Motorcycles are by definition efficient machines, but their Prius-like fuel economy often is accompanied by emissions that make a Hummer look clean. As regulators get wise to that fact and go after two-wheelers, the motorcycle industry is embracing alternatives ranging from battery power to hydrogen fuel cells.

The pace of development in recent years is remarkable considering motorcycle design hasn't changed much since the first Hildebrand & Wolfmuller appeared in a showroom 114 years ago. Materials have advanced alongside technology, but motorcycles are still an internal combustion engine between two wheels. Motorcycles may deliver 70 mpg or more, but they can be 10 times more polluting per mile than passenger cars. That has the United States and European Union pushing motorcycles to run cleaner and greener.

"As we look at the country's air-quality challenges, including greenhouse gas pollutants and criteria pollutants, what we've found is that every sector of the transportation area is going to be required to play their part in reaching our overall goals," says Karl Simon of the Office of Transportation and Air Quality at the Environmental Protection Agency. "So even though motorcycles and scooters may represent a smaller percentage of the pie when it comes to emissions inventory, it doesn't mean their makers shouldn't have proper incentive to be using new, greener technologies."

Startups like Zero Motorcycles and Brammo are leading the way, offering electric motorcycles you can buy today, but many major manufacturers are developing hybrid and e-motorcycles and looking ahead with hydrogen-fuel-cell bikes.

Most of the focus is on electric power because motorcycles lend themselves to electrification readily. They're smaller and lighter, so they don't need as much power, and range isn't as big an issue because they're often used around town, says Brammo founder Craig Bramsher. "Motorcycles are the perfect solution," he tells us. "Based on where the technology is today for 100 percent electrification, it lends itself to a motorcycle."

These bikes are more than mountain bikes with motors, though. Electric step-through scooters from Vectrix and Electric Vehicle Company will do 60 mph or more, while battery-powered dirt bikes from the likes of Zero Motorcycles and Quantya are winning kudos from experienced motocrossers. But battery bikes remain limited by range — even with lithium-ion batteries you're still looking at 75 miles, tops — and price tags that hover around five figures. Advocates say costs will come down as the technology improves and bigger companies like Honda, Yamaha and KTM, all off which promise electric motorcycles within two to three years, get in the game.

That isn't to say gasoline engines aren't going to be around for a long, long time. Batteries can't offer the range for long-distance riding or hardcore canyon carving, and they're still pretty freakin' heavy. But even gas-burning bikes could see the benefit of batteries. Italian scooter-maker Piaggio has unveiled a gas-electric hybrid scooter that gets 141 mpg and could be on the road next year, and Honda says it is working on a hybrid motorcycle that draws on its automotive hybrid tech to cut costs. Honda says the technology could be offered in displacements ranging from 50 to 1,000 cc and offer a 50 percent improvement in fuel efficiency.

Diesel technology isn't something you hear a lot about when it comes to motorcycles, but Hayes Diversified Technologies offers a diesel-burning version of the Kawasaki KLR that the Marines have been using for years, and companies like Gray Eagles are working on diesel cruisers capable of 80 mpg and 100 mph. Looking further ahead, some manufacturers are developing hydrogen-fuel-cell motorcycles. Suzuki is out in front with the Crosscage hydrogen concept it developed with help from Intelligent Energy, a British firm that pioneered hydrogen bikes with the ENV urban commuter. The two firms are working together to develop a commercially viable fuel-cell motorcycle that could be in showrooms within a few years.

Competitions like the TTxGP, a "green grand prix" slated for the Isle of Man, will surely help advance the technology, but commercial appeal remains the big barrier to getting alt-fuel bikes on the road in big numbers. Ty van Hooydonk of the Motorcycle Industry Council says there isn't much incentive to develop the bikes until there's a demand for them, given the investment manufacturers must make in R&D, tooling and the like. "If Americans want really green bikes then they'll have to vote with their wallets, and the big manufacturers will then respond," he says.

Photo by Zero Motorcycles.

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