A co-worker and I discussed the feasibility of swapping out batteries of electric cars in an effort to reduce charging time (from hours to minutes). Curious, I searched the web (and newsgroup) to see if this has been discussed before, and it has:
Let's do a preliminary economic analysis. Got some numbers to crunch. For a hypothetical service station between SF and LA, assume:
(1) 10 cars can be serviced simultaneously
(2) 15 minutes needed per battery change/fillup (i.e. full-service attendants on forklifts)
(3) each car battery holds 100 kW-hrs (3.6E8 J)
(4) each charging station in the "charging warehouse" will be 10 ft by
10 ft.(5) attendants are paid $20/hr (burden rate: workers comp, OASDI, SS, income taxes etc.)
(6) $0.15/kw-hr electricity
10 cars every 15 minutes is 40 changes per hour. Let's assume the "charging warehouse" must hold double this: enough for 80 batteries.At 10' by 10' per charging station, that's 100 ft^2 x 80 batteries =
8000 ft^2, or about 90 ft by 90 ft of charging warehouse.Charging 80 batteries per hour, at 100 kW-hr per battery:
3.6E8 J/charge x 80 charges/hr x 1 hr/3600s = 8 megawatts of electric power needed.For 15 minutes of service per customer, the station spends $5 (at $20/hr employee burden rate), cost passed on to the customer.
With electricity at $0.15/kw-hr, 100 kw-hr/battery is $15 per battery.
So, the customer spends a minimum of $5 + $15 = $20 per battery change.
This amount excludes any profit, and also excludes loan amortization for the charging equipment, "charging warehouse" engineering/construction and forklifts.
Any thoughts?
Mike Darrett