Apart from culture, cost is a factor.... we have hyperinflated everything in Kenya.... From cost analysis by KENFAP a small digester installation , burner, cylinder will cost at least Kshs. 70,000 (far higher than initial cost of LPG and electricity) - highly subsidised by donors. Add the design of the cow shed or latrine ....
LPG and hydro/geothermal electricity are the most sensible sources of energy .... this clean/renewable energy looks like too much hat