General and business operations
Anaerobic digestion is a natural process in which micro-organisms break down organic material, such as plant residues, without oxygen. This produces biogas, which consists of methane and CO₂, and other useful products such as liquid and solid fertilisers.
Green gas is methane, the same molecule as fossil gas. However, green gas is formed by anaerobic digestion of organic material. The methane has the exact same properties as fossil gas, which is why it can be mixed in the gas grid. When green gas is burned, CO2 is emitted, just like for fossil gas. However, this CO2 was absorbed out of the atmosphere by photosynthesis. Therefore no extra CO2 is emitted into the atmosphere due to green gas.
For the digester, the ideal mix of different residual streams is determined. This is called the menu. In any case, GR4SS’s menu will consist of 36,000 tonnes of roadside grass per year. Apart from this, 24,000 tonnes of plant residues will be addeds. These are often residues from agriculture and the food industry. Examples include cereal residues, potato peelings and coffee grounds.
GR4SS will not process manure. This is ensured through the permit, which states only plant residue may be processed.
GR4SS will be developed on the Leeuwarden Energy Campus (ECL). ECL is a new innovative business park on the west side of Leeuwarden.
Four sustainable streams will be made from (among others) grass; green gas, peat substitute for potting soil, biogenic CO2, and sustainable fertilizer.
The owner of GR4SS is Bermgras ECL B.V. This is a joint venture between D4 B.V., HoSt participaties B.V., and FSFE.
Normally, using peat contributes to CO₂ emissions and the destruction of unique ecosystems. By using a sustainable peat alternative, we protect natural areas, reduce carbon emissions, and preserve biodiversity while still providing high-quality soil and soil improvers.
The green CO₂ is used in the food industry, for example to accelerate plant growth in greenhouses or in the production of soft drinks.
Yes, GR4SS provides natural fertilizer substitutes and soil enhancers that reduce reliance on synthetic fertilizers, improve soil health, and promote sustainable farming practices.
The GR4SS process minimizes water use by recycling rain water and water from organic material breakdown. We are proud to say that GR4SS uses no drinking water for processes and also no process water is disposed in the sewers. GR4SS also reduces the need for water-intensive synthetic fertilizer production. There is also zero risk of water contamination due to GR4SS. No waste water is disposed in surface waters.
Verge grass
In the mowing season a part of the grass is fed to the digestor immediately. Another part is stored in an ensilage pit (graskuil). Grass is compacted and stored in airtight conditions to ferment. This way the grass will keep its properties and nutrients.
Verge grass is mowed because tall grass might affect traffic safety due to overgrowing of traffic signs and decreasing visibility. The grass is disposed in order to ensure nutrient removal and with it a biodiversity increase.
Environmental effects
A new development will always have some impact on the view from surroundings. However, with GR4SS we have minimalised this as far as possible. From the west and east GR4SS will be invisible because it is located between other developments. From the south, most of the facilities will be hidden behind a dike. From the north GR4SS is visible. The north side contains the thoughtfully designed entrance with trees, embankments and the building itself which contains a green facade with ample glass.
GR4SS will contain various processes that create sound. This includes pumps, trucks loading and unloading, and other technical equipment. Much of the noise-sensitive equipment is placed indoors. Furthermore, sound effects for the environment have been researched and assessed as within the legal frameworks. In the environmental permit limits have been set to the noise effects on houses in the environment. The FUMO will periodically perform measurements to ensure that the limits set in the permit will not be exceeded. Noise from trucks will only occur during working hours. To the west of the site sound coming from GR4SS will merge with the sound of cars from the Haak van Leeuwarden/N31.
Smell-sensitive processes like storage and processing of digestate will be placed inside. The air in the hall will be circulated and refreshed frequently. The air will then go through an air washer and a biofilter. These will remove smell from the air, before being emitted in to the outside air.
The loading and unloading of grass will happen outside because the ensilage pits are outside. The ensilage process is similar to that of farms. A grass smell might be noticeable in the surroundings of GR4SS during operations. Operations are during office hours.
Grass and other feedstock will be transported to the GR4SS facility. The biogas will be injected into the gas grid. Fertilizer, peat substitute and CO2 will be transported from the GR4SS facility to the end users. These transport mean that on average 36 trucks will drive from and to the GR4SS facility each day. Furthermore, cars from personnel will drive from and to the GR4SS facility on working days. All trucks will come to GR4SS through the Haak van Leeuwarden/N31 and the Harlingerstraatweg.
The installation meets all safety requirements. Explosion of the biogas is virtually impossible. In the unlikely event of a calamity, there is a flare with internal flame where the gas will be directed to and burnt.
For companies, governments and energy co-operations
The produced green gas will be injected in the regular gas grid where it is mixed with green gas from other suppliers and fossil gas. Companies, governments and energy co-operations are able to buy green gas from GR4SS on a PPA basis. For more information contact info@d4.nl
GR4SS still has some availability for grass input. Advantages of delivering grass to GR4SS are a competitive gate fee, the possibility of long term contracts and the most route for the grass, which makes for a competitive position in tenders. For grass suppliers that aim to make their organisation more sustainable, a two-way deal for grass and gas is a possibility. For more information contact info@d4.nl