PHT

Second-generation bio-ethanol technology

Second-generation technology to produce bio-ethanol from cellulosic material is now within a few years of viability, and companies which have large amounts of cellulosic material available (sugar and timber companies, and many others) should start planning for their possible beneficiation.
This is the message given by a South African expert in the field, Jannie van Aswegen.
Van Aswegen said that there were, for instance, about 130 plants in the US producing bio-ethanol via first-generation technology from maize; but now being examined (with government support) in the US was second-generation cellulosic technology, and some pilot plants had been set up both there and in China, assisted by enzyme companies.
Conventional, first-generation technology to produce glucose (so that fermentation can take place to produce bio-ethanol) involves using heat-stable alpha amylase and amyloglucosidase enzymes, with the feedstock of a starch base (maize or cassava, for instance, to produce the glucose for fermentation). PHT
Enzymes are not necessary when producing ethanol from molasses or sugar as these sugars are already fermentable.
The big change related to second-generation cellulosic extraction is that the cost of the enzymes needed to convert the cellulose and hemicellulose into glucose, has been reduced by over 50% between 2007 and 2010. By 2011 they should cost the same as the enzymes required in conventional, first-generation biofuels production, says Van Aswegen.
There is one other costly step which must be dealt with, however: pretreatment of the cellulosic material to "open the cellulose structure away from the lignin".
Cellulosic material consists of lignin (which acts as a "glue" for the woody structure), cellulose, and hemicellulose. Lignin must be minimised as it is an inhibitor to enzymes and yeast in the process. At present, pretreatment involves acid, alkali and steam explosion technology.
Van Aswegen says costs here are likely to be brought down to competitive levels within the next two years.
In Africa, the first large existing industry which is likely to enter cellulosic second-generation bio-ethanol production could be the sugar industry because sugar companies have resources and also produce large amounts of bagasse as a cellulose raw material. At present, bagasse is partly used to fuel the boilers at sugar mills; in future it could be used for production of bio-ethanol.
Paper mills, which have to remove lignin for the production of paper, are also likely to apply the second-generation technology early.
Other companies which have large, non-seasonal cellulosic sources could also look at this technology. For instance:
*    Seed company Syngenta has produced a high-yielding tropical sugar beet which is now being grown in a few parts of southern Africa. It produces sugar and contains cellulitic fibres, which means a dual process can be used.
*    Elephant grass, which grows abundantly in many parts of Africa – and re-grows within a few months after cutting.
*    Cobs and stover (leaves and stalks) of maize, sorghum, etc, which are currently often ploughed back into the land.
*    Companies which have access to other sources of cellulose. For instance, cellulose can be drawn from industrial waste, municipal waste, and packaging waste (wrapping, paper, etc).
Soft cellulosic plant materials are particularly attractive because of their low lignin content.
Important in Africa
Competitive, efficient biofuels technology is particularly important in Africa because currently many African countries spend large percentages of their national budgets on importing oil for use in transportation. However, African countries are not in the vanguard of biofuels development internationally.
Ethiopia is an exception to this, however, says Van Aswegen – and an example to other African countries. It is landlocked and does not have its own fuel refinery. Fuel is imported in refined form by truck from Sudan to the capital of Ethiopia, Addis Ababa.
The Ethiopian government is now supporting a number of biofuels projects both to make its fuel cheaper and to reduce carbon dioxide emissions.
Currently, 8m litres of ethanol are being produced from sugar plants in Ethiopia. A multi-million dollar plant for blending ethanol with imported petrol has been set up. Under construction currently are four more sugar and ethanol plants which, by 2012, are projected to produce 130m litres of ethanol for blending into Ethiopia’s fuel.
Why biofuels?
The first car built by Henry Ford ran on bio-ethanol, but five years later the industry switched to fossil-based fuels. Today, fossil fuels are declining in supply – yet the demand for and use of them is increasing.
Van Aswegen said currently fossil fuels make up about 75% of all energy used on earth.
By 2050, there will be an estimated 2.3bn additional cars in the world, 1.9bn of them in developing countries. On this basis, by 2030, the use of fossil fuels will increase by over 50% over current use – despite the development of hybrid cars.
With the use of bio-ethanol, carbon dioxide emissions are much reduced. The transport sector accounts for about 25% of world carbon dioxide emissions and fossil fuels are the vast majority of transport fuels.
That is why E85 was decided upon by the EU. The name E85 reflects that by the end of 2010, 15% of petrol in the EU will, by law, have to be from renewable resources.
Today, biofuels’ share of world transport energy is only 1-2%. Brazil is the big exception – 50% of its energy is from bio-ethanol. In 1973 the oil crisis prompted Brazil to make ethanol; when the crisis ended, it continued. It has developed, for instance (with General Motors, Volkswagen and Fiat), cars which can use 100% ethanol or 50% ethanol.
There has also been considerable development more recently in the US. However the US is currently only producing, from its 130 plants, 5% of its fuel in the form of ethanol. China is producing 2% and Europe 1%.
Van Aswegen said that in the US and elsewhere, food manufacturers saw the use of their raw materials as an opportunity to blame rising food prices on offtake for biofuels developments. Whether biofuels were in fact to blame was highly debatable, however, he said.