Storage of energy seems to be taking a new turn with the use of compressed air. Cars like the one below are starting to appear.

< Go on click the pic.

It looks like the Trabbi or Trabant (as it was officially known) is set for a comeback. An entrepenur has bought the rights to the name and is planning on producing a small electric town car.

The new Trabbi takes some design cues from the original, although it will use modern materials. The old car was one of the biggest polluters (the 2-smoker, sorry 2-stroke, engine was a major cause of smog pollution in West Germany - caused by the East Germans going to work on cold mornings!), but the new car will be one of the greenest cars on the market.

According to the news from the IAA in Frankfurt yesterday, the company have a concept car and are looking for investors. It will, allegedly, be aiming to go head-to-head with the likes of the Smart and the Fiat 500...

The advantage if the compressed air car is that it takes just two minutes to give it a charge that will take it another 100km. It the tank size can be doubled this could be a real winner.

CC

Note the weight of the vehicle is just 300Kg. It will be interesting to see if it passes the safety regulations which have generally forced up the weight of cars.

Weight is one big reason that modern petrol cars are not more efficient. Even the Smart weighs over 700Kg, and that does 83mpg. It will be interesting to see how optimistic their efficiency figures are. Note, their figure of roughly 150mpg for dual fuel does not include the energy required to fill the air tank. Also note, the designs I've seen thus far are unable to run on fuel alone so when your air is out, you're stuck.

Well to be honest this is not a lot of an issue. They will charge up just like an electric car from a power socket, it is just that the socket powers a small compressor instead of a battery.

Unlike an electric car they don't need the weight of a massive battery and at a suitably equipped "petrol" station they are charged in 2 minutes. Thus you could see the return of the independant service station that has been pretty much killed off in these parts by the supermarket giants.


CC

They do need the weight of a massive tank. The energy density is actually quite poor, which is why it doesn't go further.

http://en.wikipedia.org/wiki/Compressed ... gy_storage




A "small" compressor would take a very long time indeed. You'd need a massive one to do it in 2 minutes.

A tank of air containing the energy equivalent of 40litres of diesel would require 414KWhrs of energy to fill, assuming 100% efficiency. A "small" compressor such as you use in the garage might be 200Watts. That would take at nearly 3 months!

Point taken, but even so. We are not talking of 40 Litres of diesel at the moment. at a range of just 100km we are probable looking at about 5 equivalent litres. A small compressor could be much larger than 200 Watts. So an overnight charge is not out of the question. Certainly enough to get you to the service station. This is not so dissimilar to an electric vehicle.

If you're charging it from electric, then there's no difference energy-wise.

A 12 hour charge at 10Amps from a 240V (2400W - a very big domestic compressor, and the most you'd want to run off a 13Amp socket) socket gives you the equivalent energy of 2.78 liters of diesel. There's no reason to believe that a compressed air engine is more efficient than a diesel engine (in fact, quite the opposite) so that's a range of about 25 miles for a normal family car, or maybe 80 miles for a super light-weight plastic thing like your picture.

The only real advantage a compressed air car has, is that it's very basic. It can be made cheaply and does not require exotic chemicals. It can also be charged by windmills or water wheels in a wonderfully low-tech way. A solar furnace could also power a compressor using low-tech. In fact, such things were being done over 100 years ago. However, it will never go far. It's basically a clockwork Noddy car with a fancy pneumatic spring.

A battery car is more efficient, but you need exotic and toxic chemicals to make them. If every car in the world ran on our most modern efficient batteries, we'd have to scour the entire solar system for the raw materials to make them. Solar panels are even worse!

Since most electricity today is made from fossil fuels, it's actually more environmentally sound to run a small economical diesel. You're converting the chemical energy of the fossil directly into mechanical energy. An electrically charged compressed air car requires conversion from coal to electric, transmission of that electric through the grid, conversion into kinetic energy by a motor and then into potential energy by a compressor, and then back into kinetic by the engine. That's a lot of conversion losses.

Also, please note well - the faster you charge the compressed air, and the faster you drive, the less efficient the conversion. Compressed air storage is only efficient if it's isothermal. If you compress air quickly, it get's hot. As it cools down, the pressure drops - you've wasted energy compressing at a higher pressure which is then lost. Similarly, if you use the air too quickly it gets cold and the the pressure drops. Using water cooling / heating and big radiators, these losses can be reduced. However; that's not very home-friendly or small-car friendly.

Personally, I think H2 represents the most efficient solution. There are still serious technical problems to overcome with this technology though.

I strongly suspect that the people investing in these cars never studied thermodynamics at university.

The VW Lupo 3L will use 3L of diesel over 100KM...

As you say, the main advantage is that the energy from disparate sources can be stored. In a world that is becoming reliant on renewable energy this may be the killer feature that will give this technology some future.

+1

the difference between low consumption fossil fuel vehicles and compressed air powered vehicles is/are
fossil fuels have to be extracted from the ground, seabed and other places then transported to a refinery and refined from there transported to a storage facility then transported to a fuelling station which will still require underground storage for the fuel and then electric pumps to enable the fuel to fill the vehicles and this happens worldwide across the globe

with compressed air vehicles electric pumps are required for fuelling the vehicles but apart from that the transportation, extraction and storage of compressed air is not required (except on the vehicle) also the emissions from a compressed air vehicle are zero …

As I said earlier, most electricity is produced from fossil fuels. Certainly in this country.

Admittedly a power station is usually more efficient than a car engine, and the coal or gas is delivered more efficiently by rail freight or pipeline. However, the losses in distributing the electricity are very high. Additionally, if you want to charge the tank in 2 minutes then the conversion from electricity into compressed air is also quite inefficient. The air engines are also not that efficient. The combined losses probably more than equate to the distribution of fuel by tanker to be burned in a normal car.

The zero emission of the car doesn't matter on a global scale. The pollution is simply moved up-wind to the power plant.

I'm not denying the validity of the technology, but the big issue is the primary fuel source. How it's stored and transported is a secondary issue.

that is why we need to look at how power generation is fuelled

building power stations that use house hold waste and sewage
both of these produce methane which is used/stored to dry the waste/sewage then this is used/burnt to produce heat which will fuel the power station

this type of power station is based on the Swedish model which they have used successfully for many years

this also reduces the waste going to land fill and helps reduce raw sewage being pumped into the north sea and this type of fuel is by and large not only renewable but nearly inexhaustible as well …

But I have a feeling that the total energy in people's waste is less than that required to power thier country by a large margin. Plus burning waste? what about the chemicals created and the measures that must be taken to capture these.