In an earlier article I picked apart Energy Vault’s two designs to date, both of which are obviously terrible, but in different ways. The first would have been a failure of epic proportions, with a CO2e per kWh in the range of coal in the best case scenario and a short lifespan. The second was differently bad, with a CO2e per kWh worse than natural gas generation and undoubtedly much higher costs. If only there were an alternative.
And, of course, there is.
For the comparison, I’ll use the obvious gravity storage technology, pumped hydro. I’ll specifically use the closed-loop, off-river pumped hydro model. That’s the one Australia National University’s Dr. Mattew Stocks assessed with his research team, using GIS models to identify 53,000 sites with more than 400 meters of head height near transmission and off protected land globally, and maintained in the ANU global pumped hydro atlas.
The closed loop, off river, and high head heights are important. The combination means that there is very little real concern about environmental impacts. No fish runs blocked. No downstream loss of silt. Very small reservoirs. Taking Stocks’ example, a 500-meter head height facility with a gigaliter of water would store a gigawatt hour of electricity, which puts the 35 MWh Energy Vault building in humbling context. It would require two reservoirs, each a square kilometer in area, basically big ponds. Per Stocks’ study, there are 100 times the resource potential as global energy storage...
A front-page article with the byline of veteran New York Times opinion writer Nicholas Kristof is the latest poisonous example of what I call the NGO “halo effect.” Headlined “The Silence That Mee...