A lot of hype has been made on the new Hybrid Toyota Prius car in Brunei, and keen into this whole 'green' debate, I was wondering is it actually worth getting a Prius in Brunei. There has always been a view that the low petrol price would actually 'hinder' such environmentally friendly technology with the assumption that green technology are more expensive, either in terms of capital cost or operating cost. So I thought I'd give it some thought..
Please read on if you're interested in numbers and estimations, cos that's what I'm going to do..
also, Please note that this is all just my estimates, I'm plucking numbers from the internet, from wikipedia and random google searches and coming up with a 'ballpark' figure so that I can have an idea, more for my entertainment than anything else. You are, of course, more than welcomed, to join me in my amusement.
The first question of course is what is the fuel efficiency of the Toyota Prius, so I looked up wiki and decided to use an estimate of 3.7L/100km - which is pretty good. Normal cars are about 9-10L/100km. (based on summer experiences of driving up and down the coast of Brunei)
My question then became, if that was the amount of fuel consumed, how much electricity is used for the same distance. I couldn't find any good answers around, so I estimated. From the specs, the total power of the car was a combination of battery (~27kW) and the engine (~60kW).
I assumed that the energy efficiency of battery and fuel is the same, took the energy density of petrol as 34.6 MJ/L and scaled the contribution proportionally. This gave me 128MJ/100km for the petrol contribution and 57.6 /100km from electricity. Electricity consumption was converted to 16 kWh/100km.
The cost of petrol in Brunei is $0.53/L and electricity is about $0.06/kWh (for residential if i'm not mistaken).
So the cost for 100km is estimated to be (0.53 x 3.7) + (0.06 x 16) = $ 2.9/100km
Compare this to a normal car, which gives 0.53 x 9 = $4.77/100km
So the good news is that you save about $1.8 for every 100km you travel. Imagine travelling up and down Bandar to Seria (approx 100km) everyday, 20 days a month, 12 months a year.
You would travel 2 x 100 x 20 x 12 = 48 000km/yr
This brings us to a total saving of $864.
Obviously the savings depend on the cost of petrol, if price of petrol goes up, this savings will become more and more significant. Some one do the calculation taking Singapore's petrol price of hmm.. $2.5-3.0 (?)
but.. there's always a but,
The cost of the car is $58 400. A normal car would cost about $20 000.
Taking simple 'return of investment' approach, dividing the difference of cost with the savings per year, what we end up is a 44 year 'return of investment' period.
It means to get your money's worth of savings, you need to drive that car for 44 years up and down the coast of Brunei nearly everyday. I'd say it'll be a pretty good car if it lasts 44 years running up and down.
Of course buying the car is to 'save' the environment. My view is that to 'save' the environment, either the government has to subsidise such cars to make them more affordable or maybe implement some other policies which might tweak the picture I have painted above.
(If you find any mistakes in the calculations, please let me know. Thanks)
3 comments:
hello, i almost want to howl whenever i think about how cheap petrol is in brunei compared to here (or even singapore?!) i think there's something worth considering; that would be one's speed. fuel consumption is affected by speed. ok, now i'm being pedantic and stuff, but how the car is used is also an issue. a lot of short journeys could easily use up petrol ... or just even plenty of stopping and starting (eg queueing to get into gadong). the cost would also have to take into account other factors that go into keeping a car road-worthy, such as engine oil, engine coolant (especially in the tropics) and work required due to wear and tear etc. and in my case, car insurance is a big issue, i dunno the situation in brunei, but if these environmental cars incur a much smaller insurance cost, then there could be a bigger intiative for people to think about spending money on one? i do apologise for the length of this comment.
come on man, everyone knows getting a prius won't really save your money. getting a diesel car nowadays too doesn't seem to make up the ROI time fast enough. it doesn't matter how small your engine is or how fuel efficient it is. What matters is how you drive it, am I right? Let's say your car has 100bhp. Driving at 120km/h, I say the engine would be at 3000rpm and I was driving about 9.6L/100KM after about 20km. If you take another car that has 300bhp and driving at 120km/h, based on experience I know it takes much less than 3000rpm, probably around 2700-2800rpm at 120km/h. 200rpm actually makes a big difference, because on the same route, I was doing about 9.0L/100KM.
I'm not saying you should get a more powerful car, but it is how you drive that matters. Right?
"it doesn't matter how small your engine is or how fuel efficient it is. "
Thanks for your comment. I agree that the way you drive your car makes a difference but your evidence does not quite support that fact.
I also disagree that the way you drive your car is the only factor. Surely you cannot discount fuel efficiency from the equation.
In fact what you showed is that a more powerful car doesn't always mean it is less efficient. You were able to achieve the same speed with less rpm and less fuel. That's good news - more comfortable driving, less fuel spent. =)
Also, my ROI estimation is just a way of quantifying how much money we 'won't really save' by buying the Prius.
I hope this answers your question.
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