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Solving Energy Storage: A Summary of Some of the Most Promising Technologies

By Rohini MukherjeeBlog, Environment

Energy storage has become increasingly, if not urgently, important at this stage in our planet’s evolution. Lithium-ion batteries have emerged as the most high-profile solution due to electric car companies like Tesla and electronics leaders like Samsung, both of whom use this technology in their products. However, a whole new generation of emerging technologies is coming onto the scene, seeking to help manage unpredictable renewable energy outputs to provide alternative and more cost-effective power for electric vehicles. Bloomberg New Energy Finance recently reported that the global energy storage market will surge to a cumulative 942 gigawatts by 2040, necessitating $620 billion in investment into this high-growth market. Sharply falling battery costs is one key driver of the boom.

The variability of solar and wind power makes it hard for electricity providers to integrate these increasingly popular forms of renewable energy into the grid. Grids need to be reliable and stable, continuously balancing the supply and demand of electricity. Energy storage plays an important role in this balancing act and helps to create a more flexible and reliable grid system. The potential temporal mismatch of supply and demand raises two fundamental questions: how to deal with variable renewable energy at times when there is too much supply, and how to serve demand at times when supply is scarce. Electrical storage can provide a solution in the form of batteries or pumped hydro storage plants, allowing grids to shift energy over time.

Recent years have brought that storage dream closer to reality. Companies all around the world are fighting to come up with the next great battery breakthrough. From the largest global automakers to the top energy research and development institutes, the search for the trillion dollar battery technology is on. Billions are being poured into research for solid-state batteries. The implications of cheaper batteries are far-reaching, upending multiple industries and helping spur technologies necessary to help fight climate change. Batteries power the electric vehicles (EVs) that are popping up all over freeways. They also unlock solar power from the exclusive confines of the sun.

Technology and policy are finally reaching a point where it’s economical to install energy storage at home. Tesla was a leader ahead of its time when it introduced its home battery, Powerwall, in 2015. In the summer of 2018, Volkswagen invested $100 million into QuantumScape, a California-based company working on its own solid-state battery. Founded in 2010 as a spin-off from Stanford University, the company is already considered a “unicorn” with a valuation over $1 billion. Massachusetts-based, Ionic Materials is working on replacing the liquid parts of lithium-ion batteries with plastic. It has garnered some attention from big names like Renault-Nissan-Mitsubishi, Hyundai, Total, and Hitachi. Urban Electric Power is revamping age-old alkaline battery technology into high-capacity, affordable zinc and manganese dioxide batteries for home and business use and is aiming to generate between $500,000 and $1 million in sales in 2019. Highview Power, on the other hand, completely bypasses the lithium-ion battery and other chemical energy storage solutions to create a zero-emission cryogenic energy storage solution at half the cost of lithium-ion batteries. To date, they have raised over $35 million in funding. Dyson, which is most well-known for its vacuum cleaners, is trying to become a major player in the solid state battery industry as well.

There is no doubt that Tesla is facing tough competition in the energy storage market and can no longer be considered a disruptor in this space. Moreover, almost all of Tesla’s battery cells are composed of lithium-ion, which has traditionally been the obvious choice for battery storage in vehicles. The automotive sector is pushing a lot of the battery innovations in the lithium-ion space. But lithium-ion batteries provide 4 to 6 hours of grid storage and up to a couple hundred megawatts in scale. Beyond this point the challenges of lithium-ion scalability become apparent. In a rechargeable lithium-ion battery, there are electrodes where the charge is stored, and to scale this technology and store more charge the electrodes need to be thicker. But these electrodes can only be manufactured to a certain thickness. There is a threshold beyond which if the electrodes are too thick they start cracking and the battery fails. So, there is a threshold where it doesn’t make sense to use lithium-ion in long-term storage that requires significant economies of scale.

At this point, the lithium-ion battery is overrated and the least cost-effective and accessible. Impact investors are moving to a new class of technologies that achieve scalability for cost-effective storage. Flow batteries have the ability to decouple power generation from energy storage so scalability is more achievable. Flow batteries have tanks of electrolytes that run through cells with positive and negative electrodes and a membrane that allows for an ion exchange to generate electricity. With this type of technology, cheap tanks are needed, as well as electrolytes and other systems components that allow for cheaper unit production of electricity as size increases. The two main disadvantages of flow batteries are their low energy density and low charge and discharge rates compared to other industrial electrodes. Low discharge rates require electrodes and membrane separators need to be large, which increases costs.

Long duration storage is a cost-effective sustainable storage solution that achieves low cost-per-charge and discharge cycle, which is critical component needed with most renewables. Tesla and its competitors in the battery-powered EV market dominate debate over who will control the future of cars, but there’s another energy storage technology making inroads in the United States, and it is based on the most abundant resource in the universe.

Hydrogen is one of the new programs of Mission Innovation, a major global initiative to accelerate public and private clean energy innovation. The question with hydrogen is whether you can take renewable energy that you can’t fully use when available and use it to affordably create hydrogen that can be stored and used across seasons. Because hydrogen storage in tanks is very scalable, it can be used to optimize the overall level of renewables required for meeting year-round electricity needs. Alternative fuel company Millennium Reign Energy is doing just that. Millennium Reign Energy has launched several fully automated hydrogen generators available for use across residences, small businesses and agricultural sites. Another application of hydrogen storage, fuel cell electric vehicles (FCEVs), combines hydrogen stored in a tank with oxygen from the air to produce electricity, with water vapor as the by-product. And unlike more common battery-powered electric vehicles, fuel cell vehicles don’t need to be plugged in.

Finally, electrolyzers use an electric current to provide the energy that splits a water molecule (H2O) into hydrogen (H2) and oxygen (O2). Electrolyzers create the hydrogen, store the hydrogen, and then use this hydrogen to produce electricity when needed, across seasons, either via a fuel cell or gas turbine retrofitted to burn the hydrogen for power. The largest-capacity energy storage projects are pumped hydro plants, which move water to uphill reservoirs using cheap off-peak electricity and then let it flow back down during the peak when prices are higher.

Wind and solar energy have transformed the energy landscape over the past decade and energy storage will do the same in the years to come. Batteries and energy storage will forever change the way we travel and drive the transition to electric and self-driving cars. The way we power our homes will be based on a new technology of storing energy. Our devices could last literally weeks – without having to find an outlet for charging. The possibilities are endless.