these systems increased the overall amount of renewable energy being used on the grid. 

After a major natural gas storage leak and environmental issues with natural gas power plants along the coast, California regulators sought out new technologies that could complement renewable energy production to increase the amount of renewable energy being used in California. According to experts in power policy and regulation in California, the batteries were, in some cases, viable alternatives to building new power plants.  Electric utilities and third-party companies also expressed interest in these large batteries as a business opportunity by storing power when it was cheap and selling it when in demand and the power was worth more.  

In the past, lead-acid and other batteries had very significant environmental issues and led to pollution near some mining and manufacturing sites. The new generation of batteries uses less toxic substances. In the case of the iron flow cell battery installed at the farm we visited, the equipment and liquid energy storage solutions were specifically selected because they are non-toxic and a spill would in no way contaminate the farm.  Many parts of the batteries are also made of metals that are easily recycled.  

The high price of electricity in California has meant that these batteries are a cost-effective means to store renewable energy for California electricity customers. As these batteries are used more in California and in other places with high electricity costs, it is likely that the costs will come down.  This is much like LED lighting, whose price has dramatically fallen as more and more LED lights are manufactured and sold.  However, the very low power prices in Minnesota limit the economic feasibility of batteries at the present time.  Currently, myself and others in Minnesota are examining the costs and benefits of these batteries and when they may make sense to use in Minnesota. Some battery technology has already been tested in Minnesota, but it would not surprise me if the latest generation batteries begin to be considered for projects in the state within the next few years.