Wednesday, September 06, 2006

more on clean energy

One new technology for saving fuel in cars is the 6 stroke engine. This is an engine that has two power strokes for every intake of fuel. The first power stroke is from the fuel burning, the second is from water being injected into the cylinder and boiling rapidly using steam for power. A significant amount of the weight of a car or truck engine is the cooling system. With water being injected into the cylinder after every burn the engine will require no other cooling, this can mean a weight reduction of up to 500KG for a truck engine! It is claimed that this technique can "improve a typical engine’s fuel consumption by 40 percent". Note that this technique could be combined with the technology in a Prius for even greater efficiency.

Simon Richter wrote an interesting response to my blog about clean energy. I'm guessing that the part of Germany he's from is similar in some ways to Amsterdam (where I used to live).

In Amsterdam tiny cars are used a lot more than they have been in most places. There is the Smart Car but there is also a tiny car that can only seat one person (I'll update this entry with a link if someone provides me one). The tiny car appears to weigh ~200Kg, has a maximum speed of 30Km/h, and is narrow enough to fit in bike lanes. Such cars will take little petrol and can be used for shopping. The short-distance car idea is being used by many people already in northern Europe.

Simon suggests having a standard baggage container that fits in all cars. I don't think that would work as there are many different design factors (parking space, cargo capacity, and aerodynamics) which force designers to choose different shapes.

I think that a better idea would be a standard baggage trailer that could be towed by any small car. It should not be difficult to design a trailer that can be safely towed at 30KM/h behind a tiny car. The supermarkets could rent such trailers to shoppers for a nominal fee. Then most shopping trips could use the cargo capacity of the tiny car, but when buying supplies for a party you could rent a trailer from the supermarket.

Another option is having shops deliver goods to you. I have observed an increasing number of people doing this at my local supermarket. Of course you would still need to take ice-cream home yourself and maybe milk and meat too.

Electric scooters are also a good option for travel. Unfortunately in Australia there are few good options for securing them at the moment. As an electric scooter is light enough to be carried it needs to be chained to something secure. In the Netherlands this wouldn't be a problem as the bicycle infrastructure includes plenty of bike racks to which you can chain your bike, scooter, etc. Of course the Netherlands is entirely flat so there's no need for an electric scooter. Melbourne has a lot more hills and most people aren't fit enough to ride a bike so scooters are needed to replace cars.

Regarding depersonalised cars. That would require a significant social change as currently cars are extremely personalised. One thing that I had been thinking about is the idea of sharing cars with neighbors. For example if you have an apartment building and there are a few people you trust then you could share a tiny car for going shopping. Sharing a car used for driving to work or for entertainment would not work well as the car would spend most of it's time in use (or at least parked somewhere away from home). Sharing a car that's used for small journeys would be much easier as such a vehicle would spend most of it's time at home.

In Australia most families have two cars. One is used a lot (spends maybe 70 hours a week away from home) and the other is used much less (maybe 10 hours a week). Instead of owning two cars it would be possible for families to own one car and share another.

Regarding the Pebble Bed Reactor, could the people who advocate it please read the Wikipedia article. The limiting factor is not thermal expansion (solids do not expand nearly enough) but the Doppler effect (fast neutrons are not as effective at triggering fission). But in spite of that issue, let's not consider an untested new reactor design to be the savior of nuclear energy. I think that most people who read my blog have a science or engineering background and know from experience that new technologies often don't work too well in the first version. When a new CPU has a bug it's usually not a big deal. When a new OS or application has many bugs it's often expected (expecially when the OS or application comes from a monopolist). But if a new design for a nuclear reactor turns out to have a bug then it will be a more serious issue.

4 comments:

Giacomo said...

Working on energy economics, I can tell you that diffusion on such new technologies is very very slow (20-30 years to have a noticeable share).

But an other consideration. From physics, movement doesn't require energy (if you return to the initial position), so one improvement will be to improve efficiency of engines. But on the other side this would slow down diffusion of new (alternate to petrol) technologies because.

Tim D said...

movement doesn't require energy
yeah, in vacuum without gravity. (Un)fortunately we don't live in those circumstances...

Anonymous said...

Regarding the tiny cars, I think you're referring to something like the Aixam (http://en.wikipedia.org/wiki/Aixam) mopedcars.

They usually have a 50cc engine which means they can be driven in many parts of Europe without a driver's license.

etbe said...

The Aixam looks like the tiny cars I saw in .nl.

Diffusion of new technologies doesn't need to take 20+ years. In Australia I believe that the average age of cars that are in use is just over 10 years, and this is older than the cars in use in most first-world countries.

So in about 10 years at least half the cars in use in Australia should take up a new technology if there is a compelling need for it without old cars being re-fitted.

The 6 stroke engine when developed as a product will be a simple replacement for current Diesel engines that produces more power while using less fuel. I expect it to take over in a small amount of time.

Of course we don't have anywhere near 20 years before the oil reserves run low so the future may still be unpleasant.