Burning Questions

In what could be considered part of Scotland’s industrial heartland, the decision to allow a major new plant in Grangemouth providing hundreds of megawatts of heat and power made great economic sense.

Forth Energy’s Combined Heat and Power (CHP) plant comes complete with impressive statistics – capital investment of £450m, 500 jobs in the construction phase and an additional 70 permanent jobs at the port.

And, crucially, with its fuel coming from biomass – wood chips or pellets – it is judged to be a cleaner alternative to fossil fuels. Burning biomass, according to the project leaders, emits 45 per cent less carbon than gas and 80 per cent less than coal and would help provide low carbon, secure energy for Scotland, producing 120MW of electricity and 200MW of renewable heat; helping to deliver more than 20 per cent of the Scottish Government’s renewable heat targets by 2020.

Scottish ministers officially approved the CHP plant on 3 June, following a public inquiry held in May last year. Work is not due to start until next year, while further designs and plans are drawn up.

Yet, despite a raft of conditions laid out in approving the plant – such as the drawing up of a Domestic Virgin Wood Biomass Fuel Supply Strategy to ensure that wood provided for the plant is sustainably sourced, opinion is split on whether the process is genuinely a way forward for more environmental energy provision. Last year Forth Energy, a joint venture between Forth Ports and SSE, pulled out of another biomass project for Leith, one of four it had originally put forward, after a sustained campaign that brought about 1,800 letters of objection.

Despite the lower carbon emissions from wood pellets, objectors have still raised concerns that large-scale plants will have a damaging effect on air quality and have also questioned the practice of importing wood from elsewhere as fuel.

Biofuelwatch was one of the groups which had lodged objections to the public inquiry on Grangemouth, alongside others including Grangemouth Community Council, Friends of the Earth Falkirk and WWF.

The group’s co-director, Almuth Ernsting, said: “Local people in Grangemouth have been exposed to regular, serious breaches of air quality standards, endangering public health for many years – if this power station is built then they will be exposed to yet another significant source of new air emissions, which we believe is unacceptable.

Plans for a plant in Dundee have been rejected by the council, but Scottish ministers have the final say. If Forth Energy’s three remaining proposed plants in Grangemouth, Rosyth and Dundee go ahead they will be burning more than 1.5 million tonnes of wood chips or pellets every year. Grangemouth alone, depending if it opts for wood pellets or chips, will use 650 thousand tonnes of biomass a year. Ernsting said this “cannot be sustainable”.
“It will increase pressures on forests in the Americas and, whether directly or indirectly, contribute to the degradation and destruction of remaining biodiverse and carbon-rich forests there,” she said.

She added that the planning conditions which have been approved are “wholly inadequate” and said a large number of scientific studies showed that the carbon impact of burning wood from trees is worse than coal – per unit of energy – over several decades.

But Calum Wilson, managing director of Forth Energy, insisted the project would live up to its aims to produce low-carbon energy from sustainably-sourced wood.

He said: “At this scale, biomass is new to Scotland, so we have to accept that with anything new, you would expect that to spur a degree of debate and opinions.

“All we’ve sought to do is provide robust evidence to demonstrate that biomass could have a part to play in the renewable energy mix.

“This is about 70 per cent less carbon intensive than the current mix on the grid across Europe, in our view, it is something worth going for.” Wilson added that not only would the plant meet current certification schemes for sustainably sourced fuel supplies, it would also meet “robust mechanisms” being introduced by the UK Government and would continue to monitor its suppliers.

He said: “From our point of view, we need the fuel for the life of the plant, so we are as interested as anyone in making sure that sustainable forestry practices are in place.

“We went through a public inquiry where we provided evidence for our case in the public domain. I can categorically state that the fuel for our plans will be sustainably sourced.” An important aspect for Forth Energy is the method of transport of its fuel; all its proposed plants will be sited near ports, as shipping is a less-polluting form of transport.

He emphasised that producing renewable heat was a vital aspect of the plans – contributing towards Scottish Government targets of 11 per cent by 2020.

The Scottish Government’s policy on biomass is to only allow small-scale developments and those,  such as Grangemouth, which are proving combined heat and power and it has backed the developers’ claims that the project will provide efficient, reliable and renewable energy without damaging the environment.

In announcing the approval, Energy Minister Fergus Ewing said: “I have put in place a series of conditions to protect local residents from inconvenience, safeguard the appearance of the area, and protect the environment and air quality.

“The conditions to the consent also ensure that the fuel used in the biomass is from sustainable and responsible sources.” However, while discussion continues on the environmental credentials of biomass in Scotland, research is also being carried out here on an alternative treatment of biomass.

Instead of combustion, biomass, ranging from wood pellets to the sludge extracted from water treatment, is treated through pyrolysis – heated to a high temperature in a closed container. The produce, known as biochar, is a highly concentrated form of carbon and has the potential to be used in improving plant yields as animal feed and other agricultural or horticultural uses.

The UK Biochar Research Centre, based at the University of Edinburgh, was set up in 2009 and has treatment facilities on site investigating the uses of biochar.

While the key focus has been on the benefi ts of the process from the point of view of soil science, it has also been held up as an alternative way of extracting energy from biomass.

While the conventional burning of biomass releases carbon into the atmosphere, through pyrolysis, this carbon is contained in a solid form. Depending on the heat it is treated at, the amount of energy produced is about one third less than conventional biomass combustion, but about half the carbon is stored and can be reused.

The centre now wants to demonstrate how the technology could be scaled up and is hoping to set up a research facility on the outskirts of Edinburgh that would produce biochar and also show how it could be used to produce renewable heat to surrounding buildings, showing that if it could be used to heat a cow shed, or several farm buildings, it could be scaled up to provide the same for an estate or a town.

It wants the Scottish Government to assist in setting up a new pyrolysis facility and has already had discussions about the form this could take.

Dr Saran Sohi, leader of soil science at the centre, said he would like to see a unit set up producing a ton a day of biochar.

The UKBRC estimates the process could be worth, in carbon terms, 5 million tonnes of carbon dioxide per year by 2050 in terms of avoiding emissions – vitally important to the Scottish Government’s legal obligation to cut greenhouse gases by 80 per cent by the same date.

He said: “Biochar is a versatile technology. We think that by gaining experience with biochar, even where it only pays for itself through its value in soil, we can start getting experience with something that can be rolled out to mitigate climate change at a very large scale in the future.” He said the benefits to biochar would be that nutrients could be recycled back into the soil, improving its physical properties such as holding water, and promoting early stage crop growth and germination.

A pyrolysis plant on something like the scale of Grangemouth would clearly not produce as much energy as the CHP plant, but would have the potential to store more carbon.

“You get less energy out, but you also have stored carbon which has other impacts or benefits, I suppose you could say for economic activity in Scotland – so agriculture, horticulture, even animal husbandry.” Sohil said an important aspect of the demonstration centre would be the ability to produce renewable heat, however, he said not all applications of the technology would be used for that.

In water treatment, for example, where sludge would be removed and dried for reuse elsewhere, the energy produced would be reused to power the treatment process and would not leave enough to export to homes.

The Government’s decision on the Grangemouth CHP has brought a higher profile to the issue of biomass once again and Sohil said: “We’re talking about biochar systems that might look quite different from Grangemouth and almost certainly will use different feedstock, but it’s all about coming up with viable useful productive end uses for this quite diverse material.” A Scottish Government spokesperson said: “The Scottish Government has met with researchers from the UK Biochar Centre recently. Use of quality controlled biochar could potentially provide a useful way of sequestering carbon in soils and may have additional benefits such as improved soil fertility.

“However, the benefits, as well as the longterm sustainability of the biochar use, need to be validated under field conditions.”

The industry for the moment is keeping an eye on the research into biochar, but Wilson at Forth Energy said that presently, the technology is still at an early stage.

However, Biofuelwatch says it does not consider the biochar process to be suitable for energy production, saying that no such system exists commercially worldwide and “there appear to be significant technical hurdles to be overcome with modern pyrolysis.”

Ernsting added: “If modern pyrolysis systems could be made to work reliably in future, there would always be a pay-off between energy generation and biochar production.

“The more biomass carbon was retained as char, the less energy would be produced and vice versa. Producing biochar thus can’t play any role in energy generation – except by potentially limiting bioenergy generated from pyrolysis.”