A truth of modern industrial society is that it takes energy to make things.
Sometimes, that energy is better spent doing things than making the thing to save energy or “be green.”
Let’s consider a Tesla Model S battery pack. The shiny new one is 90kWh.
How much energy does it take to build a 90kWh pack?
http://www.lowtechmagazine.com/2015/05/sustainability-off-grid-solar-power.html makes some claims about lithium battery embodied energy. It claims:
According to the latest LCA’s, aimed at electric vehicle storage, the making of a lithium-ion battery requires between 1.4 and 1.87 MJ/wh
How much is that? 1MJ = 0.278 kWh = 278WH.
I’ll be nice and use the lower end for Tesla’s batteries. 1WH of lithium battery takes ~390WH to produce.
A Model S 90kWh pack, therefore, takes ~35MWh to produce.
http://seekingalpha.com/article/1261431-why-batteries-are-too-valuable-to-waste-on-solar-power-integration-and-electric-cars also does some math on the Tesla packs. Their number is 472WH per WH of battery.
Based on an embodied energy of 472 kWhe per kWh of battery capacity, the Tesla’s 85 kWh battery pack will have 40,120 kWhe of total embodied energy.
Well, 40MWh is within a reasonable tolerance of my numbers, so I’m happy enough with my back of the envelope calculations.
How far can that 35MWh take an electric bike?
A throttle-based ebike will consume somewhere around 35Wh/mi. So… a million miles. :/
What if we use a pedal assist bike at 15-20Wh/mi? Near as makes no difference, two million miles.
A typical American car travels 12k miles/yr. If you drive for 80 years, that’s 960,000 miles.
So… for the energy involved in creating one Tesla Model S battery pack, you can ride an ebike for your whole life.
Ouch.
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