Appreciate the replies Willem and Michael.
@ Willem: thank you for clarifying on the construction of the first offshore turbine. The papers that I had read on the topic stated that 1990 was the construction of the first turbine. Fortunately it is not intrinsic to the analysis, but an important fact nonetheless. Regarding your more substantive concern, I think we agree in principle -- environmental policies, like RPS, can make it profitable to pursue these sorts of projects. The fundamental problem with many of them is, what economists call, "general equilibirum" interactions. RPS and similar policies have been subject to great economic analysis; the general consensus is that they create large distortions, etc -- but this is beyond the scope of the current paper/article. The main message that I am trying to convey in the article -- and I think you agree on -- is that we need to look at these issues in terms of a system: institutions and policies (like RPS) can make certain investments fruitful. Yet, the normative implications I allude to are very complex and undoubtedly controversial -- I think it would be tough to provide evidence indicating that expansion of offshore wind would occur on a non-trivial scale given the current investment climate, lack of dynamic pricing, lack of price on clean air, lack of net metering and interconnection throughout the electricity grid, among other issues.
@ Michael: agree -- this is part of the paper I published, namely that social attitudes (whether it's from high or low income earners) can have large effects on the expansion of certain energies.