Coal and Ethanol

A Lightbulb Uses a Lot of Coal

Just a very quick post today while still on vacation in the U.S.

I was browsing around the other day, and I ran across this:

How much coal is required to run a 100-watt light bulb 24 hours a day for a year?

You can pop over there for the details, but I was shocked at the result:

714 pounds of coal, 5 pounds of sulfur dioxide, 5.1 pounds of NOx, and 1852 pounds of CO2 – for 1 light bulb. That just blows my mind. Sometimes I will leave my computer on overnight, rationalizing the decision by thinking “It only uses about as much electricity as a light bulb.” I have to adjust my thinking.

Robert Bryce on Ethanol

I have missed out on a lot of good commentary on the insanity going on in congress right now with this energy bill, but Robert Bryce – whose positions on energy issues are almost all identical to my own – summed it up well in Slate:

The Great Corn Con

Thirty-six billion gallons of ethanol a year sounds like a lot, but it’s only 2.34 million barrels per day. And given ethanol’s lower heat content—about two-thirds that of gasoline—the effective production would be equivalent to 1.54 million barrels of oil per day. The United States uses nearly 21 million barrels of oil per day, of which 12.54 million barrels are imported. Thus, even if American ethanol producers can miraculously achieve the Senate’s goal of 36 billion gallons per year by 2022, they will be producing the equivalent of just 7.4 percent of America’s total current oil needs and just 12.2 percent of its imports. That quantity of ethanol will not take America very far toward the oft-repeated goal of energy independence.

I would add to this that this calculation does not back out the fossil fuels that went into making the ethanol. Since it takes 1.0 BTUs of fossil fuel to make (arguably) 1.3 BTUs of ethanol and animal feed, it will take 36/1.3, or almost 28 billion gallons of ethanol equivalent to produce the 36 billion gallons. Therefore, the net is 8 billion gallons – less than 2% of our total oil usage. That is what is actually displaced if 36 billion gallons of ethanol is produced. Insanity.

Of course some people correctly point out that we have lots of coal, and coal-fired boilers can be used to fuel the ethanol plants. And of course this is true, but it’s going to take a lot more coal than it would take to run a million light bulbs.

19 thoughts on “Coal and Ethanol”

  1. Welcome back, Robert!

    You’re right, that is a mind-boggling large amount of coal.

  2. And another thing…

    Unless I somehow missed it, the article doesn’t mention distribution (resistive) losses. The reference I found ( suggests a figure of around 10% for the US, meaning we should multiply the numbers given by ~1.1 (as if it wasn’t bad enough already)…

  3. Of course some people correctly point out that we have lots of coal, and coal-fired boilers can be used to fuel the ethanol plants. And of course this is true, but it’s going to take a lot more coal than it would take to run a million light bulbs.

    coal = death sentence to low lying countries like Bangladesh. Gotta love the optimism.

  4. j.s. (wacki)

    Bangladesh is the least of our problems in global warming.

    Although it has a strong terrorist campaign by Islamic militants, which could spill over into India (and the UK, which has a substantial Bangladeshi minority), it probably can be contained.

    Much greater problems are afoot with global warming. Everything from the thorney problem of what to do if it doesn’t rain in Southern California, through to ecological collapse in Africa. Or mass migration of Central Americans and Mexicans into the United States.

    Beyond that you have ocean acidification, the risk of a collapse of the Greenland Ice Sheet, the potential for superstorms in the North Atlantic, and indeed the Great Permian Extinction, apparently triggered by a massive rise in atmospheric CO2.

    100 million or so Bangladeshis is really only the canary in the cage of a world of climate change.

    The damnable problem is we won’t know how bad the problem is, until it is too late to do anything.


  5. Robert – I might quibble a bit with the efficiency on the coal fired plant. 40% sounds like an average, newer plants do a bit better.

    You talked about power usage for a computer. Readers might want to check this out:
    Kill a Watt

    This is the best price I’ve seen on one. Can’t use in the UK as voltage is limited to 125 VAC. You can really see what appliances use power.

    I have been on a crusade to cut the electric bill this year. So far we are down 12% over 2006. But we are rolling into summer, about 50% of our bill is for air conditioning. I’ve been installing a radiant barrier in the attic to reduce heat load and improve comfort and save energy. While up there I am fixing insulation and air infiltration problems.

    I have replaced a number of recessed flood lights with new CF floods. For those of us in warmer climates, the 100 W light bulb puts out a lot heat, which has to be removed by the A/C. So the 714 lbs is even higher!

  6. I have seen the fact that ethanol’s net energy gain is only 30% used so often as a negative. It certainly sounds like a very low energy return (and 30% is a generous figure). But how does it compare to gasoline made from oil? Clearly it takes a certain amount of energy to produce a quantity of “regular” gasoline. What is the energy return from that?

  7. Refinery efficiency figures I have seen for motor fuel production are ~83% for gasoline and ~88% for diesel (distillate).  Robert’s ex-refinery was better, IIUC.

  8. Clearly it takes a certain amount of energy to produce a quantity of “regular” gasoline. What is the energy return from that?

    I have done this analysis on a number of occasions. The ethanol proponents like to compare ethanol’s EROEI – 1.3 – to gasoline’s efficiency – of 0.8 or so. But that’s not an apples to apples comparison. If you compare fossil fuels consumed and divide that by fuel produced, ethanol is 1.3 (again, counting animal feed as BTUs) and gasoline is around 5 – at least 4 times higher than ethanol.

    Back to fishing now with my boys.


  9. Not only do they omit line losses from distribution, those emissions figures also implicitly assume that only coal generates electricity. The actual emissions induced by a light bulb left on for a year depend on the the supply mix in the state (and energy market) in which you live. Coal generated ~50% of the supply in the US in 2005 but some states (IN, OH) source much more of their electricity from coal (about 90%). Places like WA or CA, meanwhile, rely much less on coal (10% and 1%, respectively, in 2005). So when you leave your computer on all the time, your conscience could be as clean (or as dirty) as your supply mix.

  10. Why can’t solar power be used in ethanol plants? Unlike electrcity, ethanol can be easily stored.

    Obviously, the plant load factor will be lower than for a gas- or coal- fired plant (night, cloudy days, etc), but you would sure save on fuel.

  11. Why can’t solar power be used in ethanol plants?

    You could, but it would be very expensive. If you had electricity it is better to sell it as electricity and use a lower priced fuel for heating your ethanol plant. There are 3413 BTUs per kWhr of electricity. A barrel of crude oil contains about 6 million BTUs, and a cubic foot of natural gas about 1,000 BTUs. Coal (bitumonous) has about 26 million BTUs per ton.

    So here are the price per million BTUs of heat delivered for each source:
    Coal (Appalachian), $45/short ton, $1.73/mil BTUs

    Natural gas (Henry Hub, LA), $6.81 / mil BTUs

    Oil (West Texas Intermediate, Cushing), $70/barrel, $11.66/mil BTUs

    Electricity ($0.08/kWh avg. industrial), $23.43/mil BTUs

    Even if you had to sell the power back to the utility at its avoided cost, say $.03/kWh or $8.72/mil BTUs you would still be better off to use natural gas.

  12. BTW – that is why when our clothes dryer breaks down we will replace it with a gas fired drier. I currently pay $1.25/therm ($12.50/mil BTU) for gas and $0.13/kWhr ($38.09/mil BTU).

    It doesn’t take too many loads of laundry saving $25 per million BTU to pay off the added cost of gas drying.

  13. Why can’t solar power be used in ethanol plants?

    You could get around KingOfKaty’s issue by using solar thermal instead of photovoltaic. Solar thermal with storage could even run overnight. But you’re pretty much out of luck in the late fall and winter in the midwest, which is when the corn comes in. And that’s a lot of expense for a plant that will sit idle so much.

    Corn ehtanol energy balance is best improved by integration. The ‘closed cycle’ plants which integrate ethanol and diary operations are a good example. Plants which process both grain and stover are another.

    Brazilian ethanol has superior EROEI primarily because they fire their stills with sugar cane stalks instead of natural gas. We leave our corn stalks (and cobs) in the field to rot. This is mostly historical artifact: sugar cane harvesting traditionally involves cutting cane in the field and trucking the whole plant to the sugar mill. Corn harvesting evolved such that giant combines traverse the fields, extracting the grain and leaving everything else behind.

    If we rework our combines and ethanol plants to handle stover EROEI would improve. But if we’re going to do all that it probably makes sense to use cellulosic enzymes on the stover.


  14. doggy – I really like concentrated solar power. Of the alternatives I think CSP and wind have the best shot at being competitive with today’s technology. I particularly like the conventional steam trough design. Simple and effective.

  15. Solar thermal with storage could even run overnight.

    Even so, it is an incredibly inefficient usage of energy. The vast majority of that energy is lost to the high heat capacity of water, which is the predominant component in the ethanol solution. I think I could come up with better uses for solar thermal than that.

    Cheers, RR

  16. Of course some people correctly point out that we have lots of coal, and coal-fired boilers can be used to fuel the ethanol plants.

    As you well know Robert, that would be an inefficient use of coal.

    Using coal to power an ethanol plant would mean using both coal and natural gas indirectly to make a motor fuel — coal to run the stills, and natural gas to make the fertilizer to grow the corn.

    It would be much smarter to convert the coal directly to a liquid fuel, and use the natural gas as a primary motor fuel.

    Say what you will about coal, but fortunately we at least have lots of it.

    President Bush said we are addicted to oil. Actually that’s not true: We are addicted to the luxuries that burning huge amounts of energy bring us. Oil just happens to be the most convenient and dense source of energy for us to burn.

    But as oil becomes scarcer and more expensive, our addiction to the luxury of burning energy means few will have any reservations about massive use of coal.

    The vast majority of Americans will vote to dig up and burn that coal to maintain our lifestyle, even if there are adverse effects on the environment and atmosphere.

    By the way, how many people do you think realize that both oil and coal are actually bio-fuels?



  17. Some countres have outloed the incand. bulbs, and mandate the little flourescents. You can buy the little flour, bulbs for 99 cents now in 99 cent stores. Imagine savng all that coal every year.
    Do not bach renewable fuel too much. At mre than $60 a barrel, fossil fuel demand may flatline, or even decline. The EIA has a “high price” outlook showing the world using less fossil fuel in 2030 than now. Sanford Bernstein, the Wall Street research house, has also come to the some outlook. If oil prices stay above $60, then renewables have a big future, as we will see Peak Demand for fossil oil. Jatropha looks promising, as do many kinds of ethanol or liquid fuels not based on corn. Corn is what we have now, and we have umpteen corn Senators, so corn will be our first step.
    There will also be a large decrease in fossil demand, if PHEVs come on. Actually, the future looks quite good.

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