Substitution between fuels is not always in the direction expected due to differences in their price levels, and in responses to price. For instance, for the USA forecast in 2000, the prices of oil, gas and coal are US$205, US$186 and US$54/toe respectively (in US$1990). The combined carbon/energy tax level in 2000, once the carbon contents of the fuel have been applied, works out at US$33, US$23 and US$40/toe for the three fuels respectively, re- suiting in additional tax rates of 32% on oil, 30% on gas and a massive 135% on coal. One would expect coal to lose some of its market share to both oil and gas. However, the analysis demonstrates that the price elasticity of gas is less than that of oil, with respect to either's price relative to coal. Hence oil takes over most of the share lost by coal, while due to the overall decrease in fossil fuel consumption, the consumption of gas actually falls.