The Devil and the Deep Blue Sea
September 4, 2022 § Leave a comment
California’s recent decarbonization legislation includes extending the life of the Diablo Canyon nuclear reactors in the face of environmentalist opposition. Their concern has been for the marine creatures potentially killed during cooling water uptake from the ocean. The dilemma posed in the title, similar to between a rock and a hard place, applies to the Diablo Canyon decision. A recent paper from Stanford and MIT details the issues and lands in the extended life camp with some twists discussed later here.
Back to the dilemma. No form of energy, clean or otherwise, comes without baggage. So, it comes down to compromises. Wind has avian mortality and visual pollution. Solar may carry the least baggage, but recent events pose a unique twist. The price of natural gas going up 5 and 6-fold in Europe due to climate change and Russian aggression shows that reliance on a global supply chain could be fraught. In context, over 60% of solar panel components originate in China. Sabers are rattling in the Taiwan Strait. No telling what happens to solar panel costs if things escalate.
More dilemma: opponents of the decision want to simply build more solar and wind capacity. Even Senator Dianne Feinstein weighed in with the opinion that absent the Diablo decision there would be more natural gas usage. Exactly right, especially if the course of action proposed by opponents, more solar and wind, is followed. This is because solar and wind have low capacity utilization due to diurnal and seasonal gaps in output. At this time these gaps are dominantly filled by natural gas power generation. In other words, more solar and wind means more natural gas burned until carbon-free gap fillers, such as advanced geothermal systems and small modular (nuclear) reactors, hit their stride. And that will take a decade. In the meantime, Diablo Canyon 24/7 output notwithstanding, natural gas will continue to increasingly be used in step with addition of solar and wind capacity. A mitigative measure on the associated CO2 production would be carbon capture and storage attached to the natural gas power plants. The best-in-class technology achieves this for USD 40 per tonne CO2. One of the new California bills encourages this direction. It is opposed on the grounds that it encourages more fossil fuel production. True. But, as noted above, until carbon-free gap fillers are at scale, natural gas is the only practical alternative. Rock and a hard place.
The two plants at Diablo Canyon account for 9% of the electricity and 16% of the carbon-free electricity for the fifth largest economy in the world. Removing it would make already tough zero emission goals almost unattainable, certainly the 2030 ones. This state is currently in an epic heat wave causing power demand spikes. It is also the state most vulnerable to climate change driven forest fires. It can ill afford to take out any carbon-free capacity, especially if the concerns expressed on Diablo Canyon continuance can be met by other means.
Enter the Stanford/MIT paper. It has explicit engineered solutions to minimize marine life extinction in the water procurement. It also has two other interesting suggestions to maximize the environmentally related value of Diablo Canyon. One is to use part of the output to desalinate seawater. The measures taken to protect marine life would apply here as well during the water acquisition. Since reverse osmosis produces a highly saline wastewater, the disposal in the ocean would need to follow means to minimize damage to sea bottom species. These are known methods and simply need adoption.
The other suggestion is to electrolyze water to produce hydrogen. This would be considered green hydrogen because the electricity was carbon-free. Power is employed in this way in Europe during periods of low demand. There they are piloting adding a 20% hydrogen cut to natural gas pipelines, to reduce fossil fuel use. A point of note is that the electrolytic process requires 9 kg fresh water for each kg hydrogen produced. While green electrolytic hydrogen is seductive, especially when using electricity during period of low demand, fresh water is in short supply in many areas, especially South/Central California. Could be a reason for the Stanford/MIT report suggestion regarding desalination at Diablo Canyon.
Aggressive decarbonization strategies will come with tough choices. An easy one is to target “carbon-free” rather than “renewable” energy. A harder one is to tolerate bridging methods, such as natural gas power with carbon capture and storage. The trick is to ensure that the bridges* are to definite targets. With sunset clauses.
September 4, 2022
*A bridge over troubled water, from Bridge Over Troubled Water, Simon and Garfunkle (1970)