The three fossil fuels, oil, natural gas and coal, were formed millions of years ago when dead plants and animals were trapped under deposits and became buried underneath land. Compression over time fossilised the remains, creating carbon-rich fuel sources. All fossil fuels are finite – the deposits that exist cannot be replenished when they are used. With further use, all are in danger of running out.
The question of when each one will actually run out, however, is a tricky one. There are many different opinions and calculations and none really agree on the exact timing. Many different factors need to be considered including how much of each deposit is left in the Earth, how fast we are using each fossil fuel at the moment, and how this is likely to change in the future. If we start switching to alternative fuel sources that are renewable rather than non-renewable, the reserves that we have will obvious last longer.
Some experts believe that current natural gas deposits fill around 6000 trillion cubic feet that could, with the current level of usage, last for about 50 years. This assumes that there are still no new sources of natural gas still to find. The difficulties in transporting natural gas (because of its explosive nature) mean that it tends to be used fairly locally to its source. The gas fields of the North Sea have been a rich resource for the UK but other countries in Europe obtain their supplies through long underground pipelines from Russia, which are hundreds of miles long. As the pipeline runs through several countries, the continuity of the supply can be compromised by political disputes.
The world could still have oil reserves that would fill 800 million barrels, with about half of that in the Middle East. Because we use oil to manufacture many materials, including plastics, we use oil at a much faster rate than either natural gas or coal. People have been expecting oil to run out within the next few years since at least the 1990s. No doubt it is currently getting scarcer, and as a result more expensive, but current estimates suggest we will not actually run out until between 2025 and 2070.
Coal is the fossil fuel with the greatest reserves and coal reserves are spread all over the Earth. It is very labour intensive to recover as it lies deep below the surface, usually around 300 feet below land level and deposits can only be a few centimetres thick.
Most of the coal deposits have not been tapped yet and the decline of the coal mining industry in the UK means that the coal seams still there are currently lying undisturbed. If we carry on using coal at the same rate as we do today, we could have enough coal to last well over a thousand years. However, as other fossil fuels run out, particularly oil, the use of coal may increase, reducing that time span considerably.
Shale gas and oil are natural sources of energy trapped in rocks (formed millions of years ago from decaying plants trapped in clay etc) and are extracted by a controversial process called hydraulic fracturing (or fracking). Why controversial? To extract the gas a well is drilled vertically and then horizontally along the lie of the rock. A high pressure mix of water and sand is pumped through, fracturing the rocks and releasing the gas into the cracks that are opened up. It is then brought back to the surface to be captured/piped. A similar process is used to extract shale oil. It’s believed this process affects wildlife, pollutes water and can lead to earth tremors, but there are many studies that show it as a safe energy extraction method (it’s already widely done in the US and some other countries) so there is also a strong argument in its favour as a solution to our energy problems here in the UK.
How much recoverable shale gas/oil is there? This seems to be relatively unknown as estimates are constantly changing, here in the UK it’s thought that there are more than 5 trillion cubic metres in the North West of England alone.
Governments around the world realise that we are approaching the ultimate crisis in terms of oil supply and there is a global movement to reduce the amount of fossil fuels that we use. If we can find alternative energy sources, it would not matter if oil, gas or coal ran out or not. The issue of global warming and climate change is also an important reason why fossil fuels have really fallen out of favour. Carbon dioxide emissions from burning and using fossil fuels could be contributing to global warming and causing disruption to the weather patterns all over the world.
Alternatives to Fossil Fuels
There are plenty of alternative energy sources that are renewable or in constant supply such as wind power and solar power. Most people are now realising that a massive switch to these types of power source will be required in the future but, it seems to be human nature that the urgency to make this happen will not be great enough until the prospect of running out of fossil fuels is much closer.