Is Corn a Food, a Fuel, or Both?
I have encountered a number of people who have expressed opposition to corn ethanol because they feel that it is wasting food by turning it into a fuel. You can imagine my surprise when I found an advertisement for a 'multi fuel' stove that that actually burned whole corn kernels. What made it all the more astonishing was that dry corn kernels are the cheapest fuel available, costing even less than natural gas per BTU. I think that says something about the productivity of the American farmer or perhaps the low value we have for using corn as food.
Burning wood to heat a living space goes back to the discovery of fire. However, it's not without its inconveniences, the primary one being the need to tend the fire. One needs to put the right amount of fuel on the fire and continue to feed it on a regular basis so that the heat it produces is consistent and so that the fire doesn't go out and need to be restarted. The advent of the wood pellet stove made it possible to reduce the need for a fire tender by feeding the pellets from a hopper automatically as needed. It can even adjust the fuel supply depending on the heating requirements. In some ways, the arrival of the pellet stove made burning wood nearly as convenient as oil or gas for heating. It does require another step be taken in the preparation of the wood, namely grinding it up and forming it into a consistent pellet size so that it will feed automatically into the wood stove. It's not quite as convenient as a gas furnace because you still have to buy, store, and schlep heavy bags of wood pellets to the stove and fill the hopper about once a day, but it's much better than a traditional wood burning stove from a convenience standpoint.
When I visited an ethanol plant recently, I was gratified to know that about 1/3 of the corn by weight that was not converted into ethanol was used as animal feed in the form of wet distiller's grain. Not only that, but since all of the hollow calories of the corn, namely the starches, had been removed, it was a quality feed with high concentrations of protein, fat, and other nutrients. So the guilt of seeing food being turned into fuel was somewhat offset by realizing that about 1/3 of it was still going to be used as food, albeit as an animal feed. It's important to recognize that about 70% of all corn produced in the U.S. is used for feeding livestock.
I had never felt too strong an objection to using corn for fuel. I tend to look at all biomass as a form of energy and whether you eat it, burn it to stay warm, or make fuel out of it, the effect is the same. If anything, it should make us appreciate how much energy we use in forms other than food to support our modern lifestyles. Much to the chagrin of many Americans, our average citizen has an energy consumption rate of 333M BTU/yr, or about twice what most modern cultures have. If our population were more densely arranged, making mass transportation more practical, or if we all lived closer to the equator, making home heating less necessary, we would likely have a smaller per capita carbon footprint.
In any event, with corn prices skyrocketing past 1/3 of their historic high adjusted for inflation, we're hearing a lot of objections about wasting food by turning it into fuel. I haven't heard anyone expressing relief for the farming communities that had to endure sub $2/bushel prices for their corn for the past decade. At one time, a bushel of corn had the same value as a shirt. We're still a long way from that even with $5/bushel corn. Corn hit a high $14.60/bushel in 1974 adjusted for inflation in terms of today's dollars.
Let me get back to the corn stove. Natural gas has historically had a price advantage for heating homes. Except for a short period of mismatch between supply and demand, the cost per BTU for natural gas has been more favorable than for oil or electricity. But corn seems to trump them all. Imagine that, burning food is less costly than burning fossil fuels or wood. It really made me wonder what was going on. You can see the values in the table below:
** recent prices (Feb 08'); subject to variation
I should also mention that the column for electric heating assumes resistive heating, but better performance can be achieved with a heat pump, assuming that the climate will favor the use of a heat pump.
The table above is very interesting because it shows corn is not only cheaper than wood to burn, but it's cheaper than every other fossil fuel on a cost/BTU basis. The only thing that's cheaper is coal, which at $60/ton comes out to be about $2.50/MBTU and that price is only if you can buy it by the train car load. You'd have to double or triple that price for residential delivery. That speaks volumes about whether corn is priced appropriately. Any food substance that can be burned as a heating fuel more cheaply than virtually any other common fuel tells me that society doesn't place much value on it. So instead of worrying about increasing corn prices, it could be that corn prices over the past decade have been incredibly low and are just catching up with where they should have been.
This brings up an interesting question. If a human can live on a diet of 2400 kcal (i.e. food calories) per day, how does that much energy compare with what is needed for heating one's home? Knowing that there are roughly 4 BTU/kcal, a normal food budget for one person is 9600 BTU/day. This means that there are enough food calories in a bushel of corn to sustain a person for 52 days, but only enough to heat his home for 12 hours, on average.
Should we be using corn as a heating or transportation fuel? I guess if you are of the opinion that 'biomass is biomass', then it shouldn't matter whether a farmer grows corn, switchgrass, or trees. It's all the same process of turning sunlight into carbon and so one should not be so concerned with corn's other potential uses if the cost per BTU makes it an economical choice as a fuel. I know that there are other issues involved, such as the need for herbicides, pesticides, water, and fertilizer. All these costs get amortized over the price of corn grown per acre and if you can get more usable BTUs per acre from corn than you can from an energy crop then it may be the most efficient way to produce biomass energy, at least for today.
Moving away from the unsustainable practice of digging up and burning biomass that has been buried for millions of years toward living on a balanced energy budget will help humanity to understand that the energy used for food, transportation, and heating fuel is all inter-related. Today one cannot make that connection because oil, natural gas, and coal cannot be eaten. Someday they will be exhausted, and any fuel will likely originate from biomass that can be a food, or otherwise competes with food for land on which to be grown.
Update: One of the multifuel stoves we found online recently here has a few customer reviews but they are really mixed, this is an emerging technology in many ways and we welcome your feedback and reviews below.
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Burning wood to heat a living space goes back to the discovery of fire. However, it's not without its inconveniences, the primary one being the need to tend the fire. One needs to put the right amount of fuel on the fire and continue to feed it on a regular basis so that the heat it produces is consistent and so that the fire doesn't go out and need to be restarted. The advent of the wood pellet stove made it possible to reduce the need for a fire tender by feeding the pellets from a hopper automatically as needed. It can even adjust the fuel supply depending on the heating requirements. In some ways, the arrival of the pellet stove made burning wood nearly as convenient as oil or gas for heating. It does require another step be taken in the preparation of the wood, namely grinding it up and forming it into a consistent pellet size so that it will feed automatically into the wood stove. It's not quite as convenient as a gas furnace because you still have to buy, store, and schlep heavy bags of wood pellets to the stove and fill the hopper about once a day, but it's much better than a traditional wood burning stove from a convenience standpoint.
When I visited an ethanol plant recently, I was gratified to know that about 1/3 of the corn by weight that was not converted into ethanol was used as animal feed in the form of wet distiller's grain. Not only that, but since all of the hollow calories of the corn, namely the starches, had been removed, it was a quality feed with high concentrations of protein, fat, and other nutrients. So the guilt of seeing food being turned into fuel was somewhat offset by realizing that about 1/3 of it was still going to be used as food, albeit as an animal feed. It's important to recognize that about 70% of all corn produced in the U.S. is used for feeding livestock.
I had never felt too strong an objection to using corn for fuel. I tend to look at all biomass as a form of energy and whether you eat it, burn it to stay warm, or make fuel out of it, the effect is the same. If anything, it should make us appreciate how much energy we use in forms other than food to support our modern lifestyles. Much to the chagrin of many Americans, our average citizen has an energy consumption rate of 333M BTU/yr, or about twice what most modern cultures have. If our population were more densely arranged, making mass transportation more practical, or if we all lived closer to the equator, making home heating less necessary, we would likely have a smaller per capita carbon footprint.
In any event, with corn prices skyrocketing past 1/3 of their historic high adjusted for inflation, we're hearing a lot of objections about wasting food by turning it into fuel. I haven't heard anyone expressing relief for the farming communities that had to endure sub $2/bushel prices for their corn for the past decade. At one time, a bushel of corn had the same value as a shirt. We're still a long way from that even with $5/bushel corn. Corn hit a high $14.60/bushel in 1974 adjusted for inflation in terms of today's dollars.
Let me get back to the corn stove. Natural gas has historically had a price advantage for heating homes. Except for a short period of mismatch between supply and demand, the cost per BTU for natural gas has been more favorable than for oil or electricity. But corn seems to trump them all. Imagine that, burning food is less costly than burning fossil fuels or wood. It really made me wonder what was going on. You can see the values in the table below:
| Fuel Type |
Fuel Price Per Unit** |
Unit Type | Units for 1M BTUs |
Cost @ 100% Eff. |
Efficiency of heater |
Cost to Produce 1M BTUs |
Avg. monthly cost assuming 90M BTU/yr |
| Dry Corn | $4.61 | Bushel | 2 | $9.22 | 80% | $11.53 | $86.44 |
| Natural Gas | $1.17 | 100 cu ft | 10.3 | $12.05 | 85% | $14.18 | $106.33 |
| Wood | $200.00 | cord | 0.0607 | $12.14 | 70% | $17.34 | $130.07 |
| Wood Pellets | $0.12 | lb | 125 | $15.00 | 80% | $18.75 | $140.63 |
| LP Gas | $1.64 | gallon | 11 | $18.04 | 80% | $22.55 | $169.13 |
| Fuel Oil #1 | $2.82 | gallon | 7.1 | $20.02 | 80% | $25.03 | $187.71 |
| Electricity | $0.09 | kWh | 293 | $26.37 | 100% | $26.37 | $197.78 |
** recent prices (Feb 08'); subject to variation
Cost comparisons of various heating fuels.
I should also mention that the column for electric heating assumes resistive heating, but better performance can be achieved with a heat pump, assuming that the climate will favor the use of a heat pump.
The table above is very interesting because it shows corn is not only cheaper than wood to burn, but it's cheaper than every other fossil fuel on a cost/BTU basis. The only thing that's cheaper is coal, which at $60/ton comes out to be about $2.50/MBTU and that price is only if you can buy it by the train car load. You'd have to double or triple that price for residential delivery. That speaks volumes about whether corn is priced appropriately. Any food substance that can be burned as a heating fuel more cheaply than virtually any other common fuel tells me that society doesn't place much value on it. So instead of worrying about increasing corn prices, it could be that corn prices over the past decade have been incredibly low and are just catching up with where they should have been.
This brings up an interesting question. If a human can live on a diet of 2400 kcal (i.e. food calories) per day, how does that much energy compare with what is needed for heating one's home? Knowing that there are roughly 4 BTU/kcal, a normal food budget for one person is 9600 BTU/day. This means that there are enough food calories in a bushel of corn to sustain a person for 52 days, but only enough to heat his home for 12 hours, on average.
Should we be using corn as a heating or transportation fuel? I guess if you are of the opinion that 'biomass is biomass', then it shouldn't matter whether a farmer grows corn, switchgrass, or trees. It's all the same process of turning sunlight into carbon and so one should not be so concerned with corn's other potential uses if the cost per BTU makes it an economical choice as a fuel. I know that there are other issues involved, such as the need for herbicides, pesticides, water, and fertilizer. All these costs get amortized over the price of corn grown per acre and if you can get more usable BTUs per acre from corn than you can from an energy crop then it may be the most efficient way to produce biomass energy, at least for today.
Moving away from the unsustainable practice of digging up and burning biomass that has been buried for millions of years toward living on a balanced energy budget will help humanity to understand that the energy used for food, transportation, and heating fuel is all inter-related. Today one cannot make that connection because oil, natural gas, and coal cannot be eaten. Someday they will be exhausted, and any fuel will likely originate from biomass that can be a food, or otherwise competes with food for land on which to be grown.
Update: One of the multifuel stoves we found online recently here has a few customer reviews but they are really mixed, this is an emerging technology in many ways and we welcome your feedback and reviews below.
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Wow, very comprehensive you guys! The information provided by you is very excellent. I got good knowledge from your summery. It is very useful and helpful for every one. I've got a page about food calories that you might find interesting, it's not quite biomass but it's a similar topic ;)
Your estimated BTU output for corn is wrong (sorry). A bushel of corn has about 275,000 BTU. Penn State Agricultural and Bilogical Engineering Dept. http://energy.cas.psu.edu/energycontent.html This is about 3.64 bushels per 1 million BTU, which is 80% more corn consumption than your chart indicates. This is because of the 15% moisture content that cannot be counted as fuel (in fact, costs calories to evaporate).
So, to be accurate you need to multiply your monthly cost of corn by 1.8. This puts it close to the same cost/BTU as wood pellets (ceteris paribus).
Rick Ritchie
September 25, 2008
Don't forget corn is federally subsidized so you need to add another $0.20 to $0.50 per bushel to the cost of using it. Of course fossil fuels are subsidized to a considerable extent too but I don't know the amount.