In December, the hillltop parish councils plus two Calderdale Councillors presented 22 questions to the Calderdale WInd Farm developer Christopher Wilson and his pr team.
7 questions were about the impacts of the proposed wind farm’s construction and operation on the Walshaw Moor peatland – which is highly protected under the Habitats Regulations, because of its internationally significant habitats that are vital for climate change mitigation, biodiversity and reduction of flood risk in Calder Valley.
The developer needs to calculate how green the proposed Walshaw Moor wind farm’s electricity would be, compared to non-peat sites
As far as Ban The Burn! Is concerned, the main point to come out of the meeting is that the developer must calculate how green the electricity generated by Calderdale Wind Farm would be -both on Walshaw Moor’s blanket bog, and on other appropriate, non-peat sites across England.
This is measured by the Scottish Government Carbon Calculator’s output: ‘Ratio of CO2 eq. emissions to power generation (g/kWh)’ – aka carbon intensity.
The carbon intensity measure can be used as a key factor in identifying the most suitable sites in England for the wind farm – which Calderdale Council’s Response to the Scoping Report requires Calderdale Wind Farm to do, by making a sequential assessment of sites based on the whole of England. (p5).
It would be a more useful measurement for the developers than the 426,246 tonnes of CO2 savings/year figure they’re currently displaying on the Calderdale Wind Farm website and in their Scoping Report.
As the developers told the parish councils, this is the proposed wind farm’s counterfactual carbon savings – the amount of carbon emissions from fossil fuel generation of electricity, that the windfarm would displace.
“On track for fully decarbonised electricity system in 2030s” – Department for Energy Security and Net Zero
But we know that this may not be the case in 10 years time (which could well be the point at which this highly contentious “test case” wind farm were to become operational, if it ever does). Because the electricity grid is on track to be 100% low carbon by then. In addition to statements about this by the National Grid, according to the Department for Energy Security and Net Zero, the Review of Electricity Market Arrangements programme is developing a strategy to transition to:
“a fully decarbonised, resilient electricity system in the 2030s and onwards.”
So then the proposed wind farm would not be replacing fossil fuel generated electricity, but lower carbon renewable energy generated by wind farms on non-peat soil.
And if the carbon payback measure based on “counterfactual” carbon savings from replacing fossil fuel generated energy is irrelevant after 2035, as seems likely, wouldn’t any carbon gains from peat restoration (which can take decades to be realised) be the only pay-back of the increased carbon emissions from peat disrupted by the wind farm construction, operation and decommissioning?
Developers admitted to the parish councils that they didn’t have these figures. They told Councillors that they couldn’t satisfy their request for a written calculation, with workings, showing that more CO2 would be saved during the lifetime operation of the wind farm than the wind farm’s construction and maintenance would produce.
This is unsurprising at this early stage, because the developers haven’t done the site-specific peat survey work or the wind farm design work needed to make this calculation. But in the absence of evidence, surely they shouldn’t be making claims they can’t substantiate, such as that Calderdale Wind Farm would create:
“a real opportunity to put Calderdale at the forefront of the UK’s Net Zero ambitions.”
(Calderdale Wind Farm website)
Developers’ “aim” is that proposed wind farm will save more carbon emissions than it creates
Although the developers admitted that they don’t know what the actual carbon balance of the wind farm would be, they said that Calderdale Wind Farm will use the Scottish Government Carbon Calculator to calculate this, and this will “aim” to show a positive carbon balance for the wind farm.
But Clifton Bain, the IUCN UK Peatland Programme Director, has noted developers’ optimism bias when inputting data to the carbon calculator – on occasion using very high figures for estimates on peat restoration potential, and low figures for estimates on carbon emissions from peat damage.
So this is where independent scrutiny of developers’ data is required by a competent body. Will this happen?
Another site for the wind farm, on mineral soil, is likely to be better for the UK’s net zero target (as well as habitat biodiversity and flood risk)
The developers have not yet done any assessment of other, non-peatland sites across England, and it might well turn out that the proposed windfarm would be better sited on mineral soil. Because windfarms built on blanket bogs pose particular threats to to peatland hydrology, ground level climatic conditions, habitat biodiversity, and carbon storage.
Blanket bog is basically very wet peat formed by a variety of plants – particularly sphagnum, which can hold 20 times its weight of water – that barely decompose when they die, because the bog lacks oxygen.
In this way, blanket bog acts as a carbon sink, holding the carbon from the carbon dioxide that the living plants had absorbed from the atmosphere through photosynthesis.
The peat consists of two layers: the upper, living layer is called the acrotelm and the lower layer, the catotelm, where the dead plants have turned into peat.
Being a direct product of vegetation growth, peat bogs are responsive ecosystems with homoeostatic mechanisms which are not far removed from those found in living organisms. Through changes to the vegetation, peat bogs and the peat soils they generate have the potential to respond to environmental change in much the same way as a living organism might respond.
Peatbogs and Carbon, R Lindsay
When peat is disturbed, it degrades and releases carbon dioxide to the atmosphere, becoming a carbon source instead of carrying out its natural function as a carbon sink.
There are various processes which cause peat degradation.
One is damage to, or complete removal of, the top, living layer, which exposes the lower, peat layer to oxygen. This causes the carbon held in the peat to escape into the atmosphere as carbon dioxide.
Damage to the acrotelm (the living layer) also leads to erosion of the lower peat layer. Run off during rainfall increases, due to the absence of the top layer of plants that hold water and also create a rough surface that slows the flow of water. So as well as the carbon escaping into the atmosphere as carbon dioxide, it is dissolved into the water in the reservoirs, creating the need for costly cleaning processes to make it fit for human use.
Construction and operation of wind farms also creates pressure on the peat and this compression damages its ability to hold water.
In addition, drainage around tracks and turbines dries out the peat and this can occur over a considerable area, up to 200-250m from a track. Carbon losses from peat drainage can be ongoing over years. (Lindsay, Peatbogs and Carbon). Temperate zone peatlands that have been damaged through drainage can release up to 30 tonnes CO2-eq per ha per year. A review of drained bogs across Europe gives an average emission of 4.6 tonnes CO2-eq per ha per year. (IUCN Briefing – Peatlands and Greenhouse Gas Emissions)
As peat dries out, the plants that make up its living layer (and are responsible for creating the peat and storing carbon once they die and are held in the airless bog), can no longer survive. So the whole peat-creating cycle is destroyed as the acrotelm dies. And along with this comes peat erosion and the flux of its stored carbon into carbon dioxide into the atmosphere, and into run-off that flows into rivers and reservoirs.
Summary of how carbon emissions are created by construction of turbine foundations and access tracks
There are upfront, one-off carbon losses, measured in tonnes, both from excavated peat at the turbine foundations, and losses due to drained peat around the turbines and access track.
There is also ongoing carbon sequestration loss over the same area; stopping this would require not only rewetting the peat in that area, but restoring the vegetation that sequesters the carbon into new peat.
If this rewetting doesn’t occur, in addition there will be ongoing carbon losses from the areas of drained peat, that can continue for decades. As noted in the previous section, these losses can amount to 30 tonnes of carbon emissions a year per hectare.
The carbon calculator only allows you to calculate ongoing carbon losses from peat drainage for the lifetime of the wind farm. But without rewetting, it seems that the carbon losses from peat drainage for the wind farm could continue beyond its lifetime.
Plus, the areas of drained peat can extend far beyond the surface area of the tracks and turbine foundations and their associated drains. Recent research indicates that the areas of peat drainage could extend 200-250 metres from these sites, but it seems no one really knows and it would take decades of surveying to find out.
When wind farm construction happens, it is almost impossible to recover the peat that has been dug out for the turbine foundations as a functioning bog, no matter what you do with it. And its loss as a site of carbon sequestration is permanent – as the excavation is permanent.
What volume of peat are we talking about? It’s not necessarily equivalent to the excavation volume, because there might be mineral soil as well as peat in the hole, depending on how deep the peat is. A peat management plan for Gordonbush Extension Wind Farm (which has 150m high turbines, like those proposed in the Calderdale Wind Farm Scoping Report), says,
“Initial excavation volumes for construction of turbine foundations range between 1600m 3 and 2100m 3. Based on the volume of peaty soils/peat encountered at site, volumes ranging from as little as 150m 3 to 1500m3 of peat will require excavation from the turbine bases.”
Parish councils ask about measures to reduce damage to peat from wind farm construction
The parish councils’ 5 other peat-related questions were all about how the developers aimed to reduce damage to the peat from the proposed wind farm’s construction and operation – and so minimise the proposed wind farm’s carbon emissions, the increased flood risk to the valley and biodiversity destruction.
Asked what would happen to peat excavated from the wind turbine foundations, which would be losing its carbon to the atmosphere once removed from the ground, the developer told parish councillors that Calderdale Wind Farm would “reuse” it for site restoration, such as along tracks or in areas targeted for ditch blocking.
But advice we’ve received from a peat expert is that this will not stop carbon loss from the excavated peat, and the answer didn’t address the Councillors’ question about carbon emissions from the excavated peat.
The developers need to say what the risk is of releasing CO 2 emissions in excavating and “reusing” peat in this way, since peat degrades pretty much as soon as it dries out and encounters oxygen. What volume of peat are we talking about? And will they quantify such emissions in their use of the Scottish Government Carbon Calculator for wind farms on peat?
In addition, what on-site peat surveys would be carried out to provide accurate data for input into the Carbon Calculator, in order to make this calculation?
And how long would these surveys take? Bearing in mind, for example, that better data for peat drainage from wind farm construction requires site specific surveys “over seasons, even years”, according to an Independent Review of the Carbon Impact Assessment of the Strathy South wind farm by Rebekka R.E. Artz and others.
What proportion of excavated peat is likely to be used immediately in peatland habitat restoration and what proportion is likely to be stockpiled, awaiting re use?
The developers also said that Calderdale Wind Farm proposed the use of floating tracks to “mitigate” the damage to peat – and peat hydrology in particular. However, the claim that floating tracks – which don’t actually float but are built on top of the peat – will mitigate peat damage seems open to question.
Floating tracks are an experimental construction method, and very few scientific reports exist about their long-term environmental impact. There is a need for longer term monitoring of impacts of tracks on peatlands – Dr Jessica Williams, Policy Lead, IUCN UK Peatland Programme, has told us this is required, as
“There is a lack of research from the UK on track impacts unfortunately.”
Her Review of the effects of vehicular access roads on peatland ecohydrological processes points out that,
(Williams-Mounsey, Jessica and others, A review of the effects of vehicular access roads onpeatland ecohydrological processes, Earth-Science Reviews 214 (2021) 103528)
“Changes to [peat] composition can occur rapidly as a result of a stochastic event, after long time lags”
Another problem with floating tracks is that Natural England has already refused permission for one floating track on Walshaw Moor Estate, after a Habitats Regulation Assessment concluded that it was likely to have, or may have, a significant effect on the protected breeding merlin, European golden plover, an assemblage of breeding birds and on the protected European dry heaths, blanket bog and Northern Atlantic wet heaths with Erica tetralix habitats.
One reason why the floating track would have caused such damage was because it was wrongly sited on the basis of an inadequate peat depth survey – which used the same method of “interpolated” modelling which Calderdale Wind Farm’s Scoping Report proposes to use.
The figures this method generated for the floating track proposal were found to be gross underestimates, after a member of the public, Bob Bezins, went out and actually measured the depth of the peat along the proposed track. When its true depth was established, Natural England withdrew approval and Walshaw Moor Estate abandoned the track proposal.
The developers were unable to tell Councillors about the amount of consolidation settlement of peat under crane pads and under access roads.
Asked how Calderdale Wind Farm intended to mitigate and monitor the reduction of the Moor’s water storage capacity and permeability (due to removal of peat, its replacement with structures or compacted crushed stone products, and consolidation of peat), in order to avoid increased run-off and flooding in the valley, the developers waffled and said they’ll do surveys to establish baseline data and then work out mitigation and monitoring measures.
Questioned about mitigating peat damage by siting turbines in areas of shallower peat, the developers said they will do more detailed peat surveys and are considering turbine placement to lessen peat damage. This is unsurprising. However, the layout of wind farms is determined by some pretty complex software, which won’t take peat depth into account, and they can’t just move the wind turbines willy nilly.
Save And Restore Walshaw Moor 