Tag: technology

The life of an electrical engineer

22 January 2017

Power generation
Gary Preece

A station like Drax doesn’t run itself. Its six turbines generate nearly 4,000MW of power when operating at full load. Unsurprisingly, for a site that produces 7% of Britain’s electricity needs, the role of an electrical engineer is an important one – both when managing how power is connected to the high-voltage electricity transmission grid, and how the giant electrical machines generating the energy work.

“It doesn’t get much bigger than Drax. You need to be at the top of your game, every day,” says Lead Engineer Gary Preece.

A man at the top of his game is a fair way to describe Preece. He has been an electrical engineer almost his entire life. Beginning as an apprentice working at the Liverpool dockyards at age 16, Preece has worked a range of increasingly demanding projects and roles, including engineering consultancy and work for the Royal Navy on their Type 26 Global Combat Ship, where he was in charge of designing the on-board power infrastructure.

He became a member of the Drax team five years ago.

Life on the job

“On a station the size of Drax, you don’t have a typical day. There are just too many systems that can change status, that can fail, or that require immediate attention to remain operational. It’s never-ending,” Preece says.

Working as an electrical engineer in a plant the size of Drax doesn’t just mean getting called down to help out when a fuse blows. His responsibilities as lead engineer encompass a broad range of functions.

“There’s lots to do. There’s a lot of hands-on work, but there’s also a lot of study work.” Tasks can include scoping out, planning and budgeting new projects, working with contractors and suppliers, fault analysis and power level studies.

This last role is what Preece has come to like most about the job – working with sophisticated computer simulations to model output and crisis scenarios, all so Drax can operate at its optimal level with National Grid.

“I really enjoy a lot of the theoretical work,” he says. “We can do so much with this software.”

Of course, there are times when he does have to fix things. And in a power plant, mistakes can have major consequences. “The energy levels in a power plant are so high that when something fails, it usually fails spectacularly.”

This means Preece needs to be on call all day and all night. If there’s a technology failure, he needs to be on the site, finding out what went wrong and directing recovery efforts. “There’s no hiding place. If something goes wrong, you have to fix it.”

Transforming Drax’s electric infrastructure

Sometimes individual projects can occupy all aspects of Preece: engineer, thinker and planner.

One of the most challenging was when Drax wanted to import a largely unused industrial generator transformer unit from Kent to the station in Yorkshire.

The transformer was split into three 200-tonne components. Before transit, Preece and his team conducted extensive checks on the components and oil (transformers contain oil to insulate the coil), to evaluate the state of the machinery. And these steps had to be repeated after every stage of the journey, to ensure no damage had been sustained.

After checks were completed, the units needed to be transported via the M25 motorway to ports in the south of England, from which they would travel by ship on the North Sea, ready to be unloaded and transported to Drax for installation.

However, the team hit complications, this time with the Highways Agency. “The structures were so heavy, that we had to take a ferry from a different port because authorities were worried the bridges we were planning on using to get there wouldn’t take the weight of the units. We had to do a turnaround in the middle of the motorway!”

Getting the extra transformers installed gave the plant some important breathing room in the unlikely event of a failure. “Some power stations don’t have spares. If there was a failure, they could be out of commission for months,” says Preece.

For a power station as large as Drax, that would be disastrous. But even with the extra transformers on site, the number of ways the electrical infrastructure at a power plant can go wrong is huge. That’s why experienced engineers like Preece are as indispensable as the machinery itself.

“Drax is one of the best opportunities you’re going to get for artistic licence. It doesn’t get much bigger.”

These three inches of copper can power a city

17 January 2017

Electrification

A series of unassuming cables extend out of the turbine hall at Drax Power Station. They’re easily missed, but these few inches of copper play an instrumental role in powering your home. Surging through each one is enough electricity to power a city.

But the process of getting electricity from power station to plug isn’t as simple as connecting one wire to a live turbine and another to your iPhone charger. We need an entire network of power stations, cables and transformers.

Linking the network

When the country first became electrified it did so in stages. Each region of the UK was powered by its own self-contained power supply. That changed in 1926 when the UK set up the Central Electricity Board and began what was at the time the biggest construction project Britain had ever seen: the national grid

The project took 100,000 men and five years to complete and when it was finished it connected 122 of the country’s most efficient power stations via 4,000 miles of overhead cabling. It had a sizeable effect. In 1920 there were roughly 750,000 electricity consumers; by 1938 that had risen to 9 million.

The grid has changed in the 80 years that’s passed, but it remains the network that transfers power across the country to where it’s needed, whenever it’s needed.

“The strange thing about electricity is that you could live 10 miles from a power station and you can’t be sure the electricity you’re using is coming from that station,” says Callan Masters, an engineer with National Grid whose job it is to maintain and upgrade the network. “The whole system works together – the whole system has a demand and the whole system has to deliver it.”

And to do this, the network has to be able to deliver electricity quickly and efficiently. Masters explains: “It acts like a motorway for power.”

High Voltage Tower on Sunset, Electric Pylon on field

Riding the motorway for power

The process of transporting electricity involves a series of stages, the first of which is ‘stepping up’ the voltage.

When electricity is transported via cables or wires it loses some of its energy as heat. Think of a lightbulb – as it illuminates it heats up because it’s losing energy. The lower the current of that electricity, however, the less energy is lost. So to reduce these losses when transporting power, National Grid transmits electricity at low currents, which it can do by increasing its voltage.

At the power station electricity is generated at 23,500 volts and is then ‘stepped up’ to 400,000 volts by a transformer. The first of these is located on a substation on site at the power station.

Once stepped up, the electricity is transported through high transmission cables – before being ‘stepped down’ via a transformer on the other end. This stepped down electricity is passed onto a regional distribution system, such as the overhead cables you might find on top of wooden poles before being stepped down a final time. “That’s the role of a little transformer at the end of your street,” Masters explains. Finally, the electricity is transported via a final cable into your home – this time at 230 volts.

All this needs to happen incredibly quickly. As thousands of kettles are switched on to herald the end of EastEnders, the demand of electricity surges. Delivering that electricity at the touch of a button relies on a complex network, but it starts with those inconspicuous few inches of copper at the power station.

This is how smart meters will change how you use power

5 January 2017

Electrification
An on button glowing neon blue.

Homes in the UK rely on energy almost 24 hours a day. Whether powering your computer, boiling your kettle or heating your home, electricity and heating fuels are absolutely integral parts of modern life. The same is the case with businesses and transport.

But how the gas and electricity we use to power our lives is tracked, recorded and fed back to utility companies is changing. It could mean lower bills and a more stable energy network and it’s all thanks to a small, inconspicuous box called a smart meter.

What is a smart meter?

Between now and 2020, every household and business in the UK will be offered smart meters for both electricity and, where they are on the network, gas too. A smart meter is a device that tracks your energy use in real-time and then automatically feeds this information back to your energy provider.

Better yet, in the UK they’ll be coupled with an in-home display showing what you’re using and how much it’s costing. It’s a simple piece of technology that can have a serious impact on how you use energy and how much you pay for it.

Will smart meters help reduce my energy bills?

The crucial difference a smart meter will make to household bills is seeing off estimated bills. In the past, utility companies would either ask you to take a reading from your meter, or send a representative to your home or office to get one. When they’ve not been able to do this, utility companies estimate your usage within a certain time frame and create a bill based on that.

With smart meters, the automatically-delivered details will mean utility companies have up-to-the-minute accuracy on customers’ energy usage. No more estimated bills. No more searching for your awkwardly-placed meter. No more unannounced meter readers arriving at your door.

A Haven Power smart meter in use.

Will smart meters change how I use electricity?

More than just improving accuracy and saving time, smart meters can help you use energy in a … smarter way.

They can pinpoint power-heavy home appliances as well as the times of day when you are using the most energy. With this information, you can optimise your usage to find where there are cost saving opportunities.

The data collected by your smart meter might show that you use most electricity in the evening when power demand is at its highest. Based on this you can change your habits to make the most of off-peak times and potentially lower tariffs, for example charging your battery-based appliances overnight.

Are smart meters good for the UK?

More accurate information is not only a benefit to home and business owners – the country as a whole could end up in a better place, too.

Armed with accurate numbers on how and when the country uses power, the National Grid, which manages the gas and high voltage electricity network, and Elexon, which manages the balancing market for electricity, will be able to better predict energy supply. If they track that electricity is being used at a certain time of day they can ensure generation by UK power stations like Drax, the UK’s biggest, is planned to match it. The aim is a more stable and efficient grid.

Utility companies could also use this data to create peak and off-peak times with different tariffs, opening the door for further cost savings and the smarter use of electricity nationwide. Coupled with the new market in battery technology such as the PowerVault and Tesla’s PowerWall 2, households and businesses will also be able to take even greater advantage of off-peak tariffs.

How can I get a smart meter?

Your electricity or heat supplier may install it for you, depending on the deal or package you are on. Contact them to find out what options are available.

Drax’s own electricity supplier, Haven Power, is currently investing in technology to allow it to use the new national smart metering infrastructure. It will begin rolling out smart meters to its customers during 2017 and will offer them to all of the businesses that purchase electricity from Haven Power by 2020.

Billington Bioenergy, Drax’s supplier of compressed wood pellets for heat, has installed smart meters – known as fuel level measurement systems – across various industries such as Care Home sector and Schools and projects that a third of its bulk-blown pellet customers will have them installed by 2020.

Your Christmas lights were powered by more renewables than ever before

29 December 2016

Electrification
A single strand of Icicle Christmas Lights.

Late into the evening of Christmas Day, 2016, millions of people sat down to watch Rowan Atkinson solve a grisly murder. It was the TV drama Maigret’s Dead Man, and although it wasn’t the most watched TV show on Christmas Day (that honour went to the Strictly Come Dancing finale), it did cause the biggest television-related sudden surge in electricity demand of the day, says Sumit Gumber, Energy Forecasting Analyst at National Grid.

During a critical ad break in the show, demand jumped 400 MW – roughly equivalent to 160,000 kettles being switched on – as viewers raced to make cups of tea or go to the bathroom. This is known as a TV pickup.

While this may have provided the biggest sudden rise in electricity usage of the day, it was not the overall peak. As is typical on Christmas Day, this year’s spike in demand came just before one o’clock, when families were preparing their festive feasts.

At 37.1 GW, this peak was not only lower than previous years, the power used to supply it was generated by more renewables than any Christmas before it. More than 40% of the electricity generated on Christmas Day came from renewable sources.

What characterises Christmas day?

Christmas is a day when electricity usage is at one of its lowest points. To put this year’s 37.1 GW peak into context, an average weekday during December (weekday electricity use is higher than on weekends) has an electricity peak of nearly 50 GW, usually occurring between five and seven o’clock, when people arrive home and street lighting is switched on.

The cause for the lower demand during Christmas is simple – over the festive period schools, as well as a number of offices, shops and factories are closed.

Over the last few years average Christmas Day demand has been fairly typical, sitting in a bracket of between 29 GW and 39 GW. In 2010, however, extreme cold (hitting minus three degrees Celsius) drove lunchtime peak demand as high as 46 GW, showing just how important a driver of our electricity use temperature is.

But while demand on Christmas in 2016 may not have deviated largely from the average over the last few years, there were some major leaps forward in how it was generated.

Winter landscape with wind turbines

A greener Christmas than ever before

This year, Christmas was characterised by a huge jump in renewable electricity generation.  On average, 12.4 GW came from renewable sources – more than ever before. Of that figure, wind contributed the most, generating on average 9.4 GW – equivalent to 31% of all power supplied on Christmas Day.

Compared to 2015 it’s a 63% increase and a staggering 195% uplift from five Christmases ago in 2012 when just 12% of all electricity generated came from renewable sources. Biomass generation has also increased, providing 2 GW in 2016 compared to the 0.5 GW it averaged on December 25th, 2012.

The increase in renewables also marks an important step towards decarbonisation: at its peak, emissions from electricity generation this 25th December were just 168 g/kWh, a significant drop compared to the 2012 peak of 506 g/kWh and the 303 g/kWh seen in 2015.

This year has been a year of impressive stats in clean energy: between July and September, for the first time in its 130-year-old history, more than half of Britain’s power came from low-carbon sources; on 5th May the UK did not burn any coal to generate electricity, the first time since 1881. Now, we’ve seen one of the cleanest Christmases on record. It’s a Christmas tradition that is likely to continue.

Biggest TV pick-ups, Christmas Day 2016

 

  1. Maigret’s Dead Man and EastEnders (22:30) – 400 MW (equivalent to 160,000 2.5 kW kettles switched on)

  2. Paul O’Grady: For the Love of Dogs at Christmas (19:45) – 275 MW (110,000 kettles)

  3. The Great Christmas Bake Off  (17:45) – 210 MW (84,000 kettles)

  4. Emmerdale and Doctor Who (18:45) – 200 MW (80,000 kettles)

Thanks to National Grid for this data

Explore how Britain was powered over the festive period by visiting electricinsights.co.uk.

Power and the rise of electric cars

12 December 2016

Electrification
Power supply for electric car charging. Electric car charging station. Close up of the power supply plugged into an electric car being charged.

All great technological innovations need infrastructure to match. The world didn’t change from candles to lightbulbs overnight – power stations had to be built, electricity cables rolled out, and buildings fitted with wiring. The same is true of electric vehicles (EV).

Think of the number of petrol stations lining the UK roads. If EVs continue their rise in popularity, the country will need electric car-charging facilities to augment and then replace these petrol stations.

This could mean big extensions of electricity grid infrastructure, both in the building of new power generation capacity to meet demand, and in the extension of the networks themselves.

In short, it could mean a significant change in how electricity is used and supplied.

The need for better electricity infrastructure

In 2013, only 3,500 of newly registered cars in the UK were plug-in electric or hybrid EVs. In 2016, that number jumped to 63,000. Their use is rising rapidly, but the lack of infrastructure has kept a cap on the number of EVs on UK roads. That is starting to change.

As of 2019, all new and refurbished houses in the EU will have to be fitted with an electric car charging point, according to a draft directive announced by Brussels. The UK will probably no longer be an EU member by the time the directive comes into effect, but nevertheless, the UK government is pursuing its own ways to account for the rise of EVs. It has pledged more than £600 million between 2015 and 2020 to support ultra-low-emission vehicles – £38 million of this has already been earmarked for public charging points.

There are more innovative responses to EV rise, too. Nissan, in partnership with Italian energy provider Enel, has announced it will install around one hundred ‘car-to-grid’ charging points across the UK. With their innovative V2G technology, cars plugged into these sites will be able to both charge their batteries and feed stored energy back to the National Grid when necessary. So when there is a peak in demand, the Grid could access the cars’ stored energy to help meet it.

The total capacity of the 18,000 Nissan electric vehicles currently operational on UK roads comes to around 180 MW. So even today – before electric vehicles have really taken off – this could give the National Grid an additional supply roughly the size of a small power station.

Peaks in electricity demand, however, tend to occur in the late afternoon or evening as it gets dark and more lighting and heating gets switched on. This also happens to be rush hour, so under this scheme the time of day the cars are most likely to be on the roads is also when it’d be most helpful to have them plugged in. This could lead to financial incentives for people to give up the flexibility of driving their cars only when they need to.

Power supply for electric car charging. Electric car charging station.

More electric cars, more demand for electricity, more pollution?

More EVs on the road makes sound environmental sense – they enable a 40% reduction in CO2 emissions – but ultimately the energy still has to come from somewhere. That means more power stations.

The scale of this new demand shouldn’t be underestimated: if European drivers were to go 80% electric, some studies have suggested it would require 150 GW of additional on-demand capacity – the equivalent of 40 Drax-sized power stations.

But if EVs are to live up to their green potential, that additional power needs to come from innovations in storage (such as in the Nissan example) and from renewable sources like wind, solar and biomass. Fossil fuels would ideally be used only to plug any gaps that intermittency creates – for example by briefly firing up the small gas power stations Drax plans to build in England and Wales.

What does this mean for generators?

Drax, as operator of the UK’s largest biomass power station and with plans for new, rapid response open cycle gas turbines (OCGTs), is well placed to be at the forefront of providing reliable, affordable power in the event of a widespread rollout of electric vehicles. The OCGTs in particular, are designed for use in peak times which, in the future, could be when the nation’s electric vehicles are plugged in overnight – today this is when electricity demand is at its lowest.

A future of more electric cars is a positive one. They’re cleaner, more efficient, and they are well suited to our increasingly urban lives. But now that we have the technology, we need to ensure we can deliver the lower-carbon infrastructure they need.

Retooling for a post-coal future

Dorothy Thompson, (2005-2017 Chief Executive, Drax Group)

6 December 2016

Opinion

The energy system in Great Britain is dramatically changing. Where it was once an industry dominated by coal, a predictable but dirty fuel, now our power increasingly comes from renewables. This is a trend that will continue, forcing more coal off the system.

Drax has a role in this new future of renewable power. We have already converted half of our power station in North Yorkshire to run on renewable biomass, and now, to support the needs of a system increasingly dominated by intermittent renewables like solar and wind, we are developing plans to build four new state-of-the-art flexible power stations – two in England and two in Wales.

Each will be 299 MW in size and powered by gas. Two of them could be producing electricity by 2020. It’s the next step for us in helping change the way energy is generated for a better future.

nrg19-1024x682

Supporting a renewable energy mix

Wind and solar accounted for 15% of Britain’s electricity mix between July and September from an installed capacity that has increased six fold in just six years. Biomass generation at Drax rose from almost nothing to producing 20% the country’s renewable power in the first half of this year. Renewable energy has come on leaps and bounds this decade – perhaps more than anyone ever thought it would.

But as well as being much lower in carbon emissions, renewables like wind and solar operate very differently to the fuels the GB Grid was built on – they’re intermittent. They only work when the sun is shining and the wind is blowing. So when it suddenly becomes still or dark, we need alternatives that plug the gap, deliver power and boost security of supply.

Biomass is one part of how we can do this using lower carbon fuels. Compressed wood pellets (the biomass used at Drax) is a renewable fuel that can be used to generate baseload power that can also be dialled up and down to meet demand. Like coal, it can also provide the ancillary services the Grid needs to stay stable.

Unlike combined cycle gas turbine (CCGT) power plants, which currently supply roughly 40% of the UK’s power and take 1.5 hours to start up from cold, our new open cycle gas turbine (OCGT) plants are like big jet engines – generating electricity at full power in just 20 minutes from cold or 10 minutes from a warm standby. It’s an incredibly fast turnaround and it’s what the energy network needs.

And because it’s a lower carbon fuel than coal with higher flexibility it will support the UK’s decarbonisation targets – by enabling more wind and solar on the Grid. We plan to use OCGTs to plug the gaps that intermittency creates – essentially flicking the switch on and off at very short notice. We anticipate they would run for no more than 1,500 hours per year – only at times when the electricity system is under stress. Through supporting more intermittent renewables we also help to enable more coal off the system.

A better future for customers

This new future will not only mean changes for us, the generators, but for customers, too.

How energy is supplied and used is evolving, and this is something that Drax can support with the growing retail side of our business.

We’re a company with a wealth of expertise in renewable power and we can use this to help deliver electricity to business customers in a way that caters for today’s market. We’re already doing this with Haven Power, but now we’re extending this with the acquisition of Opus Energy. With this new company as part of Drax Group we will be able to grow our existing retail offering, providing more of the UK’s growing businesses and established industrial and corporates not only with electricity, but also with gas. Our retail offering will provide businesses with a route to sell the power they generate but do not need – plus expertise in how they can use energy more efficiently.

R&D

These are the first steps in a new chapter for Drax. There will be more research and development to come. In the future we’ll be looking at how we can extend our American compressed wood pellet supply business, Drax Biomass, and at the potential for power storage systems.

If we want to continue to be a truly modern energy company that delivers on our aim of changing the way energy is generated, supplied and used for a better future, we need to be able to adapt. It’s always been a part of Drax’s history and it will be a part of our future.

This train isn’t like any other in the UK

25 November 2016

Sustainable bioenergy
Man standing in front of train

For decades the sight was the same. Day after day, trains pulling open-top wagons filled with coal would arrive at Drax Power Station. Coal was the fuel on which the station ran, but as that changes and the world moves from the dirtiest of fossil fuels to renewables and other lower carbon technologies, so too do the make-up of Drax’s daily deliveries.

Now, more than half of Drax’s power is generated from compressed wood pellets instead of coal. The trains still arrive daily, but in addition to coal carriages, more are pulling state-of-the-art biomass wagons. They’re not only the first of a kind, they’re bigger than any others on UK railways.

Moving a modern fuel

Coal and biomass are fundamentally different. Whereas coal is a durable fuel that can be left open to the elements without concern, if compressed wood pellets are left in the rain they become unusable.

In short, traditional hoppers, the large open-top train wagons used to transport coal, aren’t big enough, nor do they provide enough protection, for transporting biomass.

To deliver roughly 20,000 tonnes of wood pellets to the power station every day it would need an entirely new railway wagon. For this Drax turned to Lloyd’s Register Rail (now Ricardo Rail) and WH Davis.

DRATECH19_Train_crane_In_line_dp7ney

Putting a lid on it

One of the first things to solve was the open top. The team designed a pneumatically operated roof for each wagon that could open and close on demand – providing easy access for loading, but suitable protection for the pellets when in transit.

A similar system on each wagon’s base was introduced to make unloading just as simple. A typical hopper design includes a wide roof that narrows into a shoot at its base for releasing fuel. The Drax wagons are different.

When they arrive at the power station, automated flaps on their underside open in stages as they pass through the biomass unloading area. This releases pellets into a sorter that delivers them into storage, ready to be used for generation. With this system in place, each train can unload in under 40 minutes.

The big problem: space

A more significant hurdle to overcome was the question of space. The obvious answer was to make the wagons bigger, but UK railways have some of the most restrictive dimensions in the world thanks to its bridges and tunnels – some of which were constructed in Victorian times.

So to get a similar efficiency out of the compressed wood pellet loads as previously obtained with coal, the wagons needed to be bigger – not in physical size, but in volume.

The team looked to the normally unused space at the ends of traditional wagons to house the braking and control equipment cubicle, while the pipework was designed to run inside the wagon’s siding, creating more inside storage space.

The result is a wagon with 116m3 capacity, almost a 30% increase in volume compared to the coal wagons. They are not only the first ever bespoke biomass wagons, they’re also the largest on UK railways.

DRATECH19_Train_Journey_In_Line_dgx81z

Bigger wagons, better economy

The impact of these wagons is felt beyond just the railway lines. WH Davis is the UK’s last independent freight wagon manufacturer and relationships like this are not only good for Drax, but positively impact the wider UK economy.

A joint study by Oxford Economics for Drax calculated that in the East Midlands, where WH Davis is headquartered, Drax supports 1,100 jobs through its supply chain and the resulting economic activity. In total, the report found Drax had added £60.3 million to the local economy through indirect and induced means. Nationwide, in 2015 that impact extended to a total of £1.24 billion in contribution to the UK GDP and more than 14,000 jobs.

There’s potential for this impact to be even greater. Roughly 14 trains arrive every day at the power station from ports in Liverpool, Tyne, Immingham and Hull, delivering up to 20,000 tonnes every day to fuel the three of Drax’s six generating units that run on wood pellets. But if all six are upgraded it will mean more biomass, more deliveries and more trains.

The railways have always been a part of the power station, and in the foreseeable future it’s likely they always will be.

What does an Instrument Craftsperson do?

10 November 2016

Power generation
Instrument Craftperson in action

How do you go about fixing a turbine that, on a normal day, spins 3,000 times every minute? The first port of call is to call in someone like Alice Gill, an Instrument Craftsperson at Drax Power Station. 

What does an Instrument Craftperson do?

What I do is maintain and repair the equipment that links the outside power plant and the control room – equipment that tracks temperature, levels or positioning that then informs our operators in the control room what’s happening on the plant.

Things like an oxygen analyser. It’s a probe that sits in the boiler and monitors the oxygen level so the operator can ensure the correct ratio of fuel to air is going into the boiler to reach optimum combustion.

I might be called on to do calibration checks on that sensor to ensure that it’s working properly. Or I might be asked to completely remove it and then to repair it.

How did you come to be doing this job?

I’m not the sort of person who likes to sit down at a desk all day – I’m more of a hands on sort of person. My dad was always working and fixing things in the garage at home and I liked being in there with him.

When I was at school I decided I didn’t want to go to university so started applying for apprenticeships and looking into engineering opportunities. Drax was one of those schemes and was the one I most wanted to be selected for – luckily enough I was offered a place.

The apprenticeship was four years and there are loads of training courses and so much to learn, including hands on experience and working in the plant.

I remember first arriving to the power station and not really believing the scale of the place. You think, ‘How am I ever going to find my way around?’, but you soon get used to it and it becomes the norm.

In September I became a full Instrument Craftsperson so now I can really get stuck in.

Alice Gill at Drax Power Station

“I’m not the sort of person who likes to sit down at a desk all day – I’m more of a hands on sort of person.”

What sort of challenges do you face?

Over the summer I’ve been doing a lot of work on the turbines. It’s a big job as they’re one of the most important elements driving the plant and generating the power. During outages the whole thing gets overhauled and given a full health check.

The turbine team needs to get into machinery, which is densely constructed and put together, so it’s my job to go in and carefully remove instrumentation so they can access it. When they’re done, I have to go back in, refit everything and check it’s all working again.

How do you do that?

When you’re removing the instruments it’s a bit more of a ‘just get it off’ approach – you just make sure you get it off safely without damaging it.

Then when we’re refitting it, we’re out there with our multimeters making sure we’re setting different probes at the right voltages and that everything is calibrated correctly.

There’s a screen in our workshop we use to watch the activity of the turbine so we can see the speed of the turbine creeping up as they switch it back on. It’s always a big moment. You know things are going to be alright because you’ve done everything, but there are still some nervous people in the room. The turbines are spinning at 3,000RPM so you really need it all to be working properly.

Is there anything that could wrong on an average day?

One of the biggest things that could go wrong in my area is the potential to trip an entire generating unit. It might be that you over-pressurise something or you accidentally trigger a switch that then sets off a daisy chain of events that ends up in a unit tripping. Tripping is where the unit turns off which basically leads to a total shutdown in electricity generation from one sixth of Drax Power Station.

There’s something called the 660 club – at full load the units are operating at 660 MW so if you trip one you enter into this infamous club. There are a few guys in the 660 club but thankfully I haven’t joined! When operating at full load of 660 MW, our units supply the National Grid with around 645 MW– enough to power an entire city.

What do you do outside of work?

I’ve got a horse called Red – I’ve had him for seven years but I’ve been riding since I was eight. It’s quite different to working with things that do exactly what you tell them. When you get on the horse he just does what he wants – he’s got a mind of his own. It’s a big change!

If you’re afraid of heights, don’t do this job

27 October 2016

Power generation
Reparing the colling tower at Drax Power Station

Be they for nuclear, coal, or biomass power, cooling towers and their colossal, tapering silhouettes are the most iconic element of the architecture of energy. Drax has 12 of them.

But a structure of that size poses a considerable maintenance challenge. For the first time since Drax’s six towers were constructed between 1967 and 1974, one of them was in need of repair.

Ladder up a Drax cooling tower

What could possibly go wrong?

No matter how well you build something, things can go wrong after more than five decades of continuous operation. Each tower is made from concrete that varies in thickness from seven inches in the middle to around 15 inches at the top and bottom. Over time, even a structure this solid can begin to weaken.

Cooling towers are reinforced with steel bars embedded within their concrete which can rust and expand, causing the concrete around it to crack – a process called spalling. Water vapour, which passes through the towers on an almost constant basis, can also migrate into poorly compacted concrete inside the tower and cause further cracks.

Before the Drax team could set about repairing the towers, they needed to know where these cracks were. Inspecting a structure that tall needed an innovative solution. It needed drones.

Surveying the damage

Drones were used to make a comprehensive, photographic record of the towers that could be inspected for signs of damage. The drones also helped produce a 3D model of the structure to visualise the tower’s defects. It was the first-of-a-kind for the company.

The drone survey found that on tower 3B there were a number of cracked concrete patches on the towers that needed repairing and maintenance was scheduled to coincide with Drax’s 2016 outages – periods during the summer months when electricity demand is lower and parts of the power station undergo routine repair work.

The next challenge was how to carry out these repairs on a structure taller than the Statue of Liberty.

A 3D model of a Drax cooling tower

To inspect the cooling tower, Drax created a 3D model with the help of CyberHawk.

Engineering at an altitude

Drax tower 3B is nearly 115 metres tall, enough to fit in the Statue of Liberty or St Paul’s Cathedral with room to spare.

How do you go about repairing a structure like this? The answer: Steeplejacks. Steeplejacks were called so because, originally, they were the people used for scaling the side of church steeples to make repairs. But a cooling tower presents a distinctly different structure that can’t necessarily be climbed up from the bottom. To scale it and make the repairs, a different approach was needed.

Drax reached out to specialist steeplejack contractors Zenith Structural Access, who build devices that allow the scaling of industrial-scale structures.

Zenith’s solution was to fix a metal frame to the top of the tower, which then lowers a walkway suspended by strong metal cables down its side. From a perch suspended from the top of tower 3B, workmen were deployed to make the repairs – more than 100 metres above ground.

Suspended in their cradles, the teams sealed the surface of each crack and then injected resin to fix the cracks in the concrete shell. Where the concrete had spalled, new specialist repair mortars were applied.

Repairs on Drax Tower 3B

Regular repairs

With the identified defects on the tower fully repaired, attention can now move on to others on site. Routine inspections using drones and binoculars have been planned to take place every three years. These will monitor the condition of all the towers and allow for future maintenance to be planned in advance.

Two more towers are already scheduled for repair in 2017’s outages. Once again, it’ll be case for engineering work at elevation.