The birth of a market for trade in green power credits is inching closer. The flip side of the green credits coin -- commercial trade in carbon emissions -- is already taking off, with a pioneering deal struck in North America and growing industry backing in Europe. The European Commission also pushed tradeable "green certificates" firmly into the political arena last month. All this is having its influence on the likely structure of the power systems of tomorrow. Our "Powering Tomorrow" survey reveals that the best model for greatest uptake of wind is not all that far from today's reality.