[Gasification] Producer Gas Driven Engine w/ Liquid Fuel Assist

[Ken Boak]

List,

This link shows sugar beet yield per hectare and sugar yields 

http://www.ienica.net/crops/sugarbeet.htm


Many cultivars of sugar beet exist, almost all are capable of giving root yield of 40 tonnes or so per hectare at 15.5 - 18% sugar content, giving 6 -7 tonnes of sugar per hectare.

Using Ken's figure for 30lbs sugar to 1 gallon ethanol (US or UK gallon?),   using the lower figure of 6 tonnes per hectare would yield 440 gallons of ethanol per hectare or 178 gallons per acre.

With a typical small vehicle returning 30 to 40 miles to the UK gallon,  a maximum of about 6000 to 7000 miles vehicle miles would be possible from an acre of beet. 

However, beet requires a lot of nitrogen fertiliser to achieve these yields, and then there is the expenditure of fuel and energy used in growing, harvesting and processing the beet into sugar solution.

I suspect that running vehicles from ethanol drived from sugar beet would not be economically viable at this stage,  until there is a significant rise in the cost of fossil fuels.

It would be an interesting exercise to compare the net potential vehicle miles for an acre of sugarcane,  acre of oilseed rape, soya, sunflower, and short rotation coppiced woods.  Into this equation we need to add the potential for gasifying the crop residues in a gasifier "topping cycle",  sugar cane being particularly attractve because of the large quantities of bagasse produced.

I think the picture will be fairly disappointing, suggesting that bio-derived fuels can only ever offer a small percentage offset to fossil fuels, perhaps 10% to 20%, rather than a viable replacement.




Ken Boak