Producing methane gas with ‘Dutch seaweed’


Heating houses with green gas from locally grown seaweed?

Or, producing mayonnaise with protein from Dutch seaweed? That may sound like distant future music, but various parties in the Netherlands are working hard to construct a seaweed field outside the Haringvliet water locks in the North Sea. The seaweed is then used to produce methane gas and protein powder. Project manager Mark Soetman and Monique Sweep from Deltawind company explain the plans.

The future dream of Mark Soetman is to use 4,000 hectares of the North Sea in five years’ time to grow seaweed. That is an area of ​​roughly 7,500 football pitches. This seaweed is then converted into protein powder and green gas in a factory. The protein powder is, according to the enthusiastic project manager, of better quality than protein from chicken eggs and can be used in the food industry. Protein is used for cookies, mayonnaise, bread, meat substitutes and much more. “Protein is actually the holy grail in our search for food.” With the methane gas extracted from the seaweed, approximately 40 percent of the consumption can be supplied at the region Goeree-Overflakkee. The advantage of this is that it can pass through the same pipes as natural gas and it can be used for a stove or boiler.

And there are more people who share this dream, including Seaweed Harvest Holland, which has been working on the development of seaweed cultivation in the Oosterschelde for years, and GOA Ventures, who want to put the biorefinery process into practice together. Mark Soetman brought these companies into contact with the Cooperative Delta Wind, and together they are now investigating the opportunities for Goeree-Overflakkee.

1000 pounds a day

Before the future dream of Soetman and its partners can come true, the cultivation and the techniques for processing the seaweed must be tested. It is Seaweed Harvest’s intention to construct the first seaweed field in June. Four months later it is then possible to harvest for the first time. The aim is to harvest 1000 kilos of seaweed daily as a pilot. This is then brought ashore and processed immediately. Subsequently, a process takes place that they have christened ‘fermentation 2.0’ and in which green gas is produced faster and more efficiently than usual.

New plans for Deltawind Company

Monique Sweep, director of Deltawind says that discussions are currently underway to make a temporary production location at the Stellendam outer port for the pilot phase. That location consists of several sea containers, containing the production space, on the outside an explanation is given about the cultivation and processing of seaweed.

But before the time comes, the members of the cooperative can speak out on Saturday 30 March about this new development. Because now almost all locations where windmills are allowed on the island have been filled in, Deltawind is focusing on new projects to make the island more sustainable. There is a good list of ideas, but currently most of the energy is spent on heating homes with hydrogen in Stad aan ‘t Haringvliet and the seaweed project. Sweep: “With this project we really start from scratch and take more risk than with a wind farm, for example, but to take the lead as an energy island and to start innovative projects, you have to dare to take risks.”

Fertilizer from the waters of Haringvliet

The seaweed fields are planned in the mouth of the Haringvliet. Soetman: “That is a perfect place, because the water that flows into the North Sea from the Haringvliet is full of plant nutrients. The water is full of pokon, from a large part of northwest Europe, which means that seaweed can grow quickly. ” It is expected that one hectare of seawater will produce 225 tons of seaweed per year. That is much more than a hectare of corn or sugar beers. According to Soetman, this is due to the third dimension, in other words: the seaweed also grows vertically. Little can be seen from a seaweed field from the coast. The area is fenced off at the corners with yellow buoys, so that ships know they cannot sail there. Under water, concrete blocks with cables are attached to the bottom, which are attached to ‘underwater buoys’ just below the water surface. A grid of horizontal and vertical lines is placed between the vertical cables. Traces (seeds) of seaweed are attached to it, after which it starts to grow. If the leaves are large enough, they are cut. Seaweed cultivation is not new in the Netherlands. Seaweed has been cultivated in this way for a number of years in the Oosterschelde near the Zeeland Bridge. This is harvested and sold to restaurants that make weedburgers or use it in dishes.

Fast growth

Seaweed can be grown all year round, but different varieties are used in winter than in summer. The summer species grow faster than the winter species

Sea lettuce for example, that can double in volume in one day. It must therefore often be harvested, because otherwise the leaves become so large that the risk of drifting away in a storm becomes too great.

Fertilizer precursor

It has been known for some time that seaweed is full of energy. In the past, monks from Zeeland pulled seaweed onto the dyke, left it for a while and then spread it over the fields, where it falls apart under the ground and is a source of food for the crops. Seaweed is a precursor to contemporary fertilizer. At Petten and also in Ireland, seaweed is grown on a small scale and converted into gas by means of a bio-fermentation plant. The method used in Stellendam to extract the protein was developed in the laboratory and is, according to Soetman, much faster and more efficient. This also applies to fermentation to green gas. According to the enthusiastic project manager, this works in 2 to 3 days instead of 2 to 3 months in conventional fermentation installations.

Closed CO2 cycle

When both natural gas and ‘seaweed gas’ are burned, CO2 is released. The big difference is that the CO2 in natural gas before it is emitted was stored in the earth, so it is added to the atmosphere extra. The seaweed is different, it absorbs CO2 during the growth process, so if it is emitted, there will be no ‘new’ CO2. It is a closed system.

The initiators realize that fishermen are not cheering when part of ‘their’ North Sea is used for the cultivation of seaweed. Sweep: “But we expect this project to boost employment in Stellendam port.” Soetman: “In addition, the seaweeds will dampen the waves, reducing the silting up of the delta. In addition, seaweeds are a true estuary of new life, which will improve fish stocks locally.”

Author: Martijn de Bonte | Source: Eilandennieuws (translated from Dutch)