Biofuels

The idea was to make make a petrol, or a diesel-type fuel to power vehicles, generators or heaters etc. using crops that we can grow. This has now been extended to include both algae and cyanobacteria etc. - see Variations . . . below. This development has come about in an effort to avoid using crops that could also be used for food.

At present most biofuels are still made by crushing oily seeds e.g. Oilseed Rape, to extract the oil. This is then filtered and can be used fresh, or further purified if required. All the solid material left over after pressing is still highly nutritious and can be used as feed for livestock. Other crops used are: Sugar Beet; cereals; and even reprocessed vegetable waste. Research is currently underway to explore the possibilities of breaking down the cellulose in straw and then to reshape the carbon chains with oxygen in order to build up 'vegetable' oils and alcohols. This may give a very low energy profit, but is just an example of the things that are being tried in order to provide more liquid fuel.

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How might it work for you

This form of energy production is definitely only suited to large scale arable production. One can produce up to 2,500l/ann. for one's own on farm consumption, i.e. not for sale, without being liable to pay Excise Duty. At an average rate of 350l/tonne Oilseed Rape from the press, this means that 74.29t OSR at 2 - 3t/ha should be obtainable from 25 - 37 ha. With the most up to date double cold pressing machines, it is now possible to get 470l/t OSR at a processing rate for the larger machines of 0.5t/hr. A large processing plant in North Wales (2008) charged ca. 15p/l oil abstracted, and returned the pelleted OSR waste at £215/t - this averages 13.5MJ of metabolisible energy/kg DM; 32% crude protein and 10% oil. The extracted oil was sold on for 90p/l including tax.

The resultant pelleted pressings from 'on farm' machines are nutrient, and indeed oil rich; thus providing an ideal concentrate cake of 13% protein for stock feed. The pressings from a cold double pressing machine can be fed at a rate of 100% to cattle, whereas the pressings from the cold single presses need to be mixed with forage as otherwise they would be too high in oil content for the health of the rumen bacteria and protozoa. In the absence of stock this 'cake' could be used as fuel for a Biomass boiler.

As the cost of fuel rises, it is conceivable that this technology could spread to large domestic; or any group, where the cost of fuel is a significant percentage of the out-goings. The cost of the smallest pressing machines, plus the annual cost of crop purchase, may well become a cost effective option to buying at the petrol station.

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Facts - Energy Produced and Costs of Production

Production for sale simply means that you must be registered and pay tax and Excise Duty in the same way as any other fuel supplier. Details are to be found on the internet.

The OSR fuel can be used in all diesel engines, and should have much the same work potential. Esterification using methanol and caustic soda takes place within the small pressing machines, the by-products being glycerine and the Press cake. This part of the process is necessary to thin the bio-oil so that its flow characteristics are the same as those of ordinary diesel.

The only initial problems when changing from fossil fuel to biodiesel, seem to be associated with the fact that the biodiesel has a cleaning effect on the piping in an engine. This can result in an initial clogging of filters. One is therefore, advised to run the engine on the new fuel until clogging becomes apparent, at which point one should clean the filters and flush out the whole system including the tank with biodiesel. If this is done the problem will not re-occur and the performance will be improved.

The Costs of Production are the same as for the arable crop, but after the depreciation costs of the Oil Presser and its fuel costs are removed, the returns are boosted by the additional benefit of the Concentrate Feed produced over and above the value of the actual fuel. Higher prices could also be achieved for the oil, by including some extra processes and selling it to the Human Food industry.

Based on the oil yield given above, a crop yield of 3.25t/ha and a 2008 crop sale price of £633.65/ha, this means that each hectare yields 1137.5l oil at a 2008 price of 55p/l. NB this does not include the one off 2010 payment for the press which would have to be discounted over the initial years; nor does it include Excise Duty/litre where applicable. Definitely not free, this still represents a large saving on the price of diesel at the pump.

From June 2011, even renewable heat will attract RHI (Renewable Heat Incentive) payments for any installations completed after 15th July 2009. These are to be like the FiTs for production of electricity, only they will apply to Renewable/Sustainable Energy Installations that produce heat/fuel directly and are not connected to the Grid. Their installation does of course mean that fossil fuel is not being used for heating, or powering vehicles; and there is therefore a saving of Grid electricity and of fossil hydrocarbons.

The costs of the Presses vary (2010) between £3,300.00 and £38,000.00. Prices in GBP will vary according to the exchange rate at the time. Machines with a turnout of 5,000l/dy are available, but are for the serious manufacturer/grower and cost over £35,000.

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Pros and Cons

Once one has changed to the use of biodiesel, it is best to minimize fossil diesel by using small amounts only when it is impossible to refill with biodiesel.

Pros:

  • The agronomy and costs of production of the crops are well known.
  • It is not necessary to use a food crop.
  • Where a root crop e.g. Sugar Beet is grown in a cereal area this can benefit the biodiversity of the farm and the health of the soil.
  • The use of biofuels brings fuel supply back to a local base and local distribution.
  • Use of biofuels recycles the carbon dioxide currently in the atmosphere rather than recombining fossil carbon with our oxygen to increase the CO2 and deplete the O2 in our atmosphere.

NB During the process of combustion, both the hydrogen and the carbon in fossil hydrocarbons e.g. coal, oil and gas, are converted to carbon dioxide (CO2) and water (H2O): i.e. between them one atom of carbon and two of hydrogen take 3 atoms of oxygen out of the atmosphere and lock it up in one molecule of CO2. When biofuel or biomass is burnt, then the carbon, hydrogen and oxygen/carbon dioxide are all a part of the natural cycling of atmospheric gases. The CO2 produced by burning these fuels is soon taken up by plant life and much of the oxygen is released during photosynthesis, though some is used to make carbohydrates and fats/oils; and of course plants too use O2 to fuel their cells just as animals do. However, the carbon and hydrogen contained in fossil fuels have not been a part of the atmospheric cycling for millennia, hence their release is dangerous to both our climate and our essential oxygen levels. In the 1960s 20% of our atmosphere at ground level was oxygen; in 2011 this has dropped to only 16% of oxygen in the atmosphere! A change that is likely to be more serious for life in the waters of our planet than the increase of carbon dioxide from 0.02% to 0.04%.

Cons

  • Farm production of biofuels could result in a reduction of the area used to produce Food crops.
  • Biofuel crops cannot be satisfactorily grown on Yield Class 3 or 4 land, without risking a loss of crop yield.
  • Some crops yield more oil when grown slowly i.e. in the northern half of the country.
  • If excise tax were added on the first 2,500l, then the attractiveness of growing for oil would be considerably reduced.
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Variations on the theme

Primary biofuels are produced directly from Crops - see list given below.

The following list of crops is not exhaustive, but I hope it gives you an idea of the possibilities:

  • Grains to Bio ethanol
  • Oilseed Rape to Bio diesel
  • Olive Oil to Bio diesel
  • Sunflower Seeds to Bio diesel
  • Sugar Cane to Bio ethanol
  • Sugar Beet to Bio ethanol
  • Jatropha to Bio diesel

Secondary biofuels are created by the building up of hydrocarbon chains from the cellulose and lignin found in plant material other than the seeds. These are currently under research, but it is likely that the energy equivalent for production will be proscriptively high. This means that it is likely that waste plant material, and crops such as Switchgrass, will be better used as a biomass fuel or as a component of the mix for Anaerobic Digestion.

Tertiary biofuels These are the new 'kids on the block' and are the Algae at 50% oil content and the Cyanobacteria (see below).

  • Algae The energy costs of their production vary from: Ponded at 19g/MJ fuel equivalent (grams per megajoule - 1kWh = 3.6MJ) up to production in Perspex tubes at 320g/MJ fuel equivalent. Due to problems with contamination by wild algae in the outdoor ponds, the favoured solution is to start the colony in bioreactors (tubes), and then putting them out into ponds to bulk up for 2 - 3 days before harvest. These figures compare with the figure for extraction, refining and burning of regular diesel, of 86g/MJ fuel equivalent.
  • The newest 'kids on the block' are the Cyanobacteria e.g. Thermosynechococcus elongatus, presently being developed by Joule Unlimited of Cambridge, Massachusetts. They have persuaded these to convert up to 90% of the carbon that they produce during photosynthesis into an oil. They then helpfully release this so that it collects on the surface ready for removal. The carbon chains formed by the cyanobacteria have chains of 13 - 19 carbons in each oil molecule, a length that is ideal for a diesel fuel. They are apparently also considering converting this to bioethanol. The anticipated yield is 93,000l/ha/ann.
  • Another company (L59 based in San Francisco) is at an earlier stage, having chosen to splice the cyanobacterial genes into the very fast replicating Echerichia coli bacterium. However, this research has not arrived at anticipated yields as yet.
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    How and Why it works

    Biofuels are essentially the same as the fossil fuels into which they can be converted by the earth's processes over the millennia. They too are made up of hydro-carbon chains - hydrogen (H) + carbon (C) - to which the living plants attach a lot of other atoms and molecules. Most of these involve oxygen within the chains and trace elements e.g. calcium, magnesium, manganese, iron, phosphates, and copper etc. that remain in the extruded waste and so can add value when used to feed livestock.

    The cold pressed oils are basically composed of hydrogen, carbon and oxygen; thus they burn very efficiently to release Energy, producing carbon dioxide and water as by-products. These two by-products are a non-toxic and integral part of the Ecosphere and are thus quickly recycled by growing plants.

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    Top Tips new and used

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