Ethanol, its complex

That’s the tricky thing isn’t it?  If the production and use of ethanol emits more carbon in aggregate than the production and use of gasoline, then what’s the point?  We may replace the falling oil production, but at what price to the planet?

Then there are the other externalities to consider.  Land used for fuel instead of food.  Excess water usage.  Land degradation.  Capacity limits to scaled up production.  Biodiversity depletion from monoculture production.  Poison from the different gases released.

As outlined here, it is time to find out if ethanol is worth its weight in oil relative to carbon emissions.  Information usually obtained by plundering publications on the internet.  And what is found, is, it’s complicated. 

So there is good news and bad news.  However, to round out the debate it is interesting to note that ethanol is produced by various crops.  In the USA it is mostly corn;  in Europe it is rapeseed;  in Brazil (for example) it is sugar cane; in China it is seaweed; and in Australia it is soy bean.

Production of each of these has different carbon footprints and externalities, and even within each specific crop, there are differences that can make it carbon neutral or carbon (eq) intensive.

For example the (subsidised) corn production in the US and rapeseed in EU is causing the prices to rise internationally, and directly affecting food security for the rest of the world.  Especially poverty stricken countries, for which maize and edible oils are a large part of their diet.  The UN’s FAO called for a reduction in production of both.  Further they produced a study that shows in Latin America only Argentina, Brazil, Paraguay and Columbia could sustainably produce biofuel without affecting food security.  

Then there is this article, which suggests that depending on how the corn is produced it could be 20-30% less carbon intensive / 20-30% more carbon intensive than gasoline.  It is land usage that makes the biggest difference.  Quoting: 

“if you assume that all the land used to produce the ethanol feedstock is already in production, you tend to find a carbon footprint at the low end of the range, since there is little net reduction in the carbon sink, and ethanol looks pretty good. If you assume that all the land used to produce the ethanol feedstock came from forests that had been chopped down, or marginal land that produces very low yields, you tend to find a carbon footprint at the high end of the range, and ethanol looks bad. Thought about another way, ethanol made from corn or sugar that displaces human or animal food production is likely to be relatively greenhouse gas friendly compared to ethanol made from corn or sugar that comes from new land put into production just for ethanol.”

Then there is this report, that compares the cost of subsidising corn ethanol versus sequestering the land used for the subsidised corn as carbon sinks.  The latter trumps the former in dollar cost to the taxpayer.  And this report shows how corn is produced at the farm level, may / may not produce substantial amounts of nitrous oxide, a GHG 300 times worse than carbon.  

And then there is this study “Ethanol as Fuel: Energy, Carbon Dioxide Balances, and Ecological Footprint”.  Really, it was the most comprehensive. 

It compares the production of corn in the USA versus sugar in Brazil, as inputs for biofuel.  US comes out looking not so good, and Brazil very good (as in reports above).  

I recommend you read it.  But for a summary of US:  to produce sufficient ethanol in 2012, all the available cropland in the US must be turned over to corn.  By 2036, add in the entire range and pasture areas as well.  And by 2048, every bit of land except for the cities.  So, ethanol is not an option.  And they give many other reasons as well.

In Brazil, only 10% of cropland is required to run the total fleet for the next 30 years.  Starting to consider the complexity? They conclude:

In the Brazilian case, for carbon sequestration, it seems to be more effective to reduce the rate of deforestation than to plant sugarcane.

In the US case, the use of ethanol would require enormous areas of corn agriculture, and the accompanying environmental impacts outweigh its benefits. Ethanol cannot alleviate the United States' dependence on petroleum.

Finally, there is this recent report.  Seaweed, that has been grown at a commercial scale for more than a century in China, is now producing biofuel in small trials.  As with sugarcane, and corn, it is the sugar that is the key ingredient. And it doesn’t compete with food crops, it does not require land, plus it is a pollutant cleanser not polluter.  On a per acre basis it produces 50% more ethanol than sugarcane, and 3 times that of corn.   There is more info here.

So there it is.  No rah!! rah!! or slaps on backs for using ethanol.  It is not all the same.  Indeed much production is creating worse environmental and carbon problems than it is fixing.  The seaweed biofuel seems to be the answer.

But if I can’t get my sushi, I‘ll be cross.