By Nora Haider, WSU Extension | June 2018
Evolution of the Biomass Header
Looking down the crop row at AHB’s Pilchuck demonstration site, it is hard to imagine that these 30-foot-tall trees reached this height in only three years. As a bioenergy crop, this is the type of growth AHB researchers were hoping for. Lots of fast growing biomass, that growers could harvest on a consistent schedule as a feedstock for biofuels and bio-based chemicals produced in the Pacific Northwest. This growth demonstrates poplar’s promising potential as a bioenergy crop, but presents a challenge to researchers developing the equipment used to harvest the trees.
In May, modifications to the New Holland FB130 coppice header debuted for the second harvest at the Pilchuck site. The header attaches to a New Holland forage harvester (FR 9000) and cuts and chips woody biomass as the machinery moves down the crop row. New Holland designed this machine to process 30-foot tall poplar trees with stem diameters reaching a thickness of up to six inches. The header is specialized for harvesting woody crops like poplar and willow. It attaches to the forage harvester and increases the capabilities of the standard farming equipment, enabling the machine to process up to 132 tons of woody biomass per hour.
The front of the header is now framed by a revolving augers that help guide the poplar stems and branches into the rotating drums of the machinery. During past harvests, the exceptional height of the poplar at AHB’s Jefferson and Hayden demonstration sites proved to be the rate limiting factor during harvest. Before, the operator would have to stop and back up to capture wayward stems that did not fall in vertical alignment with the machinery. During the harvest at Pilchuck, researchers noted the improved efficiency of the harvesting process. The harvester’s operator reported an “100% improvement in stress level” as a result of the new addition.
Harvesting is expected to be the single biggest cost over the lifetime of a poplar bioenergy farm. Researchers from New Holland, the State University of New York, AHB, NewBio, and IBSS, are working to increase in-field performance to save time and reduce costs during harvest operations. The latest improvement to the woody crop header is another step towards improving the efficiency of the harvesting process.
Pilchuck Harvest Details
After a wet winter and spring the sun came out in the poplar fields east of Stanwood, Washington and dried up the ground enough for the site’s second harvest. The New Holland forage harvester and header captured three years of coppice regrowth. This is the growth that has been produced at the site since the last harvest in November 2014. Inventory results indicate exceptional growth at the site, with yields greater than anticipated. Average yields across all varieties was 15 bone-dry tons (BDT) per acre, with five (of eleven) highest performing varieties averaging between 18 and 29 BDT per acre. Stem diameters averaged 2.5 inches at breast height across all varieties, with the highest performing varieties averaging between 2.7 and 3.2 inches.
For now, the poplars at Pilchuck are resprouting and growing biomass, but their future is uncertain. AHB and GreenWood Resources hope to secure funding to keep this demonstration site in production for additional coppice harvests. The team is interested in building upon the research already occurring at the site and replacing low producing varieties with high yielding varieties. This is the only short rotation poplar demonstration site remaining in the US. Given ongoing interest and research in poplar, the site is a national resource.
Video: Click image to view the poplar harvester cutting and chipping trees as it moves down the crop row.
