There are interesting synergies between renewable energy and energy storage that have profound implications for the Smart Grid and our energy and economic security. Wind and solar are readily available domestic sources of clean renewable electricity and share a common characteristic of intermittency. Wind tends to pick up at night, and we all know when the sun shines. There are also weather-related influences that make it difficult for generation planners to have 100% confidence in these resources, unlike traditional fossil-fueled sources of electricity. Given the risk-averse nature of utilities in planning their power purchases, would they favor the purchase of renewable power from producers that could “firm” or commit that power with reserves of stored energy over those producers that couldn’t provide that additional assurance? Could renewable power producers with energy storage capabilities participate in ancillary services and increase revenue possibilities for their business? For instance, wholesale frequency regulation – the ability to inject power into the grid to maintain the desired frequency on the grid – could be supplied by clean energy storage instead of running fossil fuel-based generation facilities in a standby mode – a costly and emissions-producing practice.
What has prevented energy storage from playing a bigger role in the Smart Grid and being coupled with renewable sources of electricity? There are two reasons – technology and price. Energy storage technologies are experiencing a transformational boom, in part due to the Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E) focus on innovative breakthroughs for electric vehicle (EV) batteries. Grid-scale energy storage solutions are also benefitting from new interest and investment, and are poised to challenge traditional energy storage solutions. For example, traditional pumped hydro harnesses the energy of water running downhill to spin turbines and generate electricity, and then uses cheap, off-peak electricity to pump that water back to the top of the hill for reuse. But pumped hydro requires very select conditions – a ready supply of water, a steep hill, and the willingness to invest a billion dollars or so into a generation plant and transmission facilities.
And then there is price. Many energy storage technologies simply couldn’t compete with fossil fuels – although the negative externalities of CO2 and human health were not factored into these calculations to deliver true costs. But now there are new energy storage technologies that can cost-competitively store electricity. One interesting technology takes the common zinc-air battery, which is today used as a disposable battery for hearing aids, and makes it a high energy density and rechargeable energy storage option. What is most intriguing about zinc-air technology is what it is not – it is non-toxic and non-flammable, two attributes missing in some energy storage technology alternatives. Another positive attribute is the price point – it can achieve “grid parity” with natural gas.
One company that is focused on zinc-air is Eos Energy Storage, an east coast startup. Eos intends to sell their grid-scale product at $160 per kWh, which is one fifth the cost of a lithium ion battery system, according to Steve Hellman, president of the company. This price means that their grid-scale batteries would compete with gas-fired turbines to firm renewable power and ancillary services like frequency regulation. Since zinc-air technology is environmentally benign, it could easily be situated for distributed energy storage purposes in residential neighborhoods without complications of zoning for toxic or flammable substances. Distributed energy storage avoids the need to build expensive transmission facilities. This technology would also be welcome in substations because it would not introduce new safety risk factors for workers. In addition, zinc is readily available in the USA. Given our current energy and economic insecurities caused by a reliance on imported fossil fuels, we should look to domestic clean sources of energy and materials and leverage natural synergies between renewables and energy storage to speed their integrations into the Smart Grid.