Land use of Ethanol vs Solar for Vehicle Fuel

I took a stab at trying to figure out how much land it takes to power an internal combustion engine vehicle with ethanol vs what it takes to power an electric vehicle with solar energy.

The links in the embedded spreadsheet show my data sources. If any of these are inaccurate (or my calculations are wrong) please let me know.

Based on what I’m seeing, it looks like it takes a bit more than an acre of farmland dedicated to growing corn to power a single vehicle. That’s based on the amount of E85 fuel it would take, so it would also take some non-ethanol fuel to make that work.

For the electric car numbers, I used a watts/mile figure found on some Tesla forums and a land use calculation based on typical production of panels in large ground-mount systems. This came to 0.015 acres or 652 sq ft.

It seems like it’s quite a bit more efficient to convert solar energy into electricity, transfer that into car batteries, then use that power to turn an electric engine than it is to convert solar energy into plants, harvest those plants, convert those plants into ethanol, transfer that energy into car tanks, and convert that energy into small explosions to turn an internal combustion engine. If my numbers are correct, it looks like it’s around 70X more efficient from a land needed per vehicle perspective.

While this could be looked at from a “what’s the best use of farmland?” perspective, it’s obviously worth noting that solar panels can be placed on a lot of surfaces other than farmland, including places that don’t consume any land, like rooftops.

Another thing to consider: The cost to power an electric car can be significantly cheaper than what’s shown in the spreadsheet if you take advantage of electric vehicle charging and/or time of day pricing plans. Off-peak electricity rates (when your car is likely sitting in your garage) are far cheaper than standard residential rates.

But, wouldn’t that mean that you wouldn’t be using solar to charge your car? Correct. It looks like the future – at least in Minnesota – will involve powering our homes with solar & wind during the day and charging our vehicles with wind power overnight.

5 thoughts on “Land use of Ethanol vs Solar for Vehicle Fuel”

  1. You are welcome to plant solar panels or ? on any farmland you own, Ed. How many acres do you own?

  2. I planted solar panels on my roof in 2014.

    I imagine that a farmer is more concerned with maximizing revenue from their land than powering the largest number of vehicles per acre. If they can make more money farming corn for fuel than farming solar for fuel they’ll likely do that.

    At a state/federal policy level, aligning our incentives with more efficient land use seems smarter to me.

  3. Before ethanol, Minnesota farmers used corn as animal feed. Now, they are using corn as ethanol, biodiesel, carbon dioxide for soda fountains and (wait for it) animal feed.

    In addition to ethanol, many of today’s biorefieneries also extract the gas that puts bubbles in or soda, inedible corn oil that is made into biodiesel, and dried distillers grain, a compact, high-protein animal chow that is sometimes more valuable than the ethanol. The Chinese bought tons of it from MN before the stupid trade war began.

    I’m a big fan of solar, and I tip my hat to you pioneers who were among the first to add it.

    Wished my property was better suited for it (too much shade). But my utility does offer Community Solar and it’s the first utility in the region to try battery storage at its solar panels.

    We need policies that support any fuel or technology that helps to wean us off fossil fuels. I’m for them all.

  4. I always thought we should start putting solar panels on all new construction and then as prices drop move on to older buildings.

  5. Hi Ed,

    I had done my own analysis using the latest statistics for corn ethanol production and average utility scale solar production per acre, but using the corn growing region’s average solar insolation. I also added in corn’s additional byproduct yield as value add (wet distiller’s grains and solubles” which adds about another 37% of economic value.

    In summary, I got very similar numbers as you with Solar being about 66 times more efficient in land use for generating propulsion to our vehicles. Also, the longer term trends favors solar, as the growth of corn ethanol efficiency haven’t kept up with the increase in efficiency of solar systems (panel efficiency, panel cost, and efficiency and cost of the other system components).

    This is not even including the fact that solar panels are now designed to last 30+ years with fairly minimal degradation. Compare that with 30 years of labor, machinery, fertilizer, aquifer water, and fuel inputs for growing the corn. The impact of corn is huge!

    One could simply take 2% of the land growing corn ethanol and dedicate it to solar and raise MORE energy than the entire 98% of the other corn fields combined. On top of that given that solar tends to place panels on only 25-33% of the land, the land between the panels can be growing wild grasses or used for grazing. Dual use!

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