The four pillars of our production
Our project is based on four elements, which combine the production of plants, fish, fertile soil and energy. It is important that the individual elements are matched and harmonize with one another. The most important processes of the Food & Energy Campus are presented to you with their respective functions:
The central element of the Food & Energy Campus is the biogas plant of the municipal energy company “Stadtwerke Groß-Gerau” operated by Ingenia. The plant is fed with renewable raw materials and agricultural residues to generate electricity according to the Renewable Energy Act (EEG).
The resulting biogas is converted to about nine million kilowatt-hours of electricity per year and a similar amount of waste heat in a combined heat and power plant. As residual material from the biogas production, about 20,000 cubic meters of liquid digestates are produced, which until now have been applied as fertilizer on agricultural land within a radius of up to 15 kilometers. The associated transport volume of more than 1,000 load transports per year leads to noise and traffic pollution in the surrounding villages. In general, the application of fermentation residues to fields is related to some problems: the contained nitrogen can escape into the atmosphere in the form of nitrous oxide (a greenhouse gas) or be washed out in the soil mainly as nitrate, thus contaminating groundwater. A further disadvantage of the direct application of fermentation residues is that the residues contain only a maximum of ten percent solids – so over 90 percent is water, that is transported during the application to the fields.
In future, we will treat the fermentation residues with modern filter technologies so that the water can be separated from the solid phase and be used for irrigation or aquaculture. The remaining solids are refined to biochar with the process of pyrolysis directly on site of the campus. This biochar will be further processed to Palaterra.
On the Food & Energy Campus we will solve several problems of the use of fermentation residues: the traffic volume is reduced, the nitrous oxide emission into the atmosphere and the nitrate leaching into the ground water are avoided and the so far inefficient use of water from the residues remains in the cycle.
Pyrolysis and Palaterra
Pyrolysis refers to a process of carbonization of organic matter with heat and strongly reduced oxygen supply. We want to transform the fermentation residues of the biogas plant in Wallerstädten by a similar carbonisation process from PYREG®. With the PYREG system, the fermentation residues will be transformed to charcoal, wich will serve as source material for the production of Palaterra.
The PYREG system is a two-stage process in which the biomass is first heated in a reactor to a temperature of up to 600 degrees Celsius. In a second step, the low-temperature gases produced in the reactor are completely combusted in the combustion chamber at 1,250 degrees Celsius. Therefore, no condensates or tars arise during the pyrolysis process. We want to implement this biochar to the production of Palaterra enabling a carbon sequestration in the soil. The carbon that has been taken up by plants once as from the atmosphere, is stabilized in the biochar and will stay bound in the soil for centuries.
The most productive soils that nature offers are so-called black soils. Unfortunately, only few areas of the earth are blessed with this high-quality black soil. The Indios of the Amazon developed a method to produce such “black earth” artificially: today it is known as Terra Preta do Indio. For a long time, it was uncertain how the process of manufacturing such a substrate would work. In the meantime, it has been possible to identify the production process of Terra Preta do Indio. A partner of the Food & Energy network, the company Palaterra, played a significant role in deciphering the process. Today, this company produces Terra Preta-like substrates under the name Palaterra®. The quality characteristics of Palaterra correspond largely to the physical, chemical, microbial and biological soil properties of the Terra Preta do Indio. With the license of our partner, we want to use the biochar from the fermentation residues residues as a biological raw material for Palaterra production on the Food & Energy Campus.
Sun Light Greenhouse
The Sun Light Greenhouse from ebf GmbH is a highly energy-efficient greenhouse that combines the production of food and energy.
The west, east and north wall of the Sun Light Greenhouse are built with massive isolation materials. This helps to buffer temperature fluctuations inside the greenhouse and strongly reduces the heating requirement. A sophisticated ventilation system – using a geothermal heat exchanger – further reduces the need for energy to heat or cool the greenhouse.
In contrast to conventional greenhouses, F-clean (ETFE) foil is used in the Sun Light Greenhouse. It is a particularly robust, durable and highly transparent cover material. Unlike the conventional foils, F-clean allows the entire daylight spectrum to pass through and reach the plants. In addition, a photovoltaic system will be installed beneath the protection of F-clean to use excess sunlight and produce electricity. The durability and efficiency of the internal photovoltaic elements is increased because they are not exposed to direct environmental influences such as pollution or hailstorms. In addition, the elements are mobile and can be used to shade the plants as well as to produce electricity in a multi-functional and effective manner. The electricity produced here is either used on the Food & Energy Campus or fed into the public electricity grid.
On the campus, regional fish will be produced in closed circulation systems. The fish is kept in basins inside the greenhouses or in a separate building. In any case, it will be protected against the strong temperature fluctuations of natural seasons.
The water of the basins is cleaned in a circuit through biological filters and always remains clean for the fish. Through the use of special filter technologies, we want to collect all the nutrients and feed them to the plants of the greenhouses. This not only avoids the need for mineral fertilizers, but also prevents the occurrence of waste water enriched with nitrite and nitrate, which can be a burden to the environment.
The main product of aquaculture will be pikeperch, since the availability of fish hatchlings is given by the company Fischmaster in Trebur. This cooperation enables a completely regional production.
It is particularly important to us that on our campus the nutrient-containing waste water from the fish farming is processed and used for plant cultivation. One option is to use an aquaponic system. Aquaponic refers to a system in which the rearing of aquatic organisms – such as fish or crabs – is combined to the production of crops in such a way that both utilization systems complement each other synergistically. The waste water from the aquaculture enriched by the digested fish feed with various nutrients are fed into a hydroculture (liquid culture). The plants absorb nutrients from the sewage water and purify the water so that it can be recycled back into aquaculture. In this way, we avoid the loss of nutrients and water, the production of contaminated water and at the same time save fertilizer.