How the UK meets record gas demand
The UK's best kept energy secret lies some 20 miles off the East Yorkshire coast.
From the air there is little to see except the dark brooding waters of the North Sea.
But look closer and you will notice two gas platforms, standing defiantly above the waves.
They are the only sign of a vast reservoir, a couple of miles below, which for more than quarter of a century has been the country's most important energy storage facility.
The Rough gas field was discovered in the 1960s. By the 1970s it was helping heat homes and power factories.
In the 1980s it was converted to enable gas to be not only taken out, but also to be pumped back in. A gas storage facility was born.
The main platform is a labyrinth of pumps, pipes and compressors. In places it is showing its age, the result of decades of continuous use, exposed to the elements.
But there has been sizeable investment too, allowing Rough to continue to play its key role, explains Simon Wills of Centrica Storage during a visit to the platform.
During the summer months, when demand and prices tend to be low, large volumes of gas are stored in the Rough field.
But now, in the midst of winter, when demand is rising and prices tend to be higher, the reservoir turns into a major supplier for homes and factories across the land.
"Rough kicks in on those very high demand days when all other sources of gas are flowing, but we need even more", says Mr Wills.
"Some 10% of the UK's gas demand can come from this facility on any given day."
Moving such large volumes is only possible because the field is tapped, not by the usual two or three wells, but by 30.
Up close, each is just a few inches in diameter.
Touch them and you find each pipe is warm.
It is an indication of the temperatures and pressures at play far below.
Record energy use
This winter, Rough has been working flat out as demand from homes and power stations has soared to record levels.
New figures obtained by the BBC reveal that we used more gas in 2010 than ever before.
The year began and ended with severe cold spells as the country endured its coldest December for 100 years.
Across the year the UK used 104.3 billion cubic metres (bcm), according to the National Grid, beating the last peak of 103.5 bcm in 2003.
That surge comes at a time when the UK's North Sea reserves are continuing to decline.
As recently as in 2003, the country was self sufficient. Today, more than half of the gas used is imported.
Simon Wills says that is why we need facilities such as Rough - which helps stabilise the situation, enabling the system to respond to the huge peaks and troughs in demand throughout the year.
Last autumn, the severe cold weather of November and December meant gas started flowing from Rough earlier than usual.
By January, the field was just over 40% full, compared with 70% at the same time the previous year.
This led to questions about the amount of gas the UK had in storage.
Critics said the UK's reserves could be counted in days whereas France and Germany have several months worth of reserves.
But Nick Winser, executive director of National Grid, which operates the UK's gas network, says that argument has moved on.
"We are in a different world than we were in a few years ago when basically you ran the North Sea and you topped up with storage," he says. "It's all changed."
Mr Winser points to the addition of a new pipeline from Norway and several new importing terminals for Liquefied Natural gas (LNG).
"The truth is that in December the big peak of demand that we were getting on gas was met two-thirds through non storage supplies," he says.
"The LNG was coming out of those terminals like crazy. It really worked well, so we are in a different world now."
The UK's reliance on LNG looks set to grow.
National Grid says that the UK will import 70% of its gas by 2020 and that up to two-thirds of that will be LNG.
In the past, when LNG prices have risen around the world, shipments bound for the UK have been redirected elsewhere.
Hence, the UK's growing reliance will leave the country open to the volatility of the global markets.
So should we be worried?
Mr Winser says that depends upon your faith in the markets to deliver.
"We've seen North Sea gas go from self sufficient, to providing half our needs, towards 20%, he says.
"The market has seen us through an amazing transition in the last eight years.
"So at the moment the UK gas market is a real success story in the way in which it has adapted to the decline in North Sea Gas and even this winter shows the strength of the gas market."
But back out at sea, Mr Wills of Centrica says that because of the growth of LNG, more facilities such as Rough will be needed.
"We will need more storage," he says.
"As the UK gas fields reduce, more of our gas will come in through the continent or through LNG.
"That will tend to come in reasonably flat across the year, so storage is very useful to be able to move gas from the summer through to the winter when it is needed."
Centrica is looking at a number of new storage projects.
A decision on the biggest, known as Baird, which would be about half the size of Rough, is expected later this year.