Electricity has three properties that make it different from other economic commodities. First, it is the only product where supply and demand have to be equal at all moments in time. Electricity suppliers promise to meet the use by demanders—when you switch on your lights, you expect them to come on. Second, electricity is hard to store. Third, electricity does not really move directly from its source to its ultimate user. Rather, when electricity is provided to a power grid, it is better to think of the grid as a great pond whose water level has just increased. These three factors have inhibited the trading of electricity across regions in this country. Smith, always on the lookout for market solutions that could improve efficiency cracked the complex technical problems associated with how to trade something so seemingly amorphous as electricity. His work in this area provided the basis for a radical new system of electricity and energy trading that swept the country during the 1990s. Smith advocated an open trading system for electricity in both the wholesale and retail markets. States that have adopted his system fully have benefited greatly. Other states that still use old regulatory regimes or, like California, only applied a partial market framework have struggled.