hence with the declining costs of renewables over the past few years their use as an alternative energy source offers significant costreduction potential as well as an opportunity to mitigate ghg emissions in this context some emission mitigation measures in particular those that improve energy efficiency have been shown to lower costs or even result in cost savings in south africa for example per cent of the ghg mitigation potential in the mining sector could be realized at negative marginal abatement costs so that these emission reductions would pay for themselves department of environmental affairs