The problem with wind: It doesn't get us close to zero carbon

Wind energy requires a polluting backup system and thus fails to achieve low-carbon goals

May 05, 2011|By Alex Pavlak

The Maryland legislature has deferred a decision on offshore wind pending a "summer study." Here are questions that businessmen and prudent investors would typically ask before making a large, long-term commitment: How much will it cost? What are the benefits? Where is the plan to get to low carbon? What are the alternatives? Finding answers to these questions should be the focus of the summer study.

The issue of cost is a complicated question that is being competently debated. The only point that seems to be overlooked is that wind cost needs to include backup capacity and land-based interconnection costs, even if those costs are not part of the contract.

That brings us to the main issue: emission benefits. People want to believe that wind systems work well. A wind turbine is obviously a clean generator, so the common assumption is that wind farms will proportionally reduce system emissions. But because of its intermittency, the emission benefits of real wind farms are disappointing. The reason is that wind fluctuations disrupt efficient operation of the fossil fuel plants.

The central problem is that intermittent generators are incompatible with systems that must deliver energy on demand. Because of this, wind farms cannot stand alone; they require fossil fuel plants to provide backup power for when there is not enough wind. Indeed, most of the system power must come from fossil fuel. While storage and long-distance transmission can increase wind penetration a little, there are no competent studies showing how wind can provide most of a system's power.

With small wind farms, backup is provided mainly by fast-response natural gas turbine generators. Wind reduces emissions by saving natural gas whenever the wind blows. Since natural gas is fairly clean, CO2 reduction is only about 60 percent of what we would calculate from all the fuel consumed by the grid. Also, these backup generators are not as efficient as base load (constant power) generators. They are forever starting and stopping and operating at partial power, like driving a car in city traffic.

But the big problem arises when large wind farms force old coal plants to cycle — rapidly start, stop and change power levels — to back up wind. A report by Bentek Energy, "How Less became More," shows how wind-induced cycling can destabilize pollution abatement equipment, causing the coal plant to emit more sulphur dioxide and nitrous oxide than if there were no cycling. The Bentek study is the only study that uses actual data from real power plants and is not just an idealized set of models and assumptions. Bentek concluded that wind farms in Texas and Colorado increase system emission of sulphur dioxide and nitrogen oxide, with minor reductions in CO2. While these conclusions have been challenged as exaggerated, there is no data to refute them.

So, what is the plan? Businesspeople use strategic planning to focus resources on achieving a goal and to avoid making big mistakes. Planning starts with the long-term goal, in this case to eventually get to a low-carbon electric power system. A prudent investor would demand a plan showing how offshore wind gets there.

If the goal was simply to reduce CO2 emissions by 20 percent, wind might be a solution. But the real goal is low carbon. The risk is that to move beyond 20 percent wind to get to truly minimal carbon, installed wind turbines would have to be discarded. (For example, wind can block the subsequent deployment of nuclear power because nuclear cannot cycle to back up wind.)

Finally, an analysis of alternatives is essential. When an expert says that offshore wind will reduce CO2 emissions by so many tons per year, what does that mean? There are many ways to reduce carbon emissions today. Alternatives can be compared by calculating the relative cost of different strategies. One way to find the cheapest method of reducing CO2 is to divide the discounted cost of a particular action by the CO2 benefit from that action.

A prudent investor would not make a multibillion-dollar, 25-year commitment without 1) a clear understanding of cost; 2) scientific evidence of system emission benefits; 3) a plan showing how that investment helps achieve low carbon; and 4) an analysis of alternatives. The stakeholder responsible for demanding answers is the investor writing the check — the Maryland General Assembly. The legislature's summer study should be directed at figuring out how to best find these answers.

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 the feasibility of wind and how to develop clean energy systems. His email is

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