Is hemp the best biofuel?

is hemp the best biofuelIt is a common misconception among hemp and cannabis proponents that simply switching from fossil fuels to hemp biofuel would, in one fell swoop, solve the problems of running out of fossil fuels and the frankly terrifying consequences of continuing to use them. Far from being the planet-saving solution that they are all too often presented as, biofuels as a whole bring their own set of issues that create more problems than they solve. Nothing exists in isolation. It is vital to look at the domino effect that replacing fossil fuels with biofuels would have on the planet as a whole. However, when comparing hemp to other biofuel feedstocks, there are some advantages to be seen.

Biodiesel and ethanol can both be made from hemp

There are two types of biofuel: biodiesel and ethanol. Ethanol is made from grains (corn, barley, wheat, etc) or sugar cane, but can also be made from the inedible parts of most plants. It is frequently used as a biofuel, but usually blended with petrol. Cars designed to run on petrol can only tolerate a 10% addition of ethanol to petrol; flexible fuel cars can use an up to 80% ethanol mix. In Brazil, where vast amounts of sugar cane are grown for biofuel, some cars can run on 100% ethanol.

Biodiesel is made by refining oils and fats from plants or animals, most commonly from vegetable oil, and requires methanol. Regular diesel is often blended with biodiesel at a rate of 80% / 20% respectively, but blends can range from 2% – 100% biodiesel. A practical advantage of biodiesel is that any diesel car can run on it.

Hemp, if grown as a biofuel feedstock, would be able to produce both biofuels. Hemp seed has an oil content of 30-35% of the seed weight, giving it a fuel yield of roughly 207 gallons per hectare. This is considerably lower than palm oil and coconut, but over twice that of rapeseed, peanut, and sunflower, and four times that of soybean. The remainder of the plant can be made into ethanol using fermentation under low oxygen levels.

Land use for biofuels

The most common feedstocks used for biofuel are soybeans and corn (US), sugar cane and sugar beet (South America), palm oil (Southeast and East Asia), and rapeseed (Europe). All of these require significant amounts of fertile land in order to flourish. Great swathes of rainforest have been destroyed to create space for oil palms; deforestation is occurring on an alarming and unprecedented scale in all of these areas. This has obliterated the habitat of numerous species, many of which (such as the orang-utan) are already endangered. These feedstocks are also grown on arable land formerly used to farm crops for human consumption, driving the prices of these crops up and out of the reach of the poor. In addition, what is known as ‘secondary deforestation’ is taking place as more land is needed to farm crops for food. Biofuel targets set by various governments around the world are doing more harm than good in terms of both climate change and food supply, and it is developing nations, rather than affluent ones, that are being hit hardest by both these problems.

What advantages does hemp have as a biofuel feedstock?

Hemp has the advantage of being able to grow in less fertile soil, and its ability to grow on what is referred to as ‘marginal land’ (i.e. not fields) is highly praised by many. However, in real terms, it produces the most seed when grown on fertile land under optimum conditions. Should its use as a biofuel feedstock catch on, it is very likely that arable land would be devoted to hemp in the same way that it is to rival feedstocks now, with the same negative impact on the price of food.

The other problems with marginal land are that firstly, it supports species and processes that are a valuable part of the ecosystem. Secondly, by its very nature, it tends to be in places that are impractical to farm. The issue of how to harvest hemp in hard to reach places, and how to transport it to a biofuel processing facility, cannot be ignored. Since both activities generate CO2 by burning fossil fuels, this must be factored into its efficacy as a carbon-neutral crop. This applies to all biofuel feedstock crops, on all land, not just hemp on marginal ground: the carbon cost of ploughing, sowing, harvesting, transportation and processing is higher than that of producing fossil fuels.

Although this means that switching to hemp fuel for all motor vehicles will neither solve the energy crisis nor halt climate change, there could be a smaller-scale yet still helpful application. If farms are able to grow and process hemp on-site to make biofuels for farm vehicles and machinery, they may be able to create a self-sustaining and low-carbon-emitting ‘loop’, and end their dependency on fossil fuels. Hemp could be introduced as a rotation crop in existing food crop cultivation, lessening the impact on both food prices and fossil fuel use.

There is also the fact that hemp is currently very much a ‘niche market’ food crop, so there is not the same dependence on it as there is on corn, for example. However, this currently makes it not cost-effective enough to be grown on a large scale for biofuel production.

Minimal fertilizer and water is needed to grow hemp

Another area which requires scrutiny when looking at biofuels is the fertilizers needed to farm them. These fertilizers are basically nitrates from oil and gas – yes, fossil fuels – using the energy-intensive Haber-Bosch process to produce ammonia, which in turn is used as feedstock for all other nitrogen fertilizers. Once introduced to land, they don’t just sit in the soil. Either they get washed into watercourses where they disturb the ecosystem, kill fish, and pollute drinking water supplies; or enter the atmosphere, becoming nitrous oxide – a greenhouse gas worse than carbon dioxide – or the mono-nitrogen oxides NO and NO?, which contribute to ground level ozone (another health hazard).

Hemp requires soil fertility roughly equivalent to that of corn to grow well. However, around 70% of its nutrient requirements will be returned to the soil during and after the growth cycle (1), drastically reducing the amount of fertilizers it needs over the long term. This is a definite advantage over all other biofuel feedstocks.

The same can be said of its water requirements. One of the biggest problems with biofuels is that their production requires more water than fossil fuels, anywhere from twice to 48 times as much. Hemp requires about 30 – 40 cm (12-15 in) water per each growing season or rainfall equivalent to produce a crop, whereas corn requires around 56 cm (22 inches).

Use of the whole plant

Perhaps one of the biggest advantages of hemp as a biofuel is the potential for using every part of the plant. Once oil is pressed from the seeds, the remaining hulls and seed matter can be compressed into ‘cakes’ for nutritious animal feed. Trim from harvesting and leaves which fall off during growth return to the soil, along with the roots, replenishing it for the next crop. The bast fibres and hurds are used for fibre, paper and building materials, to name but a few products.

There are still obstacles to discovering whether or not hemp is the best biofuel. Currently, legislation which prevents hemp farming is still in place in much of the world; until this changes, a lot of hemp’s advantages remain theoretical. It is to be fervently hoped that this does not remain the case for much longer.

(1) British Colombia Ministry of Agriculture and Food Specialty Crop factsheet, via http://www.hemptrade.ca/

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