Investing in renewable energy requires patience and the capacity to absorb losses. It is not for the fainthearted. If the bet pays of, the rewards are potentially limitless. But that is a big if, and the potential losses can be devastating. Take OpenHydro, the Irish-French tidal energy company that was billed as the next big thing. Founded in Ireland, backed by high-net-worth Irish investors and the French state, it was supposed to deliver cash from the sea, harnessing tidal power through state-of-the-art offshore turbine technology. There was chatter of a stock market flotation, a €1 billion pipeline of revenues and…