Basically we burn wayyyyy too much fossil fuel – 90% of crude oil is used as a fuel for example. This has a number of problems (sorry this page is pretty gloomy!):
Fossil Fuels Release Gases and Particles When Burnt
Power stations burn loads of fossil fuels to make electricity. Cars also burn loads of petrol.
Most fuels contain carbon and hydrogen and during burning these are oxidised.
hydrogen + carbon → carbon dioxide + water vapour (+ heat)
This means carbon dioxide and water vapour are being released into the atmosphere.
Sulphur dioxide can also be produced if the fuel contains sulphur impurities. Oxides of nitrogen are also formed if fuel burns at a high temperature.
There’s also a problem with the amount of oxygen around when a fuel is burning. If there is enough you get complete combustion. If there is not enough you get partial combustion. When this happens particulates (i.e. solid particles) or soot (i.e. carbon) and unburnt fuel are released! Carbon monoxide (which is deadly!) is also released.
Sulphur dioxide is a big cause of acid rain! When it mixes with clouds it forms dilute sulfuric acid….this then falls and causes all sorts of damage!
The same thing happens with oxides of nitrogen – this time forming dilute nitric acid!
Acid rain causes lakes to become acidic and many plants die. It also damages limestone buildings and stone statues. Some have also said it hurts human health.
These environmental impacts have to be balanced against the benefits we get from the electricity and that travel that some fuels go towards producing.
Governments have made agreements to reduce emissions of air pollutants.
So Why Don’t They Just Remove The Sulphur Impurities
Basically because it costs more.
Also to do so requires energy….which usually comes from burning more fuel!
Low sulphur versions of petrol and diesel are starting to come onto the market though and power stations have Acid Gas Scrubbers to take these gasses out before they hit the atmosphere.
We could also just use nicer forms of energy…
Carbon dioxide in our atmosphere is increasing and this is thought to be contributing to global warming. Global warming is a type of climate change…it causes other types of climate change like melting of the ice caps and changing rainfall.
Scientists have recently started measuring how much light reaches the earth…and comparing it to records for half a century ago. Amazingly they have found sunlight has reduced 25% compared to 50 years ago! This has been called global dimming.
They think it is down to soot and ash produced when fossil fuels are burnt reflecting back the sunlight. Another theory is that soot and ash help to produce more clouds and these reflect the sunlight back into space.
NOTE: Many scientists don’t believe there is actually any dimming and blame it on faulty light level readings.
These are still to hit the mainstream and they have pros and cons.
This can be produced from plant material and as such is a “biofuel”. It’s made by fermenting plants and has been used to power cars in some places. Often it is mixed with petrol to make a hybrid fuel.
PROS – The carbon dioxide it produces when burnt is cancelled out by the earlier growth of the plant i.e. it is ‘carbon neutral’. The only other thing produced is water!
CONS – Engines need to be converted to use it. It isn’t widely available. Farmers might switch to producing this rather than food if demand increases, which will increase food prices.
Another biofuel. It’s produced from vegetable oils like rapeseed oil and soybean oil. It can be mixed with diesel to run a diesel engine.
PROS – It is carbon neutral too. Engines do not need to be converted. It produces less sulfur and ‘particulates’ than just diesel or petrol alone.
CONS – We can’t make enough to replace diesel totally. It’s expensive. Like ethanol it could up food prices.
- Hydrogen Gas
You get this from the electrolysis of water and it can be used to power vehicles.
Pros – The only by-product is water so it is super clean!
Cons – You need electricity to conduct the electrolysis (though you could produce this from a renewable source like solar). You need an expensive engine. Hydrogen isn’t widely available. Hydrogen is hard to store.