Forty six delegates from 13 countries met in State College, PA, USA for the 4th IEA CCC Workshop on Cofiring Biomass with Coal. Although numbers were down on previous events, the quality of the presentations and the value of the discussions enjoyed and contacts made should not be underestimated. Delegates came from a range of organisations including utilities, engineering companies, torrefaction companies, research organisations and universities.
The workshop began with a site visit through the beautiful forests of Pennsylanvia to the start-up commercial torrefaction facility of Terra Green Energy LLC. It was excellent to start a workshop by looking at some real live engineering.
The workshop proper opened on 6 November, with a review of cofiring in the USA, prepared by David Tillman (presented by Bruce Miller). He described the new cofiring plant at Virginia City Hybrid Energy Center, but concluded that despite being biomass-rich the USA would not pursue cofiring or biomass conversions without financial and political support. Paul Baruya (IEA CCC) delivered a global perspective of the biomass resource, which supports the status quo of North American wood pellets being exported to Europe. Preben Messerschmidt (Ramboll Energy) outlined the work involved in 100% bioconversion of coal-fired power plants and again stressed the importance of financial incentives.
A technical session on biomass characteristics followed, chaired by Bruce Miller (PSU). Torrefaction improves the quality of biomass for cofiring, but there are always concerns about the safe handling and storage of biomass.
Other highlights included Lester Marshall (Ontario Power Generation) describing the conversion of Thunder Bay Generating Station to use steam treated wood pellets, where he made the valid point that “there is no such thing as a ‘drop in’ fuel replacement”. In his opinion steam treated pellets outperform torrefied ones. Ben Anderson (University of Iowa) described the conversion of the University power plant to biomass and the efforts made to encourage local farmers to grow Miscanthus.
The work of the International Biomass Torrefaction Council (IBTC) including developing standards for torrefied material with ISO was covered by Sylvain Bertrand (Airex Energy). Jo James (Agri-Tech Producers) described his work to produce a bio-coal while also cleaning up polluted ground and water. Guy Tourigny (Canmet Energy) outlined Canmet’s work on testing torrefaction and densification and the valuable databases of biomass fuel characteristics that they are developing. Collins Ndibe (IFK) was upbeat about the future for torrefied material as, if successfully produced at scale, it will improve the logistics for cofiring and full conversion in the EU. Guisu Liu (Mobotec LLC) described a major conversion project in Poland which operated at up to 45% biomass cofiring. It is no longer running, due to a lack of political and financial support.
Delegates at Cofiring 4
Work is underway to develop a fuel comprised of waste coal and micro-algae in South Africa (Ben Zeelie, NMMU Institute for Chemical technology). It will be interesting to see how it develops. Sharon Miller (PSU) has also been working on cofiring micro-algae.
VTT (Janne Karki) have studied the economics of cofiring and the factors that should be included, such as different biomass types, and the importance of including cogeneration. A higher carbon price is vital.
Martin Moeller (Dong energy) gave an interesting update on work in Denmark to gasify straw. Gasification deals with the high alkaline content of the straw and separates the nutrients. The ash can be used as fertiliser. Currently a 6 MW demonstration plant is running and they are hoping to scale up to a 60 MW plant, but as so often the case, the problem is the CAPEX.
The final presentation from Miguel Angel Delgado (Fundacion Ciudad de la Energia), presented by Paul Baruya outlined some of the potential risks of cofiring in oxymode.
The workshop closed with a trip to the Energex wood pellet plant, and a tour presented by the CEO Bruce Lisle. Energex process sawdust, shavings and woodchips into 130,000 t wood pellets a year. 80% of the raw materials come from a 100 mile radius, and most deliveries are within 350 miles. The raw materials are blended, go through the first size reduction, are dried, reduced in size again and then go to the pellet mill. The expanding business primarily supplies the residential sector but is also moving into bulk delivery, and is looking at central heating in commercial applications. They are also working towards complying with standards such as ENPlus. Energex is also considering producing torrefied material in the future.
Delegates visiting the Energex wood pellet plant
Some of the conclusions from this varied workshop can be summarised:
- Many organisations are working to develop torrefied material and make it a standardised product that can be used on a commercial scale.
- Research continues on characterising various biomass fuels
- Micro-algae and coal has potential as a fuel
- Cofiring and 100% biomass conversion are feasible and can be extremely successful, but will not take place without political and financial support.