Backyard methane plant praised

Press, 25 February 1980, Page 1

Backyard methane plant praised

“We reckon we’ll have our cold cash back at the end of 12 months, if all goes well,” Mr Neville Cooper, leader of a Cust Christian sect, said at the week-end.

He was talking about covering the capital investment in a methane plant, at the community’s Springbank farm and school, with savings in petrol costs. Two farm vehicles, a truck and van, have already been converted to use of the biogas from farm wastes — mostly fowl manure at this experimental stage. Ultimately, the community will have 20 vehicles that can use the methane for fuel. The conversion of tractors will come later. “It is quite safe, quite simple,” Mr Cooper said as he filled the van’s methane cylinder during an open day at the farm. “No fuss, no bother.” “I can see where the Arabs are going to be eating their oil,”- one woman visitor said. Dr David Stewart, head of the Invermay Agricultural Research Centre’s energy and environment section at Mosgiel, said the Springbank plant was ahead of the Invermay work, mainly because of bureaucratic delays and the lack of compressors because of a factory strike in France.

Mr Cooper and his people were in touch with Dr Stewart about six

months ago, when their plant was still only an idea. They were given advice by scientists at the Invermay energy farm. “They have done in six months what we have been trying to do for eight years,” Dr Stewart told a large crowd at the field day. Dr Stewart said that any unit at least half the size of the one at Springbank would make running a car more economical on methane at present petrol prices. . The economics depended partly on how the plant was run, and what type of mixture was put through the digester. His group at the Ministry ■of Agriculture had predicted that petrol could cost 84.50 a gallon by 1985, Dr Stewart said, so the economics of a methane plant could only get better. “So far, these plants have generally been run on waste material,” he said. “But crops can be raised to go through the system — the economics are not that much worse.” Mr Cooper said his communi-ty of about 135 members had paid about $28,000 so far for the methane plant, not counting labour. More than $20,000 was needed for car conversion kits, gas bottles, and compressors.

Through extensive experiments with washing water, the community is trying to get rid of as

much carbon dioxide as if can.

Vehicles could run with biogas containing from 15 to 20 per cent methane, but the less the better, Mr Cooper said. So far, rough measurements after a double washing cycle indicate that -the Springbank plant has been able to get a' fuel with only 4 per cent carbon dioxide.

Dr Stewart said the Springbank plant would probably be able to produce the equivalent of 115 litres of petrol a day foi; vehicle use.

The Springbank plant now uses electricity to heat’ the digester, instead of using the gas itself. Mr Cooper said the gas was too valuable as a vehicle fuel, and electricity was relatively cheap. Later, a heat pump will be used to keep the digester material at blood temperature so the bacteria can do their job.

Chinese digesters, about seven million of them, produced more than 30 times the energy used by New Zealand, Dr Stewart said. The second-largest number of digesters was in India.

Five big British companies now marketed digesters. Dr Stewart said, and there was an estimated potential for at least 20,000 digesters on British farms. They could produce more energy than all Britain’s nuclear power stations.