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Biofuels   Arrow divider image - marks separation between nested pages that are listed as breadcrumbs.

What are the different types of biofuels?

Biofuels can be lumped into three major categories:

  1. Ethanol-an alcohol produced from fermenting feedstocks, which can be mixed with traditional gasoline as an octane booster. According to the U.S. Department of Energy, roughly 97% of gasoline on the market in the U.S. has at least some level of ethanol blended into it. Flex-Fuel vehicles can use gasoline with up to 85% ethanol, but conventional engines are only approved to use blends with 10% or less alcohol.
  2. Biodiesel-produced through combining alcohol with oils (vegetable, animal fat, or recycled cooking). This can be used a fuel additive and is safe for any diesel engine in mixtures of 20% or less, which can help reduce emissions. In 2015, 2.7% of the diesel fuel sold was biodiesel.
  3. “Drop In” renewable fuels-through biological and thermochemical processes, biomass can be converted into a complex mixture of hydrocarbons that mimic traditional petroleum. These fuels can be added directly to gas tanks without being blended with petroleum products, but they have not yet become cost competitive. In 2015, only 2 million gallons of drop-in fuels were produced, amounting to just 0.0017% of all fuel sold. The 2017 Renewable Fuel Standard Mandate calls for 33 million gallons of these fuels, amounting to 0.17% of expected fuel sales.

Sources:

U.S. Department of Energy
U.S. Environmental Protection Agency

What are commonly grown feedstocks for biofuels?

Ethanol biofuels have traditionally been produced using corn and sugar cane crops. However, the majority of biofuel research taking place today focuses on the development of “cellulosic feedstocks”—i.e. non-grain, non-food-based feedstocks. These include things like agricultural residues, energy crops (shrub willows, switchgrass, miscanthus, sorghum, energy cane, etc.), forest resources, other waste products, and algae. In Colorado, camelina and canola have both been grown for biofuel production.

What are the pros and cons of using alcohol as a motor fuel?

(Pros and cons listed are relative to petroleum-based fuels.)

Pros:

  • Renewable fuel source
  • High octane
  • Increased combustion efficiency

Cons:

  • Decreased fuel economy
  • Higher potential for “vapor lock” and resulting loss of engine power or stalling
  • Difficulties starting engine in cold weather
  • Can corrode engines

Alcohol is commonly blended with petroleum-based fuel to maximize pros and minimize cons.

What are the pros and cons of using vegetable oil as a motor fuel?

(Pros and cons listed are relative to petroleum-based fuels.)

Pros:

  • Renewable fuel source
  • Comparatively inexpensive when oil prices are high

Cons:

  • Decreased fuel economy
  • Increased engine wear
  • Increased engine damage through residual deposits
  • Comparatively expensive when oil prices are low

Relevant CSU publications:

Are there examples of growing on-farm fuel in Colorado?

There are a few. A group of farmers in southeastern Colorado have grown and crushed canola into oil. They mixed that vegetable oil with regular unleaded gasoline to form a triglyceride blend (TGB). They ran TGB in their farm trucks and equipment (see video below). At least one other farmer in Colorado has used canola oil as a biodiesel feedstock for on-farm use.

Also see a Colorado feasibility study on Camelina:
“Is it economically feasible for farmers to grow their own fuel? A study of Camelina sativa produced in the western United States as on-farm biofuel”


What are the greenhouse gas implications of ethanol?

According to the USDA, Corn Ethanol production achieves a 43% reduction in green house gas (GHG) emissions when compared to the GHG from gasoline (2005 baseline). The same study predicts a 48% reduction by 2022.

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Last updated: May 3, 2017 at 10:24 am