Where there’s a chill... Engineering challenges in Antarctica

Materials World magazine
,
2 Sep 2011
Antarctic field clothing – Dr Claire Lehman on a recreational crevasse visit during field training close to Rothera Research Station on Adelaide Island just off the Antarctic Peninsula. Image courtesy of Pete Bucktrout (BAS)

Mike Rose, of the British Antarctic Survey in Cambridge, UK, speaks about engineering and endurance on the world’s coldest continent. Eoin Redahan reports. 

The wind generators complain about the heat. The solar panels refuse to look at the sun. The accommodation could float away on the next iceberg, and there is a constant fear of fire. It’s Antarctica, but not as you expect it. In 1988, when Mike Rose inked his British Antarctic Survey (BAS) contract, he expected the icy breath of adversity, but floating homes and unruly fires were probably not among his concerns.

However, a seemingly disparate education provided ample preparation for his Antarctic endeavours. Rose came from a grammar school background. He completed a degree in physics, but selected modules that incorporated aspects of engineering whenever possible. From there, he spent six months at the British Royal Aircraft Establishment, before joining the UK semiconductor company Inmos.

At Inmos, he worked in the product engineering group, which acted as a link between the company’s design and manufacturing arms. He tested products, provided manufacturability feedback for designers, and tried to eke higher yields from the production people. One such product was the Transputer, which was a parallel processor used by the UK Meteorological Office in weather forecasts, and to produce fingerprint identification systems. Despite revelling in the dynamic atmosphere at Inmos, after three years he found his eyes scanning new horizons. The BAS needed a maintenance engineer on a two-year wintering contract.

Isolation station

In October 1988, Rose boarded a ship from the UK to Antarctica. After three months scrubbing the deck and tinkering with software projects, he arrived in time to spend Christmas in Antarctica. Immediately, he was struck by the isolation of the frigid wilderness.

‘Antarctica is absolutely enormous,’ he says. ‘You’re in a small bit of it, and you’re totally dominated by the locality you’re in’. Geographically, you’re isolated and constrained’. He cited the example of the Shackleton mountain range, which was only discovered in 1957, after Mount Everest had been climbed, to illustrate the island’s foreboding vastness.

‘You’re also very constrained about what you can do in terms of the cold and the weather’ he adds. ‘You can’t travel off the station on your own. You have to be in at least a two, but usually a four. When I went, there were 18 of us wintering. That’s it – you’re there for a year with those 18 people, and you can never escape those 18 people. Even though you’re in this massive wide-open wilderness, it’s actually quite claustrophobic’.

Thankfully, by the time he signed up, technological advances had improved communication with the green world. They even had satellite communications. ‘You could hand write one side of A4 as a fax each month, and that was it,’ he recalls. ‘That was your communication to your friends and family. They would then fax you in one side of hand-written A4 back’.

For Rose, even the work came as a bit of a shock. ‘It was slightly odd. I went from cutting-edge Inmos technology to big radars with high voltage power supplies, valves and things’.

Tuning the instruments

Twenty-two years later, and life on the bottom of the Earth is no longer so bleak. There are no longer 18 people nestled in each other’s pockets, fending off craziness. This Christmas, the numbers will swell to about 100. Furthermore, while the bandwidth is reminiscent of the early 90s, there is an internet connection.

Rose is currently working as part of BAS’ climate programme. While other projects include drilling through 6km of Antarctica’s core in search of million-year-old ice, his duties are loosely two-fold – powering the instruments for the climate programme and re-establishing science at the new Halley Research Station.


Rose has developed a specific interest in autonomous systems for remote instruments that garner climactic and atmosphere data. However, powering these instruments poses myriad problems. He explains, ‘Trying to get the fuel into the interior of Antarctica by aeroplane is very difficult and expensive. So, for autonomous instruments that are there for a scientific purpose, we’re looking at environmental power.’

When the sun shines, solar power is king. Unusually, Antarctic panels do not glare at the sun. They are perpendicular to the ground. ‘It works particularly well because the reflectance of the snow is so high. You get more power from the solar panel than you would anticipate from direct rays alone,’ he says.

However, in the land of 24-hour winter darkness, alternative forms of energy and storage must be developed. Rose emphasises that, ‘each experiment really has to be energy aware. You use energy when you’ve got it, and need a way of saving energy when there isn’t any available. In winter – you rely on energy stored in batteries or a wind generator.’

Currently, they use lead acid cell batteries that are freeze-tolerant at any charge state. The advantages of these batteries are that they are robust and have been used successfully for more than 100 years. ‘As long as you’re discharging them at a very low rate, you can discharge them at very low temperatures and get most of the energy out,’ he claims. ‘When solar power comes back, the batteries warm up as we pour more energy into the battery boxes. When they reach temperatures of above freezing, they charge efficiently and are then ready for the next winter’.

However, when you only have a small aircraft to ferry loads into the wilderness, weight is a perennial problem. ‘If you’re going to last a winter of 100 days, you’re down to about half a percent of your battery that you can use per day. If you want to use one watt [for an autonomous instrument], then you need 1x24x100x2W hours [of power] available to you. Essentially you rapidly end up with unfeasibly large amounts of lead acid. Once you start using more than one or two watts, it’s not really practical to use only a solar and battery combination. You need to either use less power (low power modes during winter) or add in wind power,’ he adds.

Lithium battery chemistries have been touted as possible successors. Rose claims they could offer between three and five times better energy density per kilogramme. However, unlike their lead acid counterparts, very little is known about how lithium chemistries charge in conditions of extreme cold.


The AGO is designed to operate autonomously using wind and solar power to make and record geophysical obervations. Field camp and Twin Otter in background.  


Light and breezy

And so, the quenched light of winter and callow battery chemistries place more pressure on the revolution of the wind rotor blade. Surprisingly though, harvesting the breeze in the windiest place on Earth has proven remarkably problematic.

‘Antarctica tends to eat wind turbines,’ Rose notes. ‘There are several reasons for this. Clearly, there are the very high wind speeds that you need to deal with and very hard storms. Your wind turbine has to survive in a remote place without maintenance for a year.’

In a similar vein to batteries, commercial wind turbines are not specifically built to withstand an Antarctic winter, and commissioning a company to manufacture a relatively small volume of wind turbines would not be cost-effective, especially as turbines often fail in Antarctica for unforeseen reasons. As a result, BAS buys a wide range of commercial offerings and tweaks them accordingly.

‘The biggest problem we have with the bearings is the clearance and the lubrication used on them. If you get a standard turbine from a manufacturer, then those bearings will get stiff in the cold. In part, the wind generator will stop in a period of calm. If it’s calm, the temperatures usually go even lower; the bearings go stiff, and the generator just won’t start up again.’

If this weren’t frustrating enough, their tinkering also has a distinct bearing on performance. ‘We go to low temperature bearings, which have different clearance and different grease in them to give us better low temperature performance. But, that actually gives us problems on the high temperature end because wind generators can get quite hot even when there’s quite a significant cold wind speed going past the turbine. We have had quite a few wind generators that have failed that look like they have gone over temperature,’ he says.

Rose and his colleagues have managed to improve the mean time between fail of the generators by incorporating a wind controller box that regulates the generator’s output. ‘The pulse width modulation converter loads the wind generator to control its speed. By slowing it down, the wind generator just becomes less aerodynamically efficient. It’s very analogous to the gears when cycling.’

They have also tweaked the turbine’s design by producing a stiffer mast to protect against wind-induced vibration, which speeds up bearing wear.

Antarctic generators are also generally lower in stature than commercial offerings (two metres), partly because it is too time-consuming and labour-intensive to plant them too deeply into the snow, and partly because of the lower wind shear. Such limitations are a daily reality for engineers on the frozen continent. Another reality is the need to work quickly and effectively under pressure.

‘Working at a remote field site in Antarctica is quite stressful,’ he explains. ‘There is a lot of infrastructure needed to get you to that remote field site, and there is a very large expectation that the work you do will be to a high quality’. You’ve probably been under some time pressure to get there, having chosen a weather window and taken the meteorological data’.

Installing and power autonomous instruments in Antarctica requires bespoke equipment and innovative thought. Advanced battery chemistries, pulse width modulators and cold-temperature lubricants all facilitate the accurate measurement of subtle atmospheric and climactic phenomena. But in a harsh environment, some aspects of the work will remain inalienable.

But, before you use any of those appliances, you will need a digging implement known as a shovel, a novel lubricant called elbow grease and the patience to endure interminable hours waiting for clement weather. Indeed, despite the many advances made in recent years, Antarctica welcomes technology like a zealous Luddite.  


When all Halley breaks loose


From tubular dwellings to houses on stilts, British Antarctic Survey engineers have devised novel ways of protecting research stations against the relentless ravages of ice. This Christmas, Rose and his colleagues will finish building their latest installment – Halley 6.

Halleys 1 and 2

The first two Halley stations were conventional structures, placed on the snow surface. With snow accumulating at a rate of 1.5m a year, it wasn’t long before both buildings were buried and crushed by ice.

Halley 3

Halley 3 was built in a thick metal tunnel designed to withstand the crushing forces of the ice. While it resisted these forces admirably, problems persisted with condensation. Once the tubes reached a depth of 15-20m, they became difficult to access. Eventually, living there became untenable.

Halley 4

Halley 4 was Rose’s first Antarctic abode. Like Halley 3, it was placed on the surface and was allowed to bury gradually. It was built using wooden rather than metal tubes, which helped improved ventilation and tackled condensation problems. However, once it got to a depth of 20m, the ice’s weight and pressure accumulated to crush the dwelling. Rose explains, ‘You’ve got metres and metres of snow above you. It’s like being in a swimming pool. There’s pressure in the ice. Just the same as a diver going down to the depths, there’s pressure in all directions.’

Halley 5

Halley 5 was built on legs that were jacked up a metre and a half each year to keep the building above ground. The stilted dwelling is the most successful station to date, and it is still in working order today. However, Antarctica is not easily bested.

‘It’s locked onto these legs that are in the snow,’ Rose laments. ‘And, it’s slowly drifting with the movement of the ice shelf. It drifts about 400m a year, closer and closer to the edge of the ice shelf. It is now on the wrong side of what we think is the worst-case break line for the ice shelf. A big carving event could put it on an iceberg. Because of the way that structure’s made, we can’t really move it.’

Halley 6

The latest and greatest edition will also use its legs to stay out of the ice. But, unlike Halley 5, it won’t be in imminent danger of plumbing the ocean depths. ‘The legs are on a foundation buried in the ice where the legs are on skis,’ Rose notes. ‘As such, we can periodically move it. We’re building a location that is safe now. If in 10 years time we need to move it, we can do that by towing it in modules’.

Halley 6 is built using fibreglass panels bolted onto a steel frame. Rose says fibreglass is used as it can be manipulated into complex shapes, which facilitates the building of a more aerodynamic structure that reduces snow accumulation. The station will also be divided into portable modules that can be individually transported.  


Warming to the task


Antarctic clothing comprises a mix of old and new materials. Synthetics have risen to prominence in recent years, especially in the mid and base-layers. Polypropylene has replaced wool in the base layer, as it is better at keeping away moisture and dries more quickly. While Gore-Tex has become widely popular in the wind-proofing layer, Rose prefers to a use a finely woven cotton called Ventile.

The choice of glove-type, however, is more susceptible to the idiosyncrasies of the worker. ‘Some people like to wear very thin gloves and then put those inside a very thick mit,’ he says. ‘They take their thin-gloved hand out of the thick mit to do something, and then put their hand back in. Other people tend to wear reasonably thick gloves with fingers that allow them to work without taking their hands out of the gloves.’

For a better idea of the latter method, purchase an orange, and try to peel it using your thickest pair of gloves.

Dielectrical profiling experiment on an ice core retrieved at Berkner Island

 

Scientists have succeeded in drilling a 1,000 metre-deep ice core and reached bedrock. The core gives a continuous record of the climate on Berkner spanning the past 30,000 years. This period is particularly interesting as it includes the dramatic transition from the last ice age into the current Holocene warm period, when the average temperature of the Antarctic rose by 8°C. Situated at the southern end of the Atlantic Ocean, the Berkner Island coast will give a clear view of the southern response to changes in ocean currents that are believed to have occurred during this period.