Tag: Drax Power Station

Fourth biomass unit conversion

RNS Number : 1114C
Drax Group PLC

Drax welcomes the UK Government response to the consultation on cost control for further biomass conversions under the Renewable Obligation scheme, which will enable Drax to convert a fourth unit to biomass.

The response proposes that, rather than imposing a cap on ROC(1) support for any future biomass unit conversions, a cap would be applied at the power station level across all ROC(1) units. This would protect existing converted units and limit the amount of incremental ROCs attributable to additional unit conversions to 125,000 per annum.

The response would enable Drax to optimise its power generation from biomass across its three ROC units under the cap, whilst supporting the Government’s objective of controlling costs under the Renewable Obligation scheme.

Drax will now continue its work to deliver the low cost conversion of a fourth biomass unit, accelerating the removal of coal-fired generation from the UK electricity system, whilst supporting security of supply.

Drax plans to complete the work on this unit as part of a major planned outage in the second half of 2018, before returning to service in late 2018. The capital cost is significantly below the level of previous conversions, re-purposing the existing co-firing facility on site to deliver biomass to the unit.

The unit will likely operate with lower availability than the three existing converted units, but the intention is for it to run at periods of higher demand, which are often those of higher carbon intensity, allowing optimisation of ROC(1) generation across three ROC(1) accredited units. The CfD(2) unit remains unaffected.

Will Gardiner, Chief Executive of Drax Group, commented:

“We welcome the Government’s support for further sustainable biomass generation at Drax, which will allow us to accelerate the removal of coal from the electricity system, replacing it with flexible low carbon renewable electricity.”

“We look forward to implementing a cost-effective solution for our fourth biomass unit at Drax.”


Investor Relations:

Mark Strafford

+44 (0) 1757 612 491


Ali Lewis

+44 (0) 1757 612 165


Website: www.drax.com/uk


  1. Renewable Obligation Certificate
  2. Contract for Difference




Refurbishing a 300-tonne generator core within the heart of a power station

Electricity generator

At the centre of Drax Power Station, in a corner of the cavernous turbine hall, is a white box. The inside of this box is spotlessly clean. Not only are its white walls free of dirt, they are free of even dust. But there is one outlier inside this sterile environment: a 300-tonne chunk of industrial equipment.

This equipment is a generator core – the central component for converting the mechanical energy to electrical power.

Electricity generator core

The core is driven by the steam turbine. Ninety tonnes of generator rotor spinning at 3,000 rpm with just millimetres of clearance from the core produce 660 megawatts (MW) of electricity. That’s enough – 645 MW when exported from Drax into the National Grid – to power a city the size of Sheffield.

The generator is a serious piece of industrial machinery. And despite the pristine conditions, this white box is the site of serious engineering.

A process normally done by large-scale manufacturers in dedicated factories, ‘rewinding’ a generator core – as the process is called – is a major operation.

No other UK facility is capable of doing this complex job. So it’s here, in a white box, in the middle of an operational power station in North Yorkshire, that a team of engineers is undertaking work that will secure the generator’s use for decades. This is the Drax rewinding facility.

Turbine structure

How a generator works

A generator consists of two main components, a spinning rotor and a stationary stator. The rotor, which is directly connected to the main turbine and spins 50 times every second, sits inside the stator. Both the stator and the rotor contain a large number of copper coils known as windings. These windings are what carry the electrical current.

The rotor acts like a very strong electromagnet, which, when a voltage is applied, produces a strong magnetic field. Because the rotor sits inside the stator, this magnetic field intersects the copper windings of the stator and induces a voltage in these windings, allowing current to flow.  This voltage is then brought out of the stator and passed through a step-up transformer, where it is increased to a level suitable for transmission through the National Grid.

The stator core is made from many elements with hundreds of thousands of laminations, 84 water-cooled insulated copper bars, each 11 metres long and weighing 200kg forming the windings, various insulating materials, blocks, packing, wedges and condition monitoring equipment.

Generator stators can operate for decades without fault.

DIY at Drax

In 2016, a team of engineers at Drax embarked on a project to construct a facility to rewind the stator on site. This required cross-company collaborative working to design and construct this huge purpose built facility.

Contamination can cause operational problems, so the team built a sterile, white room within the turbine hall – one of just two places within the power station with foundations strong enough to support the incredible 450 tonnes required for the rewind facility. Designed to hold the stator core and the conductor bars, air is forced out of the room to limit the possibility of contamination to the core during the rewind.

“When the unit is in service it becomes magnetic, so any metallic particles left in the space will be attracted to the core,” explains Drax electrical engineer Thomas Walker. “Once magnetised, any metal particles could be drawn in, burrowing into the insulation and core lamination.”

This is the kind of event that an electricity generator wants to avoid – but when it happens, be prepared to fix it.

Roll with it

When Drax’s stators were manufactured in the 1980s, completing their construction relied on manual handling techniques. Modern day facilities, however, rotate the core to minimise human contact.

It took just six months for a partnership involving Drax, Siemens and ENSER to manufacture what could be the largest stator rollers in the world and within that time, ship them from the US to North Yorkshire.

With the rollers installed, the next step was to move in the core. Two of the turbine hall’s cranes, each capable of lifting 150 tonnes, were combined to lift it, hoisting the core onto the mechanical ‘roller’ within the rewind facility.

Once in place, the roller rotates the core, allowing for the copper conductor bars to be safely removed and inserted. Despite this mechanical help, the removing and replacing of each one is still at its heart a human job.

“We still need 10 men to physically move the conductor bars with lifting aids, which makes it not an easy process,” says Walker. Using this method, the bars weighing 200kg each can be safely and precisely fitted into the core.

Electricity turbine generator at Drax

Opting for in-house

Rewinding a stator is a complex process. However, when the time, logistics and costs of shipping the core to Siemens – the German-based manufacturers – was factored in, the decision to do the work at Drax Power Station was an easy one.

A 300-tonne core is not easy to transport and the Highways Agency do not like things like that on the roads. They’d want us to use waterways” says Drax lead engineer Mark Rowbottom. “Logistically it just wasn’t worth it. It’s too much money to move and ship that weight to Germany. So, we looked at what we could do onsite.”

More than just an economical and logistical decision and with the UK’s diminishing manufacturing facilities, Drax is now equipped to support generator rewinds for many years to come. Building and operating the rewind facility was a project that leveraged the engineering abilities of Drax employees. They are increasingly doing engineering traditionally outsourced to equipment manufacturers.

“The experience we have gained and the close working relationship we have established with Siemens enables us to support the generator for the remaining life of the station,” says Rowbottom.

“To see the core in that many pieces and stripped down to this level is very rare,” says Walker, who began working at the plant as an apprentice. Of the 84 conductor bars, half have been fitted, and the team is scheduled to complete the stator rewind in early 2018. “I never thought I’d do anything like this but am proud to say that I’ve done it.”

7 things to see at Drax Power Station

Chimneys taller than the London Eye, domes bigger than the Albert Hall and enough steel tubing to run the length of the UK twice, Drax Power Station is a structure of superlatives. But it’s visiting the site that truly drives home the scale of the electricity generating process.

From tiny biomass pellets to landscape-shaping cooling towers, here are seven of the most-impressive and interesting parts of Drax Power Station.

Cooling towers

Arguably the power station’s most recognisable landmarks, Drax’s 12 giant cooling towers each measure 114 metres tall. To put that in perspective, each is large enough to fit the entire Statue of Liberty inside it – with room to spare.

These massive concrete structures cool the water used as part of the generation process. Water is pumped into the tower at roughly 40 degrees Celsius and is cooled by air naturally pulled into the structure by its unique shape. Once the water is cooled it is safely returned to the River Ouse.

So, what’s coming out the top of a cooling tower? Water vapour, and it only accounts for roughly 2% of all the water pumped into the tower.

Biomass domes

Standing 65 metres tall, Drax’s four biomass domes are each larger than the Royal Albert Hall and between them hold approximately 300,000 tonnes of compressed wood pellets – enough to power Leeds, Manchester, Sheffield and Liverpool for more than 12 days.

Each dome was constructed by inflating a massive PVC dome, coating its inside with a layer of polyurethane foam, and then adding steel and concrete reinforcements. Because of the sensitive nature of compressed wood pellets, the environment inside each dome must be very carefully monitored. One of the measures to keep the biomass inert is to feed in nitrogen (extracted from the air) into the dome.

Rail unloading bay

Coal’s days traversing the UK by train are almost numbered – biomass is taking over its routes. Compressed wood pellets arrive to English shores at the ports of Liverpool, Hull and Immingham and are then transported across the country in specially designed trains. Roughly 14 arrive every day, collectively unloading about 20,000 tonnes of pellets.

Drax’s bespoke wagons ensure the wood pellets are kept dry during transportation and unloaded as efficiently as possible. This includes a hatch on the bottom of the wagons that is opened magnetically to drop the pellets down into the collection area as they arrive.

Turbine hall

Here’s where the magic happens – it’s in the turbine hall that electricity is generated. Biomass is fast replacing coal to be combusted to produce steam, which is used to spin massive electromagnets at 3,000 rpm inside copper windings, which in turn generates electricity.

With each of the six turbines capable of exporting over 600 megawatts (MW) into the National Grid, the total capacity of Drax Power Station sits just shy of 4,000 MW, 70% of which now comes from sustainable biomass – an impressive 17% of Great Britain’s renewable electricity from this one, epic site.

Control room

The nerve centre of the power station, data from across the plant is fed into the control room, giving engineers a view of every stage of the generation process. The information displayed across the web of dials and screens around the room shows data on temperatures, levels or positioning of equipment, and enables operators to monitor and adjust activity around the plant.

This command and control centre at the heart of Drax Power Station is off the beaten track of most tours – so if seeing it is top of your list, please say-so on the tour booking form. As impressive as the control room and on the regular tour is the Queen’s Gallery, giving a birds-eye view over the turbine hall.

Visitor centre 

First port of call on a tour of Drax Power Station, the visitor centre offers an interactive history of Drax, from when construction began in the 1960s, via coal’s decline as a fuel source and through to the modern, predominantly-biomass power plant of today.

It’s here that visitors can step inside the electricity generation process and learn from Drax’s experienced guides about what happens at the heart of the UK’s largest power plant.

The Skylark Centre and Nature Reserve

Away from the noise of the turbine hall, a weekend trip to Drax also offers the chance to enjoy a peaceful walk through a unique natural environment. The Skylark Centre and Nature Reserve, Drax is home to more than 100 species of wildlife, including rare and endangered varieties guests might encounter along the reserve’s nature walks.

The centre offers the chance to learn more about this environment, its inhabitants and the unique story of its creation. The reserve is spread across Barlow Mound, a structure created as a means of safely storing the ash created in burning coal at the power station. More than 301 million m3 of ash is safely stored in the current site, on top of which grasses and trees have been planted to allow nature to thrive.

Its reinvention into an area of natural beauty reflects the power station’s own transformation away from coal.

Public tours of and visits to Drax Power Station are currently suspended. The suspensions are to reduce the risk to business-critical areas of our operation. We are planning to resume tours and visits in 2021, but we cannot guarantee this at the present time. Please check our website for the latest information and virtual tours.

I am an engineer

Producing 16% of Great Britain’s renewable power requires innovative people with the right mix of skills, experience and determination. Running the country’s biggest power station is a team effort – but it’s worth taking a moment to hear from the individuals at the top of their game. Meet Luke Varley, Adam Nicholson, Gareth Newton, Andrew Storr and Gary Preece.

Getting more from less

There are few things in a power station as integral to generating electricity as the turbines. Making sure they run efficiently at Drax is down to Luke Varley and his team.

Luke Varley

Varley is the lead engineer in the turbine section at Drax Power Station. His team who look after what’s arguably the heart of the plant: the steam turbines that drive electricity generation. As well as managing day-to-day maintenance, the engineers and craftspeople within TSG deliver the major overhaul activities on the turbines to keep them running efficiently and safely.

Read Luke’s story

The problem solver

How do you convert a power station built for one fuel to run on another? It takes engineers with out-of-the-box thinking like Adam Nicholson.

Adam Nicholson

Nicholson is Process Performance Section Head at Drax Power Station. He has an eagerness to find solutions. That makes him the ideal candidate for his current job: managing day-to-day improvements at Drax.

His team makes sure the turbines, boiler, emissions, combustion, and mills are not just working, but running as smoothly as possible. It’s a job that brings up constant challenges.

Read Adam’s story

Taming the electric beast

To keep a site as big and complex as Drax Power Station running, you need to be ready to mend a few faults. That’s where Gareth Newton comes in.

Gareth Newton

As a mechanical engineer in one of the power station’s maintenance teams, he’s a man with a closer eye on that animal than most.

And when something does need fixing or improving, it’s his job to make sure it happens. It’s a task that keeps him busy.

Read Gareth’s story

The toolmaster

What do you do when a piece of equipment in the UK’s largest power station breaks down? More often than not, the answer is send it to Andrew Storr’s workshop.

Andrew Storr

Before Drax Power Station was a part of Andrew Storr’s career, it was a part of his local environment.

Today, Storr does more than strip the turbines, he’s part of the engineering team that oversees them – a job that needs to be taken seriously.

Read Andrew’s story

The life of an electrical engineer

Unsurprisingly, running the country’s biggest single site electricity generator requires top-class electrical engineers. That’s where Gary Preece comes in.

Gary Preece

A station like Drax doesn’t run itself. Its six turbines generate nearly 4,000 megawatts (MW) 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.

Read Gary’s story

Batteries as big as biomass domes?

Renewables are playing a bigger part of our electricity mix as the UK moves towards a low carbon economy. How we ‘plug the gaps’ left by intermittent renewables is among the greatest challenges faced by the energy sector.

Sources like wind and solar are intermittent – they can’t generate electricity all the time. When the sun doesn’t shine or the wind doesn’t blow they lack the fuel needed to generate power and can’t feed into the grid.

This leaves a gap in the UK’s electricity supply that needs to be filled. Today that’s done by sources like coal, gas and biomass which can be dialled up and down to accommodate for the dips and peaks in generation created by changes in demand and the weather.

One alternative being touted as a possible solution is storage and in particular, battery technology. However, creating batteries on a scale big enough to meet our incredible demand is a considerable challenge. It’s a challenge that will be met in a future where giant, affordable batteries are able to store solar power captured in the summer months for use in the winter. But costs would have to come down at an even faster rate than they have done in recent years.

The challenge of building bigger batteries

To demonstrate the size of this challenge, consider the biomass storage domes at Drax Power Station. These effectively operate as giant energy stores with the flexible ability to quickly feed renewable fuel to the power station, which generates electricity on demand.

Our biomass domes can hold 300,000 tonnes of sustainably-sourced compressed wood pellets, the equivalent of 600 GWh worth of electricity. Currently, batteries cost £350 per kWh, meaning at present prices it would cost £210 billion to replace the capacity of all four of our biomass domes using battery power.

Even if battery technology advances dramatically over the next few years that figure is only likely to fall to around £60 billion. Then there is the question of the ancillary services that thermal power stations provide. The batteries of the future may be able to provide these vital services (such as synthetic inertia, short-term reserve and reactive power), but for now, providing these via battery power is prohibitively expensive and in some cases best left to biomass and gas power stations.

We should not underestimate the challenges ahead. The UK’s ever-changing power system will need to balance more electricity generated via wind and solar with affordable solutions that are also reliable, flexible and lower carbon than coal. This is why Drax is developing four rapid-response gas power stations in addition to continuing its investment in biomass generation and supply.

Inside the machine shop

A klaxon sounds and a crane big enough to lift 160 tonnes moves slowly across the inside of a cavernous warehouse. Below, a team of engineers stand around a turbine spindle the size of a double decker bus but weighing four times as much at 65 tonnes, waiting for the crane’s descent.

Around them, other engineers work on similar-sized equipment. One uses a wrench the size of an arm. Another programs a computerised lever to carefully strip millimetres from a piece of steel. It’s just a normal day inside Drax Power Station’s machine workshop.

For the last 15 years, this workshop has been refurbishing, repairing and manufacturing tools and equipment for use at the power station – a fact that sets Drax apart from other stations like it.

“We’re envied by a few stations because we do most things in-house,” says Turbine Engineer and head of the workshop, Andrew Storr. “We’re leagues in front of everyone else in the UK because we’ve got our own manufacturing and machining facility. We can do all this work on site. We’re not relying on other people.”

Storr set up the workshop in 2001 after being asked to reverse engineer a replacement set of governor relays (components that help regulate the flow of steam going into the turbines) for one of Drax’s steam turbines. Today, it’s a thriving centre of activity filled with heavy-duty machinery and ingenious engineers.

A look inside the workshop

“When you’re manufacturing spares it’s not a matter of going down to our machine shop and just saying ‘make one of those’. You’ve got to have the correct grade of material, the correct size, the correct certification for the material – you can’t just have a scrappy piece of steel that you find. It’s got to have paperwork with it to say it’s certified up to whatever it’s supposed to be,” says Storr.

Turbine bearings need to be bored to size using a horizontal borer that very accurately shaves out the lining of the inner bearing. Getting it right is incredibly important, explains Storr: “If it’s made too large it causes the turbine shaft to vibrate. If it’s made too small the bearing becomes too hot and the white metal will melt and pour out the bearing. We need to avoid both of these issues at all cost.”

The inside of the turbine blading needs to have seal strips administered by hand as they’re delicately made to limit any damage to the spinning shaft should they touch each other. Despite the wealth of equipment at the disposal of the team in the shop, success depends on the skill of the engineers using it.

There are three 160-tonne cranes in the turbine hall, each installed before the turbines were built. This meant the construction companies who erected the turbines could lift all heavy components into place with ease. “Due to their size they move slowly. It takes approximately 20 minutes for the largest hook to travel from the ground all the way to the top,” says Storr.

“In mechanical engineering it’s sometimes necessary to fit one part inside another, and once these parts are assembled they must stay locked together and not come apart,” Storr says. One way the team does this is by shrinking some components, and for this they use liquid nitrogen.

The team places the component that needs to fit inside another into a bath of liquid nitrogen and shrink it at -190 degrees Celsius. Once shrunk, the team assembles the two, placing the now smaller component into the larger one. “Eventually the inner part warms up to ambient temperature and grows in size, making the fit very tight and preventing them from coming apart,” explains Storr.

In the past, Drax would send the work they now do in the machine shop to companies off site. And because all other power stations in the area would do the same thing, wait times would often be long and the quality of the output could vary.

“When we do it in-house I can keep my eye on it,” says Storr. “I can re-prioritise things depending on what is going to be needed back on the turbine first – we’ve got 100% control over it. We can make sure everything’s hunky-dory.”

More power per pound

As the country moves towards a lower carbon future, each renewable power generation technology has its place. Wind, solar, hydro and wave can take advantage of the weather to provide plentiful power – when conditions are right.

Reliable, affordable, renewable power

But people need electricity instantly – not just when it’s a windy night or a sunny day. So, until a time when storage can provide enough affordable capacity to store and supply the grid with power from ample solar and wind farms, the country has to rely, in part, on thermal generation like gas, coal and biomass. Reliable and available on demand, yes. But renewable, low carbon and affordable too? It can be.

A year ago, a report by economic consultancy NERA and researchers at Imperial College London highlighted how a balanced mix of renewable technologies could save bill payers more than £2bn. Now, publicly available Ofgem data on which its newly published Renewables Obligation Annual Report 2015-16 is based reinforces the case for government to continue to support coal-to-biomass unit conversions within that technology mix. Why? Because out of all renewables deployed at large scale, biomass presents the most value for money – less public funding is required for more power produced.

Renewable costs compared

Drax Power Station’s biomass upgrades were the largest recipient of Renewable Obligation (RO) support during the period 2015-16. The transformation from coal to compressed wood pellets has made Drax the largest generator of renewable electricity in the country. And by a significant margin. Drax Power Station produced more than five times the renewable power than the next biggest project supported under the RO – the London Array.

Dr Iain Staffell, lecturer in Sustainable Energy at the Centre for Environmental Policy, Imperial College London, and author of Electric Insights, who has analysed the Ofgem data commented:

“Based on Ofgem’s Renewables Obligation database, the average support that Drax Power Station received was £43.05 per MWh generated. This compares to £88.70 per MWh from the other nine largest projects.”

“Biomass receives half the support of the UK’s other large renewable projects, which are all offshore wind. The average support received across all renewable generators in the RO scheme – which includes much smaller projects and all types of technology – is £58 per MWh. That is around £15 per MWh more than the support received by Drax.”

Ending the age of coal

Drax Group isn’t arguing for limitless support for coal-to-biomass conversions. And Drax Power Station, being the biggest, most modern and efficient of power stations built in the age of coal, is a special case. But if the RO did exist just to support lots of biomass conversions like Drax but no other renewable technologies, then in just one year, between 2015-16, £1bn of costs saving could have been made for the public purse.

Drax Power Station may be the biggest-single site recipient of support under the RO – but it does supply more low carbon power into the National Grid than any other company supported by Renewable Obligation Certificates (ROCs). In fact, 65% of the electricity generated at its Selby, North Yorkshire site, is now renewable. That’s 16% of the entire country’s renewable power – enough to power four million households.

Thanks to the support provided to Drax by previous governments, the current administration has a comparatively cost effective way to help the power sector move towards a lower carbon future. Biomass electricity generated at Drax Power Station has a carbon footprint that is at least 80% less than coal power – supply chain included. Drax Group stands ready to do more – which is why research and development continues apace at the power plant. R&D that the company hopes will result in ever more affordable ways to upgrade its remaining three coal units to sustainably-sourced biomass, before coal’s 2025 deadline.

Commissioned by Drax, Electric Insights is produced independently by a team of academics from Imperial College London, led by Dr Iain Staffell and facilitated by the College’s consultancy company – Imperial Consultants.

You won’t recognise this powder but you will know what it’s used for

Chances are, wherever you’ve been today, you’ve never been further than a few feet away from gypsum. It’s equally likely, however, you don’t know what gypsum is. You might not recognise it in its raw form – a soft, chalky white mineral made up of calcium and sulphur. But you will recognise the things it’s used in: buildings, food, fertilisers – the list goes on.

It’s a hugely versatile mineral, and while it’s naturally-occurring, it’s also a by-product of electricity generation.

Where does gypsum come from?

Gypsum is formed naturally when lakes or lagoons with a high amount of calcium and sulphates evaporate. This evaporation leaves behind layers of sediments, which eventually harden into a mineral (gypsum) which can then be mined.

It’s also sometimes found on the earth’s surface, where it can give rise to spectacular natural environments like the White Sands Desert in New Mexico, or slowly crystallise underground into formations like the Cave of the Crystals in Chihuahua, Mexico.

But gypsum can also be formed as a by-product of industrial processes – electricity generation being one. When coal is used to generate electricity it releases sulphur. At Drax Power Station flue gas desulphurisation (FGD) technology removes up to 90% of that sulphur dioxide, which takes the form of gypsum – a lot of it. In 2016, 80,000 tonnes of gypsum was produced and sold by Drax.

Today that gypsum is sold to just one supplier who uses it to make plasterboard, but there are a number of varied uses for this versatile mineral.


One of gypsum’s most abiding uses in human society has been in construction. In ancient times, it was used widely for making cement, or as a construction material in its own right – the interior of the Great Pyramids of Giza are lined with gypsum.

Today, it’s still a prominent feature of the building industry. Gypsum is the key component in plasterboard, which is produced by passing a gypsum paste between two sheets of paper. When the paper sets, the resulting gypsum sandwich forms the tough and ubiquitous plasterboard. Today, all gypsum created at Drax Power Station is used to create plasterboard.

It’s also a core ingredient in several forms of cement making and can – in its paste form – be applied as a plaster covering for existing walls and surfaces.

nobler Wohnung in Paris - real estate


After its use in construction, gypsum’s most important historical use is as a fertiliser. Gypsum is rich in sulphur, which plants – in particular oil and legume crops – need for healthy growth (it’s the same reason why volcanic soils are particularly fertile). Gypsum’s high calcium content also helps strengthen plant cell walls and aids in the absorption of nutrients. More than just helping the plants, gypsum fertiliser can also help reduce soil toxicity and improve its structure by allowing water to be absorbed and to drain more efficiently.


Beyond its many practical uses, gypsum also has a long history in the fine arts. Gypsum in its plaster form (often called plaster of Paris, after the Montmartre hill where it was originally quarried) can be used for sculpting and decorative ornamentation.

When left in its solid form, gypsum is known as alabaster, and has been used for millennia in monumental sculpting, often as a softer alternative to marble. Alabaster sculptures and statues have been produced by ancient societies in Egypt, Syria and Byzantium.

Gypsum powder has also been used as an ingredient in colours in delicate inks used in medieval illuminations as well as common blackboard chalk.

Little hands of kid painting on the plaster soft focus.

Cooking and brewing

The presence of nutrients like calcium in gypsum makes it an important ingredient in several recipes, including in making certain kinds of tofu. But it has a more interesting role in brewing.

The taste of beer is determined in part by the ‘hardness’ of the water used in the process. The higher the mineral content in water, the harder the water. ‘Soft’ water can be used to make sweet beers like pilsners, but if you want to make a bitter beer, gypsum can be added to harden the water with its high sulphur and calcium content, which in turn strengthens the flavour.

It’s worth mentioning, however, that only naturally-occurring gypsum is used in cooking and brewing. Gypsum acquired through desulphurisation processes is only used in industrial contexts like building.

The food industry. Glass beer bottles moving on conveyor


As it is malleable and sets quickly (sometimes within just a few minutes), gypsum has proven an ideal material for sculpting casts and splints. And anyone who has braces fitted knows only too well the unpleasant feeling of a plaster mould settling over the inside of their mouths. That’s gypsum too.

With an end date fixed for coal, it’s already a diminishing form of electricity generation. This in turn means less gypsum will created as a by-product and sold to industry.

And while this means there’ll be less of a connection between what your home is built with and what powers it, it won’t mean that you’re any less connected to gypsum every day. Gypsum has been a part of life for a long time, unlike coal, it’s one that will stick around.

Getting more from less

Luke Varley

“What can we do to ensure plant integrity, increase plant efficiency and ultimately get more megawatts out of the door for less?” This is a question at the heart of Luke Varley’s work.

Varley is the lead engineer in the turbine section at Drax Power Station, a team who look after arguably the heart of the plant: the steam turbines that drive electricity generation. As well as managing day-to-day maintenance, he and a team of engineers and craftspeople within TSG deliver the major overhaul activities on the turbines to keep them running efficiently and safely.

But as the UK’s largest power station, it’s a site that needs to run all the time – any maintenance needs to fit around that consistent operation. For the most part this happens in the summer months, when electricity demand is lower and parts of the station can be temporarily shut down to carry out repairs. Even though Varley recognises there’s a large cost involved in shutting part of the plant down, it leads to longer term gains.

“We’re taking on work to improve efficiency, because the end result is we’re using less fuel to get more electricity,” he says. A small percentage increase in biomass efficiency can represent huge cost savings, he adds.

But as a relatively new fuel, biomass – in Drax’s case compressed wood pellets – presents a unique challenge for the engineers working with it.

Luke Varley

The biomass challenge

In the days when Drax ran only on coal at full load as part of a stable national grid, turbine maintenance meant facing common problems. “Where we had problems which were familiar from one hundred years of turbine history, we knew what to look for,” Varley explains.

But now the plant generates within a far more demanding network that needs flexibility and produces more than half its power using compressed wood pellets, there’s a need for greater efficiency – it means more innovative thinking and new challenges.

For example, most plants in the industry take each turbine offline to maintain it every eight-to-ten years. But using wood pellets means the turbines need to be as efficient as possible, and this means more regular inspections.

“Every four years we go back, overhaul the module and maximise its efficiency again. That’s new to the industry within the UK. Nobody else is doing that,” he says.

Despite the challenges, Varley isn’t fazed. “The technical and management challenges, they both come with experience,” he explains. His engineering experience began before his start at Drax.

“As a sixteen-year-old I walked out into the turbine hall and looked down and thought, ‘this is a different game.’”

Destined for grease

“My dad’s been in engineering all his life. He’d be building a car and I’d be dragged to a scrap man to help take an engine block out of an old car so he could use it at home,” Varley says. “I was destined to always be covered in grease.”

So when it came to beginning his career, Varley was set on what path he wanted to take. Two options presented themselves: working as a trainee draftsman in an air conditioning company or taking an apprenticeship with National Power. An early visit to Drax helped make his decision.

“Even though I’d been around engineering with my dad, as a sixteen-year-old I walked out into the turbine hall and looked down and thought, ‘this is a different game.’” He took the apprenticeship which led him to a number of power plants, but the impression of the Drax turbine hall never left him.

Drax Turbine Hall

“Later in my career I spent a lot of my time going around different power stations, and in grandness and scale I’ve never come across anything that matches what we’ve got at Drax. So when this job came about and I was asked to join, I said, ‘Sounds good to me.’”

Today, his position of getting more megawatts out of the door for less whilst ensuring safe operation of the plant is one that comes with a lot of responsibility and is built on a long history.

“The guy who was doing this job before me took a lot of pride in it. He used to say, ‘I’ve been here man and boy, I was even here when it was built and I wouldn’t have retired until I knew it was in safe hands.’”

Varley says, “I suppose that’s the best recognition I could get, really.”