Tag: technology

Winter on the Hollow Mountain

15 January 2020

Power generation
Winter snow scene around the Hydro electric Dam on Ben Cruachan,above Loch Awe, Argyll, Scotland

Scotland’s landscape is defined by its weather. The millennia of wind, rain and snow has battered the country, ebbing away at its rivers, mountains, valleys and deep lochs forged by ice ages and volcanos. Weather also plays an important role in the country’s power generation. The country has more than 9 gigawatts (GW) of installed wind power – enough to sometimes meet double Scotland’s electricity demand – as well as having a long history of hydropower.

But while it is an intrinsic part of the country, Scotland’s weather can be anything but pleasant. Rain can be persistent and when the temperature drops in winter, it turns to snow – a lot of it. Scotland gets more snow than any other part of the UK.

Scottish poet Robert Burns described the harshness of the winter months in his 1781 poem Winter A Dirge:

“The wintry west extends his blast,

And hail and rain does blaw;

Or the stormy north sends driving forth

The blinding sleet and snaw:”

Sleet and ‘snaw’ (snow) fall occurs on average for 38 days a year in Scotland, compared to an average of 23 days across the rest of the United Kingdom, and can remain covering mountaintops long into spring.

Ben Cruachan Mountain

Ben Cruachan

The peak of Ben Cruachan in the Western Highlands is no exception. Cruachan Power Station, on the slopes of the mountain, however, must be ready to either generate or absorb electricity through all forms of weather – even the most severe.

“On a few occasions the snowfall has been so extreme that we’ve been unable to access the dam for a few weeks at a time,” says Gordon Pirie, a Civil Engineer at Cruachan. “Thankfully, we have enough controls in place where we are still able to monitor and operate things remotely.”

Mountain road from Cruachan Power Station to its dam blocked due to snow

Mountain road from Cruachan Power Station to its dam blocked due to snow

This mountainside location and winter weather can make for tough working conditions, but Cruachan is designed to handle it. In fact, in some cases it benefits from it.

Taking advantage of wet weather

Cruachan is built around the geography and climate of the Highlands. It stores water in an upper reservoir 400 meters (1,312 feet) up Ben Cruachan and uses its elevation to run it down the mountain, spin a turbine and generate power.

And when there is excess electricity being generated nationally, the same turbines reverse and use the excess electricity to pump water from Loch Awe up to the reservoir, helping to balance the grid. This acts as a form of energy storage by essentially stockpiling the excess electricity in the form of water held in the top reservoir.

For the most part the water used to generate electricity comes exclusively from Loch Awe and is passed up and down the mountain. However, 10% of it comes for ‘free’, as it’s collected from natural rainfall and surface water that makes its way to the upper reservoir through Cruachan’s aqueducts. This system of 14 kilometres of interconnected concrete pipes covers a 23 square kilometre radius around the reservoir and is designed to bring in water from 75 intakes dotted around the top of the mountain.

A North of Scotland Hydro-Electric Board diagram from c.1960s showing the aqueducts feeding Cruachan’s dam; click to view/download.

A North of Scotland Hydro-Electric Board diagram from c.1960s showing the aqueducts feeding Cruachan’s dam; click to view/download.

Some of these intakes are as small as street drains, while others are large enough to drive a Land Rover into. It’s part of Pirie’s job to keep them in good working order so they continue to deliver water to the reservoir. As the intakes are scattered around the mountaintop, they must be able to deal with whatever the Scottish winter throws at them.

Gordon Pirie, Civil Engineer and Cruachan Power Station dam

Gordon Pirie, Civil Engineer and Cruachan Power Station dam

“Even in freezing conditions the water will still flow through the aqueduct system, the intakes have a built-in feature which allows the water to flow into them even if the surface is frozen solid,” explains Pirie. “Any snow or frost on the ground eventually thaws and makes its way to the reservoir.”

As spring arrives and snow begins to thaw across the Highlands, greater volumes of water will run off into the reservoir and the power station’s engineers work to manage the water level.

Keeping water pressure under control

The power station must be able to pump water and absorb excess electricity from the grid at a moment’s notice. This ability to turn excess electricity into stored energy makes Cruachan hugely useful in controlling the grid’s voltage, frequency and in keeping it stable. However, there must be enough space available in the reservoir for the water being pumped up the mountainside to enter – even when excessive rainfall or melting snow begins to naturally fill it up.

The power station can control the reservoir levels through a number of means. This includes the ability to close off an aqueduct, or to run the turbines without generating electricity so the team can move water from the reservoir into Loch Awe below.

If the water level and pressure on the dam reaches dangerous levels a ‘dispenser valve’ can be opened in an emergency, sending a jet of water flying out the dam to cascade safely down the mountainside. However, outside of testing, this has never been necessary to do. 

And while the weather might be the most persistent natural force the power station must deal with, it’s not the only one. “Recently we had an issue with a bat roosting within one of the tunnels in which we were carrying out stabilisation works,” recalls Pirie. “It was looking for a suitable location to hibernate for the winter and the tunnel provided the ideal environment. We had to stop works to have a bat survey undertaken and apply for a bat license.”

Cruachan’s location makes for stunning views of the Highlands, but occasionally brutally cold and perilously wet conditions come with the territory. For the power station team, working with the sometimes-despairing weather is all part of what allows the Hollow Mountain to operate as it has done for more than half a century.

The Highlands around Ben Cruachan are rich with wildlife. Educational information on area’s flora and fauna can be explored at the Cruachan Power Station visitor centre.

The Highlands around Ben Cruachan are rich with wildlife. Educational information on area’s flora and fauna can be explored at the Cruachan Power Station visitor centre.

Visit Cruachan — The Hollow Mountain to take the power station tour.

How Scotland’s sewage becomes renewable energy

17 December 2019

Sustainable bioenergy
Stevie Gilluley Senior Operator at Daldowie fuel plant

From traffic pollution to household recycling and access to green spaces, cities and governments around the world are facing increasing pressure to find solutions to a growing number of urban problems.  

One of these which doesn’t come up often is sewage. But every day, 11 billion litres of wastewater from drains, homes, businesses and farms is collected across the UK and treated to be made safe to re-enter the water system.   

Although for the most part sewage treatment occurs beyond the view of the general population, it is something that needs constant work. If not dealt with properly, it can have a significant effect on the surrounding environment.  

Of the many ways that sewage is dealt with, perhaps one of the most innovative is to use it for energy. Daldowie fuel plant, near Glasgow is one such place which processes sewage sludge taken from the surrounding area into a renewable, low carbon form of biomass fuel.  

The solution in the sludge   

In operation since 2002, Daldowie was acquired by Drax at the end of 2018 and today processes 35% of all of Scotland’s wastewater sludge, into dry, low-odour fuel pellets.   

“We receive as much as 2.5 million tonnes of sludge from Scottish Water a year,” says Plant Manager Dylan Hughes who leads a team of 71 employees, “And produce up to 50,000 tonnes of pellets, making it one of the largest plants of this kind in the world.”  

“We have to provide a 24/7, 365-day service that is built into the infrastructure of Glasgow,” he explains.   

This sludge processed at Daldowie is not raw wastewater, which is treated in Scottish Water’s sewage facilities. Instead, the sludge is a semi-solid by-product of the treatment process, made of the organic material and bacteria that ends up in wastewater from homes and industry, from drains, sinks and, yes, toilets.   

Until the late 1990s, one of Great Britain’s main methods of disposing of sludge was by dumping it in the ocean. After this practice was banned, cities where left to figure out ways of dealing with the sludge.   

Using sludge as a form of fertiliser or burying it in landfills was an already established practice. However, ScottishPower, instead decided to investigate the potential of turning sludge into a dry fuel pellet, that could offer a renewable, low carbon substitute to coal at its power plants. 

Cement manufacturing fuel kilns

Daldowie was originally designed to supply fuel to Methil Power Station near Fife, which ran on coal slurry. However, it was decommissioned in 2000, before Daldowie could begin delivering fuel to it. This led the plant to instead provide fuel to Longannet Power Station where it was used to reduce its dependency on coal, before it too was decommissioned in 2016. 

Today Daldowie’s pellets are used in England and Scotland to fuel kilns in cement manufacturing – an industry attempting to navigate the same decarbonisation challenges as power generation which Daldowie was established to tackle.  

Though the end use of the fuel has changed, the process through which the facility transforms the waste remains the same.  

The process of turning waste to energy  

The process starts after wastewater from Glasgow and the surrounding area is treated by Scottish Water. Daldowie receives 90% of the sludge it processes directly via a pressurised sludge pipeline, the rest is delivered via sealed tanker lorries.   

When it arrives at Daldowie, the sludge is 98% water and 2% solid organic waste. It is first screened for debris before entering the plant’s 12 centrifuges, which act as massive spinning driers. These separate water from what is known as ‘sludge cake’, the semi-solid part of the sludge feedstock. This separated water is then cleaned so it can either be used elsewhere in the process or released into the nearby River Clyde. 

Membrane Tank at Daldowie fuel plant

The remaining sludge cake is dried using air heated to 450 degrees Celsius using natural gas (this also reduces germs through pasteurisation), while the rotating drums give the fuel granules their pellet shape. Once dried the pellets are cooled and inspected for quality. Any material not up to necessary standards is fed back into the system for reprocessing. Fuel that does meet the right standards is cooled further and then stored in silos.   

Where possible throughout the process, hot air and water are reused, helping keep costs down and ensuring the process is efficient.  

Nearly two decades into its life, very little has had to change in the way the plant operates thanks to these efficiencies. But while the process of turning the waste sludge into energy remains largely unchanged, there is, as always, room for new innovation.  

 Improving for the future of the site 

Daldowie is contracted to recycle wastewater for Scottish Water until 2026. To ensure the plant is still as efficient and effective as possible, the Daldowie team is undertaking a technical investigation of what, if anything, would be needed to extend the life of the plant for at least an additional five years. 

“The plant operates under the highest environmental and health and safety standards but further improvements are being planned in 2020.” Hughes explains, “We are upgrading the odour control equipment to ensure we have a best in class level of performance.  

The control room and plant operators at Daldowie

“Drax’s Scotland office, in Glasgow, is working with other industrial facilities in the area, as well as the Scottish Environmental Protection Agency (SEPA), to work with the local community. We are putting in place a series of engagement events, including plant tours from early 2020, offering local residents an opportunity to meet the local team and discuss the planned improvements.”    

There are also other potential uses for the fuel, including use at Drax Power Station. As the pellets are categorised as waste and biomass, it would require a new license for the power station.  

However, at a time when there is a greater need to reduce the impact of human waste and diversify the country’s energy, it would add another source of renewable fuel to Great Britain’s electricity mix that could help to enable a zero carbon, lower cost energy future.  

The men who built a power station inside a mountain

12 November 2019

Power generation
Cruachan tunnel tigers

Travelling through the Highlands towards the West Coast of Scotland, you pass the mighty Ben Cruachan – its 1,126 metre peak towers over the winding Loch Awe beneath. It is the natural world on a huge scale, but within its granite core sits a manmade engineering wonder: Cruachan Power Station.

Opened by The Queen in 1965, it is one of only four pumped-hydro stations in the UK and today remains just as impressive an engineering feat as when it was first opened.

Cruachan is operated safely and hasn’t had a lost time injury in 15 years. The robust health and safety policies and practices employed at the power station were not in place all those decades ago.

It took six years to construct, enlisting a 4,000-strong workforce who drilled, blasted and cleared the rocks from the inside of the mountain, eventually removing some 220,000 cubic metres of rubble. The work was physically exhausting – the environment dark and dangerous.

Nicknamed the ‘Tunnel Tigers’, the men that carried the work out came from far and wide, attracted to its ambition as well as a generous pay packet reflective of the danger and difficulty of the work. But few of them were fully prepared for the extent of the challenge.

One labourer, who started at Cruachan just after his 18th birthday, recalls: “I was in for a shock when I went down there. The heat, the smoke – you couldn’t see your hands in front of you.”

Inside the mountain

The work of hollowing out Ben Cruachan was realised by hand-drilling two-to-three metre deep holes into the granite rockface. An explosive known as gelignite, which can be moulded by hand, was packed into the drilled holes and detonated. The blasted rocks were removed by bulldozers, trucks and shovels, before drilling began on the fresh section of exposed granite. In total, 20km of tunnels and chambers were excavated this way, including the kilometre-long entrance tunnel and the 91-metre-long, 36-metre-high machine hall.

Wilson Scott was just 18 when he got a job working as a labourer at Cruachan while the machine hall was being cleared out.

“The gelignite, it had a smell. Right away I was told not to put it near your face,” he says, “It’ll give you a splitting headache and your eyes will close with the fumes that come off it. It was scary stuff.”

This process allowed for rapid expansion through the mountain. With three or four blasts each 12-hour shift, some 20 metres of rock could be cleared in the course of a day. Activity was constant, and to save the men having to make the journey back up to the surface, refreshments came to them.

“There was a bus that went down the tunnel at 11 o’clock with a huge urn of terrible tea,” says Scott. “Most of the windows were out of the bus because the pressure of the blasting had blown them in.”

The tea did little to make the environment hospitable, however. From the water dripping through the porous rocks making floors slippery and exposed electrics vulnerable, to the massive machinery rushing through the dense dust and smoke, danger was ever-present. Loose rocks as large as cars would often fall from exposed walls and ceilings while the regular blasting gave the impression the entire mountain was shaking.

“I’ll tell you something: going into that tunnel the first time,” Scott says. “It was a fascinating place, but quite a scary place too.

Above them, on top of the mountain, a similarly intrepid team tackled a different challenge: building the 316-metre-long dam. They may have escaped the hot and humid conditions at the centre of Cruachan, but their task was no less daunting.

Cruachan dam construction, early 1960s

Cruachan dam construction, early 1960s

On top of the dam

Out in the open, 400 metres above Loch Awe, the team were exposed to the harsh Scottish elements. John William Ross came to Cruachan at the age of 35 to work as a driver and spent time working in the open air of the dam. “You’d get oil skins and welly boots, and that was it. We didn’t have gloves, if your hands froze – well that’s tough luck isn’t it.” Mr Ross sadly passed away recently.

Charlie Campbell, a 19-year-old shutter joiner who worked on the dam found an innovative way around the cold. “You’d put on your socks, and then you’d get women’s tights and you’d put them over the top of the socks, and then you’d put your wellies on and that’d keep your feet a wee bit warmer. We thought it did anyway. Maybe it was just the thought of the women’s stockings.”

Pouring the concrete of the dam – almost 50 metres high at its tallest point – was precarious work, especially given the challenges of working with materials like concrete and bentonite (a slurry-like liquid used in construction).

“It was horrible stuff. It was like diarrhoea, that’s the only way of explaining it,” says Campbell. “There was a boy – Toastie – I can’t remember his real name. He fell into it. They had quite a job getting him out, they thought he was drowned, but he was alright.”

Many others were not alright. The danger of the work and conditions both inside and on top of the mountain meant there was a significant human cost for the project. During construction, 15 people tragically lost their lives.

Today a carved wooden mural hangs on the wall of the machine hall to capture and commemorate the myth of the mountain and the men who sadly died – a constant reminder of the bravery and sacrifice they made.

The men that made the mountain

The Cruachan ‘Tunnel Tigers’

The Tunnel Tigers were united in their efforts, but came from a range of backgrounds and cultures. Polish and Irish labourers worked alongside Scots, as well as displaced Europeans, prisoners of the second world war and even workers from as far as Asia. The men would work 12, sometimes 18-hour shifts, seven days a week. Campbell adds that some men opted to continue earning rather than rest by doing a ‘ghoster’, which saw them working a solid 36 hours.

Many men would make treble the salary of their previous jobs, with some receiving as much as £100 a week, at a time when the average pay in Scotland was £12. Some teams’ payslips were stamped with the words ‘danger money’ – illustrative of the men’s motivation to endure such life-threatening work.

While it was a dangerous and demanding job, many of the Tigers look back with fond memories of their time on the site and many stayed in the area for years after. “It was an experience I’m glad I had,” says Scott. “It puts you in good stead for the rest of your days.”

As for Cruachan Power Station, its four turbines are still relied on today by Great Britain to balance everyday energy supply. As the electricity system continues to change, the pumped hydro station’s dual ability to deliver 440 megawatts (MW) of electricity in just 30 seconds, or absorb excess power from the grid by pumping water from Loch Awe to its upper reservoir, is even more important than when it opened.

Standing at the foot of a mountain more than 50 years ago, the men about to build a power station inside a lump of granite may have found it unlikely their work would endure into the next millennium. They may have found it unlikely it was possible to build it at all. But they did and today it remains an engineering marvel, a testament to the effort and expertise of all those who made it.

Visit Cruachan – The Hollow Mountain

From coal to pumped hydro storage in 83 mountainous miles

7 October 2019

Power generation
Moving of transformers from Longanett to Cruachan

Nestled in in the Western Highlands in Scotland, Cruachan Power Station is surrounded by a breathtaking landscape of plunging mountainsides and curving lochs, between which weave narrow roads.

It makes for scenic driving. What might be trickier, however, is transporting 230 tonnes of electrical equipment up and down said mountains, navigating narrow bends.

But that’s exactly what a team from Drax was tasked with when it came to moving two 115 tonne transformers, the equipment used to boost electricity’s voltage. They were in storage 83 miles away at Longannet, currently being demolished, near Fife.

“You’re moving a piece of equipment that is designed to stay in one place. It’s not designed to go on the roads,” explains Jamie Beardsall, an Electrical Engineer from the EC&I Engineering team who worked on the project. “You’re very aware of your environment and the risks. Everything is checked and doubled checked.”

Transformers being driven to Drax’s Cruachan pumped storage hydro power station

The complicated task required colleagues from both Cruachan and Drax power stations to collaborate from the very beginning. Gary Brown, Mark Rowbottom and Jamie from the EC&I Engineering team based in Yorkshire teamed up with Gordon Pirie and Roddy Davies from Scotland who met frequently and planned the project alongside specialist transport contractor, ALE, which advised on heavy lifting and movement.

Planning and execution of the works also required constant liaison and coordination with the police and highway authorities in both Scotland and England. But more than that, the transformers’ one-by-one journey from the demolition site of what was once Europe’s biggest coal-fired power station, to a hydro-powered energy storage site on the other side of Scotland, represents the continual shift of Great Britain’s electricity away from fossil fuels.

Stepping up voltage

Transformers are an essential part of the electricity system. By increasing or decreasing the voltage of an electrical current they can enable it to traverse the national grid or make electricity safe to enter our homes.

“When we generate electricity, it is at a lower voltage than we need to send it out to the national grid,” says Beardsall. “We use transformers to increase the voltage so it can go out to the national grid and be transmitted over long distances more efficiently. We then reduce the voltage again so it can be brought safely into our homes.”

While all transformers apply the same principles for stepping voltage up and down, the two transformers that were transported through the Highlands to Cruachan were designed specifically for the pumped storage hydro power station, but stored at Longannet where there was more space. At the time, both stations where owned by Scottish Power. Cruachan was purchased by Drax on the last day of 2018.

Engineers at Cruachan Power Station in front of one of the original transformers

When transported, each transformer weighs 115 tonnes and is almost four metres high. Transporting them isn’t as simple as loading them into the back of a van.

“You can’t transport them in a fully built state, they would be too heavy and wouldn’t go under bridges,” says Beardsall. “We had to strip them back to the core and now we’re working to reassemble them on site.”

Cutting down to the core

Each transformer consists of two main components; a core made of iron, and two windings made of copper. The transformer itself has no moving parts. When a voltage is applied to one of the transformer windings (the primary winding), a magnetic field is created in the iron core. This field then induces a voltage into the other winding (the secondary winding). Depending on the number of coils on each set of windings, the output voltage will increase or decrease. More coils on the secondary winding steps the voltage up, fewer coils on the secondary steps the voltage down.

This entire apparatus is submerged in an oil to provide insulation and keep the transformer cool, meaning the first step was to drain 50,000 litres of oil from each transformer. This was then sent to a refinery to be processed, cleaned and stored until the transformers are reassembled at Cruachan.

Oil removed, the Drax engineers oversaw and managed the dismantling of the transformers at Longannet. Once the transformers were stripped down to a state suitable for movement, they were loaded up one-by-one for transportation.

Meanwhile, at Cruachan, engineers worked on construction of a purpose built bunded area for storage of the transformers. The transformers were destined to be stored on land outside the main admin buildings, adjacent to Loch Awe.

Loch Awe at Cruachan Power Station

The Loch itself is a beautiful place with abundant animal and birdlife – and a fish farm is located almost directly opposite the power station. In the event of a transformer leaking, the natural environment must be protected. An oil-tight storage area was therefore built, to ensure that no oil would end up in the Loch.

The road to Cruachan

Rather than heaving each of the transformers onto a trailer, each one was raised using hydraulic jacking equipment. A trailer was then driven underneath, and the transformer lowered onto it.

“The trailer is specifically designed to take the transformers and fit certain dimensions,” explains Beardsall. “It has 96 wheels over 12 sets of axles, each of which can be turned individually to assist in navigating around tight spots.”

The trailers are towed by large tractor units, each weighing over 40 tonnes. These provided the motive power to move the transformers. Each was moved in two stages over the space of two weeks. The first transformer over the course of a weekend, the second in the middle of the night some 10 days later.

“When we could go was governed by the police and highways agencies as they need to close the roads,” says Beardsall. “We set off from Longannet at 7pm on the Friday evening and moved them 60 miles along the route to a layby where we stored them. That leg took approximately five hours. Then the second leg was the last 25 miles to Cruachan, carried out on the Sunday morning of the same weekend.”

Navigating the Highlands with 115 tonnes of hugely valuable equipment is where the real challenge came in. Hills, dips and tight turns made for slow progress.

Generator transformer at Cruachan Power Station

The original generator transformer at Cruachan Power Station

“The average speed was about 10mph, but we’re going through the Highlands so it was quite a bit slower than that in some places. We occasionally hit 20+ mph at points, but that was definitely for the minority of the time!” says Beardsall. “Some of the roads were so narrow it was difficult to get two cars past each other. The contractors also had to put metal plating over bridges because they weren’t strong enough to take the load.”

Having safely arrived at Cruachan, the transformers are being stored at surface level until they are needed, at which time they will be taken down the half-a-mile-long tunnel into the energy storage station.

“Typically a transformer has a design life of 25 years, although they can last longer” explains Beardsall. “There are four units at Cruachan and the transformers for two of these units have already been replaced, so these transformers would be used to replace the existing transformer for the two remaining units should it ever be needed. The existing transformer having been in operation since 1965.”

Moving heavy objects is part and parcel of running Drax’s multiple power stations around the country. However, navigating the Highlands, the very terrain which makes Cruachan possible, added a unique challenge for Drax’s engineers.

Visit Cruachan Power Station – The Hollow Mountain

Read the press release

A brief history of Scottish hydropower

1 October 2019

Power generation

Over the last century, Scottish hydro power has played a major part in the country’s energy make up. While today it might trail behind wind, solar and biomass as a source of renewable electricity in Great Britain, it played a vital role in connecting vast swathes of rural Scotland to the power grid – some of which had no electricity as late as the 1960s. And all by making use of two plentiful Scottish resources: water and mountains.

But the road to hydro adoption has been varied and difficult, travelled on by brave death-defying construction workers, ingenious engineers and the inspirational leadership of a Scottish politician.

To trace where the history of Scottish hydropower began, we need to go back to the end of the 19th Century and to the banks of Loch Ness.

Loch Ness, Scottish Highlands

Loch Ness, Scottish Highlands

From abbeys to aluminium 

It was on the shores of Loch Ness that one of the first known hydro-electric schemes was built at the Fort Augustus Benedictine abbey. The scheme provided power to the monks living there as well as 800 village residents – though legend has it that their lights went dim every time the monks played their organ.

However, it was the British Aluminium Company, formed in 1894, that first realised the huge potential of Scotland’s steep mountains, lochs and reliably heavy rainfall to generate substantial amounts of hydro power. In need of a reliable source of electricity to help turn raw bauxite into aluminium, the firm established a hydro-electric plant and smelting works at Foyers and Loch Ness. Several similar schemes to support the aluminium industry soon appeared around the country.

But it took another 20 years for the first major hydro-power project to supply electricity to the public to emerge.

In 1926, the Clyde Valley Electrical Power Co. opened the Lanark Hydro Electric Scheme, which used energy from the River Clyde’s flow to create power. Now owned by Drax, it still has a generation capacity of 17 MW – enough to supply more than 15,000 homes.

River Clyde, Lanark

It was quickly followed by power stations at Rannoch and Tummel in the Grampian mountains and, in 1935, by what became a highly influential scheme in the history of Scottish hydro power at Galloway.

Drawing enough energy from local rivers to support five generating power stations, the project was the largest run-of-the-river scheme ever created. Architecturally, it also set the tone for later projects with stylised dams and modernist turbine halls.

A fairer share of power for the Highlands

The Galloway scheme supplied energy to a wide area, too, including parts of the central Highlands. Scottish Labour MP Tom Johnston, a staunch socialist and Scottish patriot saw how this new power source could provide massive benefits to northern communities. In the early 1940s, only an estimated one in six Scottish farms and one in a hundred small land crofts had electricity.

In 1941, Johnston became Scotland’s Minister for State with a vision, as he put it, to create “large-scale reforms that might mean Scotia Resurgent”. Expanding hydro power was a priority.

Tom Johnston MP

Two years later, he formed the North of Scotland Hydro-Electric Board (NSHEB). Its aim was to create several new schemes, including at Tummel and Loch Sloy, that would supply the national grid and bring electricity to more rural Scottish areas.

The projects were met with fierce opposition from landowners and local pressure groups who feared new dams and power stations would ruin the countryside and bring unwelcome industrialisation.

Public enquiries followed, but the board’s promises that the developments would be sensitive to the environment and bring cheap electricity in areas such as the Isle of Skye and Loch Ewe eventually won the day.

Thousands of local men, as well as German and Italian former prisoners of war, were drafted in to work on the projects.

Among the most courageous were workers known as ’Tunnel Tigers’ who blasted away rock using handheld drills and gelignite to create water channels and underground chambers, including at Drax’s Cruachan pumped storage hydro station.

Deaths caused by everything from blast injuries to fires were common. The men also had to cope with incessant rain and cold, and were housed in bleak military-style camps. With little to do in their spare time, besides drink, fights would break out regularly.

But the financial rewards were enormous, with wages up to ten times higher than labourers employed on Highland estates could expect.

Glenlee penstocks

The future takes shape

The board’s first small projects were completed in 1948 at Morar and Nostie Bridge, supplying electricity to areas including parts of Wester Ross. Catherine Mackenzie, a local widow, performed the Morar opening ceremony, reportedly declaring: “Let light and power come to the crofts.”

Bigger schemes were plagued by problems. Conveyor belts had to be built to transport stone across 1.75 miles of moor during construction at Sloy, for instance, and there were frequent stone and timber shortages.

But Sloy eventually opened in 1950, the largest conventional hydro electrical power station in Great Britain with an installed capacity of 128 MW. It would be followed by major schemes at Glen Affric and Loch Shin.

By the mid Sixties, the Board had built 54 main power stations and 78 dams. Northern Scotland was now 90% connected to the national grid. Hydro Board shops began popping up on high streets, selling appliances and collecting bill payments.

Tom Johnston died in 1965, aged 83. The Provost of Inverness declared: “No words can say how grateful we are.”

Cruachan Power Station

Loch Awe beside Cruachan Power Station

That same year, the world’s then largest reversible pumped storage power station opened at Cruachan. During times of low electricity demand, its turbines pump water from Loch Awe to the reservoir above. When demand rises, the turbines reverse, and water flows down to generate power. A similar scheme opened at Foyes in 1974.

Glendoe, near Loch Ness, was the most-recent major hydro scheme to be built. Opening in 2009, it has a generation capacity of 100 MW.

There are plans for a pumped storage scheme at Coire Glas, with a storage capacity of 30 GWh– more than doubling Great Britain’s current total pumped storage capacity. Drax’s Cruachan Power Station could also be expanded.

In recent years, however, the real growth has been in smaller hydro-electric schemes that may power just one or a handful of properties – with more than 100 MW of such generation capacity installed in the Highlands since 2006.

Boosting the environment and economy

Scotland now provides 85% of Great Britain’s hydro-electric resource, with a total generation capacity of 1,500 MW. Improved power supplies have attracted more industry to the Highlands, without seriously altering its character. And access roads created during hydro-power schemes’ construction have opened up remote areas to tourism.

For many, the dams built by NSHEB are among the greatest construction achievements in post-war Europe and remain an essential part of Great Britain’s attempts to move towards a low-carbon energy future.

How will 5G revolutionise the world of energy and communications?

30 August 2019

Electrification
Smart cellular network antenna base station on the telecommunication mast on the roof of a building.

What should be made of the 5G gap? It’s the difference between what some commentators are expecting to happen thanks to this new technology and what others perhaps more realistically believe is possible in the near future.

What we call 5G is the fifth generation of mobile communications, (following 4G, 3G, etc.). It promises vastly increased data download and upload speeds, much improved coverage, along with better connectivity. This will bring with it lower latency – potentially as low as one millisecond, a 90 per cent reduction on the equivalent time for 4G – and great news for traders and gamers, along with lower unit costs.

Trading desk at Haven Power, Ipswich

The latest estimates predict that 5G will have an economic impact of $12 trillion by 2035 as mobile technology changes away from connecting people to other people and information, and towards connecting us to everything.

Some experts believe the effects of 5G will be enormous and almost instantaneous, transforming the way we live. It will have a huge effect on the internet of things, for instance, making it possible for us to live in a more instant, much more connected world with more interactions with ‘smart objects’ every day. Driverless cars that ‘talk’ to the road and virtual and augmented reality to help us as we go could become part of our everyday lives.

Others see 5G as a revolution that will begin almost immediately, but which could take many years to materialise. The principal reason for this is the sheer level of investment required.

The frequencies being used to carry the signal from the proposed 5G devices can provide an enormous amount of bandwidth, and carry unimaginable amounts of data at incredible speeds. But they cannot carry it very far. And the volume of devices connected to this network will be enormous. The BBC estimates that between 50 and 100 billion devices will be connected to the internet by 2020 – more than 12 for every single person on Earth.

So in order to support the huge increase in connectivity that is anticipated a reality, there will be a need for a comparably large increase in the number of base stations – with as many as 500,000 more estimated to be needed in the UK alone. That’s around three times as many base stations as required for 4G.

To carry the amount of data anticipated without catastrophic losses in signal quality will require the stations to be no more than 500m apart. While that may be technically possible in cities, it will only happen as a result of huge amounts of investment. And what will happen in the countryside, with its lower population density? It seems doubtful in the extreme that any corporation will regard it as a potentially profitable business decision to build a network of base stations half a kilometre apart in areas where few of their customers live. And that’s without taking into account the town and country planning system or the views of residents, who may not welcome new base stations near their homes.

Until this year, the only two workable examples of functional 5G networks are one built by Samsung in Seoul, South Korea, and another by Huawei in Moscow in advance of the 2020 Football World Cup. Although the first UK mobile networks have now begun to offer the new communications standard, 5G is still clearly a long way from being able to deliver on its potential.

What will 5G mean for the world of energy?

A report from Accenture contains a number of predictions about how 5G may change the energy world by helping to increase energy efficiency overall and accelerating the development of the Smart Grid.

  1. 5G uses less power than previous generations of wireless technology

This means that less energy will be used for each individual connection, which will take less time to complete than with 4G devices, thereby saving energy and ultimately money too. It is important to remember that even though such savings will be significant, they will need to be offset against the huge global increase in communications through 5G-connected devices.

  1. Accelerating the Smart Grid to improve forecasting

5G has the potential to help us manage energy generation and transmission more efficiently, and therefore more cost-effectively.

The report’s authors anticipate that “By allowing many unconnected energy-consuming devices to be integrated into the grid through low-cost 5G connections, 5G enables these devices to be more accurately monitored to support better forecasting of energy needs.

  1. Improve demand side management and reduce costs

 “By connecting these energy-consuming devices using a smart grid, demand-side management will be further enhanced to support load balancing, helping reduce electricity peaks and ultimately energy costs.”

  1. Manage energy infrastructure more efficiently and reduce downtime

By sharing data about energy use through 5G connections, the new technology can help ensure that spending on energy infrastructure is managed more efficiently, based on data, in order to reduce the amount of downtime.

And in the event of any failure, smart grid technology connected by 5G will be able to provide an instant diagnosis – right to the level of which pylon or transmitter is the cause of an outage – making it easier to remedy the situation and get the grid up and running again.

5G could even help turn street lighting off at times when there are no pedestrians or vehicles in the area, again reducing energy use, carbon emissions, and costs. Accenture estimate that in the US alone, this technology has the potential to save as much as $1 billion every year.

More data, more power

Although 5G devices themselves may demand less power than the telecoms technology it they will eventually replace, that doesn’t tell the whole story.

More connected devices with more data flowing between them relies on more data centres. This has led some data centres to sign Power Purchase Agreements to both reduce the cost of their insatiable desire for electricity and also ensure its provenance.

Data centre

As well as data centres, the more numerous base stations needed for 5G will consume a lot of power. One global mobile network provider says just to operate its existing base stations leads to a £650m electricity bill annually, accounting for 65% of its overall power consumption.

Base station tower

Contrary to the findings of the Accenture report, a recent estimate has put the power requirement of an individual 5G base station at three times that of a 4G. Keeping in mind that three of these are needed for every existing base station, the analysis by Zhengmao Li of China Mobile, suggests a nine-fold increase in electricity consumption just for that key part of a 5G network.

With the Great Britain power system decarbonising at a rapid pace, the additional power required to electrify the economy with new technologies shouldn’t have a negative environmental impact – at least when it comes to energy generation.

However, as we use ever-more powerful and numerous devices, we need to ensure our power system has the flexibility to deliver electricity whatever the weather conditions. This means a smarter grid with more backup power in the form of spinning turbines and storage.

In energy storage timing is everything

21 August 2019

Power generation
Cruachan Power Station

Electricity is unlike any other resource. The amount being generated must exactly match demand for it, around the clock.

Managing this delicate balancing act is the job of the National Grid Electricity System Operator (ESO), which works constantly to ensure supply meets demand and the grid remains balanced. One of the ways it does this is by storing energy when there is too much and deploying it when there is too little.

Although there are many different ways of storing energy at a small scale, at grid level it becomes more difficult. One of the few ways it is currently possible is through pumped hydro storage. Cruachan Power Station in the Highlands of Scotland is one of four pumped storage facilities in Great Britain. It uses electrically-driven turbines to pump water up a mountain into a reservoir when there is excess electricity on the grid, and then releases the water stored in the reservoir back down, to spin the same turbines to generate power when it’s needed quickly.

The dual capabilities of these turbines are unique to pumped hydro storage and contribute to the overall grid’s stability. However, what dictates when Cruachan’s turbines switch from pump to generate and vice versa is all a matter of what the grid needs – and when.

The switch from pump to generate

While the machine hall of Cruachan Power Station is an awe-inspiring place for its size and location 396 metres beneath Ben Cruachan, it generates electricity much like any other hydropower station: harnessing the flow of water to rotate any number of its four 100+ megawatt (MW) turbines.

This mode – simply called ‘generate mode’ – is usually employed during periods of peak power demand such as mornings and evenings, during a major national televised event, or when wind and solar energy output drops below forecast. As a result, starting up and generating millions of watts of electricity has to be fast.

“It takes just two minutes for a turbine to run up from rest to generate mode,” says Martin McGhie, Operations and Maintenance Manager at the power station. “It takes slightly longer for the turbines to run down from generate to rest, but whatever function the turbines are performing, they can reach it within a matter of minutes.”

The reverse of generate mode is pump mode, which changes the direction of travel for the water, this time using electricity from the grid to pump water from the vast Loch Awe at the foot of Ben Cruachan to the upper reservoir, where it waits ready to be released.

In contrast to generate mode, pump mode typically comes into play at times when demand is low and there is too much power on the system, such as during nights or at weekends, when there is excessive wind generation. However, the grid has evolved since Cruachan first began generating in 1965 and this has changed when it and how it operates.

“In the early days, Cruachan was used in a rather predictable way: pumping overnight to absorb excess generation from coal and nuclear plants and generating during daytime peak periods,” says Martin. “The move to more renewable energy sources, like wind, mean overall power generation is more unpredictable.”

He continues: “There has also been a move from Cruachan being primarily an energy storage plant to one which can also offer a range of ancillary services to the grid system operator.”

The benefits of Spin mode

In between pumping water and generating power, Cruachan’s turbines can also spin in air while connected to the grid, neither pumping not generating. This is essentially a ‘standby mode’ where the turbines are ready to either quickly switch into generation or pumping at a moment’s notice (they spin one way for ‘spin pump’; the other for ‘spin generate’). These spin modes are requested by the ESO to ensure reserve energy is available to respond rapidly to changes on the grid system.

In spin generate mode, the generator is connected up to the grid but the water is ejected from the space around the turbine by injecting compressed air. The turbine does not generate power but is kept spinning, allowing it to quickly start up again. As soon as the grid has an urgent need for power, the air is released and the water from the upper reservoir flows into the turbine to begin generation in under 30 seconds.

Spin pump works on the same basis as spin generate, but with the turbine rotating in the opposite direction, ready to pump at short notice. This allows Cruachan to absorb excess generation and balance the system as soon as the ESO needs it.

“The use of spin mode by the ESO is highly variable and dependant on a number of factors e.g. weather conditions or the state of the grid system at the time” says Martin. This unpredictability of the increasingly intermittent electricity system makes the flexibility of Cruachan’s multiple turbines all the more important.

Ready for the future grid

It’s not only the types of electricity generation around the system that are changing how Cruachan operates. Martin suggests that the way energy traders and the ESO use Cruachan will continue to evolve as the market requirements and opportunities change.

Technology is also changing the market and Martin predicts this could affect what Cruachan does. “In the future we will face competition from alternative storage technologies, such as batteries, electric vehicles, as well as competition for the other ancillary services we offer.”

However, Cruachan’s flexibility to generate, absorb or spin in readiness means it is prepared to adjust to any future changes.

“Cruachan is always ready to modify or upgrade to meet requirements, as we have done in the past,” says Martin. “The priority is always to be able to deliver the services required by the grid system operator – in characteristic quick time.”

Visit Cruachan — The Hollow Mountain to take the power station tour.

Read our series on the lesser-known electricity markets within the areas of balancing services, system support services and ancillary services. Read more about black start, system inertia, frequency response, reactive power and reserve power. View a summary at The great balancing act: what it takes to keep the power grid stable and find out what lies ahead by reading Balancing for the renewable future.

What is LNG and how is it cutting global shipping emissions?

5 July 2019

Sustainable business
Oil tanker, Gas tanker operation at oil and gas terminal.

Shipping is widely considered the most efficient form of cargo transport. As a result, it’s the transportation of choice for around 90% of world trade. But even as the most efficient, it still accounts for roughly 3% of global carbon dioxide (CO2) emissions.

This may not sound like much, but it amounts to 1 billion tonnes of CO2 and other greenhouse gases per year – more than the UK’s total emissions output. In fact, if shipping were a country, it would be the sixth largest producer of greenhouse gas (GHG) emissions. And unless there are drastic changes, emissions related to shipping could increase from between 50% and 250% by 2050.

As well as emitting GHGs that directly contribute towards the climate emergency, big ships powered by fossil fuels such as bunker fuel (also known as heavy fuel oil) release other emissions. These include two that can have indirect impacts – sulphur dioxide (SO2) and nitrogen oxides (NOx). Both impact air quality and can have human health and environmental impacts.

As a result, the International Maritime Organization (IMO) is introducing measures that will actively look to force shipping companies to reduce their emissions. In January 2020 it will bring in new rules that dictate all vessels will need to use fuels with a sulphur content of below 0.5%.

One approach ship owners are taking to meet these targets is to fit ‘scrubbers’– devices which wash exhausts with seawater, turning the sulphur oxides emitted from burning fossil fuel oils into harmless calcium sulphate. But these will only tackle the sulphur problem, and still mean that ships emit CO2.

Another approach is switching to cleaner energy alternatives such as biofuels, batteries or even sails, but the most promising of these based on existing technology is liquefied natural gas, or LNG.

What is LNG?

In its liquid form, natural gas can be used as a fuel to power ships, replacing heavy fuel oil, which is more typically used, emissions-heavy and cheaper. But first it needs to be turned into a liquid.

To do this, raw natural gas is purified to separate out all impurities and liquids. This leaves a mixture of mostly methane and some ethane, which is passed through giant refrigerators that cool it to -162oC, in turn shrinking its volume by 600 times.

The end product is a colourless, transparent, non-toxic liquid that’s much easier to store and transport, and can be used to power specially constructed LNG-ready ships, or by ships retrofitted to run on LNG. As well as being versatile, it has the potential to reduce sulphur oxides and nitrogen oxides by 90 to 95%, while emitting 10 to 20% less CO2 than heavier fuel alternatives.

The cost of operating a vessel on LNG is around half that of ultra-low sulphur marine diesel (an alternative fuel option for ships aiming to lower their sulphur output), and it’s also future-proofed in a way that other low-sulphur options are not. As emissions standards become stricter in the coming years, vessels using natural gas would still fall below any threshold.

The industry is starting to take notice. Last year 78 vessels were fitted to run on LNG, the highest annual number to date.

One company that has already embraced the switch to LNG is Estonia’s Graanul Invest. Europe’s largest wood pellet producer and a supplier to Drax Power Station, Graanul is preparing to introduce custom-built vessels that run on LNG by 2020.

The new ships will have the capacity to transport around 9,000 tonnes of compressed wood pellets and Graanul estimates that switching to LNG has the potential to lower its CO2 emissions by 25%, to cut NOx emissions by 85%, and to almost completely eliminate SO2 and particulate matter pollution.  

Is LNG shipping’s only viable option?

LNG might be leading the charge towards cleaner shipping, but it’s not the only solution on the table. Another potential is using advanced sail technology to harness wind, which helps power large cargo ships. More than just an innovative way to upscale a centuries-old method of navigating the seas, it is one that could potentially be retrofitted to cargo ships and significantly reduce emissions.

Drax is currently taking part in a study with the Smart Green Shipping Alliance, Danish dry bulk cargo transporter Ultrabulk and Humphreys Yacht Design, to assess the possibility of retrofitting innovative sail technology onto one of its ships for importing biomass.

Manufacturers are also looking at battery power as a route to lowering emissions. Last year, boats using battery-fitted technology similar to that used by plug-in cars were developed for use in Norway, Belgium and the Netherlands, while Dutch company Port-Liner are currently building two giant all-electric barges – dubbed ‘Tesla ships’ – that will be powered by battery packs and can carry up to 280 containers.

Then there are projects exploring the use of ammonia (which can be produced from air and water using renewable electricity), and hydrogen fuel cell technology. In short, there are many options on the table, but few that can be implemented quickly, and at scale – two things which are needed by the industry. Judged by these criteria, LNG remains the frontrunner.

There are currently just 125 ships worldwide using LNG, but these numbers are expected to increase by between 400 and 600 by 2020. Given that the world fleet boasts more than 60,000 commercial ships, this remains a drop in the ocean, but with the right support it could be the start of a large scale move towards cleaner waterways.

What is a fuel cell and how will they help power the future?

27 June 2019

Carbon capture

How do you get a drink in space? That was one of the challenges for NASA in the 1960s and 70s when its Gemini and Apollo programmes were first preparing to take humans into space.

The answer, it turned out, surprisingly lay in the electricity source of the capsules’ control modules. Primitive by today’s standard, these panels were powered by what are known as fuel cells, which combined hydrogen and oxygen to generate electricity. The by-product of this reaction is heat but also water – pure enough for astronauts to drink.

Fuel cells offered NASA a much better option than the clunky batteries and inefficient solar arrays of the 1960s, and today they still remain on the forefront of energy technology, presenting the opportunity to clean up roads, power buildings and even help to reduce and carbon dioxide (CO2) emissions from power stations.

Power through reaction

At its most basic, a fuel cell is a device that uses a fuel source to generate electricity through a series of chemical reactions.

All fuel cells consist of three segments, two catalytic electrodes – a negatively charged anode on one side and a positively charged cathode on the other, and an electrolyte separating them. In a simple fuel cell, hydrogen, the most abundant element in the universe, is pumped to one electrode and oxygen to the other. Two different reactions then occur at the interfaces between the segments which generates electricity and water.

What allows this reaction to generate electricity is the electrolyte, which selectively transports charged particles from one electrode to the other. These charged molecules link the two reactions at the cathode and anode together and allow the overall reaction to occur. When the chemicals fed into the cell react at the electrodes, it creates an electrical current that can be harnessed as a power source.

Many different kinds of chemicals can be used in a fuel cell, such as natural gas or propane instead of hydrogen. A fuel cell is usually named based on the electrolyte used. Different electrolytes selectively transport different molecules across. The catalysts at either side are specialised to ensure that the correct reactions can occur at a fast enough rate.

For the Apollo missions, for example, NASA used alkaline fuel cells with potassium hydroxide electrolytes, but other types such as phosphoric acids, molten carbonates, or even solid ceramic electrolytes also exist.

The by-products to come out of a fuel cell all depend on what goes into it, however, their ability to generate electricity while creating few emissions, means they could have a key role to play in decarbonisation.

Fuel cells as a battery alternative

Fuel cells, like batteries, can store potential energy (in the form of chemicals), and then quickly produce an electrical current when needed. Their key difference, however, is that while batteries will eventually run out of power and need to be recharged, fuel cells will continue to function and produce electricity so long as there is fuel being fed in.

One of the most promising uses for fuel cells as an alternative to batteries is in electric vehicles.

Rachel Grima, a Research and Innovation Engineer at Drax, explains:

“Because it’s so light, hydrogen has a lot of potential when it comes to larger vehicles, like trucks and boats. Whereas battery-powered trucks are more difficult to design because they’re so heavy.”

These vehicles can pull in oxygen from the surrounding air to react with the stored hydrogen, producing only heat and water vapour as waste products. Which – coupled with an expanding network of hydrogen fuelling stations around the UK, Europe and US – makes them a transport fuel with a potentially big future.

 

Fuel cells, in conjunction with electrolysers, can also operate as large-scale storage option. Electrolysers operate in reverse to fuel cells, using excess electricity from the grid to produce hydrogen from water and storing it until it’s needed. When there is demand for electricity, the hydrogen is released and electricity generation begins in the fuel cell.

A project on the islands of Orkney is using the excess electricity generated by local, community-owned wind turbines to power a electrolyser and store hydrogen, that can be transported to fuel cells around the archipelago.

Fuel cells’ ability to take chemicals and generate electricity is also leading to experiments at Drax for one of the most important areas in energy today: carbon capture.

Turning CO2 to power

Drax is already piloting bioenergy carbon capture and storage technologies, but fuel cells offer the unique ability to capture and use carbon while also adding another form of electricity generation to Drax Power Station.

“We’re looking at using a molten carbonate fuel cell that operates on natural gas, oxygen and CO2,” says Grima. “It’s basic chemistry that we can exploit to do carbon capture.”

The molten carbonate, a 600 degrees Celsius liquid made up of either lithium potassium or lithiumsodium carbonate sits in a ceramic matrix and functions as the electrolyte in the fuel cell. Natural gas and steam enter on one side and pass through a reformer that converts them into hydrogen and CO2.

On the other side, flue gas – the emissions (including biogenic CO2) which normally enter the atmosphere from Drax’s biomass units – is captured and fed into the cell alongside air from the atmosphere. The CO2and oxygen (O2) pass over the electrode where they form carbonate (CO32-) which is transported across the electrolyte to then react with the hydrogen (H2), creating an electrical charge.

“It’s like combining an open cycle gas turbine (OCGT) with carbon capture,” says Grima. “It has the electrical efficiency of an OCGT. But the difference is it captures CO2 from our biomass units as well as its own CO2.”

Along with capturing and using CO2, the fuel cell also reduces nitrogen oxides (NOx) emissions from the flue gas, some of which are destroyed when the O2and CO2 react at the electrode.

From the side of the cell where flue gas enters a CO2-depleted gas is released. On the other side of the cell the by-products are water and CO2.

During a government-supported front end engineering and design (FEED) study starting this spring, this CO2 will also be captured, then fed through a pipeline running from Drax Power Station into the greenhouse of a nearby salad grower. Here it will act to accelerate the growth of tomatoes.

The partnership between Drax, FuelCell Energy, P3P Partners and the Department of Business, Energy and Industrial Strategy could provide an additional opportunity for the UK’s biggest renewable power generator to deploy bioenergy carbon capture usage and storage (BECCUS) at scale in the mid 2020s.

From powering space ships in the 70s to offering greenhouse-gas free transport, fuel cells continue to advance. As low-carbon electricity sources become more important they’re set to play a bigger role yet.

Learn more about carbon capture, usage and storage in our series: