We are told that 100% renewable energy is a laudable and realistic goal. The reality and the details actually contradict this. Here is the rest of the story.

Examining data from the U.S. Energy Information Administration (EIA) for past years, wind generation tends to produce the most electricity when the demand is lowest (usually around April) and produces the least amount of electricity when the demand is the greatest (usually around July and August).

A recent letter to the editor suggested Iowa could sell its excess electricity generated by wind and solar. That is already happening.

In the spring, around April, Iowa generates electricity from wind turbines that exceed demand in Iowa. Last April, the demand for electricity in Iowa was 4.25 million megawatt-hours (MWh.) Wind turbines generated 5.12 million MWh. This is clearly greater than the demand (1.48 million MWh was sold out of state). However, we still needed 150,000 MWh generated by coal and 330,000 MWh generated by natural gas to satisfy our demand for electricity. Even though Iowa has an installed wind generation capacity of 13,000 megawatts (MW,) conditions on some days were such that it could not even supply the average demand of 5,900 MW during the month of April. This made the use of coal and natural gas necessary as a backup.

Last August, the demand for electricity in Iowa was 5.03 million MWh. Wind turbines generated only 2.32 million MWh. Even doubling the installed wind generation capacity would not have satisfied the demand for August. In spite of this, 475,000 MWh of wind-generated electricity was sold out of state. The demand for electricity in Iowa required 1.8 million MWh generated by coal and 1.27 million MWh generated by natural gas. This is a case in which adding batteries would not help renewable energy because the wind did not produce enough electricity to charge them. Only during March and April did wind actually generate enough electricity to charge backup batteries.

The suggestion was made that we could buy extra energy from Arizona when our renewable generation is not producing sufficient electricity to meet the demand in Iowa. Sunny Arizona gets 30% of its electricity from nuclear, 7% from solar and 1.5% from wind. This seems to indicate that restarting Duane Arnold is a good idea.

100% renewable energy here in Iowa is not realistic. We need back up energy sources such as coal, natural gas and nuclear. Persisting in the pursuit of 100% renewable energy means that we can expect a future of brownouts/blackouts.

Chet Sullivan has 41 years of experience in energy related research and development, engineering and production.