On Sunday, 15 September 2019 13:46:15 UTC+1, Robin wrote:
Excellent as far as it goes. But doesn't even mention the possibility
of using the cat's waste (and the naturally inevitable, occasional waste
cat) in a biodigester

17 queens and one tom could produce approaching 300 kittens a year.

If you get pedigree Maine Coon or similar they fetch about £1000 a kitten.

Even moggies, if you can get £6.60 per kitten, you break even and get the heating effect for free.

Owain