![](images/images_05_03_2023/hemp_Hero%20copy.jpg)
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As the global push for renewable energy intensifies, researchers and
engineers are exploring alternative fuels that can help reduce global
greenhouse gas emissions.
One promising, yet often overlooked, candidate is hemp biofuel.
However, the plant shows promise, and there are ongoing developments
to address the production and technical challenges, which hope to
position hemp as a component of a carbon neutral future.
Hemp: A versatile and sustainable resource
Hemp is a variety of the Cannabis sativa plant that has been
cultivated for thousands of years for its fiber, seeds and oil. Unlike
its close relative, marijuana, hemp contains negligible amounts of
tetrahydrocannabinol (THC) and is thus non-psychoactive and
non-intoxicating.
What sets hemp apart
from other biofuel feedstocks is its remarkable versatility and
sustainability. Hemp can be grown on marginal land with minimal water
and fertilizer requirements, making it an attractive option for
biofuel production. On top of this, hemp is also notorious for its
fast growth, and ability to absorb significant amounts of carbon
dioxide, making it an even better choice as a source of biomass for
biofuel production. Hemp’s sustainable properties afford enormous
opportunities to make biofuels the fuel of the future. However, there
remain technical challenges with its large-scale production and
utilization that have limited its use until today.
To harness hemp's potential as a source of renewable energy, it must
be processed into biodiesel or renewable natural gas (RNG).
Hemp biodiesel
Producing hemp biodiesel is a multistep process beginning with seed
harvesting and oil extraction. Harvested seeds are typically
cold-pressed to extract the oil, and the remaining seed cake is a
useful and renewable byproduct that can be used as a high-protein
animal feed.
The next step is known as transesterification, which is a chemical
process where the extracted hemp seed oil reacts with an alcohol
(usually methanol) in the presence of a catalyst. This reaction
results in the formation of fatty acid methyl esters (FAMEs), or
biodiesel, as well as glycerol as a byproduct.
After production of the biodiesel via transesterification, all that’s
left is purification and quality assurance. The biodiesel is first
separated from the glycerol and purified through a series of washing
and filtration steps to remove any impurities and excess alcohol.
After this, the final step is to test the biodiesel to ensure it meets
required standards for use in diesel engines.
Hemp biodiesel offers several advantages over conventional diesel,
including reduced greenhouse gas emissions, lower tailpipe emissions
of particulate matter and decreased reliance on fossil fuels. As a
result, hemp biodiesel can contribute to cleaner air quality and
mitigate climate change.
Hemp for RNG
RNG production first begins with biomass harvesting and preprocessing,
where hemp biomass, consisting of the stalks, leaves and flowers, is
harvested and processed to remove impurities and reduce particle size
for optimal conversion.
With the hemp biomass prepared, the next step is anaerobic digestion
or gasification. The processed biomass is either subjected to
anaerobic digestion, where microorganisms break down the organic
matter in an oxygen-free environment to produce biogas, or
gasification, where the biomass is heated in a low-oxygen environment
to generate syngas.
Finally, the biogas or syngas is purified and upgraded by removing
contaminants such as carbon dioxide. The resulting hemp-based RNG
presents several benefits, including as a renewable and carbon-neutral
fuel source and its flexibility to be produced with locally available
resources. Moreover, RNG can be injected into existing natural gas
infrastructure or used as a transportation fuel in natural gas
vehicles, offering a seamless integration with existing systems.
Technical challenges of hemp biofuel
Despite its potential, several technical challenges must be addressed
before hemp biofuel can become a mainstream renewable fuel source. The
first of which is the current crop yield, which is not sufficient to
meet fuel demand. To compete with other biofuel feedstocks, such as
corn and soybeans, hemp needs to produce high yields of both seeds and
biomass. Breeding programs focused on developing high-yield hemp
varieties are essential for enhancing the crop's viability as a
biofuel source.
A second major technical challenge is the lack of established
processing infrastructure for hemp biofuels, which presents a
significant barrier to entry. Investment in research and development
of efficient, scalable processing technologies is needed to reduce
costs and facilitate widespread adoption.
Another technical hurdle is in ensuring consistent fuel quality and
compatibility with existing engines and infrastructure. Research into
optimizing the transesterification process and cellulosic fermentation
techniques will help improve the quality and performance of hemp
biofuels.
To overcome these challenges and maximize the potential of hemp as a
biofuel, various innovations and trends have emerged in recent years.
Researchers are exploring the potential of genetically modified hemp
strains to enhance seed oil yields and improve biomass composition.
This could make hemp a more viable and competitive biofuel feedstock.
Novel techniques, such as steam explosion and organosolv
pretreatments, are being developed to break down the complex structure
of hemp biomass more efficiently. These methods aim to increase the
yield of fermentable sugars, ultimately improving the bioethanol
production process.
An integrated approach to hemp processing can help maximize the
utilization of all hemp components, reducing waste and increasing
overall efficiency. For example, hemp fibers can be used for
biocomposites or textiles, while the remaining biomass can be
processed into bioethanol.
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The future of hemp biofuels
Hemp biofuel presents a promising and sustainable alternative energy
source for many sectors. While technical challenges remain, ongoing
innovations and developments are addressing these obstacles, paving
the way for more efficient and sustainable biofuel production. As
research and development in this area continues, the potential
applications and benefits of hemp biofuel will likely become more
apparent, contributing to a cleaner and greener future.
About the Author
Tyler Gleckler is an accomplished scientist, writer and renewable
energy expert with a strong background in chemistry. He holds
undergraduate and graduate degrees in chemistry, having studied and
worked at prestigious institutions such as the University of Oxford,
the University of Edinburgh, the National University of Singapore and
the Hebrew University of Jerusalem. With a research focus on material
chemistry and applied nanotechnology, Tyler has worked on a diverse
set of projects, spanning many subjects and applications.
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