Bio Energy Updates

There are a number of local and regional examples and initiatives underway to promote the sustainable use of bioenergy sources for heat and electricity generation.

The greatest focus appears to be in the wood energy sector where there is already good potential and enthusiasm within the region to expand the wood fuel sector.

Bio Energy: is it for you?

What sorts of fuel can I use? Is it all logs? There are a variety of fuels available: Wood Chips, Wood pellets, Logs, Straw, Miscanthus and grain.

What is a wood pellet? This fuel is made from the same kind of clean sawdust that is used for pet bedding. The sawdust is heated and compressed into hard pellets and should be dust free. No binders and glues are added. If any water gets into the pellets, they fall apart very quickly so suppliers take great care to keep them dry.

Is there some form of standard for the fuel? A new British standard has been published (number CEN335) we expect this to become an ISO standard in 2012

What are energy crops? Energy crops are species, which are grown specifically to burn for energy. They include willow and poplar trees, which are grown as a "short rotation coppice" (SRC) and cut every three years to provide wood fuel. Other energy crops include oil-seed rape which is crushed to provide the raw material for Biodiesel and Miscanthus

What is Miscanthus? Miscanthus is a species of elephant grass grown for biomass. To picture what it looks like imagine a cross between pampas grass from the front garden and bamboo. This species grows to about 15ft high when it is left to dry, cut and baled. Power stations involved in co-firing are the main users of Miscanthus and grants are available to plant it under the energy crop scheme

Reverse Auction: Part of this management includes entering your energy bills into a reverse energy auction. This works the same way as a normal auction, but the bids get lower, not bigger! The top 800 energy companies bid for your energy contract and you decide which one is best for you.

Apollo Energy Tech can also help you become CRC compliant and ISO50001 accredited.

What does "arboricultural" mean? "Arboriculture is the selection, planting and care of individual trees, shrubs, vines, and other perennial woody plants, and the study of how they grow and respond to cultural practices and the environment. " It is usually used in reference to urban tree surgery work, as opposed to "silviculture" which is the management of whole woodlands.

Nuclear Fuel, cleaner energy

Fuel assemblies
Inside most reactors, the fuel assemblies are made from small pellets of uranium dioxide, loaded into thin tubes. The tubes are usually put into vertical bundles with `spacers' to separate them.Cleaner fules

Once inside, a fuel assembly may stay there for as long as three years, but even after that length of time, all the uranium has not been consumed. But by-products begin to accumulate; some are gases like krypton, others are solids like caesium, strontium and plutonium. Before these by-products have built up too much, and water corrodes the fuel tubes, the assemblies are removed. To recover the unburned uranium, the spent fuel may be taken to a special plant where it is reprocessed to separate out uranium, plutonium and waste products.

The plutonium is a useful by-product of the nuclear power industry. It can be used as a fuel in power stations, because plutonium, like uranium, has nuclei that can split and release energy.
Uranium occurs in several different forms, identical chemically but with different-sized nuclei in their atoms. Of these different forms, called isotopes, one is uranium-235, which gets it name from the 235 particles making up its nucleus. Only seven atoms out of every 1000 in naturally occurring uranium are U-235. The rest consist almost entirely of uranium-238.

When U-238 is struck by neutrons it does not split as readily as U-235. It may be converted into a completely new element, plutonium-239. So if a reactor is made using natural uranium as fuel, the danger is that too many neutrons will be absorbed by U-238 before they can hit U-235 atoms and cause further fissions. If this happens the reactor will never get going.

There are two ways around this problem. One is to increase the amount of U-235 in the reactor fuel, by a process called enrichment, from seven atoms to between 30 and 40 in every thousand. This is done before the fuel is manufactured, usually in a centrifuge - a machine that whirls round, separating U-235 from U-238 by the outward pushing forces of high-speed rotation. The second way is to make the very best use of the available neutrons inside the reactor by slowing them down, which increases their chances of causing further fissions.

The way to slow them down is to make them ricochet to and fro off light atoms of an element such as hydrogen or carbon, like balls in a pin-ball machine. The light elements act as a 'moderator', because their job is to moderate the speed of the neutrons. Most modern reactors use both enriched fuel and moderators. Some are moderated by water (which, of course, contains hydrogen), while others are moderated by carbon in the form of graphite, which is the hard dark material known as the 'lead' in an ordinary pencil.

Obviously, a nuclear reactor produces a great amount of heat, and to stop the reactors from overheating, coolants have to be used. Pressurised water reactors use water as a coolant, so these plants need to be built near rivers or oceans. Advanced gas-cooled reactors, first built in Great Britain, are cooled by carbon-dioxide gas. In Canada, heavy water - in which hydrogen atoms are replaced with an isotope of hydrogen called deuterium cools fast breeder reactors. France has pioneered the use of liquid sodium as a coolant for their fast breeders.


Read more on Nuclear Fuel


Quick Facts

What are "arboricultural arisings?" Arboricultural arisings are material that has been produced as a result of arboriculture. They consist of tree prunings, hedge trimmings and other woody and green waste. The wood component of this potentially a valuable resource for conversion into wood fuel.


How much do Wood Pellets cost: Unlike other forms of renewable energy such as wind or solar power, biomass systems require you to pay for the fuel. Pellets typically cost between £120 - £180 /tonne and pellets cost less at £50 - £80 /tonne. Fuel costs also depend on the distance from your supplier and whether you can buy in large quantities.


Thinking about going Bio Green?

Unlike other forms of renewable energy such as wind or solar power, biomass systems require you to pay upfront for the fuel. Pellets typically cost between £130 - £190 /tonne and pellets cost less at £60 - £90 /tonne. Fuel costs also depend on the distance from your supplier and whether you can buy in large quantities.


Bio News



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