How Building More Wind Turbines Could Actually Increase Fossil Fuel Use

How Building More Wind Turbines Could Actually Increase Fossil Fuel Use

Introduction

The expansion of wind power is often seen as a crucial way to reduce greenhouse gas emissions and reliance on fossil fuels. However, some analyses have found that building lots of new wind turbines could actually increase fossil fuel usage in the short term. This counterintuitive outcome occurs due to the interaction between wind power and the operations of the electric grid.

In this article, I will examine the mechanisms by which deploying large amounts of wind power could, ironically, result in greater fossil fuel use. Understanding these dynamics is important for ensuring that policies to incentivize renewables like wind energy achieve their intended climate and emissions goals.

Wind Power and the Grid

To understand how wind power additions could increase fossil generation, it’s important to grasp a few key attributes of wind energy and the electric grid:

  • Wind power is variable and intermittent. Wind speeds fluctuate minute to minute, meaning wind turbine output is highly variable. This makes wind power more challenging to integrate than always-available sources like fossil fuels.

  • Grid operators must match supply and demand instantaneously. The electric grid requires second-by-second balancing of generation and load. More customer demand must always be met with more power generation.

  • Fossil fuels provide most “dispatchable” generation. Natural gas and coal plants can adjust their output to follow changes in demand. Other sources like wind and solar operate when the wind blows or sun shines.

  • Changing fossil fuel plant output levels affects their efficiency. Ramping fossil fuel plants up and down to balance variable wind generation reduces their efficiency and increases fuel use per unit of electricity generated.

How More Wind Can Increase Fossil Fuel Use

Here are two primary ways that deploying large amounts of wind power could result in greater fossil fuel usage, at least in the short term:

1. Cycling fossil fuel plants causes efficiency losses

  • With more wind turbines added, fossil fuel plants will need to cycle their output up and down more frequently to balance the variability of wind.

  • This cycling reduces the efficiency of fossil generators, increasing their fuel consumption per unit of electricity produced.

  • One study found that doubling wind capacity in one region increased coal plant cycling by 80% and heat rate (fuel consumption efficiency) by 2%.

2. Low wind conditions require ramping up fossil generation

  • Periods of low wind conditions require fossil fuel plants to ramp up to replace the missing wind generation.

  • Like cycling, these large ramping events also reduce the efficiency of fossil generators, again increasing fuel burn per MWh.

  • Analysis shows ramping events over 300 MW due to wind lulls increase system-wide fuel consumption.

So in essence, while adding wind displaces some fossil generation, the efficiency losses from cycling and ramping up fossil plants result in increased fuel usage per MWh of fossil electricity generated. Under the right conditions, this can outweigh the fuel savings from wind acting to displace fossil generation.

Real-World Examples

A few real-world examples demonstrate how adding large amounts of wind power can increase fossil fuel use:

  • One study by GE Energy Consulting examined integrating 12,000 MW of new wind power into the Electric Reliability Council of Texas (ERCOT) system. They found cycling operation increased as more wind was added, causing a 0.2% average heat rate increase in natural gas plants.

  • In a California ISO study, researchers warned of a “counterintuitive result” in which proposals for 5,000-10,000 MW of new renewables actually increased system-wide emissions due to fossil plant ramping.

  • Ireland has expanded wind capacity faster than its ability to transmit power between regions. This has resulted in more curtailment of wind and ramping of fossil plants, increasing system emissions.

These examples confirm that under the right grid conditions, building lots of new wind turbines can actually increase fossil fuel use due to efficiency losses as thermal plants cycle and ramp.

Solutions

While variable renewables like wind power can increase fossil fuel use in the short run, there are solutions available to mitigate this effect:

  • Fast-ramping natural gas can provide crucial flexibility to balance wind but avoids large ramping events.

  • Increased transmission capacity smoothes out variability across larger areas.

  • Energy storage technologies like batteries and pumped hydro can offset wind lulls.

  • Hybrid renewable systems, like offshore wind + hydrogen, allow stable output.

  • Updating grid operations and market structures to better adapt to variable generation.

Conclusion

In conclusion, under the right conditions, deploying large amounts of wind power can actually increase fossil fuel usage and emissions due to efficiency losses as thermal generators cycle to balance wind variability. However, smart integration strategies and grid modernization can overcome these challenges. Understanding the unintended side effects of adding renewables helps ensure policies achieve emissions reduction and decarbonization goals. Grid operators and utilities should consider tools and market reforms to minimize fossil plant cycling as wind capacity expands. With proper planning and grid upgrades, wind power can play a major role in displacing fossil fuels and providing clean energy.