Our solutions are relevant within various industries typically either within food production and bioenergy applications, for instance bioethanol and agriculture, utilizing animal waste and / or residual products to produce energy, fuel, and valuable fertilizer. Sustainable and circular in every way. Biogas not only yields a method for producing sustainable energy and fertilizer but is also a sustainable way of handling organic waste and avoiding landfilling.
We have successfully deployed our solutions over many years, across much of the globe. A cornerstone in most of our applied solutions is the biogas itself, on top of which biomethane production may be added alongside CO2 capture and utilization. Also, biomethane may be reformed further, perhaps alongside syngas from a pyrolysis process, refining the gases into even more valuable fuels. The digestate may also be refined into high nutrient fertilizers, using our patented solutions to do so, as applied in several of our larger industrial works. In the sections below, we have briefly described the processes high-level, and you are of course welcome to reach out.
In the digester, anaerobic bacteria convert organic biomass into valuable fertilizers and environmentally friendly biogas. Biogas mainly consists of methane (CH4) and carbon dioxide (CO2). Examples of biomasses are livestock manure and organic residues such as waste from food industries, ethanol facilities and other similar industries. When using waste as feedstock, biogas will have a net negative carbon footprint, not just net zero. Thus, biogas is very environmentally friendly compared to almost any other fuel, and certainly compared to fossil fuels. The amount of CO2 absorbed when the biomass was created is the same as the amount of CO2 released into the atmosphere when the biogas is produced and used, and as such complete neutral. However, there are other loops that should be accounted for also; avoided emissions from chemical fertilizer production, avoided emissions from landfilling of food waste, the total net impact is far more than just the CO2 that is part of a closed circuit.
The digestate is a valuable fertilizer and sent back to the farmers it will yield up to 10% extra produce for the farmers compared to using animal wastes directly.
The biogas can be used several manners. The simplest and most common is in a co-generation plant where it is combusted and used for producing electrical power and heat to the existing grid and district heating. Alternatively, the biogas can be upgraded to natural gas quality and distributed to the natural gas grid, commonly known as biomethane or renewable natural gas (RNG) or used at transportation fuel in compressed from (C-RNG) or as liquified biomethane (LBG). Renew Energy can provide all these solutions.
The nutrients of the degassed biomass can be further concentrated in Renew Energy’s nutrient recovery process and sold to farmers or greenhouses for specific applications and securing than as little water as possible will have to be transported. This sort of solution also opens op for high yield (in terms of gas) input, as water from the process may be recirculated to the process if refined well enough, changing the dynamics and economics of many facilities.
Renew Energy’s nutrient recovery technology is a further development of the traditional biogas plant. In the anaerobic digestion process, bacteria convert organic waste into energy and produce a significantly improved residual product. Organic bound fertilizers are converted into inorganic fertilizers more accessible for plant uptake. In the separation technology, the degassed biomass will be refined to clean process water, nitrogen fertilizers such as ammonia sulfate, compost with high phosphorous content, and potassium concentrate.
The CO2 from the biogas may also be captured and utilized since by default its purity once cleaned for H2S is by default close to food grade quality and going the last steps to ensure this utilization is a simple step to reduce sustainability and increase value drivers of a biomethane project.
The environmentally friendly fertilizer from the separation plant can be adjusted to crops far better than traditional livestock manure. The plants’ absorption of the nutrients is much more effective. Thus, the leaching of nutrients to streams and ground water is reduced to a minimum.
By producing biogas from crude slurry and utilizing the biogas, the release of methane and carbon dioxide that would be produced in on-farm containment is reduced. Furthermore, conversion of organic waste at the biogas plant improves the environment by reducing CO2 emission caused by energy production based on coal and oil.
The concentrated fertilizer product reduces the farmer’s need for storage and transport. Further, it reduces damage from wheel tracks and unnecessary pressure on the fields.
When the water is separated from the fertilizer, the result is not only a more concentrated fertilizer product but also purified water that can be irrigated on the fields or upgraded to drinking water quality.
All pathogenic bacteria, viruses, and weed seeds from the waste products are totally degraded. Further, odor nuisances from slurry and waste are completely removed.
Mechanical Separation – Decanter Centrifuge
The degassed biomass contains all the nutrients that enter the biogas plant with the feedstock. The nutrients are made more accessible to plants during the anaerobic digestion, and the degassed biomass, therefore, has a greater fertilizer value than the incoming feedstocks.
The mechanical separation is especially applicable, when distribution of the degassed biomass to local farmland is not possible. Solid biofertilizer, which is the solid fraction from the mechanical separation, is a storage stable product with a high fertilizer concentration. Therefore, the solid biofertilizer can be transported over long distances.
Mechanical separation of the degassed biomass can be a decanter centrifuge or a screw press. The degassed biomass is separated into two fractions: a fiber fraction (solid biofertilizer) containing most of the dry matter, and a thin liquid fraction (reject water) primarily containing water soluble nutrients. The reject water can be treated further in Renew Energy’s concept for advanced nutrient recovery.
Renew Energy’s concept for advanced nutrient recovery is tailor-made to meet the requirements of each individual project. The recovery process offers many possibilities, and the final design will be based on water quality demands as well as fertilizer market opportunities and requirements.
In Renew Energy’s basic model, the degassed biomass is refined into clean process water, nitrogen rich fertilizer (ammonium sulfate), phosphor rich solid biofertilizer, and a potassium concentrate.
The nutrient recovery process consists of mechanical separation, ammonia stripping, and membrane filtration. One alternative is to exclude ammonia stripping and, instead, bind the ammonia in the concentrate by adding acid.
Mechanical Separation: The degassed biomass is separated into two fractions: a fiber fraction (solid biofertilizer) containing the majority of the dry matter, and a thin liquid fraction (reject water) containing water soluble nutrients.
Ammonia Stripping:The thin liquid fraction contains nutrients (ammonia-N, P, and K). After the anaerobic digestion, the liquid also contains carbon dioxide which has to be removed before ammonia can be released. Ammonia is absorbed in sulfuric acid and ammonia sulfate is produced as a well-known fertilizer concentrate.
Membrane Filtration: The liquid from the ammonia stripping can be further treated by membrane filtration. Several different types of membrane filtration exist: micro, ultra, nano, and reverse osmosis. The common feature is that they can retain particles and salts over a certain size letting water and smaller particles pass through. The membrane filtration will create a concentrate stream and a permeate stream. The permeate stream from a reverse osmosis filtration can be used as clean process water.
Renew Energy designs robust and flexible biogas plants which can treat organic waste from various industries. Each biogas plant is designed specifically for the biomass to be treated in the plant. This way, the optimal operation solution can be obtained.. Experience over the years has shown that the biogas plant will be offered several different biomasses once the plant is in operation and flexibility in feeding system strengthens the profitability and competitiveness of the biogas plant, which is why by default Renew Energy designs for long term viability and robustness by ensuring a maximum of flexibility.
Typically, feedstock can be found in many places, like food producers, agricultural sites, but also ethanol facilities and breweries are common. Of course, your average waste collector also typically has lots of organics in the haul, which is why landfills and utilization of the organics going there are a key to ensuring big change, fast and with a minimum impact on overall societies daily procedures.
Renew Energy provides biogas plants and biorefineries based on organic residual products from the food sector. The biogas technology can solve environmental problems and at the same time produce energy to be used for process energy and/or sold as green energy. Food industries can reduce their CO2 emission significantly by employing Renew Energy’s biogas plant. Emission of greenhouse gasses caused by fossil fuels, coal, oil and natural gas can be reduced when substituted by biogas. Industries can improve their environmental performance. Renew Energy is experienced in designing biogas plants treating food waste from service and catering industries, supermarkets, and organic waste from households. It is often resources being burnt in waste incinerators or dumped in landfills. Municipalities can promote a green profile by utilizing organic waste as feedstock in biogas plants and hereby gain green energy production and recycle nutrients otherwise being lost.
Food waste is often found in urban areas where spreading of the digested biomass can be a problem as there is no access to farmland. In this context, it is an ideal opportunity to concentrate fertilizer products in Renew Energy’s nutrient recovery process and produce valuable end products which can be sold. Often, food waste requires pretreatment before it can be fed into the digesters.
Examples of biomass stemming from food waste:
- Organic household waste
- Food waste from restaurants and catering industries
- Organic waste from supermarkets
- Waste from food processing industries, including slaughterhouse and brewery waste
- Vegetable and fruit waste
Pretreatment of food waste
Some types of biomass require pretreatment before they can be fed into biogas digesters. Food waste from e.g. households, restaurants or food industries, needs to be shredded and pulped to become pumpable. If the food waste contains inorganics such as metal, plastics and glass, these are removed in the pretreatment process. Renew Energy has extensive experience in designing and including pretreatment of food waste for biogas plants.
Animal by-products not intended for human consumption are a potential source of risks to public and animal health. Within the European Union, this area is regulated by the Animal by-product Regulation. Handling of these waste streams requires a sanitation or sterilization step often placed as a pretreatment step. The slaughterhouse waste stream is normally shredded and heated to secure that all pathogens and viruses are killed.
Dry biomasses such as grass, silage, straw etc. require special feed-in systems that can shred and open the biomasses in order to secure that the solids can be mixed efficiently with the liquid in the digesters. Hereby floating layers are also avoided. Renew Energy has designed many facilities with intake and pretreatment of dry green biomass which are often key to ensuring a high, stable average gas production, especially in agriculturally based feedstock facilities.
That being said, there is a lot of focus worldwide to further utilize otherwise wasted agricultural byproducts, which is why Renew Energy constantly investigates new technologies within feeding-in of solid biomasses to be at the forefront with our knowledge.
Renew Energy provides biogas plants that utilize residual products from traditional distillation plants, 1st generation bioethanol plants, and 2nd generation bioethanol plants. Thus, use of fossil fuels can be avoided and energy be produced in the form of electrical power, steam and heat which can be used for the operation of the plant and energy surplus can be sold. Alternatively, of course the biogas can be upgraded to grid quality and sold as biomethane, leaving also a CO2-stream than can be utilized.
Water, ammonium, nutrients, and other refined residual products can be reused and sold as fertilizer products.
Read more about Renew Energy’s biogas plant in combination with ethanol plants here.
Energy production from Renew Energy’s biorefinery protects traditional ethanol plants against fluctuations of energy expenses from fossil fuels and reduces tremendously the water consumption of required by ethanol facilities, by recirculating water from the filtration process.
1st and 2nd generation ethanol plants have positive as well as negative impact on the local environment and gross energy balance. Biofuels are produced for the transport sector. However, large amounts of fossil fuel are used for the production. The negative impact will be greatly reduced, if the ethanol plant is combined with Renew Energy’s biogas/nutrient recovery plant: water can be reused, the plant produces energy for its own consumption, and the plant recovers the nutrients which can be used as fertilizers in the agricultural sector.
The net environmental benefit from combining ethanol and biogas plants will be many times greater, and the use of fossil fuels can be avoided. Besides, surplus power can be sold to the grid as green energy.
Renew Energy’s biorefinery in combination with ethanol plants can offer:
Energy efficient new ethanol plants.
- Retrofit, efficiency improvement or expansion of existing ethanol plants, where the owners wish to optimize the operating economy and improve environmental issues.
- Improvement of existing distilleries through energy savings and reduced environmental issues.
- Production of fertilizer products which can be applied to the crops grown for ethanol production.
If all residual products (whole stillage) from the ethanol plant are utilized and the plant is self-sufficient in energy and a net exporter of power for sale.
If residual products are centrifuged, the fiber fraction or distillers grain (DWG) is used for animal feed with or without drying. The thin fraction (thin stillage) is used for biogas production, and the plant will be (partly) self-sufficient in energy. At the same time, the plant can deliver large quantities of water back to the ethanol plant.
Naturally, in any case the ethanol facility can always choose to export electricity or RNG to grid, instead of utilizing the energy itself.
Biomass such as livestock manure, organic waste or residual products from biodiesel production can be treated in the biogas plant together with whole stillage or thin stillage. Thus, the energy production can be optimized.