Motorcycle Pollution: A Lifecycle Perspective

August 2, 2011
By Jeremiah Knupp
The road in to Hulett from the west over the Belle Fourche River.
Is a road full of motorcycles more forgiving to the environment than a road full of cars? Science seeks to answer this with its first life cycle perspective of a motorcycle.

“Are We Gross Polluters?” Cycle World Technical Editor Kevin Cameron came right out and asked the question in a June 2008 Web-Watch posted on Cameron’s post was a response to an LA Times article that pointed out that motorcycles put out more tailpipe pollution than their four-wheeled counterparts. The article, by Times columnist Susan Carpenter, pointed to the fact that motorcycles, which travel one percent of the vehicle miles traveled on California roads, contribute 10 percent of vehicular emissions in the state. In her closing paragraph Carpenter stated, “Long story short: motorcycles, even small ones, are more polluting than Hummers.”

Whoa. Hit the brakes. Did I hear that right? Heck, maybe we’ve been wrong all these years. The people trailering their motorcycles to rallies aren’t posers. They’re tree huggers.

In his response to Carpenter’s article, Cameron pointed out that while motorcycles produce more tailpipe emissions, they take up less space and use less fuel and other resources. Tailpipe emission tests only tell part of the story. Electric vehicles are labeled “zero emissions” but they plug into a power grid that is 55 percent fueled by coal. Ain’t no free lunches. “Who can assign an unarguable weighting to these apples and oranges, and thereby find the ‘absolute good’?” Cameron asked.

Maybe someone can.

The hottest trend in the environmental sciences these days is called “lifecycle assessment” (LCA), a big picture approach to quantifying environmental impact. It’s been applied to every environmental debate, from disposable versus cloth diapers to compact florescent versus incandescent light bulbs. It takes everything into account, from the birth to the death of a product, analyzing enough data to make the pocket protector wearers among us giddy.

The product is closer and closer to being complete. Just a few more pieces... - Kawasaki Tour - Japan 2007
Part of what a lifecycle analysis looks at is how much energy is requred to harvest raw materials during production.

Using motorcycles as an example it works something like this. How much energy is required to harvest the raw materials needed to build a bike? How much energy goes into a motorcycle’s manufacturing process? What infrastructure does the finished machine require (service stations, oil changes) and how much wear and tear does it cause to streets, highways and parking lots? What is required to maintain this infrastructure? What expendables (fuel, tires) will the machine use? What periphery industries does it necessitate (like auto insurance companies)? How long will the machine last and how many miles will it take passengers in its lifetime? What happens to it when it is no longer usable? How much pollution does its disposal cause? And the list goes on…

When it comes to transportation comparisons energy usage and emissions are tabulated relative to “passenger miles traveled” (PMT). For example, if a city bus averages 100 miles a day and its average load is 10 passengers, then it is traveling 1000 passenger miles per day. If a motorcycle travels that same 100 miles, carrying 1.3 passengers (the national average) it has traveled 130 passenger miles. The amount of energy consumed and pollution created is quantified relative to moving one passenger one mile. The comparison is now apples to apples.

On the leading edge of lifecycle analysis of transportation is a University of California Berkeley post doctoral researcher, Mikhail Chester. Chester has developed a lifecycle model that analyzes the environmental impact of transportation modes that vary from San Francisco BART trains to passenger sedans. He recently crunched the numbers on the lifecycle impact of motorcycles. For us motorcyclists his results come as our own little inconvenient truth.

Chester’s study divided motorcycles into three general categories: cruisers, touring and sport bikes. These categories were represented by a 2009-year model Harley Fat BoyYamaha VMAX and Kawasaki ZX-14, respectively. When lifetime energy consumption is graphed, touring and cruiser motorcycles use more energy per passenger miles traveled than gasoline powered cars but less than SUVs

A scooter vs. a motorcycle can be a tough decision for a beginner to make. Begin by looking at what the machine would primarily be used for and then compare the pros and cons of each.
Can a motorcycle cause more pollution than a Hummer? Maybe not, but the answer still isn’t good for two-wheeled enthusiasts.

and pick-ups (Smile, we’re not as bad as Hummers). Sportbikes, on the other hand, consume more energy per passenger miles traveled than any other form of road-based transportation, due in part to their fuel economy, high performance engines and complex and specialized manufacturing process.

When it comes to air pollution in the form of CO2 and sulfur dioxide, these relationships hold. But for emissions in the form of carbon monoxide, volatile organic compound and particulate matter, motorcycles of any type far surpass all other types of transportation. The use of catalytic converters cause a slight decrease in these numbers, but not enough to make up the gap between vehicles with four wheels and those with two.

Critics will be quick to point out the flaws in Chester’s analysis (a ZX-14 and a VMAX as representative of the majority of motorcycles on the street?). But a closer look will reveal a fair and measured approach to assessing motorcycle impact. A Harley Fat Boy, for example, is typical of nearly 50 percent of motorcycles on American streets and, according to Chester, smaller motorcycles require nearly as much energy to manufacture and maintain, while creating approximately the same amount of pollution. The study also uses conservative assumptions, like motorcycle service lives of over 50,000 miles and 6,000 mile tire life. The author admits his work is a preliminary study (it’s the first motorcycle LCA ever completed) and not the last word on the lifecycle impact of motorcycles. But the disparity in pollution between motorcycles and other forms of transportation won’t be overturned with a recount.

So what do these results mean to motorcyclists? In the past, when people point to the pollution coming out of our tailpipe, we were quick to note our fuel efficiency and small size that takes up less space on the roads and in parking lots. But the truth is, it doesn’t balance out. We’ve run out of excuses. We are gross polluters. So much for meeting the nicest people on a Honda.

A few Concours 14 and Z750 wait their turn at the final inspction station beofre being herded towards the shipping department - Kawasaki Tour - Japan 2007
One thing affecting a motorcycle’s environmental impact is economy of scale, which means they produce more waste and pollution because production methods are less efficient.

“The discussion of okay-to-good motorcycle fuel efficiency hides the discussion of direct human health and environment-impacting pollutants which tend to be larger for motorcycles than other modes [of transportation],” Chester noted.

The reasons are quite simple. The first is “economies of scale.” Motorcycles and their components, such as tires, are manufactured in smaller quantities than cars. Smaller scale production means less efficiency, hence greater pollution and more waste (and for the consumer, higher relative prices). Chester points out it takes nearly the same amount of energy to manufacture a motorcycle as it does an automobile.

The second reason lies in the nature of motorcycle engine design. Fuel efficiency is a double-edged sword. As Carpenter stated, extracting greater energy from fossil fuels results in higher amounts of pollution in the form of nitrogen oxides. Motorcycles often also lack catalytic converters and evaporative emissions equipment (in states other than California), which means they put out more hydrocarbons.

Despite our persecution complex, The Man has pretty much left motorcycles alone when it comes to environmental standards. Traditionally, motorcycles have escaped from being picked on by the EPA because of their small market share and even smaller number of miles they travel each year. But times have changed. EPA standards for motorcycles, virtually unchanged since the late 1970s, have recently been updated to a two-tiered structure, one of which was implemented in 2006 and another that took effect in 2010 (California standards are identical, but were implemented two years earlier). The appearance of electronic fuel injection, catalytic converters and secondary air injection on new model motorcycles is in response to these new standards.

A row of black Concours 14s are headd our way - Kawasaki Tour - Japan 2007
Self-regulation will become increasingly important in the motorcycle community as the industry attempts to overcome a poor public image and environmental concerns. 

So we’re gross polluters. Now what? Motorcycling is under scrutiny everywhere, with politicians and safetycrats making issues out of everything from the dangers that “lead-based” two-wheelers pose to children (OHVs are on the cusp of being exempt from the Lead Law. Read about it in the Senate Passes OHV Exemption – Onto President – Ed.)to the fact that sportbikes are more hazardous to the health of young U.S. Marines than IEDs. For those who seek to restrict motorcycles, close down off-road trails and impose impossible health and safety standards, the machine’s poor environmental performance is more ammunition to use in the fight (“Clamp Down on Motorcycles” was a May 2009 editorial that circulated through several Southern California newspapers).

In many ways the issue of the environmental impact of motorcycles mirrors the sound debate that the AMA has chosen to address. In relation to the future of our sport, it’s fundamentally a public image problem. The less motorcycles seem like practical and reasonable means of transportation and the more they seem like excessive recreational toys, the easier it is to justify their regulation. The more outrageous, the longer our forks and swingarms, the higher our handlebars, the smaller our seats and the louder our pipes the less practical our rides seem. The more pollution they belch out and the more energy they consume, the harder it is to justify their presence on public streets.

As an industry, will we choose to impose reasonable regulations on ourselves when it comes to motorcycle emissions? As consumers, are we willing to demand that manufacturers give us cleaner motorcycles with even greater fuel efficiency? If they give it to us will we pony up for the extra cost that emissions equipment or alternative fuel technology adds to a new motorcycle’s price tag? As riders, will we start looking at our motorcycles more as serious transportation and less as recreation, and acknowledge that our choices are made in the context of a world that is larger than us?

The issues of pollution and consumption facing this planet and its burgeoning population are overwhelming. There is no silver bullet solution and making cleaner running motorcycles is not the answer to all our problems. Maybe, as Cameron suggested tongue-in-cheek at the conclusion of his answer to the question “Are We Gross Polluters?,” we should just all join the Voluntary Human Extinction Movement if we want to help out the planet. But one thing is for certain; if we motorcyclists don’t start regulating ourselves then we’ll all be card-carrying members of the Two-Wheel Extinction Movement.