Tesla Motors and other manufacturers have set their sites on achieving lower lithium-ion battery costs through economies of scale, which should enable power storage systems for solar energy.
By Tesla's own estimates, a project to build a battery factory called the "Gigafactory" is expected to drive down the per-kilowatt cost of its own lithium-ion batteries by more than 30% in its first year of production. The factory is expected to open in 2017.
By 2020, Tesla believes its Gigafactory will produce more lithium-ion batteries in one year than were produced worldwide in 2013.
"We're planning to build a large scale factory that will allow us to achieve economies of scale and minimize costs through innovative manufacturing, reduction of logistics waste, optimization of co-located processes and reduced overhead," according to Tesla's blog earlier this year.
Liquid batteries with a 20-plus year lifespan
Tesla's not alone in pursuing a cheaper, more efficient battery. Start-up Ambri is developing a liquid metal battery that it claims is less expensive and longer-lasting than lithium-ion batteries; the Massachusetts-based company also has the backing of Bill Gates and Total S.A., a multinational energy company.
Kristin Brief, vice president of corporate development at Ambri, said the company is initially targeting the utility market, and next year plans to deploy five prototype systems with 35 kilowatt hours (kWh) of capacity to five customers to test.
"Following those successful pilots, we'll be ramping up a manufacturing facility to accommodate full-scale deliveries in late 2016 or early 2017," Brief said.
Ambri's cells are made of three components: a salt (electrolyte) which separates two metal layer electrodes. The cells operate at elevated temperature and, upon melting, the three layers self-segregate and float on top one of another due to their different densities and levels of immiscibility (they can't blend together, like oil and water), according to Ambri.
Ambri's prototype battery cores come in three sizes: a 6.4-kWh pack, a 200-kWh pack and a two mega-watt hour (mWh) storage system.
Ambri hasn't released information on pricing, but Brief said the company "feels very good" about where it expects prices to be compared with more common lithium-ion or lead-acid batteries.
The liquid batteries are also expected to last at least 20 years. Internal testing has shown that after more than 2,000 cycles (powering and draining), the batteries retain their same capacity.
"Our results are fantastic," Brief said. "Lithium-ion, lead-acid and other types of batteries do see degradation in performance over time, but you really don't see that in our technology."
Today, battery systems for solar and wind power are too expensive, according to Jonathan Fishman, an analyst with PTT Research. A battery backup system typically consists of vehicle-style batteries and costs as much as $400 per kWh, Fishman said.
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