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The Energy Potential of Industrial Hemp Biofuels

April 21, 2020 in General News

Now that the effects of fossil fuel use are known to be causing serious climate damage, it is incredibly important for all governments to switch to renewable energy sources. Industrial hemp may just be the solution to saving the planet. In this article I will describe all the different types of hemp biofuel, give some facts about biodiesel, discuss how hemp biofuel compares to other sources and cite a study about hemp biodiesel.

Hemp Biodiesel

Hemp seeds contain around 30% oil which can be transformed into biodiesel for vehicles, using transesterification. That is a process where reactants are mixed together; fatty acids, alcohol and a catalyst such as sodium or potassium methanolate. The end result is raw biodiesel and raw glycerol which then undergo a cleaning process.

  • Hemp can produce upwards of 800 liters of biodiesel per hectare per year. This exceeds the output of soybeans, sunflowers, peanuts or rapeseeds.
  • Hemp doesn’t require the expensive drying required of corn and sugar
  • Hemp meets the American and European standards for biodiesel quality and appears to be superior to other plant based products. The only area in which it does not outperform conventional diesel is in oxidation stability which can be rectified through the addition of anti-oxidants.

Some Biodiesel Fun Facts

  • You can use biodiesel in any diesel engine
  • It contains no sulfur
  • It is 11% oxygen by weight
  • It is ten times less toxic than salt with a flashpoint of 300°F.
    FYI: regular diesel has a flashpoint of 125°F which makes the transportation of biodiesel much safer

Why Isn’t Hemp Biodiesel More Widely Used?

  • Less Availability
  • Higher Costs
  • Because hemp seed oil is a highly desirable commodity for a variety of uses, this keeps the price of the oil prohibitively high.
  • The cost should decrease with an increase of acreage both in the US and in other countries.

Hemp Ethanol

Ethanol is derived from sugars and starches of plants. In order to create hemp ethanol, a process called cellulolysis is required. This involves several stages:

  • It must be pre-treated to make the cellulose content suitable for hydrolysis
  • Cellulase, an enzyme that converts cellulose into glucose, is required to break down the molecules into sugars
  • The sugar materials must be separated from the lignin, a complex polymer responsible for the strength of the cell walls of plants
  • The sugar solution must go through the fermentation process
  • The ethanol must be extracted through distillation
  • Molecular sieves are deployed to increase the concentration of ethanol

Hemp Methanol

Also known as wood alcohol, it is produced from the woody, pulp plant material.

  1. Dry distillation is the main process used to create hemp methanol, a by-product of which is charcoal. It can be used as a solid fuel.
  2. Pyrolysis, another possible source, is a process where high heat is applied to organic matter such as hemp, without an oxygen source. This keeps the material from catching fire. It is the most efficient process for hemp biomass conversion with a 95.5% feed-to-fuel efficiency. It is possible that hemp biomass conversion may become a replacement for fossil fuels.

Hemp Solid Fuel

Hemp pellets are made from the woody core of the plant, known as the shiv or hurd. They are an excellent alternative to wood since they produce similar amounts of heat and ash content but are not corrosive.

Hemp Biogas

Methane, the major ingredient of natural gas and close relative of methanol, is produced by the use of a biodigester to capture the gas under optimum anaerobic conditions to create hemp biogas.

How Industrial Hemp Biofuel Compares To Other Sources

  • Only algae performs better than hemp
  • Hemp on average produces nine dry tons per acre
  • Hemp is 80% cellulose, making it low-moisture, herbaceous and woody
  • Due to its high cellulose content, hemp has an estimated 540% energy gain compared to corn’s 34%
  • Hemp could quickly surpass pulpwood or kenaf in producing greater biomass tonnage per acre annually in more areas of the US

Are Industrial Hemp Biofuels Carbon Neutral?

Claims have been made suggesting that hemp biofuels are carbon-neutral; the amount of CO2 absorbed during the growing process is offset by the amount of CO2 released during use. It is important to consider all that is involved in creating the fuel from cultivation to harvest to fuel production. All these processes must be carbon neutral in order to substantiate such a claim.

Researchers do acknowledge that less input is required to grow hemp, in general, when compared to crops such as corn and soybeans.

University of Connecticut Research Study

In a 2010 study conducted at the University of Connecticut, researchers determined that industrial hemp made a viable and desirable raw material for the production of biodiesel.

Head researcher, Richard Parnas, professor of chemical, materials and biomolecular engineering at UConn, led the study. This finding is very important in identifying hemp as a plant that is not food, does not require high-quality land but can produce high-quality biodiesel fuel.

Parnas worked with James Stuart, Department of Chemistry, and graduate student Si-Yu Li, Department of Plant Sciences. They used virgin hemp seed oil to create biodiesel via transesterification. Here are their findings:

  1. The conversion rate of hemp seed oil into biodiesel is 97%.
  2. It showed properties suggesting that it could be used at lower temperatures than any other commercially available biodiesel.

Let us hope that living through this pandemic will make us humans reconsider our prior dependence on fossil fuels in favor of a renewable energy source such as hemp.

Sources:
hempgazette.com, Industrial Hemp’s Energy Potential-Biofuels
sciencedirect.com, Anaerobic Digestion of Industrial Hemp-Effect of Harvest Time on Methane Energy Yield Per Hectare
medium.com, Hemp Biofuel: No Green Deal Without It, DarbyHemp, April 19, 2019
today.uconn.edu, Hemp Produces Viable Biodiesel, UConn Study Finds, Christine Buckley, Oct. 6, 2010

 

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