As it prepares to launch an electric-car mandate in coming years, Colorado is working to learn how electric cars can help it move to a more renewable energy grid.
The non-profit Platte River Power Authority announced last month that it is teaming up with eMotorWerks, which sells home smart chargers, to sell and install 250 smart chargers for residential customers that will help maximize the renewable electricity they use to charge their cars. Colorado's grid is relatively heavily dependent on coal, at 44 percent of total electricity generation in 2017.
Study participants who buy the chargers will also agree to have their charging tracked to help the power authority determine when they plug in and when they unplug, to determine when PRPA should provide the most renewable power. This could help Platte River determine, for example, how much battery or pumped hydro storage it needs to meet maximum charging needs from homeowners overnight.
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EMotorWerks uses a system from WattTime to track the availability of renewable energy and map it against the maximum charging demand to help reduce peak loads on the electrical grid—and bring costs down for peak charging.
Using JuiceNet, by eMotorWerks, the system monitors overall grid demand watching for peaks, then tells chargers, especially those such as home Level 2 chargers, to delay charging during the highest-demand—and often dirtiest—times for the grid.
Level 2 charging (240 volts) is particularly beneficial for equalizing the load on the grid, said Christy Lewis, an electric transportation analyst at WattTime. Many of today's electric cars only require about 4.5 hours to charge on a 30-amp, 240-volt charger, while they may be plugged in for eight or 10 hours while the driver is at home at night or at work. The remaining 3.5 to 5.5 hours is an ideal opportunity for power companies to manage load, charging the cars when excess power is available, and holding off when power demand peaks from elsewhere on the grid.
By tracking when cars unplug and drivers want a full charge, a utility such as Platte River can see how much leeway they have to slow or interrupt charging to reduce the use of non-renewable power.
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As voters and politicians develop more interest in electric cars, utilities are having to respond. The Colorado Public Utilities Commission recently issued a 102-page report on preparing the state for electric cars, in part by developing small-scale pilot programs such as the one in Platte River to vet proposals for larger investments.
"As our renewable portfolio continues to expand, a better understanding of EV owner consumption patterns will provide valuable insight and allow consumers to participate in our energy future,” said Platte River CEO Jason Frisbie in a statement. Platte River will offer the $200 rebates to the first 250 customers who install an eMotorWerks JuiceBox and use the JuiceNet interface to help the company monitor their charging.
Last June, Colorado's former governor, John Hickenlooper, announced that the state would join California and 12 other states in following the Golden State's stricter emissions rules. In January, Colorado's new Governor, Jared Polis, signed an executive order expected to take the second step in requiring a percentage of cars sold in the state to be electric.