Plug-in electrics? Yesterday’s news. Pioneering automotive mavens are experimenting with the next generation of gasoline replacements for cars. Here’s how a few stack up against reality, cost, and practicality.
Hydrogen Fuel Cell
How it works: Touted by many as the next big thing in energy, fuel cells efficiently convert hydrogen and oxygen into water, producing emissions-free electricity along the way.
Costs: Very expensive today. Basic fuel-cell vehicles would cost several hundred thousand dollars, but further research is expected to bring the cost down.
Pros: Zero emissions. Hydrogen is theoretically abundant, if cheap ways to produce it from water or other common chemicals can be found.
Cons: Rocky reliability, the difficulty of storing massive amounts of hydrogen inside a car, and the lack of hydrogen-at-the-pump systems. Fuel cells don’t work below freezing.
Compressed Natural Gas
How it works: Compressed natural gas, or CNG, is made by pressurizing natural gas (mostly methane) to 100 times its natural density. CNG powers a combustion engine—some bi-fuel vehicles can also use regular petrol—but a CNG vehicle’s range per tank is often half that of a gas-powered car.
Costs: CNG is about half the price of gasoline on a per-mile basis, but prices are creeping up.
Pros: It’s not just cheaper; it’s also better for the environment than gas, with about 30 percent lower CO2 emissions.
Cons: Natural gas is still a fossil fuel (and a greenhouse gas) with its own eventual “peak.” CNG storage tanks are rather huge (typically filling half the trunk).
How it works: Propane is actually a by-product of petroleum refining that can be compressed into familiar liquid form and stored in a large tank, much like CNG.
Costs: Somewhat higher than CNG, but propane is often a cheaper retrofit on vehicles. Propane prices fluctuate with the market.
Pros: Unlike CNG, propane is not itself a greenhouse gas (since it’s heavier than air) and is generally considered “safer” than natural gas. Propane fueling stations are much more widespread than CNG fueling stations.
Cons: Actually burning propane is relatively clean, but it still creates greenhouse emissions—and it relies on gas production, limiting long-term viability.
How it works: Simply put, a solar car is an electric vehicle that is powered (or recharged) by the sun.
Costs: While solar energy is free, building even a prototype solar car has been extravagantly costly, to the tune of US$1 million and up.
Pros: Free energy forever . . . at least as long as the sun’s out. Silent. Zero pollution.
Cons: After 30-plus years of work, even the best solar vehicles are unreliable, three-wheeled single-seaters with no realistic chance of hitting the open road.