Climate pollution from wind farms on peat ‘underestimated’
Credit: Jen Stout | The Ferret | October 29, 2021 | theferret.scot ~~
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Wind farms on Scotland’s peatland could be doing much more damage to the climate than previously thought.
The volume of greenhouse gases released when turbines and tracks are built on peat could be “significantly” underestimated, experts have told The Ferret.
Peat-rich Shetland has become the epicentre of this debate – with the Scottish Government’s environment agency initially objecting to a new wind farm proposed in the isles on climate grounds.
Peat is central to Scotland’s climate change targets. Ten per cent of the world’s blanket bog is in Scotland, and peat covers more than a fifth of the land, storing 1.6 billion tonnes of carbon. The government is spending millions restoring damaged bogs, so they store carbon dioxide rather than emit it.
But this land tends to be the windiest and cheapest. During the huge boom in onshore wind over the past two decades, most turbines were built on peat, with more than 200 on deep peat.
Many more turbines are planned for the next decade. But experts in soil and peatland are warning against any further development on deep peat, and questioning construction on shallow peat too.
The developers of Energy Isles’ wind farm, planned for an area of blanket bog in the island of Yell, claim their turbines would pay back the carbon released in 1.7 years.
The figure comes from the government’s ‘carbon calculator’ – a spreadsheet tool which must be used by all proposals that impact peatland.
But experts say the calculator’s figures can be flawed, and are calling for an urgent review.
“The science has moved forward,” explains Professor Jo Smith of the University of Aberdeen, who was part of the team which created the calculator.
“There’s now more information available that could help reduce two uncertainties: the extent of drainage, and the efficacy of restoration of peatlands. Therefore, I’d completely agree with reviewing it.”
Peat bogs, in a natural state, are waterlogged. If drained, they release carbon dioxide. When new roads and turbine bases are built on peat bogs, drainage is unavoidable.
Estimating the extent of drainage is a crucial part of the calculations – if the impact is estimated to be just a few metres, the payback time comes down significantly.
Dr Guaduneth Chico, a lecturer at Nottingham Trent University who specialises in blanket bog erosion, thinks it could be “anything up to hundreds of metres.”
Only decades-long monitoring will tell us the real impact, he says.
So-called ‘floating roads’ – built on top of deep peat, rather than excavating down to the bedrock – are commonly used in wind farms.
“In one year you might not see much impact. But through time, it will potentially sink and compress the peat, affecting the hydrology,” says Chico. “Heavy equipment, cars – that’s going to make the surface sink, slowly.”
As the peat sinks, more carbon and other greenhouse gases are released.
The planning and policy system works, Chico says, by “assessing impacts in the short-term. But that’s one of the main mistakes.”
“It’s a long-term habitat. Restoring the peatland, we monitor it for three years, and forget about it. But in three years, it doesn’t change much.”
These assumptions could skew the payback numbers, says Clifton Bain, programme advisor for the Internation Union for the Conservation of Nature’s UK Peatland Programme. “There’s a risk that impact is being significantly underestimated. I think that’s highly possible, because it’s based on assumptions, on outdated data.”
Restoration is another of the calculator’s problems, experts say. Some developments – like Viking Energy’s 103 turbines in central Shetland – are built on areas of degraded peatland, which already release massive amounts of carbon dioxide. The promise of turning this peatland into a carbon sink instead of a source, through extensive restoration, brings the payback time right down to a couple of years.
But there isn’t agreement among experts as to whether restoration works.
“The science is not settled on the best ways to restore peatlands,” says Smith, “or whether it is actually possible in practice.
“If peat was previously pristine and you drain it, then it’s much more difficult to restore.”
It’s pristine peat that makes up the majority of the Yell site.
Objecting to Energy Isles’ proposal at Yell in 2020, the Scottish Environment Protection Agency (Sepa) argued that restoration would likely only return this to “dwarf shrub vegetation”, not blanket bog.
Citing its duties under the 2009 Climate Change Act to act in accordance with net-zero targets, Sepa said the Yell site was of “national importance”, and that the wind farm would create “avoidable carbon emissions”. More recent proposals, with reduced peat impact, have not yet had a response from the agency.
At the IUCN, Bain is also doubtful about restoration.
“If developers invest in restoring peatland, the calculation does allow them to add that into the mix,” he explains. “The question mark is – does it really compensate for the damage?
“I’ve seen estimates on restoration potential using very high figures, whereas estimates on damage seem to use low figures…it’s left to the developers’ judgement.”
This can make the difference between a payback time of decades, making a wind farm totally unviable, and that of a few years.
As it stands, Bain says, there’s potential for numbers to be tweaked to bring the payback time down. “I’m not saying any developer has done that,” he stresses. “I’m saying the risk is there because we haven’t got standardised numbers.”
Each wind farm has detailed plans, approved by the local authority, outlining how the environmental impact will be mitigated, and how excavated peat will be stored. Though some is allowed to be dumped as waste, much is supposed to be carefully stored and returned as soon as possible.
“The planning system doesn’t have a lot of capacity” says Bain. “There’s a flaw in the system here, that could allow poor quality restoration.”
This is where bonds are important: financial guarantees in place to ensure restoration and clean-up work is carried out, even if the developer sells up or goes bust.
But in the case of Viking Energy, a £600m project, there is still no bond in place, despite construction now being well underway.
Smith and colleagues have been sounding the warning bell for some time. In 2012 they argued, in the journal Nature, that new wind farms on peatland would “probably” no longer reduce emissions. Guaduneth Chico, using Spanish data, has made a similar argument. So is the science getting through to policy-makers?
“I don’t believe so,” Chico says. “It’s very difficult – the best we can do is collect data and hopefully in 100 years’ time somebody has that data and can say ‘this isn’t going well’. Obviously we already have indicators telling us that it’s not going in the right direction.
“We’re putting a lot of money into restoring heavily degraded peatlands, to recover their carbon sink function. But then you go to a natural peatland in Shetland and do the opposite.”
Building wind farms on deep peat must stop, all three experts agree.
“Where it made sense to build turbines on non-pristine, shallow peats 10 years ago, as time goes on and decarbonisation progresses, it makes less and less sense to build windfarms on peatlands at all,” says Smith.
Protecting pristine peat bogs should be “the bottom line”, she argues. “They’re an important resource for the world, both in terms of biodiversity and carbon storage.
“Once we’ve destroyed them we won’t have them any more.”
For Bain, it’s about shifting the way we see and value the bogs. For too long, peatland’s been seen as ‘wasteland’ – cheap, of little value, often overgrazed or planted with cash-crop trees.
Now that we know their huge role in preventing catastrophic climate change, damaging peatlands with turbine construction “looks bad”, he says. “It’s giving the renewables industry a bad name, which we don’t want.”
Striking a balance on peat
A Scottish Government spokesperson said they “note the limitations” of the payback calculations, but said the calculator still provided “the best available means” to get figures in a “consistent and comparable format”.
The government recognised the “need to strike a balance between maximising deployment to reach net-zero targets, while protecting our local communities, priority peatlands, natural heritage and scenic landscapes, while delivering economic benefits to Scotland,” the spokesperson said.
A spokesperson for SSE Renewables added: “The overall footprint from Viking infrastructure is more than offset by the work being done to restore historically eroded peatland and the creation of more blanket bog.
“Once construction is complete, the process of peatland restoration will continue, using more ‘traditional’ techniques, for example reprofiling peat hags and damming the gullies that guide water away from the blanket bog.”
These were “tried and tested” methods, he said, were overseen by people “experienced in Shetland peat restoration”.
Viking’s habitat management plan has been approved by regulatory bodies, he added, and is supported by an independent advisory group. On carbon payback times, the spokesperson said that its 1.6 year timeframe “could be argued to be an overestimate” given the reality of hydrological drainage buffers in Shetland.
Charlotte Healey, Energy Isles project manager, said: “We know the importance of peat, not only from a climate perspective but also as part of the fabric of life in Shetland over the centuries.
“As a project that began in the local community, protecting peat has always been a key issue for us and that is why our latest plans, submitted this month, reduces the amount of peat to be removed by 43 per cent with all excavated peat being used to restore areas used for construction.”
Shetland’s precious peat bog
A short drive north of Lerwick, Shetland’s capital, and you’re surrounded by peat hill. Vast, treeless expanses, dotted with sheep. Cheap, poor land.
The peat here goes deep. Metres of the stuff in some places. It grows at roughly 1mm a year – a very old, and (we now know) very precious landscape.
Up on Tait’s Hill a small team work to seal up the holes in the hagged peat: trying to stop the carbon dioxide leaching out. It’s one of many government-funded restoration projects around Scotland.
The very tip of a digger’s claw picks up a layer of turf with incredible delicacy, swivels, and puts it carefully in place. Nearby, another is building dams, which will allow water to pool up and make the bog wet again. Eventually sphagnum moss will grow, and the extraordinary biodiversity of these wetlands might return.
But while this small spot is painstakingly patched-up, a huge hole in the peat banks is visible to the north. A new road, blasted through the side of the hill, to carry machinery up to some of Viking Energy’s 103 turbine sites. The black peat is visible, a thick layer atop the bedrock.
Work began last summer, and since then the scene in central Shetland has changed dramatically – new roads, quarries, compounds and concrete plants. In the early dark of winter you get a sense of the scale. On each of the three long ridges, stretching miles north to south, strings of lights are visible along with the flashing orange of diggers and, more recently, cranes.
What is quite a dramatic landscape – deep glacial valleys – will be dwarfed by the 155-metre tall turbines, visible far and wide.
it’s not only the wind farm construction that’s notable. From a huge new converter station here, the undersea cable will take Viking’s electricity – far more than Shetland could ever use – away south, to power the mainland. Shetland will be on the national grid for the first time.
The cable brings opportunities. Two new wind farms are planned for Yell. The big island is often dubbed ‘one big peat bog’ – inaccurately, because its pretty edges are fringed with golden sands and whitewashed cottages.
But if you drive up the main road, you can see why it gets its nickname. Other than old paths, and some banks left black and jutting from years of traditional peat-cutting, the blanket bog is untouched.
180m in height. That’s nearly 600ft – higher than many of Shetland’s dramatic cliffs. Opinion is divided over its merits, though many locals support the initiative. Jobs are needed in Yell.
A government decision on Energy Isles is expected soon. But whether people like it or not, this landscape is being transformed in the race to switch to green energy.
[See: Investigating the impacts of windfarm development on peatlands in England]
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