Biomass is an environmentally clean alternative for producing fuels, chemicals, and bioproducts. Why then do we hear about cleaning or even washing biomass on occasion? Last week, I helped my wife preserve some of the bounty of our garden by canning bushels of tomatoes. There is nothing like fresh vegetables out of the garden. When I was a kid – and even now if I am really hungry – it was tempting to eat vegetables straight out of the garden without even washing them. But I’ve learned that washing off the dirt and residue not only makes them taste better, buts it’s actually better for good health.
Refining technologies are not unlike our bodies. Some can handle the impurities better than others, but they are usually after the good stuff from the biomass supply chain, the organic carbon molecules. What is the bad stuff? Well, that depends on the technology. Silica in large quantities (think of sand and grit) is often undesired but actually is a natural part of every feedstock. In excess, silica will erode equipment or even displace catalysts or other inert components. Other technologies do not handle certain ions or elements like Cl, K, P, and S very well. A crop won’t be very productive without adding some N, P, and other nutrients and some part of those elements necessary for good plant health will naturally be stored in the plant.
How then can we separate the desirables from the undesirables in a biomass feedstock? First, handle the biomass supply chain correctly and you may be able to control the undesirables reasonably well. However, if the refinery process is a little more finicky, then you need to clean it up. We recently helped a group with wood chip washing utilizing water, agitation, and density separation, but other biomass types need to stay dry for efficient processing. We have even worked with ion separation of grasses with special water washing equipment because of the need to remove specific ions. In some cases, we can change our agronomic management of the crop during the growth cycle to alter what the plant stores.
We typically design and work with our vendors and customers on screening or classification systems to remove dirt and other components from energy crops or crop residues only when required. There is normally a lot more dirt in a crop residue that has been left to lie on the bare dirt and then picked up later compared to a dedicated energy crop harvested directly from a field without ever hitting the bare dirt. This is one reason many technologies prefer energy crops. Whatever the refinery needs, Genera Energy is ready to meet the customer’s specifications and supply a quality product the first time meeting customer specifications.
By Keith Brazzell, COO
