Solar-powered charging: a step towards zero-emissions driving

Using the electric grid to power up your EV? Your environmental footprint may be larger than you think. Charging stations that use clean, solar energy to power up your car may be available in your local parking lot in the not-so-distant future.

How about charging your car while it waits for you in the parking lot? What if your driving could leave absolutely no environmental footprint?

Electric vehicles are all the rage these days, and clean energy is increasingly becoming a priority. But what many people don't realize is that our electricity has to come from somewhere -- and the U.S.' electricity sources are not always clean, or renewable.

In 2009, nearly 45 percent of electric power generated in the U.S. came from coal, according to the Department of Energy. Another 23 percent came from natural gas.

U.S. Electric Power Industry Net Generation - 2009

If we are serious about transitioning our cars to clean energy, making them electric is only half the battle. Making sure our electricity comes from clean sources is an entirely different matter.

Envision Solar, a California-based sustainable infrastructure designer, recently completed production on its first commercial "Socket," a canopy-style structure whose solar panels convert solar energy into electricity, charging your car while simultaneously shielding it from the sun.

Envision is not the only company to consider solar-powered EV charging or even the solar tree model. But its patent-pending EnvisionTrak technology re-orients solar panels according to the sun's position, increasing energy output by approximately 20 percent, according to a statement by Envision. See how the system works:

Envision Solar hopes to install its Socket in outdoor public parking areas, making otherwise unproductive areas more energy-efficient.

“We saw a need for a “mini” Solar Tree product offering, which would allow car dealerships, public agencies, utility companies, shopping centers, individual homeowners and many others to generate clean energy virtually anywhere the sun shines and shade is desired," said Envision President Desmond Wheatley in a statement.

I spoke with him recently about the Socket and the benefits of charging EVs using solar energy.

SP: Why is solar power the clean energy solution?

DW: First, it's American, it's yours, it's ours. We're not getting it from elsewhere. The coal industry is supported by foreign oil. You can't dig coal out of the ground and you can't run the coal plant without burning oil to do it.

The electric power grid in the U.S. is already under quite a lot of stress. An EV can add anywhere from half a single family residence load to two single family residence loads to the grid. Right now we're driving cars down the road powered by coal. It's a little bit like going back to the days of the steam engine.

We want to make EVs 100 percent emissions free - not just tail-pipe emissions free. We also want to minimize the grid impact of EVs. If a vehicle is plugged into Envision's infrastructure, it is generating power without pulling electricity from the already-overtaxed electric grid.

SP: On a sunny day, how long would it take to charge a typical car?

DW: Each vehicle has a different range. We would anticipate charging one average-sized EV per day using the Socket. We are combining it with battery storage in a couple of markets. We take the sunlight, convert it to electricity, store it in a battery, take that battery energy and run it through electric vehicle charging stations. This allows people to charge their vehicles 24 hours a day.

SP: What happens if it rains for two weeks straight and not enough solar energy is produced?

DW: In that case you have a fallback - the electric grid. Range anxiety is a big impediment for the adoption of electric vehicles, so we want to provide a reliable source of energy. Also, until EV adoption is widespread, these charging locations will often sit empty at first. Since we're grid-tied, the energy being created is offsetting the energy on the electric grid.

SP: How much will one unit of the Socket cost?

DW: It will depend on the local incentive market. On average, the Socket currently deployed will cost less than US$20,000 after incentives.

Photo: Envision Solar

This post was originally published on Smartplanet.com