Going to the toilet may be the answer to a cleaner environment, as a Hamilton engineering consultant sees his idea take form in America: drying sewage sludge to be used in place of coal.
At 89, Patrick Potter from Patrick Potter and Associates, a consulting engineering practice, said "it has the greatest potential of anything I have designed, the contents of your bowel, dried and turned into fuel. That fuel has 25 mega joules per kilogram - higher heating value than the best coal".
"Most coal in New Zealand is 10,000 BTUs, this stuff is 12,000 BTUs."
The system Mr Potter has designed dries sewage sludge to be used in place of coal, ideally by power stations, as a high quality fuel which has been deodorised, sterilised, and accepted by clean air authorities.
"Coal has 30-50 per cent carbon which is quite high and the dried waste has 15 per cent carbon which is quite low."