24/7 Carbon-Free Energy Is the New Net-Zero

Denton, Texas; Minneapolis, Minnesota; Reading, Pennsylvania—nearly 210 cities have pledged or have already achieved 100% clean electricity or net-zero emissions, according to the Natural Resources Defense Council. And then there’s Des Moines, Iowa, which recently pledged to achieve 24/7 carbon-free electricity by 2035—a target borrowed from Google’s corporate commitment. It doesn’t initially sound like there’s much of a difference. But there is, and it has huge implications for buildings.  

100% clean electricity goals are often phrased in terms of net-zero or carbon-neutral, which allows utilities to keep producing electricity from fossil fuels if they offset the emissions by purchasing renewable energy credits or carbon offsets. As a result, the utilities continue to rely on the fossil fuels that are part of the grid mix to power operations when renewable energy isn’t available.

Des Moines’s 24/7 carbon-free goal means that non-fossil-fuel energy has to meet all of the city’s electricity needs the same hour that the city needs it. “That means no coal, no fracked gas, and no fossil fuels in the electricity delivered to Des Moines residents by 2035,” said Kerri Johannsen, energy program director for the Iowa Environmental Council, in a statement.

It also makes load shifting of utmost importance for the utility—and means that managing the energy loads of buildings is key to success. Whatever load can’t be floated will need to be matched by hydropower or advanced (and sometimes expensive) technologies, like enhanced geothermal, long-duration storage, green hydrogen, or carbon capture. So there’s an incentive to both lower and shift loads to when there’s cheap solar and wind.

This could be achieved by:

• designing high-performance buildings that can float temperatures without active heating or cooling
• connecting hot water heaters, dishwashers, and electric vehicle chargers to demand-response programs
• using thermal or battery storage

Des Moines acknowledged this direction in its 24/7 resolution, saying, “New and existing buildings must play a key role in reducing energy demand through smart building technologies, grid interaction, electrification, and efficiency.”

Des Moines has already instituted an energy- and water-benchmarking program, according to Jeremy Caron, sustainability program manager with the City of Des Moines, so it is well positioned to target and further expand existing efficiency programs. The city is also “exploring electrification potential across the City’s buildings and [vehicle] fleets,” says Caron. “Overcoming the challenges of integrating more intelligent buildings, equipment, and vehicles with the grid will be essential to successfully meeting the City’s goals.”