(10-06-2017, 09:12 AM)manxmike1 Wrote: I sincerely hope that no-one is still labouring under the impression that the electric bikes are in any way "green". The fossil fuel used to charge the batteries (never mind create the things) far exceeds the amount used by a similar petrol powered machine over a similar distance.

Let's see if we can do a back-of-a-fag-packet calculation to work it out.

Say you want your electric bike to do 10 joules of work.
The electric drivetrain is abut 80% efficient so you need to charge it up with 12 joules of electricity.
Grid electricity nowadays is, very roughly, 50% nuclear/renewables, 30% gas, 20% coal.
So we only get 6 joules from fossil fuels - let's approximate it as 4 from gas and 2 from coal.
The gas power station is 60% efficient, so we need to burn 7 joules of gas.
The coal station is 30% efficient so we burn 7 joules of coal.
UK transmission grid losses are 8% so we need to burn another couple of joules of gas and coal to cover that, making 16 joules of fossil fuel burned.

A petrol engine in a bike is 20% efficient at best, so to do the same 10 joules of work, it burns at least 50 joules of fossil fuel. More than 3x as much as the electric bike used.