martes, 23 de mayo de 2017

Will fossil fuels run out

Greg Foot, from BBC's Earth Lab, looks into the dirty world of fossil fuels. Will we run out of fossil fuels and what cost will we likely pay for their use?

We've all heard that fossil fuels won't last forever but why. And if they are set to run out, how much is left and when will that happen. To dig to the bottom of this one, we first need a quick refresher on how the fossil fuels are created, and sadly, no, they're not mostly dead dinosaurs.
You see, the vast majority of our fossil fuels come from the remains of plants and animals. They lived around 300 to 400 million years ago. We don't see the first dinosaurs until around about 230 million years ago, so when these plants and animals died, that very, very long time ago, they were covered in layers of earth or silt, and because of the combined actions of three things: one, the compression from the weight of all that stuff; two, the microorganisms in there decomposing the contents; and three, the heat underground that transforms them into potential fuels.
Coal is the remnant of ancient plants while oil and natural gas mostly come from marine creatures. The natural gas being made in deeper hotter regions, where the oil gets a little bit more cooked.
Now we dig or drill this stuff out of the ground, and because it has been accumulating for a long time, initially there was a lot, but because it takes so long to make, we're using it much, much faster than it can possibly be replaced. This means that there is effectively a fixed amount of fuel on earth and we're using it up.
So, yes, fossil fuels are going to run out but what is left and when will that happen. Well, we can fairly easily tally up what's known as our proven resources, the supplies that we know the locations of and we think we have a good chance of getting to.
In their statistical review of world energy, BP estimated that the world had just over 1,700 billion proven barrels of oil in 2014. That's enough to make 52 and a half years of global production. They also estimated just over 187 trillion cubic meters of natural gas. That's enough for 54 years. Then 891,531 million tons of coal, enough for a whopping 110 years of global production.
But there's also the stuff that we know about can't reach but think we might be able to get to some day. Hard figures on that are understandably tougher to come by, but oil and gas consulting firm Rystad Energy estimates total probable global oil reserves at 2,092 billion barrels, which is enough for about 70 years if our use doesn't go up.
The total fuel resource, the amount of fossil fuels that could be out there that we know nothing about, could, of course, be even higher, but around four years ago an idea came out that there actually is plenty of oil left, just that we haven't got around to getting it out of the ground yet. This means the numbers for the potential oil out there could, in fact, be way higher.
We've already seen humanity use new technologies to access new fuels that we couldn't get to before. Things like new techniques to extract oil where it's all mixed up in fine grained sedimentary rocks like shale or using high-pressure fracking to extract more oil and gas from the ground. One thing stopping us using these new technologies to extract fuels is that the rising energy cost of extracting it could be just as damaging as the oil running out.
Despite the cost of oil, the amount being extracted has actually remained constant, about 75 million barrels per day since 2005, and this means a plateau has been reached where supply cannot match demand. It's also worth pointing out that fracking is far from ideal. It's been claimed that it has been linked to earthquakes and toxic tap water.
We've already seen how the economics of getting to the fuel can outweigh humanity's demand for it. In 2016 around 460,000 barrels a day of high cost production like fracking was shut down in the US due to the cost. But that just means surely it’s there for later, when the economics are right, right?
Well, maybe we need to leave it there. The planet is warming due to the burning of those fossil fuels. Burning fossil fuels releases carbon dioxide into the atmosphere, trap heat and it causes a greenhouse effect. It's been estimated that we cannot burn more than about a third of those proven resources if we have any hope at all of meeting plans to keep the temperature rise at 2 degrees centigrade or less. Although it may feel that we don't seem to be in a particular hurry to look for alternatives, energy transitions have always taken a long time. It took over 50 years for coal to replace wood as the world's leading source of energy, and another 50 years for oil to overtake coal.
So here's a promising thought. In the end, with so many options for renewable sources of sustainable power being developed, we might actually never have to answer this question of what happens when the oil is finally all gone.
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