Torrefaction

Torrefaction is an innovative process for making raw biomass suitable for energy production. Along with AgentschapNL, the Energy Valley Foundation supports business active in the torrefaction sector in the Netherlands. See also www.torrefactie.nl.

1. What is Torrefaction?

The term torrefaction is derived from the French verb "torrefier" meaning "to roast", used in particular for the process of roasting coffee beans. In its current applications, torrefaction is a mild thermal (heat) treatment, in the absence of oxygen, used to make biomass or biomass-containing raw materials (wood, paper, etc.) better suited for use as a source of energy.

2. What exactly does torrefaction do?

The product of the torrefaction process is bio-coal. Thus, torrefaction produces alternatives to fossil fuels (like pit coal and brown coal). The bio-coals produced can be used immediately in conventional coal-fired plants. This will reduce coal consumption and thus also fossil carbon dioxide emissions. This technology can play a key role in the greening of power plants currently still running on pit or brown coal. Some key benefits of this alternative fuel, compared to direct use of untreated biomass as fuel, include its greatly enhanced grindability, better energy properties (more energy content) and favourable logistical properties (more compact).

3. Is torrefaction sustainable?

This technology produces sustainable alternatives to fossil fuels, thus reducing fossil carbon dioxide emissions. The treatment temperature for this process is lower than with other techniques, which means it requires less energy. In principle, the process is energy-neutral, including predrying of the biomass or residual waste flows with heat and gas produced in the Torrefaction process. External power is only required to start the system up. After that, torrefaction sustains itself from the power generated by the biomass.
The energy content of bio-coal is higher than that of untreated biomass, so you need less of it to generate the same amount of energy. In addition to this, it takes fewer trips to ship the bio-coal to the purchaser. This also contributes to reducing carbon dioxide emissions. Ultimately, applications from this technology will make a sustainable contribution towards the greening of the Dutch energy strategy and achieving sustainability.

4. How is it different from using untreated biomass?

These sustainable alternative fuels have some key advantages over direct use of biomass as fuel. For one, they enjoy a much higher degree of grindability. Untreated biomass is often too fibrous to be ground well. Secondly untreated biomass can only be stored for a limited time period.. Bio-coal is free of these drawbacks and can therefore be used as a fuel in almost any kind of coal-fired power plant.

In addition to this, bio-coal has high-quality energy properties. The energy density is higher, which means that bio-coal produces more power than the same amount of biomass. This also gives bio-coal highly favourable logistical properties. Smaller quantities are needed to produce the same amount of power, so they require less storage space and transport.

5. What is the significance of torrefaction for the Energy Valley region/the Northern Netherlands?

Torrefaction is a fledgling industry that is on the point of breaking out. The Energy Valley Foundation wants to concentrate and retain the knowledge and employment opportunities developed in the (Northern) Netherlands. It was for this reason that we founded the Dutch Torrefaction Association (DTA) along with AgentschapNL. This trade association takes on research issues collectively and promotes this new technology in the Netherlands to bring it out of obscurity.

See also: www.dutchtorrefactionassociation.eu or www.torrefactie.nl.

6. Who is involved in the Dutch Torrefaction Association?

At this time, six companies are producing bio-coals (or are in the process of building bio-coal facilities). The members of the DTA are: Topell Energy, Foxcoal, Torrcoal, Stramroy Green Investments, ECN and 4EnergyInvest.

7. What are the benefits of torrefaction?

Its benefits are diverse:

More energy value in less material (18-20 GJ/m3 versus 10-11 GJ/m3 with biomass)
Reduction in emissions of fossil carbon dioxide from coal-fired power plants.
Logisitcs savings over untreated biomass
Simpler storage: bio-coals are water-repellent
Biologically inactive (will not rot)
Easier to process than untreated biomass
Usable in coal-fired plants with no modifications nedeed

8. Are there still other potential applications for bio-coal?

Use of bio-coal in normal coal-fired plants is currently the most readily available application. Applications that are still in the research phase are: (1) biochar: soil structure improvements and capturing carbon in soils for longer periods of time and (2) raw materials (source of C) in carbonaceous industries, as an alternative to fossil carbon. The end product could one day have a higher value in these distribution channels than it currently has as a raw material for power generation.

9. What are the roles of the Northern Netherlands and Energy Valley in the development of torrefaction?

In the Energy Valley region, construction of large power plants is in the pipeline. These can process large quantities of bio-coal. Firstly, the region has sufficient biomass-containing residual waste flows available. In addition to this, thanks to our sea ports, it is possible to develop torrefaction technology and then export the bio-coal we produce to other areas by ship.
The Energy Valley Foundation supports the initiatives in the region and supports the activities of the Dutch Torrefaction Association.

Biomass (conversion) project leader, Machiel van Steenis, is a member of the panel of experts at Club Green (www.clubgreen.nl).

10. What is the current state of affairs and the plan for the future?

Rollout of torrefaction initiatives will continue over the coming years. These plans provide for a key role for the Energy Valley region. The Energy Valley Foundation will continue to support new initiatives and facilities.