I drove back from uni the other day, and on the way I thought about different types of transportation. On this trip, for example, I only took back a few bags, but on the trip up, I had a carful of stuff. I also saw many different sizes and shapes of 'cars'- vans, lorries, little hatchbacks (like mine), family saloons, campervans and big 4x4s. These varied vehicle designs are made to do different things: a small hatchback is not designed to carry the same volume of stuff as a big 4x4, for example, but it is more fuel-efficient (as the 4x4 engine is bigger to cart around a bigger car). Most cars built nowadays are multipurpose.
In this post I'm going to talk about the different needs of the varied vehicles on the road today. These needs include range, top speed, and acceleration. Obviously, a city runabout doesn't need to have the range or top speed of a long range cruiser.
The most important part of the 'car' is the engine: what makes it go. Pretty much all engines out there on the roads are internal combustion engines, which use petrol or diesel to explode a gaseous mixture of the oil fumes and air, pushing down a piston, turning a crankshank, which turns the wheels. I'm not going to go into detail into how these car engines work, but see here if you are interested. This is all very well, and has been working around the world for over 100 years. However, these engines are very inefficient, by modern standards: 20-30% (from wikipedia). Compare this to a electric engine, for example, which has an efficiency of around 90% from batteries (source- this excellent page by the Tesla Motors Company, which has a lot of other information about efficiency as well) or about 60% from a hydrogen fuel cell (source) [*]. Add this to the fact that the fossil fuels used in the internal combustion engine are both producing greenhouse gases (CO2) and are running out, and you can see why it's worth considering other options for our transport.
[*]- Note that both battery-powered and fuel cell-powered cars use electric motors, but different methods to store the electricity (in the battery or hydrogen).
So what different types of vehicle are there? What designs do we need to use, and which type of power would be best for each?
