How Building More Wind Turbines Could Actually Increase Emissions

I have been researching the impact of building more wind turbines on emissions. While it may seem counterintuitive, there are some important factors that suggest increasing wind turbine construction could lead to higher emissions in certain circumstances.

Intermittency of Wind Power

One key challenge with wind power is its intermittent nature. The wind does not blow consistently, which means wind turbines do not generate electricity steadily. This intermittency causes problems:

• When wind speeds are low, wind turbines generate less electricity. More reliable power sources like natural gas must ramp up to meet electricity demand. This cycling of natural gas plants leads to more emissions.

• Wind turbines often generate excess electricity when electricity demand is low. This surplus energy has to be curtailed (wasted). More curtailment can mean lower emission reductions.

• Additional transmission infrastructure may be needed to transport wind power from source to demand centers. Constructing new transmission lines generates emissions.

So while wind power itself produces no emissions, its intermittency means more wind turbines do not necessarily equate to lower emissions. Emissions increases depend on how much cycling, curtailment and new transmission occurs.

Impact on Conventional Power Plants

Wind turbines mostly displace emissions-producing sources like natural gas. However, increased wind power changes how these conventional plants operate:

• Natural gas plants must cycle (ramp up and down) more to accommodate wind variability. This cycling reduces their efficiency and increases emissions.

• Low wind conditions sometimes require plants to operate at minimum output levels to ensure grid reliability. Running at minimum output is less efficient and boosts emissions.

• Conventional plants sometimes act as backup capacity for wind power. Maintaining these plants for backup purposes generates emissions.

So building more wind turbines can indirectly increase conventional power plant emissions by altering how these plants operate. More cycling, minimum output and backup capacity needs all tend to raise emissions.

Need for Transmission Lines

New wind turbines are often constructed in remote areas with abundant wind resources. Major transmission infrastructure may be needed to deliver this power to end users:

• Constructing transmission lines and towers requires concrete and steel manufacturing, transport and construction activities that generate large initial emissions.

• If transmission capacity is lacking, it may result in curtailing wind power. This reduces the emission benefits.

• Transmission projects create land disturbance that releases carbon stored in vegetation and soil.

Ensuring adequate transmission capacity enables emission reductions from new wind turbines. However, the upfront emissions and land impacts associated with new transmission can also increase emissions.

Examples Where Emissions Increased

In certain cases, adding wind power has increased emissions:

• In Texas, a large increase in wind power required cycling of natural gas plants, resulting in higher emissions.

• Curtailment of wind power in China grew from 7% in 2010 to 15% in 2015 as wind capacity expanded faster than transmission infrastructure.

• The $7 billion Energy Gateway transmission project for delivering Wyoming wind power will generate over 2 million tons of CO2 emissions from construction activities alone according to UCLA research.

These examples illustrate how under the right circumstances, expanding wind power can increase grid emissions rather than decrease them. Careful planning and grid integration strategies are needed to minimize these emission penalties.

Conclusion

While wind power emits no direct emissions, integrating large amounts of wind turbines into the grid can indirectly increase emissions in some cases. Intermittency effects that lead to more cycling of conventional plants, curtailment of wind power, and major transmission projects can drive up emissions as wind capacity expands. With careful grid planning and integration strategies, these emission penalties can be minimized. But under certain conditions, simply building more wind turbines will not guarantee lower overall emissions.