Not all the projects are abroad, however the UK ones do run at a much higher cost (+12-15p per litre, on top of the standard bulk fuel price).
However, one should consider that in the UK there are already commercial benefits and grants from the government for such projects. In many other nations where there isn’t government support there has to be some incentive to move to renewable energy, without the project issuing carbon credits it would never get off the ground and thus not reduce CO2.