Overbuilding solar cheaper than seasonal storage and natural gas in Minnesota


An interesting topic of discussion in the solar energy world is what happens when we make too much solar? When we make it too cheap? What happens if electricity goes to 1¢/kWh – or less – with the daytime duck curve? This pv magazine author thinks that entrepreneurs will easily figure out what to do with cheap electricity, and so does Minnesota.

The Solar Potential Analysis Report (.pdf download – 99 pages), prepared by Clean Power Research for the MN Solar Pathways Initiative, states that Minnesota could achieve 10 percent solar by 2025 at costs comparable to natural gas generation. Further, the report finds that expected cost decreases in solar, wind, and storage will enable Minnesota to achieve 70 percent solar and wind by 2050 at costs comparable to natural gas generation. Additionally, they also posit that overbuilding solar power and curtailing is so cheap – that it makes more sense than gas and seasonal energy storage.

Jeff Ressler, CEO of Clean Power Research, noted:

Critical to this project was the use of time-correlated solar, wind and load generation datasets in advanced software tools to more precisely see the effects of different scenarios, such as varying amounts of solar, wind and storage capacities.”

A similar hour by hour analysis was also done by Dr. Ken Caldeira when he determined that the United States as a whole could reach 80% solar+wind with 12 hours of energy storage, and that the country could reach 100% solar+wind if we overbuilt the solar power and wind in strategic places (without HVDC,). Without overbuild, or nationwide HVDC, we’d need three weeks of energy storage to reach 100% solar+wind.

In the below image, the report notes:

As can be clearly seen, Additional Solar Capacity produces a dramatic reduction in the required storage capacity – roughly a ten-fold reduction in storage capacity is achieved with 100% Additional Solar Capacity.

The report’s five key findings were:

  1. Solar and wind can serve 70 percent of Minnesota’s electrical load in 2050.
  2. Additional capacity coupled with energy curtailment is considerably less expensive than, and a viable alternative to, long-term or seasonal storage in a high renewables future.
  3. Using other flexible generation resources in limited amounts support a high renewables future.
  4. Storage is an important part of a high renewables future; it expands the dispatch capabilities of wind and solar assets.
  5. Shifting of key flexible loads may further decrease generation costs.

The report also analyzes land use and comes to a conclusion that if solar power were to meet 100% of the state’s electricity needs it would use 0.15% of the state’s land.

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