The generator game: a visit to Drax Power Station, World Petroleum Council Guide: Biofuels, 2016
Despite the industrial ravages of the Eighties, the landscape of Doncaster in England’s unfeasibly flat north-east is still one of railway sidings, chimneys and canals. There is, however, a recent exclusion from the horizon. Colliery winding gear, so long a feature of the terrain, has vanished, although from the window of a Hull-bound train you’ll still see the odd slagheap sprawled out like an oversized, fast-asleep Labrador. Coal, which powered the industrial revolution and the engines of the British Empire, is no longer mined in Yorkshire. In 1984, there were 56 pits in the region but the 2015 closure of Hatfield and Kellingley collieries brought to an end an industry that had been active since Roman times.
The one-time abundance of Yorkshire mining encouraged the arrival of major power stations, the largest of which, Drax, was opened in 1974. Despite sharing a name with a James Bond villain, the power station takes its title from a nearby settlement. In fact, the power station has a larger workforce (around 1,000) than the village of Drax has inhabitants (488).
In the lowland triangle between Doncaster, Selby and Goole, the 4,000MW power station is viewed in a positive light, not least because it is a large employer in an area that has struggled with job security for decades. Stray beyond the boundary and Drax’s perception dips. It is a known polluter; in 2007, it produced over 22 million tons of carbon dioxide (CO2), a fact Drax chief executive Dorothy Thompson was decidedly uneasy about: “We were the centre for a lot of protests and actually we were not comfortable with it ourselves,” Thompson voiced.
Drax is an RAF navigator’s dream, dominating the scenery. Once inside the perimeter fence, the enormity of the dozen 374-feet-high natural-draft cooling towers and 850-feet-high reinforced-concrete chimney – the highest industrial chimney in the world when built – is overwhelming. Drax produces 7-8 per cent of the UK’s electricity but in an attempt to reduce emissions, a huge debarcarbonisation project was initiated. In 2004, the power station trialled the burning of biomass (that is, woodchip pellets) and hasn’t stopped. Currently, Drax has four coal-burning generators and two biomass, which has led to a halving of its carbon footprint in five years; soon, it will be three coal and three biomass. Upgrading turbines has further reduced CO2 emissions by a million tons a year.
The essential differences of coal and woodchip biomass are instantly apparent as you wander into the interior of the site. Coal is stored in the open, beneath grey Yorkshire cloud mass, but biomass pellets are useless when damp so are housed in four purpose-built, 164-feet-high domes, each capable of holding 80,000 tons. Typically, pellets are made up of compacted treetops from logging operations and sawmill waste; they smell a little like hamster food. Drax consumes 7 million tons of pellets a year. To put this into perspective, the US produces 93 million tons of biomass waste annually.
Pellets give off a fine dust and because of this, are highly prone to spontaneous combustion. Drax treats biomass as if it’s gunpowder, which is why nitrogen is pumped into the domes to avert the sort of freak blazes seen in recent years at Tilbury and Ironbridge power stations. Nothing is left to chance.
On average, 17 biomass trains arrive at Drax each day, six days a week, from the Port of Tyne, Immingham, Hull or Liverpool, packed with pellets sourced from around the world but predominantly from the US and Canada. Unfortunately, as we viewed a drop-off, the DB Schenker Class 66 locomotive on the front was having mechanical issues – a rare occurrence – but it allowed close inspection of Drax’s massive stainless-steel biomass wagons. At 62-feet long and capable of carrying 70 tons of pellets, they are 30 per cent bigger than any other freight wagon in the UK; 200 are in operation.
Pellets are released from the wagons through an underside trapdoor and travel via Drax’s Spaghetti Junction of conveyor belts to storage. Small amounts of contamination occur but magnets quickly lift out rogue nuts and bolts. Interestingly, the previous week, a woman’s stockings and suspenders were removed from a Baltic consignment – hardly a CO2 nightmare but a unique find, it must be stressed.
Whether coal or biomass, power stations mostly burn dust. To achieve this, raw material is ground to smithereens by ten large ball bearings inside a Babcock & Wilcox pulveriser. The powder is then blasted into one of six, 15-storey-high, 4,000-ton boilers. A single pellet, or what remains of it, will last under a second in the furnace. Roughly, twice the amount of biomass is needed than coal to produce the same amount of power.
In theory, biomass is a carbon-neutral source of energy; that is, when we burn wood, all the carbon absorbed by vegetation as it grew is released back into the atmosphere (or, looking at it from another angle, when you burn wood and release its carbon into the atmosphere, you need to plant trees to soak up the carbon). With coal, carbon is freed that has been locked underground for millions of years. CO2 released by the burning of fossil fuels made up 76 per cent of global greenhouse-gas emissions in 2014. The reality is, carbon neutrality when burning biomass is difficult to achieve because conversion of wood to pellets and its transportation will most likely use fossil fuel. Nevertheless, with wind power and solar energy still in their infancy, biomass is a step in the right direction.
Drax sources its woodchip pellets from sustainable forests – what it calls “good biomass” (“bad” being from unsustainable sources). Before a consignment is shipped to Yorkshire, suppliers must pass strenuous screening and sustainability audits, conducted by independent bodies. Rigid requirements are written into contracts and if there is evidence that strict standards are not being met, Drax will terminate the contract and find alternative sources. Since upgrading to biomass, Drax has reported an 86 per cent carbon saving compared to coal and with plans to go fully biomass if it can attain government support, the carbon saving will further increase.
Roused by research and development, power-generation technology forges ahead with an ingenuity that we would hardly have believed possible at the turn of the century. At the 2015 UN Climate Change Conference held in Paris, an agreement was reached by 174 countries to set a goal of limiting global warming by 2°C. As the policy-advising organisation the International Energy Agency has recently stated, “In the 2°C scenario, almost 30% of direct industrial CO2 emissions reductions by 2050 hinge on processes that are in development or demonstration today.”
It’s easy to assume that Drax, frequently labelled a “dinosaur” due to its previous pollution figures, will ultimately face the same extinction as the nearby collieries that once supplied it. More likely, biomass and coal will continue to play their part among an ever-widening array of power-generating options in the UK, with natural gas leading the pack. And if Drax’s primary fuel source makes use of waste from certifiably sustainable timber in a programme that increasingly strives for carbon neutrality, it’s a difficult proposition to ignore.
For tours of Drax Power Station, visit drax.com