Biomass: Torrefaction case study

Andrew Mourant

Part 2: Holland, with limited natural supplies of biomass, is an unlikely location for the world's biggest torrefaction plant, but for almost a decade the Dutch have been pioneering this field.

Researchers in the UK are studying the science of torrefaction – roasting woody biomass in an airless environment at around 280C so it can be fired alongside coal at power ­stations, as we reported in the last issue.

But where most of the world has been slow to try it out on a commercial scale, Dutch firm Topell Energy BV took the leap five years ago.

The work of academics attached to the Energy Centre for Netherlands (ECN) was the catalyst – those same academics are now key employees at the company run by former Dutch MP and Shell executive Jules Kortenhorst. “We're still at the early stages and not yet profitable,” admits Kortenhorst, a Harvard MBA. But “2013 is big for us”, he says. “We're homing in on a couple of projects and there are potentially other customers ready to commit. I can't disclose where our second plant will be but it will be in Europe. We also have further (possible) projects in North Africa, Europe and Latin America.”

The torrefaction industry is still in its infancy. The amount of power generated from torrefying 60,000 tonnes annually (Topell's current output) is “very modest”, Kortenhorst acknowledges. “That goes to show how important scaling up is,” he says.

He seems to have had little problem persuading investors it's a worthwhile prospect. Topell's work has gathered momentum since its test reactor was commissioned in January 2009. After experimenting with 800 different biomass samples, the company says it's arrived at an optimum pellet size. Processes have been refined – how to re-use the released heat; how to cool the product and make it compact.

The prototype plant attracted a “limited” government subsidy and then last summer Topell secured a further €13mn in finance, “significantly strengthening” its intellectual property position. The money came from various sources: Yellow&Blue Clean Energy Investment Management; Innogy Venture Capital (an existing investor); management team members and business angels.

Yellow and Blue is backing torrefaction because it sees the process as ‘instrumental in unlocking the potential of biomass for large-scale energy production,’ according to managing director Albert Fischer. Moreover, as Kortenhorst notes, studies by ECN show torrefaction could work for all sorts of biomass fuel sources, from woodchip to palm kernels.

An injection of extra funds will allow Topell to ramp up production at its plant near The Hague and, Kortenhorst says, “rapidly grow business” through selling additional plants. The company has signed a new partnership agreement with UK-based Torftech Group, whose reactors Topell uses. The Dutch company has secured manufacturing rights to build and modify the reactors specifically for torrefaction applications. The deal will “enable gas and solids to be contacted more efficiently”, it says.

Learning curve

Currently, Topell mainly uses forest waste bought from a local wholesaler to power its plant. There are, however, few swathes of woodland on its doorstep. Rather, the plant's location was chosen because it is close to engineering experts.

“We knew going into this project we'd need people on hand for technical problem-solving and to get it to work,” says Kortenhorst. “If we'd built our first plant in Africa, that would have entailed a lot of travel. However we expect that future plants we build for customers will be nearer forests.”

Kostenhorst is reluctant to discuss technical difficulties encountered along the way. He says the core process “works very well…challenges have centred around auxiliary processes such as heat generation”. Capital budget for the prototype was €20mn but Kortenhorst expects Topell's next plant to have a capacity of “in the region of 75,000 tonnes and be cheaper”.

He does not think torrefaction should be pursued at all costs however. “Biomass can make a tremendous contribution to renewable heat and power but only if done in a sustainable manner and if it doesn't lead to competition with food or protecting biodiversity,” he stresses.

Topell business director Robin Post van der Burg agrees – He claims CO2 emissions created by trucks transporting raw biomass to the plant, power consumed on site and fuel used by shipping exported pellets are similar to wind and solar.

Still, Kortenhorst believes the big business potential for torrefaction lies in its “many other applications… such as gasification and pyrolysis…you ensure that the pyrolysis oil, or syngas, will be cleaner”.

One thing seems clear: worldwide there's no shortage of raw material – Hawkins Wright, a research agency for the forest products industry, has forecast the world could have the capacity to produce 12 million tonnes of torrefied pellets by 2016. Meanwhile a report compiled by the European Climate Foundation, forest owners, pulp and paper companies, utilities and NGOs, and analysed by consultants McKinsey, suggests investors are likely to show interest as commercial plants become more refined, volumes increase and costs fall.

McKinsey's own research concluded that there's enough land and biomass supply potential for “ambitious global targets …without compromising food production”. This is based on projections of land available for bioenergy feedstock production in 2020 using an inventory from the United Nations’ Food and Agriculture Organization with food needs factored in.

US go slow

So it's all the more surprising that in scientifically-advanced areas of the world, especially those with abundant local supplies of biomass, the commercial possibilities for torrefaction haven't been widely explored. Still, there are pockets of activity in America; and one project is being pushed by HM3 Energy based in Gresham, Oregon.

But why has the US lagged behind? HM3 founder and president Hiroshi Morihara, who set up his company in 2008, thinks it's because the technology was slow to arrive. Like Topell, HM3 Energy has spent years testing and refining; and next year (2014) expects to set up its first commercial operation.

Morihara is making the commitment despite an uphill battle to find backing. “We do lot of educating but it's very difficult to talk to people with influence in government and to private investors,” he says. “A lot of my time is spent on presentations to companies so that they understand what we're doing.

“I think for investors, a major stumbling block is that [power] utilities aren't signing up long term contracts to receive torrefied biomass, so it's very difficult to raise money to build a plant. Traditional biomass pellets have been produced for many years for other purposes – home heating and animal bedding, and plenty of manufacturers make them. But there's no other industrial use for torrefied material.”

Undeterred, he plans investing $20mn on his commercial plant in Prineville. The site lies on the doorstep of two national forests with vast supplies of raw material that in the past has been slashed and burnt. A large-scale thinning programme is underway to help prevent forest fires, yielding rich stocks of forest waste that will travel no more than 40 miles to the plant.

Morihara expects the plant to produce 45,000 tonnes in its first year, rising to 90,000 tonnes in 2015. Power generation companies will want substantial assured supplies, he says- big boilers need 8-10,000 tonnes.

He's studied the technology from all angles. “As we use forest waste, we have a process that removes dirt and so the torrefied material will be pure.” Moreover, Morihara believes HM3's ‘densification’ technique, producing briquettes with 50 times the mass of pellets, will give a competitive edge. He claims the equipment needed for this process is far less costly than for traditional pellet or briquetting machines.

“Torrefied mass is very abrasive and the die may overheat because of friction. It could cause a fire. The abrasion also causes dies to wear out quickly – they'll have to find new alloys if they're going to give then a longer life. Briquettes are abrasive too but because of their far bigger mass, more tonnage can be produced before the die wears out. Another aspect of our design is that die temperature can now be controlled.”

Back in 2010, HM3 carried out experiments using 100% torrefied biomass in a small boiler. Tests included first trying the pulverised fuel blended 50% with coal, followed by a switch to 100% biomass that ran for about two hours. Morihara says it performed ‘just as coal’ except that a feed rate of about 20% less was needed to maintain the furnace temperature. He hailed the outcome as ‘a historic accomplishment’ given it was previously thought that a mix of more than 25% biomass with coal would cause problems in the boiler.

Although currently small, HM3 Energy has big ambitions. When the plant is fully operational, Morihara expects to employ 21 at Prineville and a further 35 gathering and transporting forest waste.

And the future? “Essentially we'll be looking towards [selling] licences far away from here,” he says. “We're negotiating with many companies in Asia and one in Europe.” As with Topell, it's about spreading the word and marketing the idea. So far, the world would seem to offer both companies something of a blank canvass.

About: Andrew Mourant is a freelance journalist whose specialisms include renewable energy, education and the rail industry

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