Salty solution to energy storage

Separate salt and water, and they long to come back together. That special chemistry could provide an innovative solution to the dilemma of storing and extracting surplus energy generated by intermittent energy sources such as solar, wind and wave power.

Entrepreneur and mechanical engineer Devesh Bharadwaj is a University of Victoria graduate who founded Pani Energy Inc. in March 2017—while still an undergrad—after he developed a more energy-efficient process to desalinate water for human and industrial consumption. Along the way, Bharadwaj got intrigued by the idea of reversing the desalination process as a means of storing energy, taking advantage of the concentration differences between salt and fresh water.

Pani Energy is a start-up formed in collaboration with UVic through the Coast Capital Savings Innovation Centre, the on-campus incubator that supports entrepreneurs through venture services, campus workspace, funding, connections, and business pitch and plan competitions.

Bharadwaj’s work with reversing the desalination process led to Pani’s new “Osmotic Energy Storage” technology. He will demonstrate that technology in Vancouver this week at the GLOBE Forum, a biennial three-day event to bring together business and governments from all over the world to accelerate the shift to a sustainable, clean economy.

The unpredictability of energy produced by sunshine, wind and waves is a major barrier to countries and regions that don’t have the mountainous terrain suitable for generating hydro-electricity. Intermittent sources provide clean, renewable energy, but can’t be counted on to provide consistent power when it’s needed.

“Take water up a hill and let it fall down, and it spins a turbine that produces electrical energy. The majority of the planet stores its energy this way, through what’s known as pumped hydro,” explains Bharadwaj. “But that requires a certain terrain—hills, mountains—to be able to take advantage of gravity. In the osmotic energy process, it’s the mixing of the salt and water that spins the turbine. Our method stores energy using a difference in salt concentration, making it unconstrained by geography.”

Similar to the way that a bank of batteries stores energy from solar panels for use on a day without sunshine, Bharadwaj’s technology stores it by using that energy to separate salt from water on sunny days, then mixing the salt back into the water to draw out that stored energy when it’s needed. The technology is intended for large-scale applications, as the tanks of briny and fresh water require significant space.

Bharadwaj expects the storage cost per kilowatt hour to range from 10 to 60 cents, a significant savings compared to costs of between 70 cents and $1.70 kw/h for storing energy in lead-acid batteries. “Our goal is to be cheap and environmentally benign,” he says. He hopes to have a pilot plant operational by 2020.

Funding for Bharadwaj’s work comes from the National Research Council, ECO Canada and private investors.

A backgrounder on Pani Energy is available.

A press kit containing high-resolution photos and video clips (interview and B-roll) is available on Dropbox.

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