- Can hybrids make a difference in the near future? by
- Environment | 11:57 a.m. | Tue 9 Oct 2007
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The future may be bright for hybrids, but it would have to be a very distant future, judging by the evolution of the car to date, and by the deeply ingrained tendencies of British drivers.
Over the past decade there has been little improvement in the efficiency of the UK car fleet. In 1995, our average car could manage 32 miles per gallon (mpg) and by 2005 it could manage just 33mpg. This tiny increase was due entirely to the increased proportion of diesel cars in the fleet. Meanwhile, the growth in size of the fleet (and the corresponding growth in total mileage) actually led to a slight increase in carbon dioxide (CO2) emissions over the same period.
There have, of course, been improvements in car technology. The engines themselves are more efficient, developing more power from less fuel, and the bodywork is more aerodynamic. However, these improvements have been largely compensated for – some might say squandered – by the increased weight of today’s cars.
So, can hybrid technology really deliver increased fleet efficiency where the natural evolution of traditional cars has failed to deliver?
First of all, it’s important to remember the hybrid is not a new species so much as an evolutionary step. It looks the same, drives the same and uses the same fuel as a traditional car. The addition of batteries and an electric motor simply allows the internal combustion engine to be a little smaller and to be used more efficiently.
As a rule of thumb, today’s hybrid technology can increase the efficiency of a petrol car by around 50%. Coincidentally, this is approximately the same as the difference in efficiency between equivalent petrol and diesel cars. So, whatever today’s petrol-hybrid technology could do for the UK fleet’s CO2 emissions, the same could be achieved by increasing the number of diesels on the road. Only the diesel-hybrid, which has yet to be released, looks likely to raise the bar significantly.
Let’s consider some numbers for a moment. According to the Department for Transport there are 27.8 million cars licensed on UK roads today with 2.2 million new cars licensed each year [1]. This means just under 8% of the fleet is replaced each year. Hybrid registrations, meanwhile, totalled just 9,000 in 2006 – just under half of one per cent of new registrations overall [2].
If hybrid technology (applicable to petrol and diesel) became dramatically more available and popular, would it really make much difference to the overall emissions of the fleet?
Let’s assume a quarter of the UK’s new cars were fitted with hybrid technology. This would be over half a million new hybrids per year, more than twice the current combined UK sales of Toyota and Honda (the only two car companies offering hybrids in the UK) [3]. Let’s further assume these hybrids were 50% more efficient than today’s fleet average. By multiplying the numbers together we only get a 0.7% fleet-wide improvement in efficiency.
Hybrids are a very long way from the 25% take-up assumed in this quick calculation but perhaps the most sobering statistic is that over the last seven years, traffic, as measured in vehicle-miles travelled, has been increasing at a rate of 1.2%. Just as increasing car weight squandered the last decade’s engine efficiency improvements, increasing traffic is likely to squander any real efficiency improvements that hybrid technology can deliver.
While hybrids may be able to reduce the rate of increasing emissions, it seems the only way to achieve significant reductions is to drive less.
- 6 comments
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The Prius is 100 percent more efficient than its traditional petrol equivalent. But it has allot more too it than just hybridization.
Hybridization is focused on improving the "Partial Power" efficiency of automotive systems. So, no, you are wrong about traffic squandering the gains of a Hybrid car, where cars have to operate in the partial power regime.
Diesels have good partial power efficiency, but for some reason cannot match a Prius in heavy traffic conditions. So, your comment would be correct if you had applied it to Diesel cars.
For experts, it seems like the lead commenters on this board have not done their homework. Another oversight is the comment by the Engineering professor comments regarding power for hybrid cars. Hybrid cars sold today, do not use electricity from the mains at all. Those that do are called Plug-in Hybrid Vehicles, which get 4 times the mileage of a typical equivalent vehicle, not including the energy cotribution from plugged-in electricty. As power plant heat engines are so much more efficient than present heat engines in cars, the fuel efficiency, including the gasoline equivalent of the electricty is something around three times that of the typical petrol car.
donee...
Why jump to solutions when we have yet to measure the problem?
I believe the problem is the daily growth of the fleet along with the daily supply and demand of oil. For cars and trucks in a city like Beijing 2,000 NEW cars or trucks enter the streets EVERYDAY! Traffic cops die in their 40s and everyone on the streets wears masks. The oil sands of Canada are like a million dollar bank account attached to a machine that only spits out 20 dollar bills. With one or two billion low income first time car buyers coming online, there will be a global crisis before we get any substantial alternatives into the fleet. Cars connect everything in our lives and truck deliver everything we consume. Only cheap and clean will save the planet.
Starting to really enforce traffic speed limits would be handy for a quick reduction of GHG emissions. Why can't speed recorders be added (obligatorily, of course ;) ) to car trip computers? Then drivers would get their speeds recorded by their cars, for a quick download and analysis by a traffic cop. Flash memory is now so cheap you could probably record car's speed every second for the entire service life of any car. Anyway, speed limits are already there - we just choose not to enforce them too strictly, so that people can have some incentive to buy overpowered cars and then test their performance on public roads, also used by pedestrians, kids, cats, dogs etc. As long as we choose to close our eyes to anything that might actually put any limitation on automotive business, it will only grow as dictated by people's natural want to drive around, the faster and farther, the better. When all cars are hybrids, driving will be cheaper through better efficiency, so people will drive more, nullifying the efficiency gain. So far it was like this, then why think it is going to be otherwise in the future? Either people learn to self-limit themselves, or some limitation will have to be imposed on them - by law or by nature, in one of its surprising ways.
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