The Silly BMW 745h

August 30, 2007 | etbe

BMW has released a new prototype hydrogen powered car. The bmwworld.com web page about it claims the cruising range is 190 miles. Added to the 400-mile range of the normal fuel tank, the 745h can go 600 miles between fill-ups. The first issue is that 10 miles are not accounted for (maybe it finishes the 190 miles of hydrogen power at the top of a hill). But more seriously the hydrogen needed to drive for 190 miles would take as much space as petrol needed to drive for 646 miles (hydrogen needs 3.4* the volume to store an equivalent amount of energy). I wonder if that BMW has any space left in the boot/trunk?

Now we have some green bloggers praising BMW. An internal combustion engine that burns hydrogen will not give no emissions other than water vapour, it will produce some nitrogen oxides. The processes to produce hydrogen for fuel all consume unreasonable amounts of energy (more than is required to charge a plug-in hybrid).

BMW demonstrates their level of interest by giving the cars to some celebrities. This gets some PR but no analysis of the performance. They also introduce the prototype based on one of the most expensive models (the 745) which you almost never see on the roads. If they produced a 318 or 520 that ran on hydrogen it would demonstrate some level of interest in getting this working for the mass market.

If BMW wanted to make their cars more environmentally friendly they would start by adopting some of the technology from the Prius. Rumour has it that part of Toyota’s plan to make money from Prius development is in licensing the technology that they patent. A couple of years ago I test drove a BMW 316 and a Prius. The Prius was very quiet and gave a smooth ride (you might call these luxury features), and also gave decent performance (it’s widely regarded that luxury cars should perform well – pity the BMW 316 is a slug).

In Australia the concept of “badge engineering” of cars is well established. When government subsidies favoured large manufacturing runs the Ford Laser and Mazda 323 were essentially the same car. Maybe BMW could adopt this concept and sell a re-badged Prius i-tech with a few extra luxury features as a BMW 4 series (it’s a much better car than the 3 series BMW).

Finally bmwworld.com has an amusing FAQ about hydrogen power, here are some of the mistakes that they make:

They say “About 45 billion kilograms (50 million tons) [of hydrogen] is produced every yearâ€”enough hydrogen to fuel 250 million fuel cell cars“, but only if the average fuel-cell car uses 180Kg of fuel per year. According to Wikipedia hydrogen has slightly more than 3* the energy density per mass than petrol, so 180Kg of fuel would be equivalent to 540L of petrol per year. The Australian Bureau of Statistics states that in 1996 the average annual distance travelled by car (it’s not clear whether this is per car or per person) was 14,600Km while among the countries listed the lowest was Japan with 10,130. When efficiently using hydrogen in a Prius (that is quoted as using 5.4L of petrol per 100Km) you might expect that 540/5.4*100=10,000Km could be travelled on the 180Kg of hydrogen. So the FAQ claim that 250M cars could be powered by the current hydrogen production would only apply if the cars are of Prius efficiency and driven the typical distances of Japanese drivers, or the cars were 46% more efficient than the Prius and driven in the Australian manner. Of course in the US things are even worse with 17,862Km being the average distance driven which means that their hypothetical fuel-cell car would need to be 78% more efficient than a Prius.
They state that “the majority of merchant hydrogen is produced by a process called steam methane reforming“. Why not just run cars on methane then? Anything that burns can be used to fuel cars, and methane has a much higher boiling point than hydrogen so it would be easier to store and transport (see the Wikipedia page on methane).
In regard to hydrogen production they say “about 95% of the total global hydrogen production is captive meaning it is used at the site where it is produced“, that is of course because it’s difficult and expensive to transport hydrogen.
The final amusing fact is that it is noted that most hydrogen comes from fossil-fuels. What problem are they trying to solve here? Hydrogen isn’t going to help the environment if it comes from fossil fuels, it will be more expensive than other fuels. Apart from getting government grant money for BMW it doesn’t seem to do any good.

Hydrogen Powered Cars Will Never Work

August 28, 2007 | etbe

One of the most important issues for a commodity fuel for vehicles is that it be convenient and safe to transport. For quite a while LP Gas has been available as a cheaper car fuel. Even with increasing petrol prices it’s acceptance is well below 100% due to extra expense in storing the fuel (high pressure and more insulation are required), the more expensive technology in the engine to heat the fuel before injecting it into the engine, and the extreme difficulty in creating something as convenient as a Jerry Can for transporting LPG.

LPG is mostly comprised of Propane and Butane. Propane has the lower boiling point of -42.09C. Hydrogen however has a boiling point of -252.87C and therefore is much more difficult to store and transport.

The next problem with hydrogen as a fuel is that it has a very low density. The energy density per volume of liquid hydrogen is 10.1MJ/L while the energy density of petrol/gasoline is 34.6MJ/L. Not only is liquid hydrogen difficult to transport but the vessels you transport it in need to be 3.4 times the size! Having a 3.4x larger fuel tank in a car may not be a huge obstacle, but then there is the issue of trucks used to transport it to fuel stations which are already at maximum size so the truck fleet will need to be 3.4x larger with more people driving them etc.

Once these problems are solved there are a variety of safety issues. Hydrogen burns with an almost invisible flame, sustains a fire when at a concentration of between 4% and 75% of the air and ignites at a low temperature. For an explosion you need a concentration of between 18.3% and 59%. I won’t risk promoting foolish behaviour by describing details, but when younger I have performed experiments with ethanol and witnessed experiments with petrol that demonstrate that they are both far less dangerous. Page 22 of this document by the US Bureau of Transportation and Statistics gives more information about the fire risks posed by hydrogen fuel. Page 35 of the same document describes fuel cells as being 45% efficient and an internal combustion engine for methane gas as being 30% efficient thus giving overall efficiencies of 33% and 29.5% respectively. Of course using an Atkinson Cycle engine will give a significant efficiency benefit over an Otto Cycle engine and outweigh this. Also it should be noted that fuel cells tend to require expensive materials such as Platinum in their manufacture.

Hydrogen is promoted by clean-coal advocates (not that any form of coal power is clean) and the nuclear industry (electrolysis is one way of using a huge amount of electricity). But there are many better options for powering cars that are available right now at minimal cost, these include bio-Diesel, ethanol, and plug-in hybrid or electric vehicles.

LED Headlights in Audi Sports Car

August 23, 2007 | etbe

It’s interesting to see that Audi is releasing a car with LEDs for all lights including the headlights. This is being promoted as an environmental benefit, however a quick google search revealed that my Volkswagen Passat apparently takes 55W headlights (giving a total of 110W of electricity used). Even allowing for some inefficiency in the alternator this would make a very small impact on the fuel use of a engine rated at 140KW. The Audi in question is the R8 (wikipedia link because the Audi web site is badly broken) and has a 300KW engine…

A simple implementation of LED headlights will do some good for plug-in hybrid cars and all-electric vehicles where saving power is more important – when the technology filters down to cheaper vehicles. Also one possible use for the technology is to dim the headlights by turning off some of the LEDs in the bank (according to the LED Wikipedia page it is currently impossible to create a single LED that takes more than 1W of power, so a bank of LEDs would be used). Currently you have a choice of using “parking lights” or “head-lights” when driving, and when driving just before sun-set or at night in the city (where the street lights are bright) you need head-lights to allow other drivers to clearly see you but don’t need them as bright as they have to be when driving at night in the country. So a range of levels of luminosity could be effectively used in headlights to increase efficiency in some situations and increase light levels in others.

According to the Luminous efficiency Wikipedia page current LEDs are up to three times as efficient as quartz halogen incandescent globes and future developments are likely to increase that to six times the efficiency. Combine that with more effective use of headlights to provide the light at the location and level that’s needed and the result could be using at little as 10% of the electricity for headlights on average!

Another thing that I would like to see is the Adaptive Headlights feature of the better BMWs (which I referenced in a previous post about the BM 5 and 7 series) implemented in a cheaper and more reliable manner. The feature in question is that the headlights will turn when driving around a corner to show the road ahead instead of just shining off the edge of the corner. Implementing such a feature with incandescent lights is difficult because they have to be physically turned and moving parts tend to break (which increases maintenance costs and decreases the overall reliability of the vehicle). An obvious alternate design is to have a set of LEDs pointing in different directions and which LEDs get power would determine where the light goes (this would also react faster than physically moving a light). Once LED headlights become common the Adaptive Headlights feature could be implemented in the cheapest cars on the road with minimal extra cost – currently it’s a feature that would be expensive to implement and would increase the sale price of a small car and probably the service price too.

Religion and Cars

July 19, 2007 | etbe

The Catholic Church has recently issued a set of 10 road commandments. Number 9 is “On the road, protect the more vulnerable party” which ties in with an article by Barney Zwartz published in the religious column of The Age about the spiritual issues related to 4WD cars.

Barney makes better points than the Catholic Church starting with “How can Christians living in suburban Melbourne justify getting around in huge four-wheel drives? It’s harder to imagine a more “me-first, up yours” statement to the rest of the world*“. He also links to a report by the Australian Academy of science showing that 4WDs are less safe for their owners (which fits the theory of some Christians that bad actions tend to get punished in this world as well as the next).

Prius vs small non-hybrid car

June 11, 2007 | etbe

In response to my comment and post about the cost of driving to work there was a comment on the blog post I responded to suggesting that a small car is better value for money than a hybrid car.

The claim was made regarding a Nissan Pulsar, but to investigate this I decided to compare the Prius with the Corolla Hatchback, as far as I can tell the Corolla Hatchback is the nearest non-hybrid car to the Prius that Toyota sells (being similar in size, weight, and performance). Comparing cars of different make adds extra variables into the equation. Unfortunately the Toyota web site fails to provide specifications for the Prius and only provides a PDF file with minimal information on the Corolla, but it is enough for some minimal calculations.

A car company run by intelligent people would publish the specs on all their vehicles and provide a search form to compare selected models. The Standard Performance Evaluation Corporation has a good search method that allows easy comparison and ranking of items in their database (here is an example). It would be good if Toyota would permit us to compare models in their car range in a similar manner.

According to the Toyota web site the Prius uses 4.4L/100Km when driving in the city and the manual transmission version of the Corolla Hatchback uses 7.4L/100Km (7.7 for the auto). For the average 16,000Km that an average Prius owner drives that would save 480L of petrol which would save about $700 at current petrol prices.

The Corolla Ascent Hatchback (the cheapest of all Corollas) is $21,000 while the cheapest Prius is $37,400. If you compare the Prius with the cheapest Corolla then it’s a $16,400 price difference. If you save $700 per annum then it won’t cover the interest on a $16,400 loan or match the interest rates earned by a bank term-deposit if the $16,400 was invested. So it seems apparent that at current petrol prices (NB petrol prices are expected to increase) and with average Prius driving patterns a Prius will not be more economical than a cheap Corolla.

Currently the Commonwealth Bank of Australia offers 6.05% interest on term deposits of between $10,000 and $25,000. This means that $700 per annum would be the interest on a term deposit of $11,500. If we compare the Corolla Ultima Sedan at $32,000 with the Prius at $37,400 the difference in price is less than $11,500 – but the cars have incomparable sets of luxury and safety features. The Prius i-tech appears to have a super-set of the luxury and safety features of the Corolla Ultima Sedan but at $46,900 is again going to cost more for the average Prius driver.

The Prius is a very quiet car to drive, there is almost no engine noise (when driving at speeds where the Petrol engine is operating there is usually more noise from other vehicles) and no gear changes (handy if passengers are consuming hot or sticky drinks). It has a good set of safety and luxury features and is also a prestige car (no-one will say “oh wow, you’ve got a Corolla”). If you assign a dollar value to these features then a Prius may be the most economical car that meets your requirements!

Finally, let’s keep in mind the fact that petrol prices are steadily increasing. If you save $700 by driving a Prius this year then you may save $1000 next year. There is also the option of converting a Prius to a plug-in hybrid which will be a useful option if petrol prices hit $10/L! Also the amount of money saved will depend on the use of the car. If you are running a courier or taxi business then a Prius will probably be a lot more economical than a Corolla due to the greater distances travelled and the travel in the slow city traffic that the Prius was designed for.

PS All prices are in Australian dollars and concern products on offer in Australia, I would like to see comments from other people who perform the same calculations for their countries.

Update: If this interests you then you may want to read other posts I filed under the Environment and Cars categories.

hybrid Porsche

March 31, 2007 | etbe

The April 2007 issue of the RACV magazine announces that Porsche is working on a hybrid vehicle. It seems that the award-winning Lexus hybrid vehicle has demonstrated the value of hybrid petrol-electric technology for performance vehicles and that Porsche want to catch up.

The trend seems to be towards all vehicles that are desirable being available in either hybrid or Diesel variants, and we’ll probably see hybrid Diesel vehicles on Australian roads soon.

old drivers

March 13, 2007 | etbe

This morning when walking through a shopping center car park on my way to work a grannie came fairly close to squashing me. She accellerated her Mazda 323 backwards as hard as possible and hit a purple Magna. The back ends of both cars were seriously damaged, and the Mazda (which received the worst damage) was possibly a write-off (it doesn’t take that much damage to make an old car an insurance write-off). The damage was surprising given that there was only about 4 meters between the cars before the crash, the roar of the engine however did indicate that full accelleration was being used. The area between the vehicles was where I had just walked a few seconds earlier…

I phoned the police and waited until they arrived. They might end up forcing her to have a driving test, but it’s most unlikely that she will lose her license. One of my relatives passed such a test more than 10 years after I refused to ever be a passenger in his car.

What is needed is periodic testing of all drivers with the same standards as used for initially getting a drivers license (currently the standards are much lower). I would probably have to practice my parallel parking before such a test (it’s something I hardly ever do) but I expect that I wouldn’t have any difficulty in passing – as would all good drivers.

features of BMW 5 and 7 series

March 7, 2007 | etbe

I was reading the brochure about the BMW 530i Touring (which seems to be the BMW name for what is known as a “Station Wagon” in Australia or an “Estate” in Europe). I looked at the brochure on the “Touring” because I am interested in a Station-Wagon – the Sedan version of the 5 series is almost the same in every way other than size and shape.

Here are some of the interesting features:
Adaptive headlights, they turn in to a corner when the car is cornering (showing where you are about to go instead of showing you the scenery off the road) and the high-beam switches off when an oncoming vehicle is detected.

Head-up display for speed, navigation, and other driver-relevant information.

Park distance control (PDC). Gives audio and visual alerts when you are about to hit something at low speed.

Eight air-bags of which only the necessary ones will inflate in a collision, and the inflation power will be determined by the severity of the collision.

Dynamic stability control (DSC), traction control, corner brake control, and more. Described as “all of the known features of DSC”.

Seat-belt pre-tensioners in the rear and pyro-technic tensioners for front seat belts.

Rain sensor that turns on headlights, and optional head-light washers.

According to it’s brochure the 7 series has bumpers that regenerate their original shape in collisions of speeds up to 6Km/h and a tire defect indicator. Apart from that there doesn’t appear to be much benefit over the 5 series apart from more luxury features.

To get the PDF files from BMW Australia (without following my links which BMW will probably break soon) you have to fill in a form with “contact details”. To enter that form you need a browser that works with their javascript (which means not Konqueror) so that you can enter your postcode and be prompted with a list of suburbs that match the post-code. The second-last page of that process allows you to download PDF files and it seems to indicate that your data will not be stored if you don’t continue past the stage where you download the PDF files. It would be good if BMW could get smart and make their PDF files as easy to download as Mercedes does.

In terms of safety features it seems that the 7 series offers little over the 5 series. By comparing the brochures it seems to me that the Mercedes S series (as described in my previous blog post) has many more safety features than any BMW. Assuming that the BMW documents are accurate they don’t seem to compare well with the Mercedes S class. From a quick search on drive.com.au (the best web site for buying used cars in Australia) it seems that the Mercedes keeps it’s value better than the BMW – other people apparently share my opinion of the relative merits of the cars.

In future posts I’ll summarise the features of some other cars that I consider interesting.

spare tires

March 2, 2007 | etbe

The following letter was published in the RACV Magazine. The Royal Automobile Club of Victoria is a driver advocacy organization that provides roadside assistance and insurance. The fact that they published my letter means that the idea can’t be totally wacky so I’ll blog it. ;)

There have been many mentions recently in RoyalAuto about space-saver spare tires. Some manufacturers claim that they are to save weight which seems to be a benefit for the driver.

I wonder if most drivers really need a spare tire. For my own driving I only have a flat tire about every second year and I almost never drive outside the metropolitan area. Given how rarely I call for road-side assistance I think I would be better off without a spare tire and with the option of having the RACV deliver one for me if I needed it.

I expect that the time taken to deliver a spare tire would be greater than that required for a regular road-side assistance call, and that it might count for more than a regular assistance call, but given that the cheapest roadside assistance package has 8 calls a year I expect that most years I would still use less than half my quota of calls.

Not having a spare tire would save some weight (and therefore fuel) and would provide a little extra cargo space.

Also it seems to me that small cars are unlikely to ever be driven outside the area that is serviced by the RACV and similar organizations. For a small car the lack of a spare tire in the car design would offer a significant improvement to cargo capacity. If the RACV and other organizations endorsed and supported cars without spare tires then the car manufacturers could design small vehicles with more cargo capacity and less fuel use.

Mercedes S class and car safety

March 1, 2007 | etbe

The S Class Mercedes has some really interesting safety features, see this 6.8M PDF file for details. If you are interested in technology then you want to read it just to learn about all the cool features – it’s got more technology than a Prius!

The S class includes the following features to protect the occupants in the event of a crash:

Tire pressure monitors
Electronic Stability Program (ESP) to selectively apply the brakes to reduce the risk of skidding
Active suspension
Pre-Safe is a management feature that recognises a potential collision by the steering and braking patterns of the driver and prepares the vehicle for an impact. This can involve adjusting the sun-roof, the seat-belts, and the driver’s seat position to prepare for impact, closing the side windows, and inflating air chambers in the sides of the seats.
Head rests that automatically adjust in the event of a rear impact

The following features reduce the risk and/or severity of a crash:

Night view (infra-red) display gives a display of potential obstacles ahead without dazzling oncoming traffic
Distronic Plus is a brake assistance package that includes automatic braking based on radar surveillance of the traffic ahead
4Matic is a new feature that combines AWD with the traction-control feature that has become common on all expensive cars. This means that when any combination of wheels starts to spin on water or ice the brakes will be applied to them so that the wheels that have good grip can still be used for acceleration.

After a crash there are more safety features that can help you:

The engine can be automatically turned off after an impact and if necessary the fuel supply can also be cut
The hazard lights and emergency interior lights can be automatically activated
The side windows can be partially lowered, if your car lands in water deep enough to submerge it then you MUST open the windows as soon as possible – otherwise water pressure may make it impossible to open the doors – people forget this so it’s good to have an automatic feature
Automatic door unlocking after an impact (good for rescuing unconscious occupants)
Cutting points marked on the windscreen and rear window for the benefit of emergency workers who need to cut the roof off with the “jaws of life”

These features are documented as being available in the latest S Class, I haven’t investigated what is available in the cheaper models and I’m not even sure where to find information on the safety features available in older models (a second-hand E class is more in my price range). But if I won the lottery a S class Merc would be high on my list of things to buy!

If you know of other cars that have a similar set of safety features to the S class and cost less then please let me know.

I will probably write a blog post about the BMW safety features in the near future. I couldn’t do so immediately because the BMW web site sucks. They have a form for me to fill in contact details so that they can post me a brochure (I want to read it NOW ONLINE). The form doesn’t like my postcode and refuses to proceed (it should at least have an option for them to contact me via email or phone).

etbe – Russell Coker

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