Khanh-Quang Tran, an associate professor at the Norwegian University of Science and Technology’s (NTNU) Department of Energy and Process Engineering turns 79% of kelp into bio-oil. Kelp, also known as seaweed, offers all of the advantages of a biofuel feedstock with the additional benefit of growing, not surprisingly, in the ocean.

Diver In a Kelp Forest. Click image for the largest view.

Diver In a Kelp Forest. Click image for the largest view.

Tran conducted preliminary studies using sugar kelp (Laminaria saccharina), which grows naturally along the Norwegian coast.  The results have been published in the academic journal Algal Research.

Tran said, “What we are trying to do is to mimic natural processes to produce oil. However, while petroleum oil is produced naturally on a geologic time scale, we can do it in minutes.”

Tran heated the kelp in small quartz tube ‘reactors’ – which look like tiny sealed straws – containing a slurry made from the kelp biomass and water to 350º C (662º F) at a very high rate of 585º C (1085º F) per minute.

The technique, called fast hydrothermal liquefaction, gave Tran a bio-oil yield of 79% meaning 79% of the kelp biomass in the reactors was converted to bio-oil. A similar study in the UK using the same species of kelp yielded just 19%. The secret, Tran said, is the rapid heating.

Biofuel has long been seen as a promising way to help shift humankind towards a more sustainable and climate friendly lifestyle. The logic is simple: petroleum-like fuels made from crops or substances take up CO2 as they grow and release that same CO2 when they are burned, so they are essentially carbon-neutral.

Tran like others references the International Energy Agency (IEA) report “Tracking Clean Energy Progress 2014 that said biofuel production worldwide was 113 billion liters in 2013, and could reach 140 billion liters by 2018. But the IEA says biofuel production will need to grow 22-fold by 2025 to produce the amount of biofuel the world will need to keep global temperatures from rising more than the oft quoted mystical 2oC.

Like others Tran is trying to solve the biomass feedstock problem. It’s relatively easy to turn corn or sugar beets into ethanol that we can pump into our car’s fuel tanks. But using land that can produce human food biomass for fuel is more and more problematic as the world’s population climbs towards 8 billion and beyond.

To solve the arable land limits, biofuels are beginning to be produced from non-food biomass including agricultural residues, land-based energy crops such as fast-growing trees and grasses, and aquatic crops such as seaweed and microalgae.

However, all of these feedstocks have their challenges, especially those that are land based. At least part of the issue is the fact that crops for biofuel could potentially displace crops for food. But seaweed offers all of the advantages of a biofuel feedstock with the additional benefit of growing at sea.

Turning big pieces of slippery, salty kelp into biocrude is a challenge, too Many studies have used catalysts to help make the process go more quickly or easily But, catalysts are normally expensive and require catalyst recovery. The UK study noted above that resulted in a 19% yield used a catalyst in its process.

Tran said the advantage of his process is that it is relatively simple and does not need a catalyst. The high heating rate also results in a biocrude that has molecular properties that will make it easier to refine. But Tran’s experiments were what are called screening tests.

Tran worked with batch reactors that were small and not suitable for an industrial scale. “When you want to scale up the process you have to work with a flow reactor,” or a reactor with a continuous flow of reactants and products, he said. “I already have a very good idea for such a reactor.”

Even though the preliminary tests gave a yield of 79%, Tran believes he can improve the results even more. He’s now looking for industrial partners and additional funding to continue his research.

Hitting 79% in the first development step is a huge encouragement. It would be great if the funding for more research found its way to Tran. This is another example how important high temperature process heat is going to be in the future. Great ideas like this one are going to be extremely useful and will need other great ideas to mature as well.


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