"Global Warming" may fuel the real Middle East war as cleaner biofuels ramp up against the dirty smudge of Fossil fuels. We have recent agreement among most of global scientific community that fingers the main culprit (ozone layer and global warming) to be the rapid increase in burning of fossil fuels. America is ponying up nearly a trillion dollar economic penalty of two expensive "Gulf" area wars a decade apart. While many critics of these forays tag them as "oil wars", it underscores need for growing and developing renewable biofuels, and other non fossil fuel alternatives. We are now burning nearly 5 billion gallons of "corn liquor" ethanol. Like the old jokes, we have some good news in that it comes from your own shelled corn, but some bad news that we are competing with our own meat complex for supplies of corn-soy based feeds. Prices have hit recent highs well over $4 per bushel, and any disruption in production could shoot the moon on historic prices. North American agriculture is first and foremost a maize-growing machine, with wheat and soybeans along with Canola (rapeseed), for example, lagging behind. However, many future sources of biofuel feedstocks are coming into their own, including canola oils, sugar cane, switchgrass, cellulosic biomass from virtually any plant by-products. All these fuels can be used to produce your heat for buildings and for drying grain on farms, or in rural industry, for example. Raw shelled corn itself will produce efficient heat energy and is easy and clean to handle. Here are things to consider when burning straight shelled corn versus other biofuels:
Cost of BTUs compared
Shelled corn contains about 7000 Btu (British thermal units) per pound at 15% moisture, or about 392,000 BTUs per 56-lb bushel. It is better to use dry corn as a fuel source, because dry corn is easier to handle and store than wet corn, and because dry corn produces more energy per unit weight of corn. Energy content per pound of corn is dramatically lower for high-moisture corn because more of the weight of the corn is water, which doesn't produce any energy, and because more energy from the corn dry matter is needed to evaporate water from the kernels and less is available for heating.
Compare corn burners for efficiency. Advice from University of Minnesota Extension site is that you should compare cost per unit of energy produced and usually cost per million BTUs is a common way.
Example U of M gives: Calculate cost per million Btu for 15% moisture shelled corn that costs $2.00 per bushel and is burned in a stove that has an efficiency of 65%. Cost per million Btu = [$2.00/bu ÷ (392,000 Btu/bu x 0.65 efficiency)] x 1,000,000
= $7.85 per million Btu
Here are energy content, burner efficiencies, and costs per million Btu at average efficiency and the indicated price for several fuels:
Fuel oil, 140,000 Btu/gal, 70 to 90% efficiency (80% avg.), $1.50/gal: $13.39 per million Btu
Propane or liquefied petroleum gas (LPG), 92,000 Btu/gal, 70 to 90% efficiency (80%avg.), $1.00/gal:
$13.59 per million Btu
Natural gas, 100,000 Btu/ hundred cubic foot (ccf), 70 to 90% efficiency (80% avg.), $0.80/ccf:
$10.00 per million Btu
Electricity (resistance heat), 3413 Btu/kWh, 100% efficiency, $0.08/kWh:
$23.44 per million Btu
Keep in mind that the price for corn and for conventional fuels will fluctuate over time and that the cheapest fuel today might not be the cheapest fuel in the future.
Other Minnesota Advice Includes:
New Corn Burners Are Expensive
Fuel cost per unit of energy is very important, but you also need to consider the cost for the burner, fuel storage, and other equipment needed to store, handle, and use the fuel, equipment maintenance, and labor to handle the fuel and remove ash. If you are considering new construction or are replacing a worn out system, you can compare the annual cost of owning and fueling a conventional heating system vs. the annual cost of owning and fueling a corn burning system. But if you already have a conventional system that is in good working condition and will be kept as a back up system, then you need to compare the full cost of owning and fueling a corn burning system to the value of conventional fuel saved. A supplemental corn burning system can easily cost several thousand dollars, so annual ownership costs can be a significant addition to the cost of the corn fuel.
Labor costs are likely to be higher for corn burning systems than for conventional fuel systems, although labor costs for corn systems might be lower than for bulky biomass materials (like fire wood, straw, or hay). Very little labor is required to fuel, maintain, and clean conventional fuel systems. Corn-fueled systems can be relatively easy to automate, but some labor is required to periodically refill the corn hopper and to remove the ash or clinkers that are left after corn combustion.
Fuel handling and storage
Corn is easier to handle than some other bulky biomass materials (wood, straw, or hay, for example) because it flows fairly well through hoppers and augers and because corn has a better energy to volume ratio (it takes less space to store the same amount of energy for corn than for bulky biomass materials). But corn is not as easy to handle and is not as energy dense as most conventional fuels.
Corn handling and storage will be relatively easy on farms that produce corn, but it will be more of a challenge for people who don't produce corn - especially for people living in urban areas. Non-farmers will have some difficulty obtaining, hauling, and storing the amounts of corn needed for heating a home or other buildings. Also, the cost per bushel will probably be somewhat higher for people who buy a few bushels at a time.
Owners of corn burning systems who store corn inside their home need to use tight storage containers, clean up corn spills immediately, and avoid storing corn for long periods of time to prevent problems with rodents and with stored grain insects. Some species of insects that infest stored corn could also move into food products stored in the home.
Burner design
Designing corn burners is more challenging than designing burners for some other biomass materials because it's more difficult to get enough air into the fuel pile with shelled corn than it is for bulky biomass materials, and because corn ash melts at a different temperature than ash for some other biomass products. Corn ash tends to produce a hard, glassy slag that can coat the inside of the burner, or corn ash can produce hard chunks (clinkers) that need to be removed frequently (perhaps daily). It isn't impossible, but it would be difficult to build a homemade burner or to modify a wood-burning stove that works well with corn. Several companies that have tried to build shelled corn burners have failed, so it might be best to buy a corn-burning stove from a company that has been in business for several years and that has a number of satisfied customers.
Long run needs for heat energy
In the short term, it might make sense to burn corn to produce heat energy, but it's hard to know whether burning corn makes sense in the long run. If our goal is to find something that farmers can grow that will help solve our need for heat energy, corn might not be the best answer. It takes a lot of energy to grow, dry, and transport corn, it takes a lot of energy to produce the fertilizers and pesticides used to produce corn, production of corn makes the soil more vulnerable to erosion than does production of some other crops, and corn might be more valuable for feed, food, and liquid fuel uses than for heat energy production.
Here is a good Canadian website:
Ontario Ministry of Ag
Here are some questions, adapted from the Ontario website, that you should consider before purchasing a corn burner:
What is the heat output of the burner? Do you know how much heat is needed to maintain the heated space at the desired temperature, to dry the crop, or to meet other needs for heat energy? If you are trying to heat your whole house with a stove or space heater, does the house layout allow for the convective movement of heat through the whole house? Most newer houses are not built to allow convective air movement. What is the size of the fuel hopper? Will it require filling on a daily, weekly, or biweekly schedule? What is the seasonal heating efficiency of the corn burner? Does the unit meet UL standards? Does the unit have hot exposed surfaces that could cause burns to skin? What type of exhaust venting is required? Does it require a chimney with a flue liner or can a combination flue/fresh air vent pipe be used? Are you prepared to clean out the clinker daily and clean the heat exchanger of ash on a weekly basis? Will the stove handle granular solid fuels other than shelled corn? This is important in the event that the economics of burning corn become unattractive or an alternative low cost pelleted fuel becomes available. Will the corn burner be a primary heat source or act as a supplementary heat source? Stoves with small fuel hoppers will not meet heating needs for long periods of time, unattended. How and where will corn be stored?
(Article Review Series)
