Investigations on potentials of energy from sewage gas and their use as stand alone system

As the biomass sources are available around us is like waste but if this waste could use for producing electricity then it would be more beneficial for us because these sources are renewable. So in view of this if we examine the sewage we can see that there are biogases like methane, carbon dioxide etc. We can use these gases for producing electricity by the burning of these fuels. Another possible way is that if we block the hole of the sewage water for definite area and opens this for some specific place then there will be gases with high pressure we can utilize these gases for rotating the turbine of generator.