BY HEATHER JOHNSTONE
With greater environmental awareness and the growing desire to make the best use of potential and existing fuel stocks the global energy landscape is changing.
As countries aim for domestic energy security and try to minimize environmental impact and the effect of variable fuel costs, there has been a continued push to diversify and examine alternate or non-traditional fuel sources. One such sector that is attracting attention is biofuels.
Biofuels can be described as any fuel (liquid or gaseous) that is derived from biomass any recently living organisms or their waste byproducts and is recognized as a carbon-neutral, renewable energy source.
Recent policy and legislation, and government initiatives to promote the greater utilization of biofuels tend to concentrate on their use in the transport sector. For example, the European Union’s new Renewable Energy Directive legislates that out of the target of 20 per cent of total energy from renewables by 2020, 10 per cent of renewable energy, i.e. biofuels, must be used in transport.
Also last month, Steven Chu, the US energy secretary announced that the Department of Energy would be investing almost $800 million of the funds from the American Recovery and Reinvestment Act in advanced biofuel research, development and test projects.
However, biofuels are beginning to garner interest as a viable fuel source for generating electricity, as countries explore options to produce their power in a low-carbon and sustainable manner. One of the most commonly used biofuels for power generation, especially in Europe, is biodiesel.
A number major power OEMs are looking at biodiesel as a viable fuel source. GE Energy, for example, has demonstrated the performance of biodiesel on both its heavy-duty industrial and aeroderivative gas turbines over a range of operational loads.
Furthermore, in February of this year, leading engine manufacturer, Cummins, announced the approval of the B20 biodiesel blend for use with its 19-78-litre, high-horsepower engine platforms aimed at the power generation market.
Algae’s versatility nature producing biofuels and capturing CO2 from power stations Source: RWE Power
While between February and April of this year, Wärtsilä of Finland, another engine major, successfully performed a test series to demonstrate the capability of its engines to run on a range of vegetable and animal-based oils jatropha, fish and chicken oil.
Last year, Wärtsilä also secured an order for an engine-driven combined heat and power (CHP) plant that will run on biofuel from the jatropha plant. It will be the first power plant in the world to produce both electricity and heat using this fuel source fuel.
Large-scale production of biofuel-generated electricity for inclusion into the mains grid is a possibility being discussed by governments across world. However, biogas rather than biodiesel may hold the key to being able to provide a reliable supply to industrial-scale power plants.
Biogas is produced by the process of anaerobic digestion of organic material, such as sewage and landfill. To date, its utilization remains relatively small-scale, and biogas projects are often referred to as waste-to-energy projects. The UK’s Ener-G Group is involved in a project in South Africa, which will see landfill gas from Johannesburg City Council’s landfill sites ultimately generate 25 MW of electricity.
There are signs however, that both large businesses and governments are thinking seriously about biogas’ large-scale potential, since it is possible to purify it to the quality of natural gas, and it can be fed through existing gas line infrastructure.
Another unusual source of biofuels attracting attention is the humble algae, simple unicellular or multi-cellular water-borne plant-like organisms that use photosynthesis to transform carbon dioxide (CO2) and sunlight into energy.
What is particularly interesting in relation to biofuels has been the discovery that as part of the photosynthesis process algae is able to produce 15 times more oil per acre than other plants commonly used for as feedstocks for biofuels, such as corn and switchgrass.
A research team at the University of Virginia in the US is currently testing the theory that algae will grow even better when fed extra CO2. Proving this theory will confirm algae’s industrial ecology viability not only producing a biofuel but also helping to reduce emissions of CO2, such as coal power-plant flue gas, which contains between ten to 30 times more CO2 than in normal air.
RWE Power, a leading German power generator, is doing exactly that. At its Niederaussem power station, near Cologne, the company is conducting a novel carbon-fixing pilot project where microalgae, housed in a specially designed facility, are being fed a flue gas slipstream from the power plant. According to RWE Power, its algae plant can produce up to 6000 kg algae (dry substance) per year, with 12 000 kg CO2 being bound.
The diversity of biofuel feedstocks is quite breath taking. However, what is clear is that as we move towards a low-carbon world biofuels will play an ever more important role in how we generate our electricity.