covering of the electricity supply of the united states with offshore wind would thus cost an astonishing additional outlay of usd billion per year table reports the total cost of electricity supply on a usdmwh basis for all scenarios analysed two additional tables in appendix b report the cost increase per unit of renewable production and the total cost of electricity supply on an absolute basis tables b and b respectively however introducing large shares of renewable energy with low variable cost has also significant impacts on the optimal structure of the electricity generating mix on resulting electricity prices and on the profitability of existing dispatchable power plants which make up the pecuniary externalities referred to in chapter