Vetiver and Energy

A university student wanted to know the energy value of vetiver which reminded me of a note from Gueric Boucard (Dominican Republic), Gueric uses vetiver as feed stock for his power plant, and energy prices are on the rise again:

  • A vetiver plantation in the tropics under irrigation or good annual rainfall will produce up to 80 tons per hectare per year of dry vetiver grass.
  • The grass can be baled with a standard hay baler after 3 or 4 days of sun drying.
  • The dry grass was found to have a calorific value of 7,000 btu per pound. (about one half of that of coal).
  • A modern thermal power plant would require 1000 tons of vetiver bales per day to produce 50 Megawatts around the clock. ( I know this, because there is a 50 Megawatt power plant in my backyard, in Barahona, D.R. which burns 500 tons per day of coal imported from Columbia with 13,000 btu/lb)
  • 1000 tons of vetiver bales more than equal 500 tons of coal, and can be harvested from a 12.5 hectare field easily in one day.
  • Hence to run the 50 Megawatt power plant 365 days per year on vetiver hay will require a plantation of 4,563 hectares, surrounding the plant. (think of a sugarmill surrounded by fields of sugarcane).
  • Unlike sugarcane, the vetiver plantation does not need to be re-planted. The vetiver plantation will just grow back with natural rainfall and can be considered a renewable and sustainable FUEL MINE, which can be harvested every year, at any time of the year, for 20 years or more, just adding some fertilizer.
  • If the power plant owns the farm land (like a sugarmill) and its own farming operation, I estimate the raw cost of producing one ton of vetiver biomass fuel at no more than US$15/ton, once the plantation is established.

Power plant engineers will have only one question for you: What is the cost of the fuel per Million btu (MMbtu)? Here is how to calculate:

  • If one pound of dry vetiver leaves has 7000 btu, then it takes 1,000,000 divided by 7000 to establish how many pounds of the fuel will produce 1,000,000 btus. 1,000,000 divided by 7000 = 142.9 lbs. if one ton of vetiver fuel (2000 lbs) cost US$15, then US$15 divided by 2000 and multiplied by 142.9 gives you what it costs to produce 1,000,000 btus, that is: Vetiver fuel cost: US$1.07/MMbtu
  • If you do the math for one of the cheapest fuels, which is COAL with 14,000 btu/lb, at US$45/ton (in the US), you will find: Coal fuel cost: US$1.60/MMbtu
  • Let’s try it for crude petroleum, just for kicks. At only $100 per barrel ( a barrel = 42 gallons or 336 lbs). One ton (2000 lbs) divided by 336 lbs = 5.95 barrels per ton….., multiplied by $100 = US$595/ton of crude petroleum. Now, petroleum has about 18,000 btus per pound…., so 1,000,000 divided by 18,000 = 55.5 lbs. It takes only 55.5 lbs of crude petroleum to produce a MMbtu. But US$595 divided by 2000 and multiplied by 55.5 lbs gives the fuel cost per MMbtu: Crude petroleum fuel cost: US$16.5/MMbtu

I don’t rest my case yet. One could argue that planting vetiver for fuel, is one of the easiest and safest farming operations (no diseases, no weather damage, no nothing) and one of the most lucrative uses for tropical farmland….., if electricity at US$0.12 per Kw/h is the final product.

If somebody in the third world ever figures this out, one of the biggest problems will be to insure that food crops are not displaced for fuel production. Really, only second rate farmlands should be used or cleared for vetiver fuel production.