THE POWER SUPPLY CONUNDRUM

Figure 1 - Power Generation and the “Grid”

The power company provides power on a electric supply system (we’ll call it “the grid”). Simply, the grid is anything outside an “electric meter”. Suppliers that put electricity onto the grid sell it to the electric company at a wholesale rate. Users, that take electricity off the grid buy the electricity at a retail rate. The retail rate includes a number of charges for maintaining the electric lines and power supply infrastructure. (If you look at your electric bill, many of these charges are listed.) The “device” that measures all this is your electric meter. If you supply your electricity needs “behind your electric meter” (say, with a wind turbine) you provide yourself electricity at the equivalent of a wholesale rate. Whenever you need to get electricity from the grid, you have to buy it at the retail rate. Since the Town has many electric meters and with the current regulations, if we built a BIG wind turbine to supply the whole town, we would be continuously putting electricity on the grid (at getting paid ‘wholesale’) and using it behind some other town electric meter I (buying it back at “retail). That throws a ‘monkey wrench” in the economic analysis for building a wind turbine.

One way to solve the problem is to have a wind turbine “behind a town electric meter” that exactly matches the demand eliminating the need to place power on the grid or take power for it. That is the basic premise of erecting a wind turbine at a school where the annual power demand is close to the turbine output. But, alas, the wind does not always blow when the peak electrical demand occurs and no cheap and effective “power storage” devices have been devised. So, even at a school, we are faced with continually putting power on the grid and taking power from it all day long.

This does not help the economic value of wind turbines.

The next questions is, “ why not just let the meter run ‘backwards’ when we put electricity on the grid and run ’forward’ when we use electricity from it?” . That sounds great, but the power company says “Wait an minute, we have to maintain power generators and power lines and then provide you electricity (and backup capacity if your wind turbine stops) for free?.”

Because small wind power projects are essential to the sustainable energy goals the rule-makers are working on schemes to provide wind turbine owners some relief in the amount of credit they get for putting power on to the grid. The Portsmouth Economic Development Committee is actively participating in the discussion of changes in the regulations that would make economics of a town wind turbine even more positive.