Do something good for Earth Day: Change how you get around

Last month, at an event to show off Tesla's newest electric car, CEO Elon Musk proclaimed, "This is the year of the solar roof and Powerwall."
It's a sentiment that might seem out of a place at a car reveal party, but Tesla's energy collection and storage systems are inextricably tied to its vehicles. The Powerwall is Tesla's wall unit, which serves as a giant battery to supply electricity for a home or electric car; the solar roof is made up of small solar panel-tiles that turn sunlight into el