The EV of the Sea
The Marjorie K’s dramatic appearance last April at the Second International Solar and Advanced Technology Boat Race fit well with the race organizers’ intention to raise the profile of solar power. Solar-powered boats in particular tend to be ignored, says race adviser Hans Tholstrup. When people think of vehicles powered by solar, or photovoltaic (PV) cells, they focus on cars, Tholstrup says. “The reason is that we see cars as a necessity in life,” he explains. “We use them to get to work or to the shop. We’re a car culture.” Tholstrup, a self-described “futurist and adventurer” cheerfully admits to this bias himself; a former race-car driver, he drove the first solar-powered car across Australia in 1982. But propelling a boat with solar energy is in many ways easier than using solar energy to power a car, he says. Boats don’t have to deal with hills, the energy-draining stops and starts of traffic, or the shade cast by trees and buildings. “In addition,” he notes, “a pleasure boat lies idle all week long, when it could be absorbing power. You would have well and truly fully charged batteries.”
Others also believe PV cells to be well-suited to use on boats. David Roche, special projects manager at the University of New South Wales’ Photovoltaics Special Research Centre (PSRC), points out that boats operate at lower speeds than cars and, when outfitted with properly designed hulls, consume little energy. “You can do a lot with just eight square meters of solar panel, which you can easily get with most small craft,” Roche remarks. But that doesn’t mean there aren’t significant engineering challenges left. “The biggest obstacles are developing an efficient, cost-competitive cell and storing what you’ve generated” in batteries, he says. Roche notes that though the price of PV cells has dropped from thousands of dollars per watt a few decades ago to $4 per watt today, they still cannot compete with conventional electrical power, which costs one-quarter to one-half that much. He expects the PV industry needs at least another decade to compete with traditional power sources (see “Superior Solar Cells” sidebar).
On this subject, Dane is optimistic. “The silicon wafers used now in photovoltaics are in the same position that silicon chips were for computers 20 years ago,” he says. “The price is coming down, and the power is going up.” What’s more, Dane says, the enormous load of batteries required by an electric vehicle – the greatest drawback to a solar-powered car – can be a bonus for an electric boat. “You need tons of lead in the keel anyhow, so just put batteries in there instead,” he suggests. “What’s a burden for a car is ballast for a boat.”