All-Electric Storage

...for triple current US demand and consumption.

Originally published here.

The US Administration has established a goal of transitioning all energy end uses in the economy to electric end uses by 2050. This would be a massive undertaking, requiring the application of currently non-existent technology, particularly in industrial and transportation end uses.

The US currently consumes approximately 4,200 TWH of electricity each year with a generation fleet of approximately 1,200 GW. The transition to all-electric everything would require an increase in electric generation to approximately 13,000 TWH from a storage supported predominantly intermittent generation fleet of approximately 6,000 GW with a capacity factor of approximately 30%, depending on the mix of wind and solar in the generation fleet.

A recent paper, summarized by its primary author, concludes that a predominantly intermittent renewable powered electric grid would require storage equal to approximately 25% of annual generation to assure reliability. Thus, the US all-electric everything grid would require electricity storage capacity of approximately 3,300 TWH. However, research suggests that battery life could be extended by operating the batteries between 20% and 80% of rated capacity. The batteries would be expected to experience charge below 20% only rarely, so this condition could be safely ignored. However, to avoid charging the batteries to above 80% of their rated capacity while assuring adequate capacity, total electric storage capacity would be increased by 25%, to approximately 4200 TWH.

The primary battery storage system currently being installed for grid level storage is the Tesla Megapack, which stores 19.6 MWH deliverable at a rate of 4.9 MW over a 4-hour period. Restricting the Megapack to a maximum 80% charge would reduce its storage capacity to approximately 15.7 MWH. Under these conditions, satisfying the storage requirements of the all-electric everything grid would require approximately 270 million Megapacks at an approximate installed cost of $2.2 quadrillion.

There are expected to be lower cost storage options, some with longer storage duration, in the future. NREL estimates current 4-hour battery costs at $500 per kWh, which is projected to drop to approximately $250 per kWh by 2050. The Tesla Megapack stores 19,600 kWh at an installed cost of approximately $415 per kWh. Form Energy claims that their iron-air battery could be sold for 10% of the price of a lithium battery such as the Tesla Megapack, though their battery is not yet available commercially. However, even if this or other lower cost, longer duration batteries became commercial immediately, they would only reduce the projected cost of storage for the all-electric transition from $2.2 quadrillion to $220 trillion.

The all-electric transition is the most challenging aspect of the Administration’s Net Zero goal, since it requires a rough tripling of US electricity generation and also requires twice as much storage as the transition from fossil to renewable generation in the electricity sector. This transition has already begun, with the major promotion and incentivization of electric vehicles and public charging stations for those vehicles. Fortunately, it is to occur over a period twice as long as the electricity sector transition.