Using existing fish processing plants, kelp and fish waste can be turned into a diesel-like fuel to power generators or fishing boats in rural, coastal Alaska, according to a team from Pacific Northwest National Laboratory (PNNL).

Many isolated communities rely on diesel generators for energy; diesel, however, is expensive since it must be barged or flown in. In search of a cheaper, sustainable fuel, researchers at PNNL turned to two plentiful marine resources in Alaska: kelp and fish processing waste.

It is viewed quite widely, and this report assumes, that Alaska will have a thriving kelp industry within the next 5 to 10 years that has the potential to not only lead the United States in kelp production for food (initially), but also become a significant leader in world kelp production with additional non-food products, including fertilizers, biochemical and food additives, as well as rare-earth elements. However, this report provides another view of how the Alaska kelp industry could additionally capitalize on the use of fish waste, existing fish processing facilities, and MRE [marine renewable energy] concepts to provide additional value and benefit for energy and other products for coastal Southwest Alaska communities. While additional study is needed, Alaska communities in the Southwest Alaska Municipal Conference (SWAMC) region, and others, could derive significant economic benefits from such a symbiotic relationship.

—“Kelp Energy Products and Marine Renewable Energy for Coastal Alaska Communities”

They found that by using existing fish processing plants, Alaska’s kelp harvest and fish waste could be transformed into a diesel-like fuel that is carbon neutral. The waste-to-energy fuel could then be used to power generators or fishing boats.

The research team crosswalked different species of Alaskan-grown kelp with potential uses ranging from fertilizers to the recovery of rare Earth metals from the sea. But economically, the most practical opportunity was liquid fuel when it was combined with fish waste.

The challenge was putting all the pieces together in a way that made financial sense and resulted in cheaper fuel than flying or shipping in diesel.

—Michael Rinker, PNNL program manager

The research team had three goals: (1) use existing waste; (2) leverage current facilities; and (3) develop small-scale fuel processing structures for converting waste to fuel.

The team examined three main pathways: anaerobic digestion to produce methane; hydrothermal liquefaction (HTL) to produce an oxygenated biocrude; and fermentation to produce ethanol.

The researchers found that if they take fish waste and combine it with kelp, they could use HTL to turn it into a usable biocrude or low-grade fuel that could potentially cost anywhere from $3.18–3.64 per gallon, depending startup costs—significantly cheaper than the roughly $7 per gallon for fuel that must be flown in.

This highly oxygenated fuel isn’t suitable for diesel trucks, but can be used as a maritime or bunker fuel to power generators. The researchers noted that converting the biocrude to a higher-quality fuel requires additional steps and the addition of hydrogen, which ultimately drives up cost beyond what makes financial sense.

The end product isn’t a high-value fuel like you’d find at a gas station, but it is definitely useful in some cases and better than what they have now, in terms of cost.

—Michael Rinker

This research was supported by EERE’s Advanced Manufacturing Office and the Water Power Technologies Office.