System for the energetic utilization of biomass

Abstract

System for the energetic utilization of biomass, comprising a biogas plant (1), a CHP unit (3) connected to an electricity grid (5) and a heat network (6) and a gas processing plant (2) for the production of biomethane from biogas, at least connected to a natural gas network (4), characterized in that a methane fuel cell (9) is included in which the biomethane from the gas processing plant (2) can be combusted, further comprising a methane plasma lysis unit (8) operated by electrical energy and a hydrogen burner and / or a hydrogen fuel cell (15) in which hydrogen formed in addition to carbon can be combusted in the methane plasma lysis unit (8).

Description

[0001] The invention relates to a system for the energetic utilization of biomass, comprising a biogas plant, a combined heat and power (CHP) unit connected to an electricity grid and a heat network, and a gas upgrading plant for producing biomethane from biogas, at least connected to a natural gas network. The system also functions as a CO2-negative power plant that removes carbon dioxide from the atmosphere, consists of several components, and is scalable. Biogas plants for the anaerobic digestion of organic matter with CHP units and / or gas upgrading are well known in the prior art.

[0002] The disadvantage is that the use of the various products of the biogas plant, including the residues from fermentation, is not always possible, at least not at all times and to the full extent.

[0003] It is therefore an object of the present invention to propose suitable utilization and storage options for the products of the biogas plant.

[0004] The problem is solved by the protection claim; advantageous embodiments can be found in the dependent claims.

[0005] The first component of the system according to the invention is a biogas plant. The biogas plant produces biogas, consisting of biomethane and other gases. The biomethane is separated from the other gases in a gas upgrading plant, resulting in a low-grade gas in addition to the biomethane. The biomethane makes up approximately 60% of the total biogas. The low-grade gas is processed in a combined heat and power (CHP) unit suitable for low-grade gas, and the electricity generated is then fed into a power grid. The CHP unit can also be operated directly with biogas, depending on availability, demand, and the capacity of the gas upgrading plant.

[0006] The heat generated is either immediately fed into a district heating network and used by the connected consumers, or stored in a heat storage unit, preferably a brick storage unit, most preferably located under a building, for later use. Brick storage units are known from the prior art.

[0007] Storage via so-called geothermal probes beneath the building is also possible, although the soil composition and groundwater levels must be taken into account. A brick storage tank would be the preferred option, as it can be insulated much more effectively to prevent heat loss.

[0008] There are further processing options for biomethane. If it is not needed in the vicinity of the biogas plant, it can be fed into a gas pipeline or natural gas network. For use at the biogas plant, there are two alternative ways to process the biomethane. Primarily, biomethane could be converted into electricity and heat using a fuel cell configuration. Heat is then used immediately or stored as needed. Electricity can be continuously fed into the public grid as required. If there is no demand, electricity production is reduced. The fuel cells are scalable.

[0009] An excess of biomethane can be produced. This excess biomethane is fed into methane plasmalysis, where the gas is split into hydrogen and pure carbon in a 1:2 ratio. Plasmalysis is an electrochemical process that requires a voltage source. The term describes, on the one hand, the plasma-chemical dissociation of organic and inorganic compounds (e.g., CH and NH compounds) in interaction with a thermal / non-thermal plasma between two electrodes, and on the other hand, the synthesis, i.e., the combination, of two or more elements into a new molecule (e.g., methanation). Plasmalysis is a portmanteau of plasma and lysis (Greek λκσζ, "dissolution").

[0010] The hydrogen produced could be used in fuel cells, provided they are already equipped to operate on hydrogen. This would significantly reduce electricity generation costs and greatly increase fuel cell efficiency, as hydrogen currently has to be extracted from biomethane. Methane plasma lysis requires 10 kWh of electricity to produce hydrogen with an energy content of approximately 55 kWh. The resulting carbon is needed in the chemical and steel industries. If the hydrogen is not needed, it can be fed into the public grid, if available. Any heat generated can be fed into the grid or stored immediately.

[0011] In the biogas plant, the digester or fermenter, the residual materials are extracted and subjected to pyrolysis. These materials are thus converted into biochar, which can then be enriched with nutrients and, for example, supplied to agriculture, thereby creating a nutrient cycle. The biochar binds the carbon for up to 1000 years.

[0012] The stored heat in the brick storage unit can be used directly as needed or fed into the district heating network. In the latter case, the temperature level would need to be raised from the low-temperature range (20 to 25 °C) using an industrial heat pump to a suitable temperature for injection. Preferably, the temperature should be raised at or near the point of consumption, as this method of transport would significantly reduce heat losses.

[0013] Products generated in the system according to the invention include electricity, heat, biomethane, hydrogen, pure carbon, and biochar (bound carbon). CO2 certificates are issued for the biochar, which can be sold.

[0014] The invention is explained in more detail below with reference to the description of exemplary embodiments and their illustration in the accompanying drawings. The drawings show: Fig. 1: schematically a block representation of an embodiment of a system according to the invention, Fig. 2: schematically a block diagram of an embodiment of a system according to the invention with pyrolysis, Fig. 3: schematically a block representation of an embodiment of a system according to the invention with a heat pump.

[0015] Fig. Figure 1 schematically shows a block diagram of an embodiment of a system according to the invention comprising a biogas plant 1 that produces biogas from organic materials by anaerobic digestion. The biogas is fed to both a gas processing unit 2 and a combined heat and power (CHP) unit 3. Furthermore, organic residues remain after anaerobic digestion, which can be used as fertilizer in agriculture, but within the scope of the present invention are subjected to pyrolysis (for further details, see [reference to be added]). Fig. 2).

[0016] In gas processing plant 2, the biogas is split into biomethane, i.e., largely purified methane, and a collection of the remaining gases, primarily carbon dioxide, but also traces of methane. This gas, with its low methane content, is therefore referred to as low-grade gas. The biomethane is fed into a natural gas network 4 or, particularly if the natural gas network 4 cannot accommodate it, is supplied to a methane plasma lysis plant 8 and / or a methane fuel cell 9.

[0017] The low-grade gas is also fed into CHP unit 3, which must be designed for the combustion of low-grade gas for this purpose. In CHP unit 3, heat and electricity are generated during the combustion of biogas and low-grade gas. The heat is fed into a district heating network 6, provided it has the capacity to absorb it. Otherwise, the heat is stored in a brick storage tank 7 for later use. The brick storage tank 7 consists of a quantity of bricks, preferably salvaged from the demolition of old buildings, between which pipes are laid through which a heat transfer fluid circulates. This heat transfer fluid heats the bricks in the brick storage tank 7, and the heat can then be extracted later.

[0018] The methane fuel cell 9, which is supplied with biomethane, also generates heat and electricity. As with the CHP unit 3, the electricity is fed into the power grid 5 and the heat into the district heating network 6 or the brick storage tank 7.

[0019] Hydrogen and carbon are obtained from methane plasma lysis 8, using electrical energy. The hydrogen is preferably combusted in a hydrogen fuel cell 15, where, analogous to the methane fuel cell 9, heat and electrical energy are generated. These are fed into the electricity grid 5 or the district heating network 6.

[0020] Fig. Figure 2 schematically shows a block diagram of an embodiment of a system according to the invention with pyrolysis 11. In this process, the residues originating from the anaerobic digestion in the biogas plant 1 are pyrolyzed to biochar 12, thus immobilizing carbon in order to remove it from the atmosphere in the interest of climate protection.

[0021] Fig.Figure 3 schematically shows a block diagram of an embodiment of a system according to the invention with a heat pump 12. This system is used when the relatively low temperatures of the heat stored in the brick storage unit 7 need to be raised to a usable level. If the temperatures in the brick storage unit 7 are sufficiently high, the heat can be fed directly into the district heating network 6 or directly to consumers, generally referred to as the point of consumption. Otherwise, if the available temperature is lower than the required temperature, the temperature in the heat pump 12 is increased and the heat at the required temperature is fed into the district heating network 6 or supplied to the consumers. Reference symbol list 1 biogas plant 2 Gas processing plant, gas processing 3 CHP units 4 Natural gas network 5 Power grid 6 District heating network 7 brick storage 8 Methane plasmalysis 9 Methane fuel cell 10 residual materials 11 Pyrolysis 12 Biochar 13 Heat pump 14 heat consumers 15 Hydrogen fuel cell

Claims

[1] System for the energetic utilization of biomass, comprising a biogas plant (1), a combined heat and power plant (CHP) connected to an electricity grid (5) and a heat network (6) and a gas upgrading plant (2) for the production of biomethane from biogas, at least connected to a natural gas network (4), characterized by , comprising a methane fuel cell (9) in which the biomethane from the gas processing plant (2) can be burned, further comprising an electrically powered methane plasma lysis unit (8) and a hydrogen burner and / or a hydrogen fuel cell (15) in which hydrogen formed in addition to carbon can be burned in the methane plasma lysis unit (8). [2] System according to claim 1, comprising a pyrolysis plant (11) in which organic residues (10) from the anaerobic digestion in the biogas plant (1) can be converted to biochar (12). [3] System according to claim 1 or 2, comprising a brick storage unit (7) in which excess heat not immediately consumed from the CHP unit (3) and / or at least one of the fuel cells (9, 15) and / or the hydrogen burner can be stored for later use. [4] System according to claim 3, comprising a heat pump (13) which can raise the low-temperature heat from the brick storage (7) to a temperature level desired for further use. [5] System according to claim 4, wherein the heat pump (13) is arranged at a consumption point. [6] System according to one of the preceding claims, wherein the CHP unit (3) is designed at least for the combustion of low-grade gas supplied from the gas processing plant (2) in addition to the biomethane. [7] System according to one of the preceding claims, comprising a control device which controls the instantaneous capacity of the production facilities and directs material flows of the produced substances according to supply and external demand.

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