In preparation for the 28 day period where people can submit objections to the Forth Energy plans, I’ve expanded and re-written the post below, with links to key resources on the Greener Leith website here:
http://www.greenerleith.org/forth-energy-fact-myth-leith/
This post has been revised several times as I’ve found new sources, and spoken to other people. I’m actively seeking constructive criticism and/or help to work this out. Last updated at 13/11/2010
I’m just back from a visit to the Forth Energy exhibition about the Leith Biomass plant, where I tried to discuss the sustainability case for the plant with 3 and sometimes 4 Forth Energy staff at once. Quite intimidating it was, as they all seemed bigger than me and they almost had me convinced with some arguments that I hadn’t considered before (It would seem others have had similar experiences). It was only on the way home that I had a ‘wait a minute’ moment and having digested the experience, I’m now feel even clearer that the Forth Energy environmental arguments don’t stack up.
So let me start at the beginning, (I felt that I had to) as this can be very hard for non-specialists to work out. I feel I should state at this point that I have an MSc in Energy and Environmental Management – and I have been working in the environmental sector for a number of years, but I still have felt the need to start from first principles. This is my personal view on the sustainability of the proposed Forth Energy plants. I’ve tried to link to my sources wherever I can, so that you can judge for yourself whether they are credible. They seem like it to me.
When you burn wood, just like coal, you release carbon. With a large plant like the one proposed by Forth Energy – you burn lots of wood and therefore release lot’s of carbon. What makes biomass ‘greener’ than coal is that, if you plant enough trees, eventually you can reabsorb that carbon back out of the atmosphere and lock it up again. In contrast, when you burn coal the carbon is released and there is no comparable mechanism for re-absorbing the carbon released, so over time – coal is much worse for the environment. However, the key point that Forth Energy staff would not acknowledge is that it takes time for biomass plants to deliver a carbon saving. Any carbon saving.
When I went to speak to representatives of Forth Energy today, they referred constantly to their claim that their plant emits only 11% of the carbon of a coal power station over the lifetime of the biomass plants operation. This claim is the main basis of their sustainability argument and it is repeated ad infinitum in the press. They argue that the 89% emissions saving is delivered as soon as the biomass plant is turned on – because it means that somewhere else a coal powered plant is turned off. Or to use their language, biomass displaces coal as a fuel for electricity generation. However, it shouldn’t take anyone long to work out that this argument doesn’t really work. We’ve already established that burning biomass emits carbon – just like coal. Indeed, some research suggests that the emissions associated with power generated from biomass are 50% greater than coal per unit of energy generated.
To put it another way – imagine, you work for the National Grid. You have a slider switch that controls two power plants that generate the same amount of electricity. One of the plants is a coal fired plant, and the other burns biomass. You can either turn on the biomass plant or the coal plant depending on whether you push the slider to the left or the right. If your priority was to cut carbon emissions on that particular day, it wouldn’t make any difference where you put that slider – carbon would still be getting pumped into the atmosphere in very large quantities. And some would argue that it would be the biomass plant producing more carbon than the coal plant.
Forth Energy staff told me today, repeatedly, that the biomass plant would deliver an instant 89% emissions saving, by allowing that person at the national grid to turn off a coal fired plant and replace it with a biomass plant. (I offered to record my conversation with them but they declined, so you’ll have to take my word for it). The only circumstances I can imagine in which turning on a biomass plant could be said to deliver an instant carbon saving is if the developers had planted an entirely new dedicated forest to supply it, and left it to grow to maturity, prior to building and running the plant. I think we can be certain that this is not a situation that applies to Forth energy. Indeed, Forth Energy staff told me they’d not signed any fuel supply contracts yet.
So, it seems clear to me that building a biomass power plant won’t deliver an instant carbon saving by displacing coal. To reach that 89% saving, Forth Energy are going to have to run the plant for a long time. And this is where the idea of a “carbon debt” comes in. To run that biomass plant, Forth Energy will need to cut down millions of trees, transport them to Leith and burn them, and release lot’s of carbon. That carbon is only taken out of the atmosphere again when an equivalent amount of trees have regrown to re-absorb the carbon.
But actually, the situation is not as simple as how long a replacement tree takes to grow. Forth Energy should know this, as I’ve sent them the link to the latest research undertaken by the Clean Air Task Force, that identifies the factors they need to consider. They are:
1.The lifecycle of the wood (e.g., logging debris, whole trees, trees vulnerable to catastrophic events) in the absence of the biomass energy opportunity.
2. The type of energy that will be generated (heat, electricity, combined heat and electricity), because different types have different efficiencies and thus different CO2 emissions profiles.
3. The type of fossil fuel being displaced (coal, oil, or natural gas), because different fuels have different emissions profiles.
4. The management of the forest—management can either slow or accelerate forest growth, and therefore recovery of carbon from the atmosphere.
In the Clean Air Task Force Review, they present a graph that shows the cumulative carbon effects of burning and planting trees for a hypothetical plant burning wood. This is an elaboration of a research model, first developed by a team of researchers at the Manomet Centre for Conservation Sciences. Whilst this graph is based on certain assumptions about the fuel source that do not directly apply to the Forth Energy plants (the Forth Energy plants will burn some ‘recovered waste wood’ too), it’s a useful illustration of the principle (to see a larger image click on the graph):

You’ll note that even after 32 years of running this hypothetical biomass plant, net carbon emissions are still 147% of those that would have been produced by simply burning coal. So far from producing an instant carbon saving, the biomass plant above generates an increase in net carbon emissions compared to coal for many decades. Clearly, there are plenty of circumstances where biomass is not going to be an answer to the very urgent problem of climate change. This requires us to cut our emissions now, not increase them in the short to medium term.
That is why Scottish Government legislation specifies a target of an 80% cut in Greenhouse gas emissions by 2050. Similarly subsidies for Renewable Energy are paid over a 20 years timescale, and most reasonable people would agree with me here – that in return for receiving a public subsidy, a power plant should deliver a meaningful carbon saving within this timescale.
When you speak to Forth Energy staff they will try to dismiss the Manomet research model as inapplicable to their proposals. Largely, because the graph above would vary somewhat if you made different assumptions about the lifecycle of the fuel sources used – that’s the first factor in the Clean Air Task Force list.
It’s impossible to know what other assumptions have been made about the other types of fuel crops that will be burnt by Forth Energy in Leith. However, they say that up to 30% of the fuel could come, not from virgin timber, but from waste wood, short rotation coppice and even straw. Whilst undoubtedly cleaner than coal, in most cases these crops do not seem likely to deliver that 89% saving against coal when used just to generate electricity – like the proposed Forth Energy plant in Leith. Indeed, they can be worse than burning natural gas for electricity from a carbon emissions point of view, and it would seem that they are unlikely to deliver much, if any, carbon saving over UK grid electricity by 2030, as this assessment from the Environment Agency (the equivalent of SEPA in England and Wales) shows:

Despite the difference in the fuel sources, I believe the “Manomet model,” that seeks to place the cumulative carbon flux from a proposed plant in a time sequence, is valid and can be applied to any specific plant. It just happens the Forth Energy would prefer not to plug more specific numbers into this model for the Leith plant. It’s not hard to tell why. Based on their findings, the Clean Air Task Force research concludes:
“Further promotion of utility‐scale biomass should be discontinued immediately as a threat to climate, and forests.”
When I discussed the second factor in the list – the type of energy generated – with Forth Energy staff things started to get really odd. You’ll recall they were very keen to talk about displacement when they were talking about electricity generation. But when it came to heat, the Forth Energy staff dismissed what happens to the heat as ‘irrelevant’ to the carbon equation. So when I pointed out that this cannot be true and that research I’d seen shows that dumping the majority of the heat in the sea (as is the current plan in Leith) will increase the length of time the plant will take to pay back its carbon debt – I was met with emphatic denials. “The heat is a bonus” they insisted.
Now, clearly it isn’t just a bonus. If there’s any opportunity for ‘displacement’ it’s by using the heat generated by the plant to displace the use of fuel used (usually natural gas or oil) for space heating in nearby buildings. Using the heat will clearly reduce the demand for fossil fuel from other sources. Not using the heat from the plant, is pure and simply a waste – and means more wood must be burnt, releasing more carbon, per unit of useful energy out of the plant. The Manomet research study compared various predicted carbon dividend or debts, that a biomass plant (burning hard wood from commercial timber plantations in the states) would deliver, depending on the type of fuel that was being displaced.

Whilst the numbers in this table are not directly transferable to Scotland – the trend it illustrates still applies. Biomass used to replace oil or gas in a combined heat and power (CHP) situation (where the heat is used constructively rather than dumped in the sea) delivers a carbon saving much more quickly than a situation where biomass is simply used to produce electricity. In the case of electricity produced by burning natural gas, that large negative number in the 2100 box implies that the biomass used to replace this fuel will take many, many decades – if not centuries to deliver a carbon saving. The Forth Energy plant in Leith will only burn biomass for electricity when it becomes operational. And remember, we don’t have centuries to tackle climate change.
And this is where my conversation with Forth Energy got even stranger. It’s been very hard to get a straight answer out of Forth Energy over the length of time that they used to produce their “Life Cycle Analysis”. Today, they told me emphatically 25 years. So, bearing in mind the graph above, even allowing for the fact that Forth Ports claim they’ll be able to source fuel from sources that may suck up carbon more quickly than the forests used in the model in the Manomet report it’s extremely hard for me to understand how they can possibly claim a 89% carbon saving over coal power in 25 years. Even allowing for faster growing fuel sources, it looks to me as if they’ll be lucky to achieve parity with coal in 25 years, let alone an 89% saving. Hardly a compelling reason to build the plant or provide the plant with hundreds of millions of pounds of subsidies for “renewable energy” over the first 20 years the plant will operate.
But there’s a further factor that doesn’t play well for the Forth Energy plans. In Scotland, the discussion is not even about whether this plant can achieve carbon savings compared to burning coal, or even gas, for electricity. In Scotland about a third of our power comes from renewable sources already, and this is set to increase to 80% by 2020. If this were to represented in the first graph above – it would mean that the flat horizontal line that represents emissions from fossil fuels, would start higher up the graph and be tilted, so that the line rises towards the top left corner. We could call this line “business as usual in Scotland”.
It relates to the third factor in our list that affects how long any given biomass plant will take for the plant to deliver a carbon saving. If the energy generated by the biomass plant is ‘displacing’ an energy mix that is already comprised of a high proportion of low carbon fuels (e.g. Natural Gas, Wind, Solar, and even Nuclear) then it seems likely that it will be even longer before the Leith biomass plant realises any kind of carbon saving at all.
Now, Forth Energy claim that it is unfair to compare their plant to the average carbon emissions embodied in grid electricity, because the power they generate from the biomass plants will be displacing coal power from the grid – and when there is lots of wind power being generated, then all the other power stations are basically ‘turned off’ in order to accommodate it in the grid. But remember Scotland has the potential to generate 123% of its electricity demand from renewable sources. A few decades into the future, if we’re going to be generating a sizable proportion of our energy from renewables or indeed a surplus of renewable energy, there may not be much coal fired plant left to displace.
Furthermore, in the unlikely event these Forth Energy plants do find a heat customer willing to pay to be connected to the plant to use even a small part of the heat that they generate – then they’ll have to keep running the plant almost continuously anyway to supply them. On this basis it would seem entirely reasonable to compare the energy they generate to the average carbon intensity of the grid – both now, and looking into the future.
When you consider all this, it makes that Forth Energy carbon saving claim of 89% delivered over 25 years of operation, seem even more unlikely to me.
And of course we haven’t even considered the fourth factor. That is the management of the forests where the fuel is sourced, and this is also another aspect of the plans which simply cannot work. The scale of the timber demand of these plants, and proposed plants like them elsewhere in the UK is simply huge. And although Forth Energy claim that they will only source their fuel from third-party certified sources, the scale of the demand for biomass will have an impact globally. Indeed, on current evidence the UK demand for wood fibre imports, as a consequence of these plants, and the others like them proposed around the UK, is set to equal the entire current global trade in wood fibre. This means that third party certified wood may become too expensive for other industrial uses, leading to job losses in the UK, and it would also seem likely that this demand will trigger a growth in timber use from non-certified, poorly managed forests by other users.
The impact of a ‘biofuels land grab’ in the third world, whether directly caused by Forth Ports, or indirectly by other timber users who find themselves priced out of the certified timber European market – could exacerbate carbon emissions, as more and more ‘virgin forest’ (which is a good carbon store and net sink) is replaced by intensively managed monoculture commercial plantations (which store less carbon). This conversion will therefore produce a further net emission of carbon. Now Forth Energy may claim that it is unfair to implicate their proposals in a global environmental problem. But the combined timber demand that their plants will require is absolutely huge – and many, many orders of magnitude greater than the smaller, more efficient, biomass plants being built or proposed in other places in Scotland, that use timber entirely sourced in Scotland. Furthermore, if Forth Energy intend to use faster growing ‘energy crops’ then is likely to contribute even more to carbon emissions from indirect land use change. So whilst these crops, like short rotation coppice, can be harvested more frequently, and thus lock up carbon more quickly as they grow, if their use was expanded rapidly to a commercial scale more land use changes would result – often at the expense of land used for producing food, or other types of forest which work as a better carbon store and absorb more carbon over the long term than these types of energy crops.
There are links to various reports in this Guardian article that show that these indirect land use changes, driven by the growth in commercial biofuel explotation will lead to increased carbon emissions, a loss of biodiversity and increased staple food prices.
For these reasons set out above, I’m feel more certain than ever that the Forth Energy claims for their plant are indeed likely to be ‘greenwash,’ and that without truly independent research that applies a model similar to the Manomet approach to the specific circumstances surrounding the Forth Energy biomass proposals, we will never get to the bottom of the true carbon impact of these plants. Until then, The Scottish Government should refuse planning permission and support call a moratorium on all large, electricity only, biomass proposals.
Other strange things Forth Energy said #1:
In our conversation Forth Energy staff said they were looking at using Eucalyptus trees, grown in Scotland, as a possible fast growing feedstock for their plants. Whilst it is possible to grow Eucalyptus trees in Scotland, to my knowledge there are no commercial scale plantations of these trees in Scotland and no plans to establish them. Even if there were, it would take at least 25 years, at least, for any commercial plantation to get established and reach maturity. 25 years is the predicted lifetime of the plant.
Other strange things Forth Energy said #2:
I put it to them that their suggestion, that the proposed plant on Leith Docks would ever supply the council HQ next to Waverly station, with heat was, frankly silly. They argue that it was technically possible to this and therefore it was not misleading to include this site as a possible heat customer of the plant. This is true – it may be technically possible to supply heat to that distance. It is certainly desirable to build an extensive heat network covering the north of the city.
However, they provided me with no credible evidence that they could overcome the political, practical, regulatory and financial challenges of digging up the whole of Leith Walk, Leith Street and Carlton Road and retrofitting the council HQ to deliver this vision. The fact remains that on the basis of the current plans, the heat that is generated by the plant will be dumped into the sea.
Correction/ Update at 12.11.2010
Here are the typical CO2 savings Forth Energy claim for the similar Dundee plant. In fact, they claim higher savings than those I cited in this post originally, and I’ve amended it accordingly. Nevertheless, the difference makes no material difference to my main point – Forth Energy do not provide information on when the claimed savings will be realised, depsite their staff claiming that “all the assumptions are in the environmental statement.” If these savings are only delivered many decades, or indeed centuries, after the projected lifetime of the plant, we must question how useful this development will be.

Furthermore, contrary to claims by Forth Energy staff, there is no information on how long the Life Cycle Analysis (LCA) conducted by SISTECH assumed the plant would run for.
Also – there is an interesting table included in the appendices which shows what emissions are included in the LCA and what has not been counted. You can see it here:

Note that the LCA is based on the ‘expected electricity/heat output’ and not the actual heat use at the time of construction. So, there we have it – in order for the Forth Energy claims to stack up they must use the heat. It is not “a bonus,” as Forth Energy staff claim. It is a fundamental foundation to their carbon reduction claims.
You will also note that the model does not take into account the carbon released from land use change, for example from soils, when forests are harvested. Most of the carbon stored by forests is in fact sequestered in the soil over many decades, and logging tends to cause this captured carbon in the soil to be released relatively rapidly.
There are a number of other flaws with the LCA. For example, when it comes to wood waste, it assumes that all wood waste that is diverted from the waste stream to the biomass plant would have otherwise gone to landfill – and would immediately decompose releasing methane to the atmosphere. This is not the case. Because of the increasing landfill tax, there are greater and greater incentives to recycle, or re-use wood. Even burning waste wood in a different, more efficient, wood fired CHP plant, where the heat is actually used would deliver a better carbon saving than burning it in the plant proposed for Leith!
Furthermore, even where wood waste is land-0filled, the decomposition of wood takes places slowly over a number of years. Therefore, any time based analysis of the climate change impact of the proposals would need to take account of this. Lastly, in many land fill sites, the methane produced by decomposing biological material is captured and burnt to produce electricity, converting it back to CO2. As the Forth Energy report states, 1KG of methane has 23 times more impact on climate change than 1KG of Co2. By assuming that all the wood waste burnt in the Forth Energy Biomass plants is helping to avoid an immediate release of Methane elsewhere Forth Energy can claim “Even though the overall percentage of wood waste to be included in the fuel mix is very small (<2%), the avoided methane emissions are significant.”
Similarly, whilst the LCA readily ascribes an optimistic carbon saving to waste wood diverted from the waste stream and burnt inefficiently, it does not ascribe a carbon cost to burning timber that could otherwise be used for activities that do not lead to such a rapid release of atmospheric carbon. For example, use of timber in furniture or as a building material.
All of these assumptions serve to over-estimate the CO2 savings the plant will deliver in the short – medium term.
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