Wind energy is clean, but wind energy systems are not 

Last year, Gov.Martin O’Malley proposed to build 500 megawatts of offshore wind. The debate centered around how much this would really cost, and the proposal died. This year, the proposal is to spend a fixed amount of money by capping the amount by which Maryland electric bills can increase. The state would be saying, essentially: Give us a billion dollars so we can build some offshore wind.

Like most Marylanders, I want electric power that is cheap and clean. However, I oppose offshore wind – because it is not cheap, and wind systems are not clean.

In its Annual Energy Outlook 2011, the Energy Information Administration at theU.S. Department of Energyestimated the cost of electricity from new-construction generators entering service in 2016. The stated purpose is to compare technologies without the confusion of incentives and subsidies. Here is the Annual Energy Outlook’s comparison of energy technologies and their cost in cents per kilowatt hour: natural gas, combined cycle, 6.2; advanced nuclear, 11.4; solar photovoltaic, 21.1; offshore wind, 24.4. These numbers are average wholesale cost estimates. Without subsidies, offshore wind is about four times more costly than new natural gas.

But my main complaint about offshore wind is not the cost but the fact that even though wind turbines are clean, wind systems are not. Wind turbines require polluting fossil-fuel backup to provide most of the power. This dilemma can be explained with a simple thought experiment:

Consider a model electric power system – say, the state of Maryland – with no electricity imports or exports across state borders. Assume a constant load with no daily or seasonal variation. Assume that load is being met with natural gas generators, and we will add wind farms to the grid.

Add a few wind turbines, and whenever the wind blows, the grid operator can throttle back the generators, save some natural gas and reduce emissions. A little bit of wind on a high-carbon system reduces emissions a little bit. But we can’t discard the natural gas generators, because we need them when there is no wind.

On adding more wind, the system reaches a “wind penetration limit” when, on windy days, the system gets all of its electricity from wind and all of the natural gas generators are shut down. If we installed still more wind turbines, the grid operator would have to shut them down just when they were most productive. Because the amount of wind is variable, the natural gas generators provide no power on windy days, all of the power on calm days, and, say, 75 percent of the power on average.

But a system that derives three-quarters of its power from natural gas is not a clean system.

In an effort to increase wind penetration beyond 25 percent, advocates have explored compressed-air storage, plug-in electric vehicle storage, long-distance transmission, overbuilding with wind curtailment, demand management and wind-plus-hydro subsystems. All of this helps a little, but none of it changes the game. Most of the energy in a wind system that must deliver energy on demand comes from fossil fuel backup.

The main justification for offshore wind has been that it is the only way to meet the state Renewable Portfolio Standard (RPS). That is true. But the RPS is based on two false assumptions. It assumes that clean generators produce clean systems; our model shows that is not true for wind. The RPS also assumes that if we get a 20 percent emission reduction with intermittent renewables, we can get the other 80 percent some other way. How does that work exactly? We cannot start and stop nuclear power plants to back up wind.

At the executive level, the Department of Energy understands these nuances. This is why President Barack Obama has advocated clean energy standards – not renewables – in his past two State of the Union addressees. It is time for Maryland to rethink the RPS. A reasonable plan is to replace the RPS with a clean energy standard that includes natural gas and nuclear power.

Alex Pavlak, a resident of Severna Park, is an independent PhD professional engineer with a wind turbine patent. He has published a number of papers on clean energy systems.