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The Supercapacitor In Your Next Microhybrid

By Bill Moore

There a pretty good chance that the next time you buy an automobile, even if it's not an EV, it's going to have a supercapacitor in it to help recapture braking energy and instantly restart your car's engine, among other functions now being explored by global carmakers as they search for evermore cost-effective solutions to reduce tailpipe emissions and improve fuel economy.

Here are two terms you need to become more familiar with: microhybrid and supercapacitor.

Why, you ask?

Because if industry projections prove accurate, in five years time there are likely to be 50 million motor vehicles on the world's road being powered by microhybrid powerplants. And, depending on what researchers at the United States Automotive Battery Consortium (USABC) and their cost-share partner, Maxwell Technologies, learn as a result of a newly funded $2.68 million grant, supercapacitors - also known as ultracapacitors - could reduce the size of electric car battery packs while also doubling their life span.

As electronic devices, capacitors have been around for as long as there have been batteries, but while both provide electrical storage, they differ fundamentally in how they store that energy and for what purpose, explains Jens Keiser, a senior product marketing manager for Maxwell Technologies, the market leader in the field.

Batteries are 'energy' storage devices, meaning they are design to chemically release electric current over a relatively long period of time: minutes-to-hours, making them ideal for propelling electric cars scores-to-hundred of miles.

Supercapacitor/Ultracapacities are 'power' storage devices. They are designed to release their electrical capacity from milli-seconds to a few seconds. They also can accept that power in similarly short spans of time. This makes them ideal for capturing the electrical energy created by a hybrid or electric car' regenerative braking system.

EV World's Bill Moore talks with Keiser in this 17:35-minute interview about the purpose of the recently-announced cost-share research program and the current state of the supercapacitor market in the automotive industry.

What he learned came as a surprise. Supercapacitors, which have been used largely experimentally in the recent past by various university teams in US DoE and General Motors-funded EcoCar Challenges, have now found their way into production vehicles: more than a million of them, to date, with the industry leader being PSA Peugeot Citroen in France with their e-HDi microhybrid system.

PSA e-HDi microhybrid drive system

What USABC and Maxwell are aiming to do over the next number months is to explore the opportunities and obstacles to marrying lithium-ion batteries to supercapacitors, a union that could not only reduce the size of the battery - and thereby its cost - but also increase its useful life. Research by Argonne Labs outside of Chicago suggests, says Keiser, that such a union should double the battery life since the supercapacitor, which is capable of tens of thousands of charge/discharge cycles, could handle the power demands of the vehicle drive system: acceleration, deceleration; with the battery doing what it does best: the gradual, steady energy release of powering the car down the road.

Of course, the trade-off historically has been the higher cost of supercapacitors, but according to Keiser, like lithium battery prices, those costs too are coming down. The future of supercapacitors seems bright enough, especially with a projected market of 50 million microhybrids by 2020, that Maxwell has built a new production plant in Arizona in anticipation of the need for their supercapacitors by carmakers around the globe.

Times Article Viewed: 12800
Originally published: 31 Dec 2014

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