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Biomass energy – Part Of A Sustainable Future?
Biomass energy is not usually on people’s minds as are alternate energy sources such as wind, solar or hydropower energy when thinking about renewable sources of energy. Notwithstanding, it represents very common and available forms of energy indeed. It is rapidly becoming a more popular idea as oil prices rocket ever upwards. And it can mitigate global warming. In Europe its current use accounts for 0.95% of energy production. For 2010 that is forecast to be around 8%. In the USA now it accounts for over 3%. Biomass energy can really come from so many sources. What we are talking about here is any animal or plant-derived materials, for example such as 
You see now what I mean with "very common and available", don’t you? Bio energy is renewable and solar in origin. It is renewable as the materials it comes from can be replaced, or grown, in a short period of time. And burning biofuels is not necessarily a contributor to global warming in the way that fossil fuels are. Biofuels do not add to the net amount of CO2 already present in the atmosphere. This is because carbon in the biofuel is locked up only for the short period of time in plants or animals and can be considered as recycled as newly growing crops and animals once again take up the atmospheric CO2 used in burning. Of course biomass energy is solar in origin because plants use photosynthesis to fix CO2 and animals lived on plant material before they ultimately ended up as “waste products.” Sorry. You want to say something here? Yes, of course you’re right … Fossil fuels are also solar in origin and are theoretically renewable. All we need to do is to grow thick forests for a few million years so they may become coal and oil! But renewable energy is considered to be so only in the context of short human life times. But, I know, everything is interdependent and connected and sometimes it seems that all we do is make boundaries where there are none… Indeed. OK, back to the practical world of renewable bio energy… Biomass energy – Direct and indirect uses Biomass energy can be used directly or indirectly. Firewood is a common example of direct use by combustion. But biomass energy can be transformed into other forms of fuel. Ethanol from agricultural crops such as sugar cane and methane from manure and sewage are examples of indirect use. Biomass energy – conversion Biomass energy in the forms of gas can occur spontaneously, as marshgas, or landfill gas for example, but alcohols do not. Agricultural wastes or manures undergo certain processes first. The two main processes are thermal and biological Thermal and biological biomass energy conversion Thermal conversion can happen in three ways
Combustion of course means that biomass is burned, similar to coal and oil, to make electricity. When mixing biomass with coal, this co-firing process is very efficient. Solid municipal waste is also burned to generate electricity. Pyrolysis is a chemical process of decomposition of biomass materials. It is a heating process without the involvement of oxygen. The recycling of used vehicle tyres uses pyrolysis. Gasification involves processes that turn parts of solid biomass materials into gas. Pyrolysis can do this for example. Biological conversion can happen through Digestion and fermentation of biodegradable wastes occurs in large digester power plants where bacteria convert waste into gas. The produced gas drives turbines that generate electricity from these wastes. The solids that are left behind may be used as fertiliser, depending on the biomass materials used. Biofuel Biofuels that can be made from biomass are
Biogas Biogas can be captured from marshes, from landfill or wastes such as sewage, and burned to produce electricity. It can also be generated intentionally through anaerobic composting. When refined it can be used to power vehicles directly. Bioethanol Bioethanol is made from a large range of crops. Grains, rapeseed, canola, hemp, maize, sugarcane and virgin oils are some. It can be mixed with petrol for use by vehicles and is becoming commercially available in some countries. The UK government’s Renewable Transport Fuel Obligation for example, requires 5% of all motor vehicle fuel to come from renewable sources by 2010. In Brazil ethanol-blended fuel cars now outnumber petrol-fuelled cars and in Sweden there is no excise duty and free parking for drivers on ethanol. In this diagram you can follow the production process from corn and biofibrous crops to ethanol:
The process from corn and other plantfibrous crops to ethanol
Biobutanol Biobutanol is produced through fermentation, using the Clostridium acetobutylicum bacteria. It can be directly used in some internal combustion engines designed for gasoline use and is more similar to gasoline than is ethanol. Biodiesel Biodiesel is produced from domestically grown renewable products.
In the USA it is widely commercially available
and is perhaps most famous through Some people have now taken to biodiesel making themselves as it is a relatively simple process. Home biodiesel production may be a growing trend, providing savings and representing a direct contribution to a sustainable world. Of course disadvantage of biomass energy is also part of the equation and you should know about that.
But if you really want to know whether it is part of a sustainable future you need to know something about the advantage of biomass energy as well as its disadvantage. I'll see you about that on another page. |
