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Continuing the back of napkin calculations, to compare train cars with batteries: Rail cars costing $10^5 can hold 100 metric tons or 10^5 kg each. Cost is $1/
by gshubert17 10y ago
Continuing the back of napkin calculations, to compare train cars with batteries:
Rail cars costing $10^5 can hold 100 metric tons or 10^5 kg each. Cost is $1/kg. This will be amortized over the system's useful life. 1000 meter height differential at 10 m/sec^2 stores 10^4 J/kg. System stores about 10^4 J/$.
Tesla's Powerwall stores 10 kWhr for $3500. That's about 10^4 J per $ (since an hour is 3600 seconds).
What surprises me is that these order-of-magnitude costs are about the same -- 10^4 Joules per dollar.
- evgen 10y agoA 5800CF open-topped hopper can hold 200 metric tons of pea gravel (at least according to the people selling them) so you just doubled the J/$ of the Powerwall. This is also using new rail cars, if you buy used then the price for the same rail car drops down to the 20K range according to online rail car brokers. Now we are looking at 1/4 the price for a train car solution.