Raw biodiesel also tends to have a higher cloud point than conventional diesel, although it varies with the quality of feed stock, processing and additives. The National Biodiesel Board (NBB), the biodiesel industry's trade association, claims that additives and blending with the right kinds of conventional diesel can keep biodiesel blends working in very cold climates. The organization has collected several testimonials from biodiesel users — the City of Brooklyn Park, Minn., Yellowstone National Park, City of Denver, Colo., City of Ann Arbor, Mich. — that work through freezing winters with B20 blends.
The NBB is cataloging states' authority to regulate fuels; their status in adopting ASTM D6751 as the fuel specification for biodiesel; and assessments of their capacity to analyze fuel samples. Information gathered from this project will be presented on NBB's State Fuel Quality Index web page.
Ethanol production shares some energy-efficiency concerns often expressed concernning the cost to make biodiesel. Fermenting fuel-quality ethanol from grains such as corn or corn sorghum is energy intensive, but comparing 2001 production data to 2006 data, a study by Argonne National Laboratory suggests that American ethanol producers have reduced water use nearly 27 percent, electricity use nearly 16 percent, and reduced total energy use nearly 22 percent. The domestic ethanol industry simultaneously increased production nearly 300 percent.
Making ethanol from cellulose, rather than grain, expands the types and amount of available raw materials to produce ethanol, including many materials now regarded as wastes such as corn stalks, rice straw and wood chips. So called "energy crops" of fast-growing trees and grasses can also provide cellulose feed stock. A recent Stanford University study asserts that switchgrass produced 540 percent more renewable energy than the amount of nonrenewable energy consumed in making it.
Sugar cane is an even better ethanol raw material. Brazilian sugar growers produce feed stock for 45 percent of that country's ethanol production on only 1 percent of its arable land. Brazil is nearly energy independent, thanks largely to the size of its ethanol industry.
Opponents to grain-derived biofuels argue that cropland diverted to growing fuel feed stocks must be replaced given a growing, increasingly meat-fed world population. They warn that using more grain for biofuels contributes to market dynamics that have been inflating food prices out of reach of the poorest portion of world population.
Markets are much too complex to either vilify or exonerate biofuels for encouraging the slashing of rainforests or rise in food prices. In reality, elevated fuel costs are the primary source of food-price inflation and, ironically, increasing biofuels use is likely to reduce fuel costs. Rapidly growing middle classes in Asia and India are buying more dairy and meat products, too, which greatly intensifies demand for agricultural land (it takes about eight times as much corn to produce the same number of calories from meat as from bread).
Use of marginal land in the United States, where subdivision and mall development costs nearly three acres of farmland every minute, is controlled fairly carefully. So it should be no surprise that the rate of rainforest deforestation, in countries without strong controls on land use, shadows grain prices. Losing rainforest releases CO2 and diminishes the earth's ability to absorb more of the greenhouse gas.
The jury is still out on how grain-derived fuels will affect greenhouse gases, but sugar and waste-stream feed stock such as wood waste appear to be better for the environment and global food economics than fossil-derived fuel. Refinement of cellulosic and biomass conversion suggests that biofuels makers are moving toward even more convincing solutions.
Commercialization of a process called Fischer-Tropsch converts natural gas or biomass to an ultra-clean, diesel fuel. Not only does this gas-to-liquid (GTL) synthetic diesel fuel reduce particulate matter and NOx emissions from current diesel engines, but when using biomass as the feed stock the process gasifies the whole plant. The result is that converting biomass to liquid fuel by way of Fischer-Tropsch uses less land area per unit of energy compared with grain biodiesel or ethanol.
It seems the stepping stone for developing GTL-fuel processing will be remote natural gas reserves — too expensive to bring to market in gaseous form. One PetroSA plant in South Africa and Shell's Indonesian plant currently produce GTL fuels suitable for heavy-duty diesels. Discussions are under way to develop GTL production in Alaska. Existing technology, pipeline capacity and North Slope gas reserves are adequate to deliver more than 1,000,000 barrels per day.
Synthetic diesel powers a range of diesel engines overseas. Southern-California testing with International Class 6 delivery trucks retrofit with Johnson Matthey diesel particulate filters proved that Shell GTL reduced emission of hydrocarbons, carbon monoxide and particulate matter by 99 percent, and reduced NOx by 14 percent. No maintenance or component-life problems were reported in 24,000 miles of use. Fuel economy didn't change significantly.
Cetane number of GTL fuels is usually greater than 74, much higher than conventional diesel. This may be a hint of what has pushed a diesel-powered Audi to two straight road-race wins at Le Mans, and claiming first and second places in this spring's Long Beach Grand Prix. Audi's R10 is the first grand-prix winner with a diesel engine, and it is fueled by a version of Shell's GTL synthetic diesel.
With governments pushing increased production of biofuels and the promise of safe, high-performance fuels such as biodiesel and synthetic diesel, the economics to simply convert today's construction equipment to a cleaner fleet have never been better.
The Running Green Series
Diesel Owners’ Turn to Carry the Clean-Air Ball
Breathing Easier with Aftertreatment
It's Not Too Late to Sample Diesel Retrofits
Emissions Regulations Squeeze Construction Equipment Owners
Reducing and Reusing Wastes Builds Leaner Shops
|National Average Fuel Prices|
|Per Gallon||Per Diesel-Equivalent Gallon*|
|* Diesel-equivalent gallons = amount of fuel that contains the same energy as a gallon of diesel|
|** Compressed natural gas, in diesel-gallon equivalents|
|Source: U.S. Department of Energy, October 2007|