Should Biomass Plants Decouple Preprocessing and Conversion?

biomass plants

In biomass plants across the country – from Iowa to Minnesota and Maine – there is a direct link between preprocessing biomass fuel and converting it into energy.

Most of the time, the two happen at the same facility – and this process occurs with a decidedly low-tech approach that places no particular care on better preparing feedstock for conversion.

Now, industry experts and researchers are advocating that this process – known as “direct coupling” – be decoupled into a more methodical way of preparing feedstock so that it flows smoothly through the process until it is used in a boiler for energy production.

The Odd Decouple

A piece in Biomass Magazine titled “The Odd Decouple” provides an in-depth description of this practice and offers a few arguments about why decoupling should be the paradigm moving forward. In the piece, the author, Tim Portz, writes:

“These approaches, characterized by few, if any, additional efforts to better prepare the feedstock for conversion, are common throughout the biomass-to-energy industry. According to researchers at the nation’s national laboratories, this low-tech approach must evolve if the biomass-to-energy industry is going to significantly increase its contributions to the nation’s power, heat, and fuel portfolios.”

The approaches in question involve biomass fuel being handled, sized, and dried at the conversion facility in a direct couple. As the author points out, direct coupling is an exception, not a rule, when it comes to other industries that handle mass amounts of solid material.

Better if Handled Separately?

The federal government, via the Department of Energy, has been studying this issue for years. In July 2016, the DOE made a recommendation that the industry develop mechanisms that “transform raw feedstocks that are aerobically unstable and highly variable into a high-density, flowable format that can be traded as a commodity.” The argument against direct coupling is that this process can be better carried out if the two components – preparation and conversion – are handled separately, in dedicated facilities.

To that end, the DOE recommends a series of depots for biomass feedstocks spread throughout the country that would receive shipments of fuel sources, size and upgrade them for conversion, and then distribute them to the end-user facility for conversion. Doing so would result in a shift from a passive system – the one in place now – to a more active system in which there is more direct control over the preparation-to-conversion process.

Doing so, advocates argue, would not only streamline operations and improve efficiency; it would increase the quality of the feedstock so that it has a compounding effect.

A Crossroads for Biomass Plants

Of course, creating such a system would require significant investment beyond what has already been put into the industry. If there is a clear, compelling reason in the eyes of owners of biomass plants – such as higher rates or lower costs – then the industry could move in that direction. That, arguably, is a less difficult prospect than convincing state and federal legislators – many of whom are skeptical about biomass to begin with – to offer or increase subsidies and tax breaks in order to fulfill the vision the DOE has for the industry.

Nevertheless, the biomass-to-energy industry is facing a crossroads between continuing on as a fledgling industry or becoming a mainstream force in the nation’s energy production. Decoupling could be a major step toward moving past the crossroads in the right direction.