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Why was the world’s biggest biomass power station closed down – and what does this mean for forests?

Background to Tilbury B:

On 13th August, Tilbury B, so far the world’s biggest biomass power station commissioned so far, was shut down for good.  It is sited along the Thames east of London and was opened as a coal power station in 1968 and later acquired by RWE Npower.   It was one of several UK coal power stations which did not meet the EU’s 2001 Large Combustion Plant Directive (LCPD) because of its very high sulphur dioxide

Historically, UK coal and oil-fired power stations have been amongst the most polluting in Europe and few of them are fitted with the expensive technology to reduce sulphur dioxide (SO2) and nitrogen oxide (NOx) emissions.   The UK emits more SO2 than any other country in western Europe.  Under the EU’s LCPD directive, companies were given the option to either retrofit their coal power stations with SO2 scrubbers, to purchase enough SO2 permits from better quipped power stations or to ‘opt out’, which meant they would keep running their plants for a set number of hours and for no longer than until the end of 2015.  Tilbury B was one of seven ‘opted out’ plants, slated for closure.

Rather than closing down Tilbury B, RWE Npower decided to convert it to burning wood pellets instead.  Although burning wood results in similar levels of pollution as burning coal overall, it contains far less sulphur and emits less SO2.  The ‘first stage’ of the conversion was completed at the end of 2011 and in early 2013 the company got planning permission to expand the plant’s capacity and to continue to run it on wood pellets long-term.

E.On soon followed RWE’s example and converted its Ironbridge power station to biomass, as did Drax, who are converting half of the UK’s biggest coal power station to run on wood pellets.  Drax is one of several power stations threatened with closure in the medium-term because they do not meet stricter new EU emissions standards that will come into force in 2016.

Within a few months of re-opening on biomass, Tilbury B suffered the worst fire of its history and it took several months before the damage was repaired.  When submitting their application for long-term planning permission, RWE set out the high level of investment that they sought to make to reduce the risk of similar accidents as well as air pollution from the plant.

RWE’s dubious official reasons for closing Tilbury B

RWE’s decision to suddenly abandon their plans and close the plant for good therefore came as a surprise, given the substantial investments they had already made.   This, after all, had been the UK’s flagship biomass project: The first coal-to-biomass conversion in the UK and one of the first worldwide.  This was a test case for the industry.  If the Tilbury B biomass power station was not viable, what does this mean for the other ambitious coal-to-biomass conversion plans, including those by Drax in the UK?  So far consented coal to biomass conversions in the UK, if they all go ahead, will require more than 50 million tonnes of wood a year – over 5 times as much as all the wood produced annually across the UK.  This is in addition to the wood needed for several dozen proposed and often consented new-build biomass power stations.

The wider consequences of RWE’s decision clearly depend on their reasons for closing Tilbury B.  RWE’s official reason was that the UK government failed to offer them sufficient subsidies and support, thus making the additional new investment required unviable.  This made little sense: Supporting coal-to-biomass conversions lies at the heart of the UK government’s renewable energy policy and Tilbury B’s subsidies had been guaranteed until 2027.  Furthermore, those guarantees were enough to persuade Drax to invest in eventually burning nearly 16 million tonnes of imported wood a year.  A government consultation cited by RWE which might prevent them from getting even higher subsidies remains just that – and open consultation.  A company pulling the plug on a multi-million pound investment because of a government proposal that might result in them not getting even more subsidies than they’d already been guaranteed at the time the investment was announced defies common sense.

Clearly, RWE has had a different reason for abandoning their flagship biomass project, one that they do not wish others to know.

It is also clear that, whatever RWE’s reasons were, Drax remains no less determined to expand their biomass burning capacity, with investments into both the conversion of a second power station unit and in securing more wood supplies from the southern US, British Columbia and, recently, Ontario.

Two different biomass models, two different outcomes: Drax versus Tilbury B

Any informed guess as to why Tilbury B got closed down while Drax is powering ahead with its biomass conversion thus needs to be based on a comparison between the two company’s biomass strategies.

There is little difference between the two power stations (except that Drax is bigger) and thus the technical challenges of running them on wood pellets.  Both Drax and RWE have been relying largely on wood pellets from North America where pellet production is rapidly expanding.  Admittedly, Drax, unlike RWE attracted a loan by the Green Investment Bank and a public loan guarantee for its conversion project, but RWE is one of Europe’s 10 biggest energy companies and has far greater assets and revenues.

But perhaps the biggest difference lies in both companies’ wood supplies, even if both source them from the same regions.  RWE opened the world’s biggest pellet plant at Waycross, Georgia, in May 2011, just months before commissioning Tilbury B to run on biomass.  Earlier this year they announced plans to sell that plant but so far it has not been sold.  Waycross is surrounded by large areas of pine plantations, originally planted to supply the pulp and paper industry.

Drax has announced plans to build two pellet plants of its own, in Louisiana and Mississippi but so far they have relied exclusively on pellets bought from other companies, such as Enviva.  A recent investigation of Enviva’s largest pellet mill, at Ahoskie, North Carolina, published by Dogwood Alliance and NRDC shows that they are targeting native hardwood wetland forests, high in biodiversity and rich in carbon.  The Dogwood Alliance/NRDC evidence does not prove that none of the pellets bought by Drax come from plantation pines – proving a negative like this would be virtually impossible.  Yet the pellet plants owned by Drax’s two southern US suppliers – Enviva and Green Circle Bio Energy – all happen to be located close to biodiverse native hardwood forests.

As a Biofuelwatch Freedom of Information request revealed earlier this year, Drax’s technical data shows that they can only burn pellets from slow-growing trees with a low bark content – other types of biomass are too high in alkali salts and corrode their boilers.  The documents do not make it clear whether pines grown on plantations in the southern US are too fast-growing for Drax’s boilers.  Yet it seems little coincidence that the most successful pellet companies in the southern US are the ones targeting hardwood forests – unlike RWE who struggle to even sell their pellet plant that depends on plantation wood.  Perhaps RWE simply invested in the wrong type of wood supplies for its power station – in wood that would ultimately corrode their boilers.

What are the consequences for forests?

Tilbury B’s closure prevents as many as 7 million tonnes of wood being burned every year.  This, without doubt, is good news for forests.  Vast areas of pine plantations in the southern US have been established at the expense of biodiverse forests and the escalating demand for wood pellets by European energy companies is competing with the pulp and paper industry.  Burning huge numbers of plantation pines in power stations will force the paper industry to look elsewhere for supplies.  This will mean more forests in the same region being converted to plantations, as well as destructive tree plantations elsewhere at the expense of forests and forest-dependent peoples, for example in South America.  And while RWE’s wood from Georgia almost certainly came from pine plantations, there is no evidence that their pellets from British Columbia were not sourced from clearcutting of natural forests.

If energy companies such as Drax are indeed coming to depend on slow-growing hardwood trees for their large converted biomass power stations, on the other hand, the impacts on forests will be far more direct.  Only small fragments of the native forests of the southern US have so far survived clearcutting and conversion to plantations, and many of those are remote wetland forests, and refuge to large numbers of species.  If European energy companies such as Drax or E.On come to depend on slow-growing hardwood, much of the region’s biodiversity and remaining forests could be wiped out entirely in a short span of time.  After that, the industry would rely on the destruction of slow-growing forests elsewhere, perhaps elsewhere in the US, most certainly in British Columbia and Ontario and possibly in Russia and the Baltic States, too.

[Note: As we explained in a previous article, the situation is different where purpose-built biomass power stations are concerned.  The sourcing restrictions specifically apply to converted coal power plants.]

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25 Sep, 2013
Posted in News, Forests and Climate Change