This week at Mawson: 21 July 2017

One of the things that separates Mawson from the other two Australian continental stations is the two wind turbines. With the hub of the turbine standing at around 30 metres high and a rotor diameter of 30 metres wide they’re not easy to miss. With the capability to produce three hundred kilowatts each, the turbines regularly produce more than 70% of the stations power with a fair chunk of that power used to heat the station via electric boilers.

The job of maintaining the turbines falls to the two electricians on station. This mostly involves looking at a computer screen but occasionally climbing the turbines is necessary. The turbine towers each have one ladder that goes all the way to the top and has a track down the middle which you attach onto with your safety harness.

When you do finally make it to the top of the tower, after catching your breath, you climb into the body of the turbine (nacelle). It’s a tight squeeze and at this point you’re thinking maybe that extra sausage roll at smoko was a bad idea.

When up there you start to cool down quite quickly and realise that the fibreglass shell isn’t the best of insulators, but if you’re lucky the turbine will still be warm which is very handy if your hands get too cold. The shell does do a good job of keeping out the wind so there’s no wind chill to worry about but at temperatures regularly below −20°C in the winter an extra layer of fleece is welcome underneath the overalls.

Most of the work up in the turbines is fairly routine like changing out the grease canisters and making sure everything is well lubricated, but occasionally there are bigger jobs like changing out the nose cone supports which after withstanding winds of 100 knots at times throughout the year can develop fractures from time to time.

But after the work is done, and if the wind is not bad, you can pop the top hatch and take a few photos from one of the best viewing platforms in Antarctica. Then it’s time to get back to the red shed and warm up.

Until next time,

Mark (Station Electrician)

At the risk of being called a renewable energy sceptic, sadly the wind doesn’t blow all the time at Mawson. Every now and then it might blow too hard and the turbines stop producing power and go into a ‘safe mode'.

Wind turbines were installed at Mawson as we have fairly reliable katabatic winds nearly every day. A katabatic wind is caused by the cooler air up on the plateau sliding down towards the warmer coastal air. It’s a similar principal to a sea breeze in Australia.

So when the wind isn’t blowing at Mawson, we fall back on good old diesel generators ‘gensets'- although it’s more correct to say that we combine both wind and diesel power to give us a reliable and stable power supply. We need power to keep the lights on and Facebook running, but this is only a small proportion of our energy needs. The biggest use of energy is heat to keep the station warm. As you have seen, inside the station we wander around in Hawaiian shirts!

The first photo shows the system as it was running this morning. We had one genset running but only at about half load and the two wind turbines were cranking out 185 kilowatts (Kw) each. We always need one genset running to control the frequency of the power and take up the variability in the wind output. The diesel set will produce about 140kW but the system will automatically start another set if the load gets to 130kW. Sadly however, sometimes if we get a lull in the wind then the second set can’t start quick enough and the one genset goes into overload.

The four diesel Caterpillar 3306T engines are pretty old sets dating back to the 1980’s with zero electronics, but they are very reliable and pretty fuel efficient even without whizz-bang engine control modules. They run to around 40,000 hours due to their constant light load. Two engines will normally run the station comfortably. So what do we do with all that electricity from the turbines you ask? Well we need lots of energy to heat the station so we turn it into heat via electric boilers when the turbines are cranking. We also recover the ‘waste’ heat from the engines to heat the water and when the turbines aren’t running the ‘waste’ heat from the two engines is enough to keep us warm. It’s a pretty efficient system and we do manage to use almost all of the energy produced by the burning diesel.

The photo of our heating system shows that the water returning from the station comes in at 60 — 67 degrees. You can see it goes through the engines via heat exchanges and because there is only one engine running at light load it is coming out of the engines at only 68 degrees. This is where we use the wind turbines. We have three 90kW (270kW) electric boilers, that’s 270 kettles, which then heat the water up to around 70 to 72 degrees to then send it back around the station. If and when it gets really cold and there is no wind then we have diesel fired boilers to heat the water.

The advantage with the electric boilers is they can be turned on and off (in stages) to match the power the turbines produce and in theory if we get ‘a hole in the wind’ the boilers can switch off pretty much instantly to allow the diesel engine to try to hold the load. Sometimes we get a power outage when the boilers aren’t quite quick enough or the turbines stop producing and it’s too much load for the generator.

The computer is constantly monitoring the wind and if it thinks that may happen it will start a second genset anyway and run in safe mode.

On average we burn just under a 1000 litres of diesel per day which is around half the consumption of the other two continental stations — as they have less reliable wind and no turbines. And on a good day with good constant wind we can get that down to 500 litres per day!

Until next time,

Brian (Station Mechanical Supervisor)