Saturday, 1 February 2014

Heating your car or biking 500 km?

Introduction

It’s been freezing in Tammisaari for a couple of weeks now. That hardly (or actually not) affects my use of the bike, but it does make use of the car more complicated.



Many middle-European readers might not be aware of this, but most Scandinavians plug their car to the grid when it’s cold. Motors don’t like a cold start (a fact that middle-Europeans do know rather well) and therefore it’s a smart idea to preheat the motor block before starting. And drivers don’t like scratching snow and ice from their windows, so therefore it’s a smart idea to at once get an electric heater going which heats the inside of the car just enough to ‘melt the windows’. Now let’s first make this clear: when in need for a car at -15 degrees C, I don't say that using those two devices would not be the best thing to do. That's not the point of this story.
A motor block heater consumes about 500 W. A ‘cockpit’ heater about 1000 W (with a good deal of variation). When the temperature is a humble -10 degrees, heating for about 1 hour is the absolute minimum required, while 90 minutes is better. 

Summary: just preparing your car for a ride by -10 degrees easily takes over 2 kWh.

The random question that came up in my head was: with this amount of energy, how far would I get with a bike?


Materials & methods

(if you're not a fan of technical details, you can easily skip this paragraph)

To find the answer, I used one of my favourite apps, the bike speed calculator from Kreuzotter.
As a bike I chose an energy-efficient velomobile, in this case the Quest. I set the temperature at -10 degrees, chose off-road tyres because spiked tyres aren’t possible to choose in the app. For power input I select 150 W. By multiplying the predicted speed with the time it takes to spend 2 kWh, I find the distance which can be biked with the same energy as it takes to heat the car.



I want to compare this result with a more average bike (let’s say a MTB), so I repeat the same procedure for this bicycle type.


Results


(Here follow some boring calculations for the skeptics. If you prefer to just believe instead me you can skip to the next paragraph). 

When riding Quest at 150 W, my speed with off-road tyres and at -10 degrees would be about 37,2 km/h. 2000 Wh / 150 W = 13,3 hours. 37,2 km/h * 13,3 h = 500 km. With a mountain bike, the result is about 330 km.


Or, simply put: With the energy it takes to just heat my car in Finland to be able to start using it at -10 degrees, I could bike almost 500 km with a good velomobile! With a mountain bike, that would be ‘only’ 330 km.
Notice, if I would drive using less than 150 W, the distances would only get longer (and the difference between velomobile and MTB would also increase).  


Conclusion

This advanced study was nothing more than just another way of looking at energy and using it wisely.
It shows that using the car for short distances has never been more stupid than during a Finnish winter. (Did I mention some of my neighbours are taking the car to go to work, which is about 1 km away? If only they knew that for the same amount of energy they spend on heating there car in one week, they could have biked to the south of France!) But who cares about the real price of energy when it’s paid by the next generations/people on other continents anyway?

2 comments:

  1. This post makes it clear how folish most people use energy, of course it's understandable that they use heating, but for this kind of distances I rather walk then use a motorized car! It's a pity that not more people thinks like us........

    Regards, Adri.

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  2. Thank you for this inspirational posting.
    I sincerely appreciate everyone who promotes a more sustainable way of life.

    ReplyDelete