"Back in the old days, people knocked on my door and complained about the smell," said Ong-Arj, who owns 4,000 pigs in Nakhon Pathom, 55 km (35 miles) west of Bangkok in the heart of Thailand's hog country.

"Now? They hardly even notice. People around here are happy to show you how to get to my house," Ong-Arj told Reuters after showing off a biogas plant he designed himself during a tour of his 9.7 hectare (24 acre) enclosed pig farm.

Using a simple system to capture the methane gas from pig manure and convert it into electricity, Ong-Arj slashed his power bill by thousands of dollars and cut gas emissions that harmed the environment and annoyed his neighbours.

"The smell has gone. The flies have gone and I have more cash in my pocket," said the 35-year-old father of two. Thailand has begun to embrace biogas -- created from sewage, manure or grass -- as a cheap, environmentally friendly way of slashing its reliance on imported fuels.

The Ministry of Energy has set a target of building 1,540, 100 MW bio-gas plants by 2011, many of them fuelled by solid waste and polluted water.