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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.

The UK’s secret economic juggernaut: the North

The North of England is home to some 15 million people. This makes up almost a quarter of the UK’s total population, and includes a mesh of proud local identities.

Compared to the rest of the UK, however, there is a persistent gap in GVA (gross value added) per capita and productivity performance. Analysis by the Treasury claimed that if the North’s economy grew as quickly as the UK average to 2030, its economic output would be £37 billion higher in real terms. There’s huge potential in North, but it needs the right support to unlock it.

The Northern Powerhouse Partnership is a business-led organisation aiming to do just that. In a new report, Powerhouse 2050: Transforming the Northit explores four areas of the economy, originally identified in the Northern Powerhouse Independent Economic Review, where the North has the potential to be a world leader within the next 33 years.

Given the right cooperation between business, university and government investment, these four sectors could create 850,000 more jobs and contribute an extra £100 billion to the UK economy by 2050.

New extra large press starts production at Nissan Sunderland, via Nissan Europe Newsroom

Advanced manufacturing and materials

The North has a strong history in manufacturing, from traditional steel production in Sheffield to shipbuilding in Hull. The region is currently home to several car manufacturing plants, including Vauxhall, Jaguar Land Rover and Nissan.

Building on this pedigree, the North’s real strengths lie in its ability to improve processes and productivity, as well as the development of new products.

Two key areas where it could be a world leader heading into 2050, are new lightweight and 2D materials, as well as high-precision engineering. Close connections between research institutions and manufacturing industries will help provide businesses in the region with access to cutting edge technology and the highly-skilled workforce needed to operate it. 

Siemens and Drax engineers worked together to upgrade turbines at Drax Power Station. The five-year, £100m project was completed in 2012 [find out more]

Energy

The North has a long history of powering the UK and today still generates 41% of England’s electricity. Building on this strength in the field, the region has the potential to evolve into a world leader in the modern, low-carbon energy sector, through the repurposing of existing infrastructure, such as Drax Power Station’s transition from coal to biomass fuel.

“The North is uniquely placed to deliver the UK’s energy needs,” said Drax Power CEO Andy Koss. “There are huge opportunities for us as a region – not just in terms of potential jobs and the economic benefits, but also the positive environmental impacts associated with decarbonisation.”

Electricity generation, storage and low carbon technologies including nuclear, offshore wind and bioenergy are already well established in the North. However, there are also opportunities to re-use existing infrastructure, such as ‘greening’ the gas grid in Leeds by converting it to low carbon hydrogen. 

Digital

The digital and tech sectors are often seen as a major driver for well-paid jobs that can drive national productivity and the wider economy. And while London remains the central hub for venture capital funding and high-profile startups, a report by Tech Nation found almost 70% of total investment in tech went to companies outside the capital in 2016.

This includes £78 million raised by Manchester tech businesses and £61 million invested in Sheffield companies. In fact, the wider digital sector, from adtech to fintech, now employs 168,671 people across city clusters in the North.

This is a strong base from which to grow the region’s tech and digital scene, which will be supported by initiatives such as the £400 million Northern Powerhouse Investment Fund and the £30 million for the region’s new National Innovation Centre for Data. 

Health innovation

The North has long-established strengths in fields such as life sciences, medical technologies and devices. These include pharmaceutical and medical device manufacturing hubs across the region.

What makes the UK unique in the health innovation space is its ability to leverage the National Health Service as an asset for research, innovation and in developing new models of healthcare delivery – and the North is no different. This collaboration can allow companies and institutions in the field to sit at the forefront of implementing and developing treatments, medicines and devices for the 21st century.

The future of health innovation will be closely connected to tech fields of big data and AI and these, along with other types of research will require close collaboration between businesses, the NHS and the regions’ universities.

Within the relatively small UK, the North may still be a small part, often eclipsed by the country’s capital. But as the report shows, there is not only huge potential yet to be realised, but a strong history on which to build.

Longleaf Pine: how wood product markets help to conserve a protected species

Longleaf pine forests were once a dominant ecosystem across the Southern US’ Gulf and Atlantic states, spanning from the east coast in Virginia as far west as Texas. However, centuries of overuse and conversion to agriculture and to faster growing pine species mean today less than 5% of the estimated 90 million acres remain.

Restoration of the longleaf pine savanna is now underway and the careful management of both public and private forests is key to preserving this ecosystem. Wood product and biomass markets play an important role in this, ensuring there is an economic incentive for landowners to plant high-value longleaf pines and manage them in a way that promotes conservation.

An ecosystem shaped by fire

The ancient abundance of longleaf pines across the southern US owes to their highly pyrophytic nature, meaning they are resistant to fire. This allowed the trees to survive both the naturally occurring forest fires from summer thunderstorms and those started as land management by native Americans. These regular fires help give the longleaf savanna its distinctive features, with a limited canopy providing ample sunlight and allowing grasses and herbs to grow in the nitrogen-rich soil.

As colonial settlements expanded across North America, the long straight timber offered by the pines, as well as the resin and turpentine, made these forests a valuable resource. Longleaf pine ecosystems reached a depleted state.

The restoration push

Today, America’s Longleaf Restoration Initiative (ALRI) is taking strides to restore the species. The collaborative effort between public and private sector partners has set a 15-year goal of increasing longleaf acreage from 3.4 million to 8.0 million acres by 2025. 

These ecosystems are currently home to an estimated 900 endemic plants and 29 federally listed species including the red-cockaded woodpecker, gopher tortoise and indigo snake.

Restoring the environment in which the flora and fauna can flourish is not as simple as planting large numbers of longleaf pine trees.

“Conservation efforts must focus on not only the planting of the pine, but also the restoration, development, and maintenance of the pine savanna ecosystem,” says Kyla Cheynet, a forest ecologist at Drax Biomass. “This system requires predictable disturbance to maintain the open canopy and rich herbaceous vegetation.”

The role of the wood product market

These disturbances include prescribed fires and the careful harvesting of trees to ensure the landscape maintains its open canopy that allows plenty of sunlight to reach the grasses and other vegetation along the forest floor.

The ALRI’s 2016 report highlighted the importance of thinning and prescribed fires in conserving longleaf savanna. It found that while new planting of longleaf pines declined slightly (8%) from 2015, the wildlife quality, plant diversity and overall health of forests improved by removing competing tree species and allowing more sunlight to enter the forest.

Harvesting or thinning longleaf pine forests provides a small percentage of the fibre used to manufacture compressed wood pellets used at Drax Power Station, but these markets help to incentivise responsible forest management and offer a source of profit for landowners. These revenue-generating practices are crucial to ensuring the continued survival of longleaf pine forests by preventing them from being converted to agricultural land or lost to development.

How artificial intelligence will change energy

At the beginning of 2016, the world’s most sophisticated artificial intelligence (AI) beat World Champion Lee Sedol at a game called ‘Go’ – a chess-like board game with more move combinations than there are atoms in the universe. Before this defeat, Go had been considered too complicated for even the most complex computers to beat the top humans.

It was a landmark moment in the development of ever-more sophisticated AI technology. But the future of AI holds more than simply board game victories. It is rapidly finding its way into all aspects of modern life, prompting the promise of a ‘Fourth Industrial Revolution’.

One of the areas AI has huge potential is in our energy system. And this could have implications for generators, consumers and the environment.

Artificial intelligence playing traditional board game Go concept

The National Grid gets wise

Earlier this year the UK’s National Grid revealed it’s making headway in integrating AI technology into Britain’s electricity system. It announced a deal with Google-owned AI company (and creator of the Go Champion-beating system) DeepMind which is set to improve the power network’s transmission efficiency by as much as 10%.

One of the National Grid’s most important tasks is maintaining the frequency of Britain’s power networks to within ±1% of 50Hz. Too high a frequency and electrical equipment gets damaged; too low a frequency and you get blackouts. Managing this relies on ensuring electricity supply and demand are carefully balanced. But this is made increasingly difficult with the growing number of intermittent renewables – such as wind and solar – on the grid.

The ability to process massive amounts of information from a wide variety of data points (from weather forecasts to internet searches to TV listings) and create predictive models means AI can pre-empt surges in demand or instances of oversupply. In short, it can predict when the country will need more power and when it will need less.

More than this, it can respond to these fluctuations in sustainable and low-carbon ways. For example, it can automate demand side response, where energy users scale back their usage at peak times for a reward. Similarly, it can automate the purchasing of power from battery systems storing renewable energy, such as those connected to domestic solar arrays.

These solutions, which would see AI help to manage supply and demand imbalances, would ease some grid management pressures, while large thermal generators controlled by human engineers back up such automation with their continuing focus on maintaining grid stability through ancillary services.

The role of the smart city

An undoubtedly large factor in the growing sophistication of AI in the energy space is the amount of energy use data now being captured. And this has much to do with the increasing prevalence of smart devices and connected technology.

Smart meters – which will be offered to every UK home by 2020 – such as Alphabet’s Nest smart thermostat, and start-up Verdigris’s energy conserving Internet of Things (IoT) devices are just a few of the emerging technologies using data to improve individuals’ abilities to monitor and optimise their household energy use.

But at scale, information collected from these devices can be used by AI to help control energy distribution and efficiency across entire cities – and not just at a macro level, but right down to individual devices.

The idea of a central computer controlling home utilities may seem like a soft invasion of privacy to some, but when it comes to the energy-intensive function of charging electric vehicles (EVs), much of this optimisation will be carried out in public on street charge points.

As AI and smart technology continue to grow more sophisticated, it has the potential to do more than just improve efficiency. Instead, it could fundamentally change consumers’ relationships with energy.

Changing consumer relationships with energy

Start-ups in the energy space, such as Seattle-based Drift, are exploring how trends such as peer-to-peer services and automated trading can be enabled through machine AI and give consumers greater control over their energy for a lower price.

The company offers consumers access to its own network of distributed and renewable energy sources. Currently operating in New York, it uses AI to assess upcoming energy needs based on data collected from individual customers and location-specific weather forecasts. It then uses this to buy power from its network of peer-to-peer energy providers, using high-frequency, algorithmic trading to reduce or eliminate price spikes if demand exceeds expectation.

Yet to be operational in the UK, this sort of automation and peer-to-peer energy supply hints at the increasing decentralisation of energy grids, which are moving away from relying only on a number of large generators. Instead, modern grids are likely to rely on a mix of technologies, generators and suppliers. And this means a more complex system, which is precisely why automation from a central AI system could be a positive step.

Not only could it bring about optimisation and efficiency, but it could slash emissions and costs for consumers. This silent automation may not have the same headline-grabbing qualities as beating a world champion in their chosen sport, but its impact to the country could be far greater.

Inertia: the shock absorbers keeping the grid stable

From the comfort of home, it’s easy to assume Britain’s power is run across a consistently calm and stable system. And while this is for the most part true, keeping it this way relies on a set of carefully calibrated and connected tools.

These include frequency response – which keeps all electricity around the country on the same frequency – and reactive power – the quiet force moving electricity around the grid. But there’s another at play, and at least by name, it’s something you’ve probably heard of: inertia.

System inertia is energy stored in spinning plant that slows down the rate at which frequency changes. Rapid changes in frequency can create instability in the system. Think of it like a car – inertia does the same job as shock absorbers in the suspension, smoothing the sudden bumps and potholes, keeping the wheels on the ground to maintain control.

However, the changing nature of Britain’s energy system is creating challenges in ensuring there is enough inertia available for a stable future grid.

The energy system’s shock absorbers

Inertia describes objects’ natural tendency (whether they’re moving or resting) to keep doing what they’re doing until forced to change. For example, when you kick a pebble, forces like friction and gravity prevent it hurtling endlessly off into the distance.

Electricity generation in thermal power stations such as Drax involves many moving parts, none more important than turbines and generators. In a turbine, high pressure steam hits a set of blades which makes it spin. A little like running a fan in reverse. The spinning motion is used to power the generator which is a rotor wound in electrified copper wire, transforming it into an electro magnet. As this magnetic field passes through copper bars surrounding the rotor it generates electricity.

This spinning turbine has inertia. If the fuel powering it is suddenly switched off it will continue to spin until it is stopped either by friction or by force. Every thermal generator in the UK system spins at 3,000 rpm, has inertia, and generates electricity at a frequency of 50 Hz. In the UK, all electricity is generated at the same frequency and crucially needs to remain stable – even deviations of 1% from this can damage equipment and cause blackouts.

Managing frequency is done by managing generation. If demand exceeds supply, frequency falls; too much supply and frequency rises. National Grid closely monitors frequency across the system and automatically instructs power generators like Drax to respond to changes in frequency by dialing up or down generation.

And ensuring this change in generation is done smoothly and instantaneously relies on using inertia. For example, using the inertial forces of spinning generators, power stations are able to respond instantly to requests to alter generation.

So, inertia is important to the stability of the power system. But because of the changing nature of today’s grid, we are facing challenges when it comes to inertia. Many forms of renewable generation aren’t built around spinning turbines. And this means no inertia.

Future Challenges

Renewable sources like the wind turbines currently operational in the UK and solar PV, alongside energy imported from the continent, do not provide inertia to the grid.

This means as the UK moves to decarbonise the energy system and rely on more intermittent and often embedded renewable energy rather than thermal-generated electricity, questions arise over where the grid will get the inertia needed to remain stable.

One possible solution is synthetic inertia. While wind turbines do not contain inherit inertia, modern suppliers are now enabling the machine’s rotating blades to create synthetic inertia, which can add extra power to the grid to support generation loss. Some regions, including Germany and Quebec, now require inertia-generation in turbines as standard.

This can’t be done with solar PV. However, smart grids and improving storage technologies have the potential to deal with a lack of inertia. Batteries, which can absorb electricity when there is an oversupply and then release it again when demand is high, can respond near-instantly to fluctuations to help maintain the grid’s frequency.

There are, of course, renewable sources that offer natural inertia, including hydro, tidal and biomass generation. But as the UK shifts to more renewable energy sources with no naturally occurring inertia, these turbine-based generation methods will be vital in ensuring wider grid stability.  Gas has an important role too, as a lower carbon alternative to coal power and one that will increasingly shift from being the backbone of Britain’s electricity system to playing a supporting, flexible role.

This short story is adapted from a series on the lesser-known electricity markets within the areas of balancing services, system support services and ancillary services. Read more about black start, 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 and Maintaining electricity grid stability during rapid decarbonisation.

The technologies transforming the next decade of energy supply

In the last decade Britain’s energy system has seen a fundamental shift towards cleaner and renewable energy. And while proactive governmental policy has played a large role, much of what has made this shift possible is technological improvement.

Innovations in energy technology will play an equally major role in ensuring the same level of progression over the next 10 years. A report by National Grid has identified some of the most promising of these emerging tech solutions, and outlines which have the highest probability of aiding our continued decarbonisation.

Future scenarios aside, what’s certain from looking at this year’s Electric Insights is that, a decade from now, the power system will look very different. These are the technologies that could change it.

Homes that power themselves

Solar is already an important part of Britain’s renewable power infrastructure, but it has the potential to grow through smaller domestic setups, too. Access to DIY rooftop solar is becoming increasingly prevalent, with even home store giant IKEA allowing customers to pick up a solar panel and battery system alongside flat-pack furniture.

Meanwhile, solar technology continues to improve, helping it become more easily integrated into buildings. Tesla is soon to introduce solar arrays that look almost identical to high-end roofing tiles as well as transparent, solar power-generating windows. Homeowners and business are also looking to onsite biomass boilers to take control of their own green energy.

As such systems reach mainstream consumers they present the potential to create a more decentralised energy system.

Photo courtesy of Kite Power Systems

A new type of wind energy – powered by kites

Wind is already a key source of renewable energy, with on and offshore wind turbines now commonplace in many parts of the UK. But innovation continues, and now companies are looking to higher altitudes to improve the efficiency of wind generation.

In May of this year the UK gave the go ahead to the world’s first kite farm, a wind generation facility that will use two massive kites flying in loops roughly 450 metres above the ground to pull turbines and generate electricity. The company behind the project, Kite Power Systems, claims the system offers a lower Levelised Cost of Energy (LCoE) and operational maintenance cost than conventional wind.

Bigger, more efficient batteries

Many of the technologies set to shape the future of green energy, from domestic solar to electric vehicles (EVs), are dependent on innovations in battery technology.

Solid state batteries, which use a solid electrolyte rather than the semi-liquid type found in standard lithium-ion batteries, offer a number of potential performance benefits. These include six times faster charging, twice the energy density, and a longer life cycle.

The challenge is producing the batteries at a large scale and a competitive price point. Companies including Dyson, Bosch, Tesla and Toyota are all making strides in bringing them to market, with the latter aiming to implement the technology by 2020.

Wind turbines that don’t turn

The wind turbine has become an icon of renewable energy, but this could change – not because of a decrease in wind energy, but in a transformation in how they look.

Innovation in the wind energy space has led to the development of bladeless turbines, which offer the potential to reduce costs and minimise the noise and visual impact associated with traditional turbines.

Rather than rotating blades, bladeless turbines oscillate as wind passes a single, conical mast. Spanish bladeless turbine developer Vortex claims the lack of contact between moving parts can cut 80% of maintenance costs due to there being no need for lubricants and spare parts replacements. The firm hopes to bring industrial-sized turbines to the market by the turn of the decade. 

The next generation of nuclear

The next generation of nuclear reactor technology could offer the potential for more efficient, economic and safer nuclear energy. Current solutions being developed include reactors cooled by lead and gas, and a molten salt reactor, which uses molten fluoride salt to dissolve fuel.

Hopes for these ‘generation IV’ reactors include the ability to work faster and more efficiently, delivering more energy from the same amount of fuels, and the ability to use waste products from older reactors. The first generation IV systems are expected to be ready for commercial construction around 2020 to 2030.

The renewable technologies set to thrive beyond 2030

While the immediate future holds massive potential for a handful of energy technologies, there are others that will take longer to come to fruition. Once realised, however, they could provide significant breakthroughs.

Methane hydrate, found primarily under permafrost and near the ocean floor, is thought to offer greater supplies of methane than all the planet’s natural gas and oil sources combined.  Burnt as a natural gas, methane releases much less CO2 than other hydrocarbons and can greatly reduce transport emission when used as a liquefied natural gas (LNG) in vehicles.

Finding a way to safely extract these methane deposits could provide as much as 1,500 years’ worth of energy at current production rates.

Meanwhile, the greatly reduced release of radioactive material from nuclear fusion over nuclear fission could offer a huge advantage in its development as a future energy technology.

There is, however, no magic bullet that will be the single solution to a cleaner energy future. Instead, like today’s power system, it will rely on a mix of technologies, fuels and generators, working together to ensure a stable – and cleaner – energy system.

The silent force that moves electricity

In the early evening of 14th August 2003, New York City, in the midst of a heatwave, lost its power. Offices, stores, transport networks, Wall Street and the UN building all found their lights and phones cut off. Gridlocked streets and a stalled subway system forced millions to commute home on foot while those unable to make it back to the suburbs set up camp around the city.

It wasn’t just the Big Apple facing blackout – what had started with several power lines in Northern Ohio brushing against an overgrown tree had spread in eight minutes to affect eight US states and two Canadian provinces. In total, more than 50 million people were impacted, $6 billion was lost in damages and 12 deaths were reported.

While a software glitch and the outdated nature of the power system contributed to the disaster, the spread from a few high-voltage power lines to the entire North West was caused by a lack of reactive power.

The pump powering electricity

Electricity that turns on light bulbs and charges phones is what’s known as ‘active power’ — usually measured in Watts (W), kilowatts (kW), megawatts (MW) or in even higher units. However, getting that active power around the energy system efficiently, economically and safely requires something called ‘reactive power’, which is used to pump active power around the grid. Reactive power is measured in mega volt amps reactive (MVAr).

It’s generated in the same way as active power by large power stations, but is fed into the system in a slightly different manner, which leads to limitations on how far it can travel. Reactive power can only be effective locally/regionally – it does not travel far. So, across the country there are regional reactive power distributors servicing each local area (imagine a long hose pipe that needs individual pumps at certain points along the way to provide the thrust necessary to transport water).

But power stations aren’t the only source of reactive power. Some electronic devices like laptops and TVs actually produce and feed small amounts of reactive power back into the grid. In large numbers, this increases the amount of reactive power on the grid, and when this happens power stations must absorb the excess.

This is because, although it’s essential to have reactive power on the grid, it is more important to have the right amount. Too much and power lines can become overloaded, which creates volatility on the network (such as in the New York blackout). Too little and efficiency decreases. Think, once again, of the long hose pipe – if the pressure is too great, the hose is at risk of bursting. If the pressure is too low, water won’t travel through it properly.

This process of managing reactive power is, at its heart, one of ensuring active power is delivered to the places it needs to be. But it is also one of voltage control – a delicate balancing act that, if not closely monitored, can lead to serious problems.

Keeping volatility at bay

Across Britain, all electricity on the national grid must run at the same voltage (either 400kV or 275kV – it is ‘stepped down’ from 132kV to 230V when delivered to homes by regional distribution networks). A deviation as small as 5% above or below can lead to equipment being damaged or large scale blackouts. National Grid monitors and manages the nationwide voltage level to ensure it remains within the safe limit, and doing this relies on managing reactive power.

Ian Foy, Head of Ancillary Services at Drax explains: “When cables are ‘lightly loaded’ [with a low level of power running through them], such as overnight when electricity demand is lower, they start emitting reactive power, causing the voltage to rise.”

To counter this, generators such as Drax Power Station, under instruction from National Grid, can change the conditions in their transformers from exporting to absorbing reactive power in just two minutes.

This relies on 24-hour coordination across the national grid, but as our power system continues to evolve, so do our reactive power requirements. And this is partly down to the economy’s move from heavy industry to business and consumer services.

The changing needs for reactive power

“Large industrial power loads, such as those required for big motors, mills or coal mines, bring voltage down and create a demand for more reactive power,” explains Foy. “Now, with more consumer product usage, the demand for active power is falling and the voltage is rising.”

The result is that Drax and other power stations now spend more time absorbing reactive power rather than exporting it to keep voltage levels down. In the past, by contrast, Foy says the power plant would export reactive energy during the day and absorb it at night.

As Britain’s energy system decarbonises, the load on powerlines also becomes lighter as more and more decentralised power sources such as wind and solar are used to meet local demand, rather than large power plants supplying wider areas.

This falling load on the power system increases the voltage and creates a greater need for generators to absorb reactive power from the system. It highlights that while Drax’s role in balancing reactive power has changed, it remains an essential service.

This short story is adapted from a 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 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 and Maintaining electricity grid stability during rapid decarbonisation.

What you need to know about Britain’s electricity last quarter

Drax EI header

For an hour over lunch on Wednesday, 7th June, more than 50% of Britain’s electricity came from renewables. It was only the second time this had ever happened – the first had come just two months earlier, in April.

The second quarter (Q2) of 2017 was a period largely made up of firsts for Britain’s electricity system. While there were only two instances of renewable power tipping the 50% mark between April and June, overall, wind, solar, biomass and hydro energy made up more than a quarter of all Britain’s electricity for the first time ever.

These findings come from Electric Insights, research on Britain’s power system, commissioned by Drax and written by top university academics. Over the past year, the quarterly report has shown breaking renewable records is becoming the new normal for Britain’s electricity. Last quarter was no different.

Here, we look at the key findings from Q2 2017 and what they mean for the changing nature of the energy sector.

Daily electricity generation graph

More than half Great Britain’s electricity came from renewables. Twice

Wind, solar, biomass and hydro accounted for 51.5% of the UK’s electricity for an hour on 7th June, generating 19.1 gigawatts (GW). Combined with nuclear power and imports from France, low-carbon output was a record 28.6 GW – a massive 89% of total demand. This followed 30th April, when Britain’s electricity edged over the 50% renewable mark for a shorter, but no less significant, period.

The percentage of renewables making up our power supply is set to grow as additional renewable capacity comes onto the grid. There is currently 6 GW of additional wind capacity being constructed in Britain. Solar capacity has already hit 12.4 GW – more solar panels than analysts thought would be installed by 2050. Plans to convert more of Britain’s coal units to biomass will increase the availability of renewable power further, still.

25% electricity infographic

Electricity was cleaner than ever

There was a key date in the history of coal during Q2. On 21st April, Britain recorded the first full day it had gone without burning any coal since 1882 – the year Holborn Viaduct power station became the world’s first coal-fired public electricity station.

While that date is symbolic of the UK’s shift away from coal, in practice, it means carbon emissions are also dropping to historically low levels. Carbon intensity reached a new low in Q2, averaging 199 g/kWh over the quarter – 10% lower than the previous minimum set last year. For context, carbon intensity averaged 740 g/kWh in the 1980s and 500 g/kWh in the 2000s.

An important indicator of this falling carbon intensity is that Britain’s electricity now regularly drops below 100 g/kWh, and reached an all-time low of 71 g/kWh on the sunny and windy Sunday of 11th June.

100,000 electric vehicles infographic

Electric cars are cleaner than before

One of the greatest decarbonisation challenges moving forward is how we transform transport. Electrification is the primary driver of change in this sector, and Q2 saw Britain hit a significant milestone as the total number of electric vehicles (EVs) in the country surpassed 100,000.

The potential of EVs in cleaning up transport is significant, but there are also concerns they could, in some cases, increase CO2 levels due to pollution from power stations. However, as the last quarter’s data shows, EVs are in fact twice as carbon efficient as conventional cars thanks to the amount of renewable and low carbon electricity on the system.

“According to our analysis, looking at a few of the most popular models, EVs weren’t as green as you might think up until quite recently,” says Dr Iain Staffell From Imperial College London. “But now, thanks to the rapid decarbonisation of electricity generation in the UK they are delivering much better results.”

25% solar infographic

The most solar power a quarter has ever seen

The longer days in Q2 enabled solar power to become a key source of electricity, and for eight hours over the quarter it generated more than all fossil fuels combined. It also set output records by supplying 25% of total demand on 8th April, and producing 8.91 GW on 26th May.

While wind remains the largest source of renewable energy generation in the UK, solar’s influence is growing – especially as decentralisation of the power system continues to proliferate.

Of Britain’s 12.4 GW solar capacity, 57% is concentrated in 1,400 solar farms of around 5 MW each, while the rest is distributed across almost one million rooftop arrays in homes, businesses and other institutions. In fact, during June, 10% of all Britain’s electricity came from these sorts of decentralised sources – sources of power not on the national grid.

This is unlikely to spell a fundamental shift to an entirely decentralised power grid in the short term, but it does hint at the changes the sector is seeing. From its carbon profile, to its variety, to its flexibility, Britain’s power system is changing – and that’s a good thing.

10% decentralised energy infographic

Explore the data in detail by visiting ElectricInsights.co.uk

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.

15 words foresters use

Wind-shaped tree in a field

In Japanese, there’s a single word to describe sunlight filtering through the leaves of a tree: komorebi. It’s a poetic term to describe an image almost everyone recognises, however English has no direct translation.

But while English lacks a ‘komorebi’ equivalent, it does contain a significant number of words that speak to the very specific features of the forestry industry – terms that describe the crooked nature of a tree open to the elements on a mountain side, or words for the process of stripping a grown tree of its limbs.

Here, we look at the unusual, the uncommon, and the whimsical words that make up the language of forestry.

Silviculture

Seen as both a science and an art, silviculture is the practice of controlling the establishment, growth, composition, health and quality of forests. This goes beyond just managing working forests for wood products markets, however, and includes those dedicated to everything from leisure to wildlife.

Comminution

One of the first steps in the production of biomass such as wood pellets is reducing down the raw materials like the fresh felled green wood, and this relies on a process known as comminution. This is carried out by a range of specifically designed machinery such as rotary hammer mills, chippers and grinders, but can also be done in the forest using mobile chippers to reduce tops and branches.

Krummholz

From the German word ‘krumm’ meaning crooked, bent or twisted, krummholz is a term for trees that are stunted and sculpted by harsh winds found near the tree line of mountains, or on coastlines where there are large quantities of salt in the air. Exposure to the elements often means these trees are windblown into surreal shapes, while branches on one side are often deformed or dead.

Underdog

A key component of any sports movie, the origins of the word underdog may actually have come from the logging industry.

In pre-mechanised times, logs would be placed over a sawpit and cut up the middle with a long two-handled saw. The unfortunate sawyer working at the bottom, often knee deep in rainwater, under a falling rain of sawdust, was known as an underdog. However, other theories exist which claim the term originates from dog fighting.

A hypsometer

A hypsometer, used to measure angles to determine the height of trees

Hypsometer

A hypsometer is a tool used to measure angles. When used by foresters, it can determine the height of a tree. To use it, foresters measure the top and bottom of the tree from a measured distance away and use trigonometry to calculate the height.

Hoppus foot

The standard measurement of volume used for timber across the British Empire, the hoppus foot was introduced by English surveyor Edward Hoppus in 1736. The imperial measurement was developed to estimate how much squared, useable timber could be converted from a round log, while allowing for wastage.

A mobile wood chipper

A mobile wood chipper in operation in Arkansas

Slash and brash 

Slash and brash are both terms for the woody debris left by logging operations. However, while slash can be chipped and sold as biomass, brash is not normally removed. Instead, it can be spread along routes used by forestry machinery to prevent ground damage in what are known as brash mats.

Leader

The very top stem of a tree. This typically develops from a tree’s ‘terminal bud’, which is the main area of growth in a plant and is found at the end of a limb.

Two men using a cart to transport a log

Foresters using horses and rail carts to transport timber in California, 1904

Hot logging

Hot logging is the process of loading logs onto lorries and removing them from forests immediately after felling – when they’re still hot from the saw. This is in contrast to the more common process of storing or decking logs on site before removing. Hot logging is often used when ‘whole tree harvesting’, as the trees are removed from site and processed at the mill to maximise recovery of high value saw timber material.

Snag  

Dead trees might not seem like the most useful plants in a forest, but snags prove otherwise. Snags are standing dead or dying trees, and they serve an important role in forest ecosystems. Often missing their top or most of their smaller branches, snags provide habitats for wide varieties of birds, mammals and invertebrates, as well as supporting decomposers such as fungi. In fresh water environments snags also make essential shelter for fish spawning sites.

Beating up

Towards the end of the growing season, trees that have died shortly after planting are counted and replanted in what is known as beating up. This process also allows foresters to identify and address any issues that may have affected growth.

Thinning

A staple of responsible forestry, thinning is the practice of periodically removing a proportion of trees from a forest to reduce competition and provide the healthiest, most valuable trees with greater access to water, sunlight and nutrients. As well as opening up more resources for the remaining trees, this process also provides feedstock for the biomass and paper industries.

Rotation

In managed forests, foresters keep a range of different age trees to ensure a constant flow of healthy and mature wood. Rotation is the term for the number of years required between new planting (typically of seedlings) and final harvesting. In the US south rotations of plantation pine are commonly about 25 years, and 45 years for naturally regenerated pine, while in the UK this is closer to 60. For the same species in even more northerly Finland rotations are typically between 80 and 90 years.

Snedding

Coming from the Scandinavian word snäddare, meaning smooth log, snedding is the process of stripping shoots and branches from a branch or felled tree. Known as limbing in US, snedding is carried out with by chainsaws or more heavy-duty harvesters and stroke delimbers.

Mensuration

How to you measure the total wood of a forest? Mensuration, that’s how. Mensuration is a form of mathematics that allows foresters to measure the volume of standing or felled timber. It is an important tool in not only the quantifying of how much product there is to sell, but in monitoring and managing the health and growth of a forest.