[Gasification] Biomass gas ref. Vol2, Issue15

[Col]

Hi,
I was interested to see comments re the use of Bio-gas for production of ethanol and thought it may be of interest to some who would nopt of seen a posting I made to " Heatengines" so I am including it here.

Hi, 

There is also other ways of producing ethanol that can be explored with overall benefits other than just fuel production. 

This is a case that I was involved in a few years ago . 

A dairy factory producing casein had as leftover waste large quantities of whey which was disposed of by spraying over farms as fertilizer (not all that good) It was dicovered that it was leeching it's way into the local streams and not helping the quality of the water. This did not impress the local authorities so other methods had to be divised to get rid of the whey i.e spread over a much greater area or dumped at some comercial handling facility (very expensive) An ethanol plant was built on site to turn the whey into ethanol. (Works very well). This however also so had waste at the end of the process plus the waste was at about 45Deg.C This was put into a large settling pond. The pond was covered with a black plastic sheet and bug developed to generate methane from the warm waste stream. The bugs were top secret for a few years and access to the site was very restricted. The bugs were very good at their job and generated a lot of methane but are also temperature sensitive. If a cloud passed over the pond the methane production decreased. In this particular case this did not matter. I developed a control system for changing one of the plant natural gas fired boilers into a dual fuel unit with NG as the startup & low fire fuel with the Bio Gas taking over when demand exceeded low fire conditions and when the rate of fuel usage exceeded the production rate of BG then the NG would make up the balance. The system worked exactly as I had calculated on paper (first time theory and application matched perfectly) Waste from pond was clean water and sludge that was emptied out every 12 months or so. Used as land fill (non toxic.) 

In this case a number of problems were attended to. 

!. Ground water pollution cured. 

2. Ethanol produced (mostly sold for making Vodka and for pharmaceuticals but could be used for fuel) 

3. Reduction in Nat Gas useage for generating steam to run entire complex. 

4. Waste now non toxic and easily and cheaply dispossed of. 

5. Immediate savings of $500K + per year in fuel cost, More than double that in reduced waste disposal costs. 

6. General enviromental improvement. 

As a further point of interest I know of a person who is currently getting a patent on a process that reduces the energy requirements to get the alcohol from 7.5% to 96% by an estimated 50%. (his figures not mine)

Col