Week of 4/17/2005

Dear EarthTalk: Which is better for the environment, a car powered by gasoline or one that runs on "biodiesel"?

—Pierre Vincent, Edmonton, AB, Canada

Biodiesel is one of the cleanest burning alternative fuels available today. Diesel engines that run on biodiesel emit substantially less carbon monoxide and soot compared to engines that run on regular diesel fuel. They also emit almost no sulfur oxide or sulfates, major components of acid rain. Biodiesel also won't add carbon dioxide (CO2) to the atmosphere, and as such is not a significant contributor to global warming. According to the National Biodiesel Board, it is the only alternative fuel to meet Clean Air Act testing requirements.

The reason biodiesel is so green-friendly is that it comes from plants, primarily soybeans and rapeseed. (Rapeseed, in some varieties of cooking oil, is marketed as the more familiar-sounding Canola oil.) Like all plants, these crops absorb CO2 during their lifetimes. Later, when burned, they emit only about as much CO2 as they absorbed before they were harvested, thus making them what is called "carbon neutral."

Biodiesel can power any standard diesel automobile without any major engine modifications. While it can be used in its pure form, biodiesel can also be mixed with less expensive standard diesel fuel to significantly reduce pollution compared to using standard diesel alone. Those who want to go a step further can retrofit their existing diesel-powered cars to run on straight vegetable oil, as some environmentally ambitious drivers have done, obtaining oil from the fryolator of their local fast food or Chinese restaurant.

But such drastic measures are not really necessary. Already there are some 150 retailers in the U.S. that offer biodiesel. They can be located through the websites of both the U.S. Department of Energy's Alternative Fuels Data Center and the National Biodiesel Board. In Canada, unfortunately, according to the Ottawa Business Journal, the first biodiesel retailer only just opened in May of 2004, though the Great White North boasts a large number of retailers of ethanol, another promising alternative fuel made from agricultural stock. Meanwhile, for those in the market for a car that can run on biodiesel, the Go Biodiesel Cooperative lists more than 200 widely available diesel engine automobiles made in the last few years.

Federal tax incentives signed into law by President Bush last fall are expected to increase biodiesel demand from an estimated 30 million gallons in 2004 to more than 124 million gallons per year moving forward. With crude oil prices skyrocketing of late, biodiesel producers are projecting even faster growth.

But while biodiesel is a good choice for existing owners of diesel-powered vehicles, it is not the cure-all to our energy and national security woes as some environmentalists suggest. While there is plenty of French fry oil to go around for the occasional convert, replacing America's gasoline-powered cars with biodiesel vehicles would require substantial amounts of farmland for the production of crops needed to produce vegetable oil. The result would either be the loss of much-needed land for food crops or the vast expansion of resource-intensive agriculture into existing green space.

CONTACTS: National Biodiesel Board, www.biodiesel.org ; Alternative Fuels Data Center, www.afdc.doe.gov ; Go Biodiesel Cooperative, www.gobiodiesel.org.

Dear EarthTalk: Are there any efforts underway to increase the recycling of construction waste?

—Tim Moss, Westport, CT

According to some experts, construction and demolition projects together contribute as much as 60 percent of all solid waste in the U.S., so the building industry is certainly ripe for some increased recycling efforts. According to the Sourcebook for Green and Sustainable Building, a free resource available online, some 8,000 pounds of waste are carted off to a landfill during the construction of just one 2,000 square foot home.

Reducing and recycling these materials conserves landfill space, reduces the environmental impact of producing new materials, and can reduce overall building project expenses pretty significantly by saving on both disposal costs and the purchase of virgin materials. Recyclable construction materials include lumber, paper, cardboard, metals, brick, concrete, carpeting, plastic, pipe, drywall, gravel and dirt.

William Turley, executive director of the Construction Materials Recycling Association, says that more than 300 million tons of concrete, asphalt, steel, brick, siding and wood—much of which could be recycled—are disposed of annually, compared to about 225 million tons of everyday household trash. Besides its sheer volume, construction and demolition waste deposited into landfills can also contain a significant amount of solvents and chemically treated wood that can pollute both the soil and the groundwater.

The recycling of waste during a construction or demolition project can be both costly and a big hassle, compounded by a great lack of facilities across the country devoted to processing such materials for re-use. However, a growing industry of professional separators and sorters is just starting to emerge, according to Turley, and is beginning to attract business in the Northeast as well as in Florida and California where it costs more to dump waste than to recycle it.

The National Association of Home Builders produces a useful field guide outlining different approaches builders can take to managing waste. Of course, the best way to prevent waste in the first place is good planning. Design should be based on standard sizes and the use of high quality materials whenever possible, while materials should be ordered accurately. This approach can reduce the amount of material needing to be recycled and bolster profitability for the builder while saving money for the customer.

CONTACTS: Sourcebook for Green and Sustainable Building, www.greenbuilder.com/sourcebook ; Construction Materials Recycling Association, www.cdrecycling.org ; National Association of Home Builders, www.nahbrc.org.