Watermelon Juice — Next Source of Renewable Energy


Hundreds of thousands of tons of watermelons are tossed every year because they aren’t good enough for market. A new study finds that the juice from these watermelons could easily be used to create the biofuel ethanol and other helpful products.


According to a new study to be published in the journal Biotechnology for Biofuels, 20% of the watermelon crop doesn’t go to market every year due to imperfections, bad spots, or weird shapes. These watermelons are left in the field and then plowed right back into the ground. According to the authors of the study (Benny Bruton and Vincent Russo from the USDA-ARS, South Central Agricultural Research Laboratory, and Wayne Fish), these watermelons could be used to produce the biofuel ethanol.

The watermelon juice can be fermented and used directly or it can be used as a “diluent, supplemental feedstock, and nitrogen supplement” with other biofuel crops. If it is used as a supplement to other crops, it could first be used in nutraceutical production and serve an economic and health purpose in that capacity as well. Watermelons could be used to produce the nutraceuticals lycopene (found to be important to prostrate health) and L-arginine (an amino acid that is critical for the production of nitric oxide). After being used to produce these, the waste juice can be used for ethanol production.

Hundreds of thousands of tons of watermelons are lost every year. They are grown and then left in the ground because of superficial imperfections. The authors of this new study show that they could be very useful as a renewable energy source. “The results of this investigation indicate that watermelon juice as a source of readily fermentable sugars represents a heretofore untapped feedstock for ethanol biofuel production. The 8.4 t/ha of unmarketable watermelons left in the field at harvest would produce about 220 L/ha of ethanol for on-farm use or as an additional revenue stream for the grower.”

Fuel your next car with watermelon juice.

Image credit 1: Scott Butner via flickr under a Creative Commons license

Image credit 2: rawallison via flickr under a Creative Commons license

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4 Comments

  1. How much energy would be used to get all these watermelons to a processing plant to convert them to fuel? If it has an energy density similar to corn then it is a waste and they should be left to rot in the fields to replenish the soil.

    Also realize if they are removed then extra fertilizers will be needed to replenish the missing nutrients…

  2. I’d have to agree with Chris if the ethanol were produced at a location some distance from where the melons were grown. On the other hand, if one were to introduce one of the SmartGrid’s ideas and process the melons at a facility close to where they were grown, it might make sense.

    A year or so ago I spoke with some potential ethanol manufacturers in California who were going to do exactly that, build a methanol facility in a corn-producing area of the central coast. The by-products of the process were to be sold locally to cattle ranchers for a feed supplement.

    Another logical step in this chain would be to distribute E-85 ethanol in the locality where it is produced, again reducing the impacts of transporting the finished product.

    I don’t know if the project ever got off the ground, and I would love to hear from others who may have first-hand knowledge of such facilities and any documentation that may be available on the energy yield to energy production costs.

    Respectfully submitted,

    Tom Coalson

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