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Peanut Shells to Power
Prodeman’s 10-MW power plant in Cordoba, Argentina, is fueled by peanut shells. BY HOLGER STREETZ
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rgentina produces 1 million tons of peanuts on 1.2 million hectares (ha) (4,633 square miles), rotating use of the fields for peanut production every fourth year. The harvest of Argentina’s peanut fields largely depends on the amount of rainfall. On average, the yield is three tons per ha. Producing nearly 90%, Cordoba is the hotspot of Argentinian peanut production. In the heart of peanut plain, Prodeman, a vertically integrated peanut producer, built an electric power plant that generates 70 gigawatt-hours of electric power annually. I was able to interview Jorge Rubén Ciravegna, the engineer behind Prodeman’s 10-MW renewable power plant, which is solely burning agricultural waste from peanut production.
Energy Dense
The fuel for Prodeman’s power plant is abundant. Each hectare of peanuts leads to 1.1 tons of peanut shells. One cubic meter of peanut shells weighs 300 kilograms (kg), or 18.7 pounds per square foot. Peanut shells have a high calorific value of 17,570 kg. One ton of peanut shells produces 1.25 megawatt-hours (MWh) of electricity. Farmers used to be glad to get the hardly putrescible agricultural waste off their fields. Now, prices for peanut shells range around $35 per ton. Prodeman’s power plant operates 24/7 with raw material stock from leased land that is farmed with its own equipment. Since the company’s approach is to add as few additional energies as necessary, baling the peanut shells is the only treatment. This improves transportability and storing, as harvesting and power generation are delayed. Baling densifies the material by a factor of 3.5 and enables Prodeman to source from a larger radius, storing the material more efficiently. The plant burns peanut shells in a water tube boiler to produce high-pressure steam.
The steam turbine operates with 480 degrees Celsius at 67 bar pressure (900 degrees Fahrenheit at 972 psi) and a constant throughput of 40 tons/hour. The peanut shell consumption is 0.8 tons/MW, equating to up to 200 tons for daily consumption. The steam turbine is capable of producing 80,000 MWh of
electric energy annually, which is supplied to the national electric grid. To further increase its utilization ratio, Prodeman uses the ash resulting from peanut shell combustion to produce bricks. The project complies with the provisions of the 2015 Paris Agreement and allows greater sus-
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24 BIOMASS MAGAZINE | ISSUE 2, 2021
