Modeling the environmental impact of PV and wind large scale penetration in regional grids

We are proposing a model for quantifying the environmental impact from a non-optimal operation of conventional fuel generators serving as reserve capacity for accommodating the intermittent generation from PV and wind. Fluctuations in RE generation would necessitate fuel generators´ up- and down-ramping and part-load operation, causing additional emissions. The net emission savings from RE integration are due to the displaced conventional generation minus the incremental emissions from suboptimal and part load generation. The described hourly dispatch and emissions modeling is part of a model development effort proposed for utility planning purposes. The model is applied to a zone of the New York State, using actual solar and wind generation data and a hypothetical fleet of gas and diesel power generators. Results show that RE fluctuations cause a 8-10 % increase in the CO₂ g/kWh emissions from fossil-fuel generators, compared to the no RE scenario, due to frequent cycling and start-up of generators. These increases are more than counterbalanced by the zero operational emissions of PV and wind.