Continuing our discussions from the last three months, we now look more closely at what it will take to achieve carbon pollution-free and fossil fuel-free electricity production for Wisconsin’s electric cooperatives. We know we need to replace approximately 900 megawatts of coal and 75 megawatts of natural gas-produced electricity with non-carbon producing sources by 2050 to meet the goals set by the Biden Administration.
For this assessment, we have reviewed and analyzed multiple reports and studies and are basing much of the context on Princeton University’s Net-Zero America report. Wind and solar must be a large part of the transition to meet the administration’s goals. Still, these are intermittent resources, which means, unlike coal, nuclear, or natural gas, they cannot produce electricity 24 hours a day, 7 days a week.
Wind turbines obviously rely on the wind blowing to be productive. According to the University of Michigan Center for Sustainable Systems (CSS), their average capacity factor is 35%. A system with a capacity factor of 100% means it is producing energy at its maximum capacity the entire time. Compared to traditional sources of power generation, the capacity factor for wind is considerably lower because they are intermittent sources of power and in real-time, power output can vary considerably.
Data from the U.S. Department of Energy’s Wind Vision Report also shows that on average, large (more than 20 megawatts) wind projects require 82.4 acres of land area per megawatt of installed capacity. This means that here in Wisconsin, to have the potential to generate the 975 megawatts of wind energy, we would need 80,340 acres of land for wind turbines, and remember, they are only 35% productive, on average.
Wind is a key part of the transition to a carbon-free energy future, and as technology improves and the size of newer turbines increases, the output is improving, but wind energy currently presents real challenges in terms of reliability.
Next, let’s consider solar, another key part of the transition. Like wind, solar is an intermittent resource, as it requires the sun to be shining, which happens roughly 12 hours a day. Other factors that affect the efficiency of the solar panel are snow, clouds, and the panel itself. According to the U.S. Energy Information Administration, the average capacity factor for utility-scale solar generation was 24.9% in 2020 across all states. In Wisconsin, the capacity factor for utility-scale solar is considerably lower, and for a newer system is at best 20%.
According to the report Land-Use Requirements for Solar Power Plants in the United States from the National Renewable Energy Laboratory, at a conservative 13-14% efficiency, it would require roughly 14 million acres of solar panel-filled land to generate enough electricity to power the United States. Adjusted to a 20% capacity factor, this would be nearly 9.5 million acres of land. According to the Wisconsin Department of Agriculture, Wisconsin is home to 64,793 farms totaling 14.3 million acres, so it would take about two-thirds of our agricultural land, filled with solar panels, to power the entire country. Unlike wind turbines, a farmer can’t plant a crop under a solar panel array. Again, as technology improves, solar panels are becoming more efficient. However, they still depend on the sun, and reliability must be considered.
According to Badger State Solar’s figures, if we take a look closer to home in the Wisconsin electric cooperative footprint only, a bit more than 8 acres of land will be used per megawatt of potential output. For the co-ops, converting 975 megawatts of fossil fuel generation would require 7,800 acres of land for solar panels with a capacity factor of about 20%. Excess renewable generation, battery storage, and more transmission lines would be required to offset the significant difference between the fossil fuel and solar capacity factors.
Another challenge to overcome as we transition to more renewable energy is how to move it from where it is generated to where it is needed. According to the Princeton Study, we would need to increase high-voltage transmission lines by 60% by 2035. Finding sites suitable to develop projects presents potential roadblocks to wind, solar, and transmission line deployment.
Wisconsin’s electric cooperatives already have more than 260 megawatts of wind and solar energy, which accounts for more than 20% of the fuel mix used by a majority of our cooperatives today. Our cooperatives are making progress using a thoughtful, planned, deliberate approach that ensures reliability when the sun isn’t shining and the wind isn’t blowing.
Next month, we will continue our deep dive into what it would take to achieve a carbon-free energy future by looking at baseload options: nuclear power, and combined-cycle natural gas plants with carbon capture sequestration.