Regulatory 'balancing' and the efficiency of green R and D

We identify and analyse several dynamic implications of setting environmental standards such as to 'balance' marginal costs and benefits. The adoption of such a regulatory approach is shown to effect (i) the speed of improvement of abatement technologies; (ii) the 'direction' (in a sense to be defined) of that improvement; (iii) its source and the distribution of the rents from it; and (iv) the rate of development of defensive (averting) technologies. Existing views are thoroughly synthesised in the context of a simple diagrammatic model, several new results are derived and at least one conventional wisdom questioned. The message of the analysis for legislators and regulators is that cost-benefit balancing should be done with care.