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Energy and biofuels



I am writing in connection with the comments made by Dr. U. Pethiyagoda in response to renewable energy and biofuels in The Island on Nov 1st, 2012.


Your determination of alcohol in beer and toddy at 5-6% is correct. Wine and cider too operate at the same alcohol tolerance. However this limitation is not universal. In the production of ethanol, in Sri Lanka and in a few countries I had worked in, the operating alcohol tolerance is 7.5%.In Sri Lanka at the three distilleries , when they were functioning the operating tolerance was 7.5% that was with Baker’s yeast. At Pelwatte it is said to be 12%. The yeast strain was identified by the Production Manager while preparing for his Masters Degree.


Somewhere in the pre - 1973 period, when Seeduwa distillery was operated by the Excise Dept, an outside expert attempted to ferment sugar ( sucrose) direct to ethanol. The experiment failed and the sugar solution was brought to the Kantale distillery where I was working. We found that over a lead time running into months a culture of yeast had developed which tolerated 10% ethanol.


We used to get wet sugar from the Food Dept, on the regular basis, and was converted to crystal sugar or to alcohol or both. The operation depended on one factor, was the Sugar Factory in operation or not. Not being experts we adopted a simpler system, and the sugar yielded alcohol within 72 hrs, the normal cycle (run).


The range of 10% is nothing to wonder about. That is the tolerance claimed by many in their publications on the production of ethanol in the US, Canada, Australia, Brazil and the EU.


Turbo yeast – there are many who make this yeast variety available- claims 18% tolerance. Pot ethanol, in their web site claims a tolerance of 20%.


As the alcohol content in the mash goes up the energy required to separate the alcohol from water to alcohol at 96%v/v goes down. The energy required is generally indicated in terms of x lbs of steam per gallon on ethanol at 96%.These tables are available- published. In the US at 7.5%v/v ethanol the steam requirement was said to be 19lbs/gal US. In the distilleries at Kantale and Hingurana it is 30lbs/gal UK ( manufacturer’s specification).


The next question you raise is on the source of energy. Internationally, the energy is obtained from fossil fuels. That is a question that is being raised today. Alternate fuels are available. Wood, Dry burnable garbage, bagasse ( not necessarily of sugar cane alone), solar power and geothermal power if you can establish distillery near a very hot water well.


The question of energy in vs energy out ie is the input energy which is generally based on fossil fuels and the output energy based on the distillate is another question that is being raised. In working out the EIEO, the energy cycle of the raw materials life cycle is taken into consideration. There are questions raised about this matter, with most people in the US agreeing that this figure is positive, while two Professors in the US disagree. In all these discussions the energy costs of the full cycle is taken into consideration not the distillation alone ie the total cost of producing the ethanol.


I am privy to a system where the heat requirement can be reduced by about 80% of the figures given above.


Drs. Nande Dharmawardena, C. S. Weeraratne and J. Ratnasiri penned those articles taking into consideration the present back ground in the market. Furthermore Saudi Arabia is projected to be a net importer of petroleum in the near future.No longer can crude be found at 69ft below ground as experienced by Capt Drake in 1858.The recent discoveries off the coast of South America, the crude lies 23,000 – 35,000 feet below the sea level with 7000 ft of rock in between. In the foreseeable future one cannot expect Petrol at Rs 0.50 cts per litre, my experience in 1971 just before the OPEC crisis, nor at Rs 150.00 per litre. It might hit Rs 250.00 or more within the next few years.


Under these conditions, it is upto the researchers to work out the solutions to our energy problem.No doubt their solutions may not be perfect, the corners will have to be cleaned up by and by. What they have done should be welcomed. The missing cogs will have to be worked out by and by.


Our sugar industry did turn out biofuels in the years preceding the change of Government in 1977. Some of the Corporation’s cars, pick-up trucks, motor cycles were run on the biofuels-bioethanol so produced.


Regarding the conversion of polythene to petrol, I do not know what happened to that much publicised project. What I know is a Japanese gentleman holds a patent to such a process. He used a small pot still with a rectifier to do the conversion. His process was available for sale.It could be operated based on polythene discarded by the households. The still was for the householders.


Regarding the straw to butanol process, something I know is that Mitsubhishi Company holds a patent to convert rice and wheat straw to ethanol. Conversion of cellulose to ethanol and Butanol is big business in the West. We should appreciate what the triad did at Peradeniya.


Considering the full life cycle cost analysis, since straw hardly has a market, this project should be feasible, whatever the energy used.


I do hope that this meets with your curiosity.


Upali Wickramsinghe


spupalisw@yahoo.com


 
 
 
 
 
 
 
 
 
 
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