21 February 2006

Diesel Plug-in a White Elephant?

While most people see the gasoline-electric hybrid car naturally evolving towards the plug-in concept, it's not so clear what will happen with European diesel powered cars. While the diesel is clearly more efficient than the spark-ignition engine it is also, and has always been, more expensive to produce. Generally speaking the hybrid electric vehicle is the most efficient in city-type driving while the diesel is superior for highway speeds and distances. Marrying the diesel to the hybrid concept would seem to give the best of both worlds it would have a major impact on the sticker price. Current fuel prices are not high enough in North America to justify either technology with the exception of high mileage users like taxis.

The plug-in vehicle concept enables a car to travel a typically commuting range on electric power alone while retaining a gasoline engine for longer trips. This maximizes flexibility while reducing the need for a huge and expensive battery pack. The introduction of the plug-in concept reduces the significance of the internal combustion engine to that of an on-board generator however. This begs the question, will there ever be value in trading a gasoline engine for a diesel model on a plug-in hybrid? Which improves fuel economy more, swapping the gasoline generator for a diesel or adding additional battery capacity? E.g. for the price of changing to diesel you can add 20 km of all-electric range through batteries.

It's not practical to answer this question without data on driver's habits. We would need to know the actual distribution of trips in terms of distance and type (city or highway) at a minimum to evaluate which gains the most: extra battery capacity for more all-electric kilometers or improving the efficiency of the on-board generator. My suspicion is that the diesel does not come out ahead for the majority of users unless they have a very long commute, such as someone living in exurbia.

So where does this leave Europe? In a sad way, I think by trying to be progressive they have taken the wrong path and are now tied to the diesel concept. This may be another case of governments picking the loser. Government is historically inept at choosing the right technological solution and should whenever possible simply set criteria on environmental/energy issues and avoid endorsing particular solutions.


Anonymous said...

Europe is in no way "tied to the diesel concept". Diesel is a lot more popular in large parts of Europe than in the US, but gasoline still makes up a very large portion of the market (about half IIRC).

All European car manufacturers has at least as many gasoline engines as diesel ones.

All European gas stations sell at least two kinds of gasoline.

Engineer-Poet said...

It doesn't look like the governments mandated anything; they just set fuel prices high to cut demand, and the populace tried to optimise their transport systems with technology from 50 years ago.

Anonymous said...

You compare diesel engines, an existing technology, with plug-in hybrids, a non existing technology. Not fair.

Your point that "governments peaking a loser" is obviously absurd.

Europeans have selected diesels. Japanese have selected very small cars. Both have reduce their oil consumption.

In the future you can have plug-in diesels, if plug-in hybrids appear in the market, something which is not a done deal.


Anonymous said...

Is one nice feature of the diesel plug-in hybrid that one can use biodiesel to further reduce our dependance on oil?

Anonymous said...

My diesel car does about 55mp British Gallon. (about 4 litres) Average. Town and Country.

Far better than the prius hybrid that I sometimes drive for work.
Okay, the prius is bigger (not big enough for our opposition leader Cameron, though).

One worry I've always had with the hybrid concept is that the extra weight you had with batteries and transmission / brake rechargers etc. must outweigh some of the benefits.

Anonymous said...

just to add ...

I've never really got the point of having huge cars. It's not like the car I have (citroen C3) is not designed to contain humans.

I fit inside it ! I've had five people in it ...