Need help - my brain is mush and the longer I look at it the more I don't understand it...can someone please tell me if this calculation is correct:(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

A car is run for 400 hours per year, with a total mileage of 10,000 a year.

The car uses diesel and consumes 2,000 litres a year.

A litre of diesel costs £1.10 and holds 38.7MJ of primary energy.

If the engine is 20% efficient overall, how much energy would need to be stored in 95% efficient batteries to give a range of 300 miles on full battery charge?

2. Relevant equations

n/a

3. The attempt at a solution

Background Calcs:

Convert MJ to J: 38700000J

Total Joules (J x 2000 litres): 77400000000J

Convert 400 hours to seconds: 1440000s

Energy 77400000000 J

Time 1440000 seconds

= Power 53750 Watts

53.75 kW

1 watt = 0.001341022 horsepower

Convert W to hp: 72.07993734 hp

Answer (attempt!):

Primary energy (1 year): 400h*53.75kw=21.5MWh

Energy to 95% efficient batteries: 21.5 x 100/20 x 100/95 = 113.2MWh

Therefore 300 miles: 300/10000*113.2=3.4MWh

I appreciate your help!!!!

Thanks guys

+ :zzz: + = me

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# How to calculate required battery charge for 300 miles

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