Whats wrong with Ethanol from Sugar Cane

Much has been said about Brazil’s success in using ethanol made from sugar cane to help them become energy independent. They have been very successful in growing sugar cane and converting it ETOH (ethanol, ethyl alcohol). Does this mean though that the US could do the same and preserve our current wasteful lifestyle? Unfortunately, I doubt it.

Lets look at some energy consumption numbers (data from the year 2003).

In the US, we produce 11 barrels of oil per year per person. We use 27 barrels per year per person, so we need to make up the energy equivalent of 16 barrels per year per person if we are to achieve energy independance.

Brazil, produces 3.35 barrels of oil per year per person, and use 4.2. So in Brazil, they need to make up only .85 barrels. That is almost 20 times less per person than in the USA.

Their real success is in the fact that they use so much less energy per capita than we do. If we (in the US) used the same amount of energy per person as Brazilians, the US would be an oil exporting nation, and would be energy independent. In fact, we can use 3 times as much oil per person as Brazil, and still be energy independent. However, that would not support our present lifestyle.

Brazil produces 420 million tons of sugar cane each year compared to 25 million tons grown in the USA (including Hawaii)1. That is almost 17 times the amount the US produces. Under ideal conditions, 1 ton of sugar cane can be processed into 18+ gallons of ETOH2 , which is the energy equivalent of 13 gallons of gasoline. If we used the entire yearly US crop of sugarcane to make ETOH, it would make at most the equivalent of 325 million gallons of gasoline. Since we use 8 million barrels (336 million gallons) of gasoline per day, the entire sugar cane crop amounts to less than 1 days supply of fuel. Can we ramp up our sugar cane production by a factor of 400? Of course not. Sugar cane only grows well in a tropical climate. Most of the US is not tropical, and is not suitable for sugar cane production.

Outside of the geography issue itself, there is also an issue of water. Brazil is a tropical country, with plenty of rainfall. Sugar cane requires an annual rainfall of at least 2 feet, which means we would have to heavily irrigate the cane while Brazil does not. How much water is that exactly? Well, here are my calculations:

50 square yards will grow 2-3 tons of sugar cane per year so an acre will grow about 250 tons (3250 gallons of gas). Two acre-feet of water equals 650,000 gallons of water. So we are talking about using 650,000 gallons of fresh water to gain 3250 gallons of fuel, or about 200 gallons of water per gallon of fuel. Considering water is also a scarce resource, does that make sense?

For these reasons, I do not see how sugar cane is going to be a major energy source for the USA. Instead, the hype about ETOH from sugar cane, or worse, from corn does nothing except allow people to believe that they will be able to continue their present energy usage into the future. What we should be promoting instead of alcohol is conservation first.

1 Sugar Cane Production

2 Conversion to Ethanol in Brazil

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