NYC Monthly Climate Dinner -- csaeed

If we are to transition to a non-nuclear grid powered by renewables (wind, solar, hydro, geothermal, wave) we face the intermittency problem. People want the lights kept on even when the weather isn't cooperating, which means that some form of battery storage is needed. I was in the same room as Al Gore 7 years ago when he said "Wind and Solar are already cheaper than fossil fuels." which is highly misleading -- they are cheaper in the middle of a sunny, windy day, but on calm nights and calm, cloudy weeks, battery backup is needed, and that's expensive.

One approach that is suggested is to have an extensive long-distance power grid, to get electricity from places where the weather is cooperating with renewables to places where it isn't, greatly reducing the chances of blackouts. However, high voltage power lines have major NIMBY problems -- you need permission from every county they run through, which is difficult and time-consuming because they're ugly and spoil the view. There have been improvements in power line technology where much larger amounts of power can now be transmitted through a set of power lines than was previously available

There are some places using lithium-ion batteries to back up renewables on the grid, but these usually have a capacity of about 4 hours, nowhere close to enough to keep the power on for a calm, cloudy week.

There is a battery storage site in Lincoln, Maine based on Form Energy iron-air batteries that is on the grid and has a 100-hour capacity (clarification -- this site is only a partial backup of the grid in that area, but the location, once fully charged, takes 100-hours to fully discharge the battery). Form Energy also has installations in progress going on in other states.

The following table was generated from a lengthy conversation with ChatGPT.
The costs of energy storage are the capital costs per kWh, not the cost to the electrical consumer per kWh they consume.

Technology	Favorable siting ($/kWh @ ~100h)	Unfavorable siting ($/kWh or status)	Typical round-trip efficiency (%)	Feasible or prohibitive under unfavorable siting? (why)
Pumped hydro (above-ground reservoirs)	~100–250	Prohibitive	75–85%	Prohibitive. Requires two large reservoirs, substantial elevation difference, water rights, and a very large land footprint. Without favorable geography and permitting, there is no realistic fallback configuration.
Pumped hydro (underground / shaft / mined)	~150–300	Prohibitive	70–80%	Prohibitive. Depends on highly specific geology and extensive tunneling/lining. Without ideal rock conditions, excavation costs and risk become overwhelming and projects are abandoned.
Sodium–sulfur (NaS) batteries	~380–520	Prohibitive	70–85%	Prohibitive. High-temperature electrochemical battery (~300–350 °C) using molten sodium and sulfur. Safety exclusion zones, standby heating, insurance, and AHJ constraints make multi-day siting near load unrealistic.
Lead-acid batteries	~330–420	Prohibitive	70–80%	Prohibitive. At ~100 hours the footprint, ventilation, spill containment, and poor cycle life force extreme oversizing, turning projects into land-use and permitting non-starters.
Vanadium redox flow batteries (VRFB)	~330–450	Prohibitive	70–85%	Prohibitive. Massive electrolyte volumes at ~100 hours require large tanks and secondary containment; chemical handling and zoning constraints dominate without abundant cheap land.
Gravity-based storage (Energy-Vault-type concepts)	~150–250	~300–600	70–80%	Feasible but usually unattractive. Poor siting drives up civil works, foundations, structural height/weight requirements, transport logistics, and zoning/visual constraints.
Zinc-based batteries (hybrid, bromine, etc.)	~350–450	~400–550	60–75%	Feasible but marginal. Scaling to ~100 hours increases tankage and balance-of-plant complexity; unfavorable sites amplify footprint, maintenance, and EPC risk.
Lithium-ion (NMC)	~330–400	~420–550	85–92%	Feasible but practically unattractive. At ~100 hours, thermal management, fire-safety spacing, and insurance/AHJ requirements scale non-linearly on constrained sites.
Lithium-ion (LFP)	~300–380	~380–500	85–90%	Feasible but practically unattractive. Safer than NMC, but footprint, HVAC, inverter scaling, and permitting constraints still dominate at multi-day durations.
Non-vanadium flow batteries (iron, organic)	~280–400	~350–500	65–80%	Feasible but case-by-case. Lower toxicity than VRFB, but still tank-heavy; tight footprints and zoning limits erode their main advantage.
Thermal (heat-based electricity storage)	~60–110	~120–300	30–50%	Feasible but site-sensitive. Often benefits from industrial integration and ample space; without those, balance-of-plant and permitting costs rise, though buildability remains.
Compressed air energy storage (CAES)	~15–35	~80–250	45–70%	Feasible but highly site-dependent. Favorable costs assume salt caverns or excellent geology; without that, mined caverns or other costly storage options sharply increase civil-works and storage costs.
Iron-air batteries	~30–60	~60–90	50–60%	Feasible. No special geology, no high pressure, and reduced fire risk. Unfavorable siting mainly increases soft costs rather than fundamentally changing viability.