It's not safe to leave fossil fuels in the ground

Better to extract the fossil fuels, capture the carbon, and store that instead, says Professor Jon Gibbins.

I had the chance to speak to the University of Edinburgh's Professor of Power Plant Engineering and Carbon Capture, Jon Gibbins, last week, for a piece in next week's magazine. During the course of our interview, he focused heavily on an argument for using carbon capture and storage (CCS) technology which I hadn't heard before.

He said:

We've never really been short of fossil fuels. We thought we were, but really it's obvious, and maybe this gas business makes it painfully obvious that we're not short of fossil fuels. We are short of space in the atmosphere. And nobody knows what the climate response would be. There's a wide range of predictions, but there's enough fossil fuel to take you anywhere within that range of predictions that you want to go. And you really don't want to be sitting there having that experiment.

So as I say, we've got two choices, I think. We've got the choice of saying that renewables are so wonderful and cheap – or nuclear or anything else, or fusion – will be so cheap that we don't use the fossil fuels. They're just too easy to use. So we either sit there and keep on putting fossil carbon in the atmosphere, and see what happens, and then probably what happens is you realise it's not a good idea and you have to do things in a panic.

Now, maybe a few people would be doomed – or maybe more than a few – in that situation. Or, we say look, how much money are we spending on renewables? Even in our straitened times, quite a lot. How much would it cost to spend an equivalent amount of money on CCS? Well it wouldn't cost us a thing, actually. Because you're just shifting money from one low-carbon source to another. That's all. It's not energy costing money, it's just not spending all of it in one direction.

In other words, we ought to focus on CCS at least as much as – if not more than – renewables, not because they are better per se, but because they are better at constraining future action. Only if we burn fossil fuels with CCS can we be sure that the carbon they contain won't enter the atmosphere some other way.

If we build enough renewable energy capacity to supply our entire system, there are still fossil fuels ready to burn. The people who built the renewable capacity may not want to burn them – but what about the next government? Or the next generation?

The history of humanity is a history of ever increasing energy demand. As a result, we ought to assume that any un-used energy source won't stay that way for long. If we do assume that, then maybe the best thing to do isn't try to completely end our usage of fossil fuels, but to ensure that if we use fossil fuels, we only ever use them in a safe way (that is, with CCS technology).

There are two potential advantages to this: firstly, it gives us more time to prepare an energy system totally unreliant on fossil fuels, and secondly, it means that when we do switch to a renewable economy, there's no chance of freaking out and switching back.

The full interview with Professor Gibbins will be in the 4 November edition of the New Statesman.

The Sleipner gas platform, some 250 kms off Norway's coast in the North Sea. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.