What will power our cars in the future?

Hydrogen

Hydrogen is a very simple atom consisting of one proton, one neutron and one electron. It's the first element on the periodic table and is found as the molecule H₂. When mixed with oxygen, hydrogen will burn and produce water vapour.

The difference between oil and H₂ is that oil is an energy source and H₂ is an energy carrier. Oil occurs naturally and can be seen as a giant battery. We tap it out of the ground, refine it and put it in our cars. The oil will eventually run out.

Hydrogen doesn't occur in gaseous form in sufficient quantities for us to just take it out of the air. We have to make the hydrogen. To make the hydrogen you need to use energy. Once you have the hydrogen, you can put it in your car. There are a number of unique problems that still need to be solved before we can fill up with hydrogen. We need a good way to make the stuff. One of the more popular methods involve stripping the hydrogen from natural gas. This however releases CO₂ and is very inefficient. Right now it's more efficient to store electricity in a battery and use the battery to drive a car than to make hydrogen using electrolysis and put the hydrogen in a car.

Hydrogen can be used in a car in two ways. You can either burn it like in a normal engine or you can use it in a fuel cell to make electricity. Honda makes the FCX Clarity which uses hydrogen in fuel cell, while BMW has demonstrated 7 series running on hydrogen in a normal engine.

Some problems still exist with hydrogen besides manufacturing it. Hydrogen is difficult to store. To store enough hydrogen in a car to get any decent range you need to both cool it and compress it. The extreme pressures that hydrogen is stored at makes designing a strong enough tank a challenge. These challenges has been largely overcome. See vehicles from Mercedes Benz and BMW.

Bio-Diesel and Ethanol

Bio-Diesel is widely used in Europe. It is made from plant oil and no modification to existing vehicles are needed. Ethanol is also popular and is often mixed with normal petrol to produce a fuel call E10. This is 10% Ethanol and 90% Petrol. All modern cars can use Ethanol blended petrol without problems. In most countries petrol is blended with Ethanol in varying ratios. In Brazil, however, you can fill up with pure Ethanol, but this requires modifications to the engine. Following the oil crisis of the 1970s, Brazils' government started a program to produce vast quantities of Ethanol from sugar cane. This program has proved to be very effective. Brazil has managed to wean themselves off oil. The flipside of the coin is that they need a massive amount of land to grow all this sugar cane. The process of clearing land for growing fuel is even more destructive than the effects of climate change. Do not support bio fuels unless:

• The source crop is inedible. There are plants that produce oily seeds that are poisonous.

• The source material is grown on land that cannot be used to grow a food crop like wheat or corn. Hardy grasses can grow where wheat, corn and sugar cane would fail.

• No land was cleared to grow the source crop. Chopping down a tree to grow a fuel crop is stupid. You're removing a natural device that can actually absorb and store CO₂.

Food is supposed to go into stomachs, not fuel tanks.

Electricity

The idea with electricity is quite simple. Place an electric motor in a vehicle instead of an internal combustion engine. Add batteries to the vehicle to produce electricity and off you go. So far electric-only cars have proved impractical for a number of reasons:

• Insufficient range

• Poor performance

• Long recharge times

• Big, heavy and expensive batteries

Many of the problems listed above are being solved rapidly. Modern batteries have far greater capacity per unit mass now than even 10 years ago and new developments in battery technology are now happening at a rapid pace. A new alternative to batteries are ultracapacitors.

Plug-in Hybrids

Hybrid vehicles currently on the market like the Toyota Prius and Honda Civic, derive all their power from petrol. This means that they never need to be plugged in to recharge. An additional fuel saving can be realised however if we recharge the hybrids' onboard batteries from the mains instead of the petrol engine.

This is the idea behind the plug-in hybrid or PHEV (Plug-in Hybrid Electric Vehicle). A PHEV will work just like an existing hybrid, except that it has a bigger battery, more powerful electric motor and is recharged from a mains socket. You don't have to recharge the PHEV though. You can if you want to, but you don't HAVE to. If you do recharge from the mains, you'll see improved fuel economy. If the electricity used to recharge the PHEV is derived from nuclear, wind or solar power, you'll not be emitting any more CO₂ into the atmosphere.

Auto makers realise that most people only travel about 50km per day. This means a PHEV can run in all-electric mode for that 50km. A 100km electric range would be enough. If you want to go away for a holiday though, your car will use normal petrol to give you a range of 800km, but with all the benefits of a hybrid. You therefore have the best of both worlds, pure electric and hybrid.

CalCars is a non profit organization turning standard Toyota Prius into PHEVs by addding extra batteries that allow the hybrid car to be driven for many kilometres on battery power alone and recharged by plugging into a mains outlet. The CalCars "Prius+" can still can be operated like a normal Prius whenever needed.

For the moment hybrids have the edge. They have proved VERY popular with the buying public. This will encourage auto makers to make improvements that will further reduce emissions.

Visit the ENERGY section at Physorg.com