Background: Germany is highly dependent on natural gas, the availability of which has become uncertain due to Russia's invasion of Ukraine. Biogas provision in Germany is realized by more than 9500 mainly farm-side biogas plants that have the potential to increase the security of gas supply. Main text: To assess the potential contribution of biogas to a secure gas supply in Germany, we combine a literature-based analysis of the current status and potentials of the biogas supply chain with calculations of the marginal costs for producing biogas under the current market conditions. Biogas provided 50 TWh of final energy in Germany in 2021, primarily in the form of power and heat. The production of biomethane, which can in principle replace natural gas when fed into the gas grid, amounted to 10 TWh in terms of the lower heating value, which corresponds to a share of about 1% of the German gas market in 2021. However, at the end of 2021, biogas significantly contributed to the provided power (13 TWh or 22% of power supply from natural gas) combined with co-generated heat (13 TWh or 2% of heat supply from natural gas). Increasing flexible power provision from biogas is promising under the current power market conditions. In contrast, the current biogas substrate mix will lead to crucial limitations: 75% of the input into German biogas are energy crops, which are limited in availability under rising agricultural prices. Conclusions and recommendations: In conclusion, biogas can only make up a small share of the current natural gas consumption. An immediate programme to mobilize the use of biogenic by-products, waste, and cultivated biomass without requiring additional land is recommended. We also propose measures to increase the flexibility of power production and heat use and more greenhouse gas-related incentives of biogas supply for the medium term. Finally, we see the need for additional efforts for non-food feedstock mobilization on a European scale by realizing the envisaged tenfold increase in the contribution of biomethane to a production goal of 35 billion cubic metres by 2030 in the REPower EU Plan of the European Commission.
Keywords: Biogas; Biomethane; Gas supply; Ukraine; Nutrition crisis; Energy security
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1186/s13705-023-00389-1.
As of 2021, the German energy supply was based on 15.9% renewable and 84.1% conventional (fossil and nuclear) fuels, referring to the primary energy demand of 3,748 TWh [[
Germany's natural gas consumption (
Graph: Fig. 1Natural gas consumption in Germany 2021
Figure 2 summarizes the use of bioenergy in Germany in 2019, representing the energetic biomass use as a flow from the resource (biomass from agriculture, forestry and biogenic residues and waste, on the left) through the type of energy carrier (in the medium term) to the use in different sectors (on the right), including export and by-products. The fluxes were calculated following the method described by Thrän in [[
Graph: Fig. 2Energetic use of biomass and the resource-to-bioenergy flows in Germany in TWh in 2019; based on data taken from [ [
Biogas is a renewable gaseous energy carrier, consisting mainly of methane, CO
Figure 2 also shows that biogas, as well as biofuels, is mainly generated from agricultural biomass and generates relevant by-product streams, amongst which digestate is the main component. Digestate is returned to fields and grasslands for nutrient recycling and humus reproduction. By using agricultural biomass and providing fertilizer, it is much closer interlinked with the agricultural sector than other renewable energies. Notably, the high relevance of prices for agricultural products and land as a key resource for the current biogas production indicates a strong food-energy nexus: when assessing the role of biogas in a secure gas supply, it is important to consider how Russia's war against Ukraine and its changing export policies affect agricultural production as a whole, including the availability of biogas substrates. Grain export reduction is particularly critical at a time when parts of Africa are experiencing the worst drought in four decades, and hunger crises acutely affect other regions [[
Alongside this background, this contribution to the debate poses questions about the potential contribution of biogas to the security of gas supply in Germany under resource-related, technical and market constrains and concludes with possible measures on how to secure and expand biogas production under different constraints immediately (within the next 2 years) and in the medium term (up to 2030).
To answer this question, we combined a literature-based analysis of the current status and the potential for increase of the German biogas production with a calculation of the marginal costs for farmers producing biogas under fixed feed-in tariffs and those who produce in a flexible mode closer to the market conditions. This includes the following steps.
In regard to the current contribution of biogas to the gas security in Germany, we summarize publicly available official statistics concerning energy production and consumption. The status quo is then compared with the current relevance of natural gas in the German energy system under the consideration of the technical requirements for biogas to be used as a substitute. For the discussion of further potentials of flexible biogas, biomethane and related heat production in 2030, we rely on the existing data regarding alternative biogas substrates, the political framework and literature. Potentials for alternative substrates are found in the publicly available residues and waste resources database of the DBFZ [[
Both global problems in food security and possible fertilizer shortages affect the prices for crops and thus the availability of substrates for biogas production. To assess this food-energy nexus, we used a simplified economic approach following the hypothesis that farmers decide to use land for energy or food & feed production economically based on the expected revenues for both alternatives. Revenues from biogas production for energy are still dominated by public subsidies from the REA, which are still the only or dominant source of income for the majority of biogas plants. Revenues for food and feed production are largely determined by market prices, which are much more directly determined by the ongoing crisis and show large amplitudes in 2022.
To assess the influences of current market events on biogas production in Germany, we calculate the (
We compute power provision costs of a typical inflexible German biogas plant with different energy crop input prices and compare them with typical remuneration levels for power from biogas given under the REA. This leads to maximum energy crop prices payable for a plant depending on the plant scale, Capex, Opex and the feedstock mixture under the given assumption without additional revenues from flexible power generation.
These maximum energy crop prices were subsequently compared with those of other agricultural production systems with the gross margin in €/ha as a reference value. The target value is the marginal price of the crop considered. The marginal price of a specific crop is the price at which it generates the same gross margin as the energy crop (silage maize in this example). If this price is reached, the energy crop reaches the economic viability threshold and is no longer the sole best use of the scarce production factor of land.
The assessment is done in a generalized approach (average value) for a typical German biogas plant, which was derived from the DBFZ biogas plant database [[
Biogas producers who are not producing solely under the REA, can benefit from higher energy prices and increased energy price volatility in two ways. First of all, the recent construction of the floating market premium, without the option of negative values, leads to the effect that if the market price exceeds the individual feed-in tariff, plant operators receive the actual market price instead of just their fixed tariff. Figure 3 presents the daily averages in 2022 compared to a benchmark level for the assumed feed-in tariff. For all days with higher prices, the plant can gain the average market price instead of the feed-in tariff. This is also valid for single hours, which were not shown here to keep the figure uncluttered.
Graph: Fig. 3Daily price averages for the day-ahead market at the power exchange bidding zone Germany + Luxemburg [ [
Regardless of the total price level at the power exchange, flexible biogas plants can benefit from price volatility by focusing their power generation to the most expensive hours of one day. In this way, the plant can reach a power price above the average price level, which was the reference for calculating the floating market premium. Additional revenues via price-driven operation depend mainly on the power quotient (PQ), which describes the ratio between installed and rated capacity and is equivalent to the inverse value of daily runtime per 24 h. The potential extra earnings were limited by restrictions such as the available amount of gas storage, heat supply obligations and the revenue share for power market aggregators, because most plants do not reach the minimum capacity to participate in the spot market directly.
In contrast to the impact of higher agricultural prices, the assessment of higher or more volatile power for power supply, i.e. the assessment of a typical flexible biogas plant does not make sense. Hence, we will demonstrate the development of price spread on the power market since the gas crises started and discuss its effects in a qualitative way.
With the assessments of the impact of higher agricultural prices on biogas production and power from biogas plants, we determined uncertainties for existing biogas plants under different remuneration schemes, but also presented ways to circumvent them.
To bring those different aspects together, we finally discuss the results to:
- propose robust pathways for further biogas development in Germany and
- evaluate Germany's possible contribution to REpowerEU.
The production of (raw) biogas in Germany amounts to 94 TWh/a (primary energy content) [[
The different applications are shown in Fig. 4: the biogas is predominantly used in combined heat and power units (CHPU); typically, in raw form with a methane content of about 50–75% in plants located on farm sites.
Graph: Fig. 4Current contributions of biogas and biomethane to gas consumption. FED refers to the amount of energy after conversion of biogas or natural gas to heat and/or power. PED refers to the energy content of an energy carrier prior to conversion, meaning that final energy output will be lower due to conversion losses depending on the efficiency of a combustion process in the case of energetic uses
Natural gas can be replaced 1:1 by biogas if the latter is upgraded to biomethane. In this case, it can be fed into gas networks and thus made accessible to all areas, in which natural gas is used. This is currently the case in about 230 of the more than 9,000 biogas plants, with an output of about 10 TWh of biomethane [[
For additional substitution of natural gas, therefore, three biogas options can be considered in the short-term: (a) increasing heat use in CHPUs; b) flexible power production or (c) upgrade to biomethane and feed into the gas grid.
- Heat from biogas is mainly generated in combination with on-site power generation; solely heat generation from biogas is not established. The heat extracted is used directly on site or fed into local heating networks. The increasing flexibility of power generation from biogas is usually combined with heat storage and therefore does not limit the use of heat in the future. The volume of currently generated heat amounted to 13 TWh/a [[
26 ]], which corresponds to about 2% of the heat from natural gas (approx. 550 TWh/a) [[29 ]]. - Regarding power, total generation from biogas amounted to 28 TWh in 2021 [[
26 ]], which corresponds to about 6% of Germany's power demand (562 TWh in 2021) [[30 ]]. However, as already mentioned, only one-third of on-site biogas power generation plants operate in a flexible mode, i.e. power is provided when power is scarce and therefore expensive, leading also to the use of flexible gas-fired power plants. Flexible biogas plants currently provide 13 TWh/a of power (own calculation based on [[29 ]]), which is about 22% of power from gas-fired power plants (use of natural gas for power generation amounted to about 60 TWh/a in 2021) [own calculation based on [[29 ]]]. - Processing of biogas to biomethane and injection into the gas grid is currently carried out to the extent of approx. 10 TWh/a. This corresponds to about 1% of the current natural gas consumption in Germany. This biomethane is then used for power generation, as a fuel, and to a marginal extent for pure heat supply, and could potentially replace natural gas in other areas of application (e.g., material use in the chemical industry).
In volatile markets and political environments, the role of biogas for energy supply is permanently changing. Since the beginning of the war in Ukraine in February 2022, the production conditions as well as income opportunities have shifted notably. One key development to consider here is the rising price of biogas substrates, which has been affected by the war in multiple ways. Whether the production level of biogas in 2021 can be sustained in the near future will therefore depend on whether prices for key substrates, such as maize and wheat, still enable a competitive use in biogas plants. This question is also interesting as it provides insights for policy-makers whether they have to intervene into energy markets for the sake of food security.
Table 1 shows the results of the calculation of the maximum payable silage maize prices in relation to the REA payments for the German standard biogas plant. The calculation is based on the REA remuneration on the right side of the table. The reference maize prices are derived from the REA payments using a German standard biogas plant. The reference price for silage maize is the maximum price that can be paid by the standard biogas plant at a given REA payment in order to cover costs. The equilibrium prices for wheat and grain maize were derived from this price for silage maize. If this price is reached or exceeded on the free market, silage maize is no longer competitive for biogas use. Also, the gross margin is given in the table. The gross margin in Table 1 is the equilibrium that arises with the given price for maize. From the DBFZ operator survey, it can be deduced that the average REA feed-in tariff paid in Germany is approx. 0.185 €/kWh. According to the calculations, this results in a maximum payable price of 40 €/t silage maize as a biogas substrate, which corresponds to an equilibrium price of 263.35 €/t for wheat and 230.50 €/t for grain maize (Table 1). Figure 5 visualizes the dependency of the marginal prices of wheat and grain maize in relation to the REA feed-in tariffs and the resulting maximum payable maize silage prices for the German standard biogas plant and aggregates the results from Table 1 graphically. In addition, wheat and grain maize prices are included. It can be concluded that in comparison to wheat, maize silage is not competitive at the Matif price levels (Delivery May) for wheat until an REA payment above 0.23 €/kWh is achieved. The results are considered for the German standard biogas plant defined here.
Table 1 Results of the equilibrium price calculation
Equilibrium price calculation Reference price calculation Wheat Corn (grain) Silage maize (reference) EEG payment [€/kWh] Gross margin [€/ha] 2351.41 0.228 Equilibrium price [€ t/FM] 390.09 332.85 60.00 Gross margin [€/ha] 2101.41 0.217 Equilibrium price [€ t/FM] 358.41 307.26 55.00 Gross margin [€/ha] 1851.41 0.206 Equilibrium price [€ t/FM] 326.72 281.67 50.00 Gross margin [€/ha] 1601.41 0.196 Equilibrium price [€ t/FM] 295.03 256.08 45.00 Gross margin [€/ha] 1351.41 0.185 Equilibrium price [€ t/FM] 263.35 230.50 40.00 Gross margin [€/ha] 1101.41 0.174 Equilibrium price [€ t/FM] 231.66 204.91 35.00 Gross margin [€/ha] 851.41 0.164 Equilibrium price [€ t/FM] 199.98 179.32 30.00 Gross margin [€/ha] 601.41 0.153 Equilibrium price [€ t/FM] 168.29 153.73 25.00 Gross margin [€/ha] 351.41 0.142 Equilibrium price [€ t/FM] 136.61 128.14 20.00 Gross margin [€/ha] 101.41 0.132 Equilibrium price [€ t/FM] 104.92 102.55 15.00
The calculation is based on the REA remuneration on the right side of the table. The reference maize prices are derived from the REA payments using the German standard biogas plant. The reference price for silo maize is the maximum price that can be paid by the standard biogas plant at a given REA payment in order to cover costs. The equilibrium prices for wheat and grain maize were derived from this price for silage maize. If this price is reached or exceeded on the free market, silage maize is no longer competitive for biogas use
Graph: Fig. 5Competitiveness of silage maize in comparison to the alternative cultivation options of winter wheat and grain maize in relation to their current trade prices and in dependence on REA payments
Between 2005 and 2020, average producer prices in Germany ranged between 96 and 220 €/t for winter wheat and 104 and 211 €/t for grain maize [[
With the onset of the Ukraine conflict on the 24 February 2022, the trading prices on the Matif commodity futures exchange (Marché à Terme International de France) for wheat and grain maize rose rapidly. Wheat was at times around 420 €/t and grain maize around 370 €/t [[
Prospects for biogas production are not only affected by higher prices for agricultural substrates. A second development to consider are the rising prices for energy in Europe, which provide opposite incentives in the direction of an increase of biogas production. Plant operators that run an on-site CHPU or, indirectly, as well as a biomethane CHPU, can gain additional revenues on the power market [[
Graph: Fig. 6Price duration curves for EPEX-Spot (left) and average dynamic price spreads for the n -best hours per day comparing to daily averages (right), market-zone DE-LU [ [
Over the last years, power prices have not only increased in absolute numbers, but have also become significantly more volatile. As shown in the right subplot of Fig. 6, dynamic price spreads, for example best 12 h per day, were less than 10 €/MWh in 2020, 20 €/MWh in 2021 and almost 50 €/MWh in 2022.
Due to revenues depending on both power market prices in general and price volatility, incomes differ substantially between individual plant concepts. Nevertheless, the specific revenues for power prices above an assumed feed-in tariff is about 6.57 Ct/kWh (considering EPEX Spot prices until 31st of October). The additional revenues for price-driven power generation for flexible biogas plants can be estimated using a moderate degree of flexibilization with a power quotient (PQ = installed capacity / rated capacity) of PQ = 2, which is equal to a daily runtime of 12 h. According to Fig. 6, in 2022 the gross price spread for the 12 best hours of each day is around 50 €/MWh. If one accepts that biogas plants could not fit perfectly to the ideal generation schedule and an average share of optimal marketing of 80% is assumed, together with an assumed profit-sharing rate of 80% between the direct marketer and the plant operator, 3.2 Ct/kWh can be additionally generated. Thus, the total specific income for the given assumptions will reach 28.3 Ct/kWh.
When the German government agreed to the "Electricity price brake and skimming off of additional revenues law" on the 15th of December 2022, power from biogas got an exemption from skimming off of additional revenues [[
The analysis of the current role of biogas in Germany indicates that biogas mainly refers to the power (and combined heat) sector. Biomethane, which has the potential to substitute natural gas via the gas grid, is still of minor importance at the moment. Regarding a secure gas supply in Germany, the contribution of biogas is limited by high uncertainties of energy crop availability for biogas production, which might even endanger current production. On the other hand, biogas has the potential to contribute more to power supply security, via a higher degree of flexibility under stronger electricity market signals.
To optimize the contribution of biomass to gas supply, both changes in the production and use of biogas should be considered. However, it must be taken into account that the major share of biogas in Germany is provided from energy crops, which are increasingly being diverted to other markets (animal feed) as a result of rising prices for agricultural raw materials. Thus, before considering the expansion of biogas production, measures must first be taken to secure the current production level. Overall, five key measures to improving gas supply security through biogas are possible:
Currently, 13% of the arable land in Germany is used to produce biogas substrates [[
Maintaining the contribution of biogas to energy supply security therefore requires a rapid shift to agricultural by-products and biogenic waste. A wide range of sectors still promising untapped potentials for by-products and waste for energy purposes (27—76 TWh/a) can substantially contribute to the substitution of energy crops (currently approx. 70 TWh/a) [[
Efforts to reform the substrate base for biogas in the direction of substrates which do not compete for arable land should nevertheless not lead to a categorical exclusion of the energetic use of arable crops. This would erase bioenergy's positive effects for food security in terms of stabilizing agricultural prices and thus income for farmers [[
Power generation can be made more flexible, for example by increasing the power generation capacity of biogas plants or by adding gas storages. By and large, the current production of 28 TWh/a of well controllable power could be generated in flexible mode in 2030. This would correspond to up to 46% of the power supply from natural gas. However, the potential decline in biogas production from energy crops as well as economic barriers, especially for smaller plants, must be taken into account.
Further flexibilization of the existing plants is already stimulated by the current regulatory framework supporting the production of biogas. Since 2014, public subsidies for power output under the REA have been complemented by separate payments for excess capacity as a precondition for flexible power generation. Furthermore, since 2017, output-based subsidies have been restricted to a certain share of capacity in order to further incentivize flexible power generation. However, this quasi-flexibility requirement only applies to a certain range of plants (new installations or existing installations extending their remuneration period). Furthermore, the capacity payments alone are often not sufficient to convince plant operators to switch to a new (flexibility-oriented) remuneration scheme, which is reflected in a low participation in the REA tenders [[
In addition to increased flexibility in power generation, optimizing heat use in the combined heat and power systems can also contribute to the substitution of natural gas. The potential for increasing the use of heat in existing biogas plants has been assessed by Steubing et al. [showing the potential for a slight increase in the biogas-based share of gas-based heat from 2% to about 3% (approx. 16 TWh)] [[
In the short term, biomethane supply as a direct natural gas substitute can hardly be increased to any significant extent, since existing plants for upgrading biogas to biomethane usually have a high utilization rate already.
In the medium and long term, an expansion of upgrading capacities as well as the injection of biomethane into nearby gas grids is possible and reasonable. By 2030, an additional 15—20 TWh/a of the current biogas production could be processed in this way [[
Between the different measures we see synergies and also competition: while a better integration of typically locally available residues and waste streams (measure 1), accelerated flexibilization (measure 2) and excess heat use in CHP plants (measure 3) can be well combined and are applicable in many biogas plants, the expansion of biomethane production (measure 4) is of special interest for larger plants and the competition for substrates.
Beyond these four options—development of additional biomass potentials, accelerated plant flexibilization, use of excess heat and increased upgrading of biogas to biomethane—further contributions of biogas to gas supply security by 2030 are conceivable only through severe restrictions of applicable sustainability requirements and an extensive expansion of government support measures. These steps are, however, disproportionate to the small additional biogas or biomethane volumes that could be generated as a result. In order to reduce dependence on natural gas, other measures, namely reducing consumption, increasing energy efficiency and expanding sector coupling (electrification of heat supply), should therefore take precedence over the former.
Considering the different limitations and challenges is not only relevant for the German biogas policy but also when discussing Germany's contribution to the REPowerEU Plan, which was one of the EU responses to the Russian aggression [[
With regard to accelerating the shift to renewable energies, the document explicitly mentions (amongst other measures) the scaling-up of biomethane, with a production goal of 35 billion cubic metres (bn m
The Staff Working Document [[
Scarlat et al. [[
This assumed realistic mobilization rate of 71% is, however, far from that demonstrated in Germany, where calculations by Majer et al. [[
Moreover, other sources' estimates differ: In Abdalla et al. [[
Put concisely, all figures assessing the current EU biogas potential have some degree of uncertainty, and assumptions vary widely between the studies. Production increases seem possible, but very much dependent on success in mobilization, and definitely apply to different countries at different levels.
When considering that the current German biomethane production amounts about one-third of the current total EU production (1 bn m³), it must be emphasized that an additional German contribution to the REPowerEU goals for biomethane is possible but not in proportion to the total increase envisaged by REPowerEU, simply because the German market is already very advanced by comparison to other Member States and under the current uncertainties of substrate availability, the level of biogas production in Germany thus needs to be stabilized rather than increased (at short notice).
Particularly France, but also Italy and the Netherlands have recently overtaken Germany with regard to the number of new biomethane plants built, with Denmark and France leading in the way of production growth rates. Plants in these countries also largely run on agricultural residues—and to a lesser extent on solid municipal or industrial organic waste—instead of energy crops. The above-mentioned substitution effects of food/feed production have therefore much less impact on biogas production in these countries. Moreover, as there were relatively few political incentives for biogas production in Spain or Belgium in past years, there is a substantial untapped potential in these countries [[
Germany invested substantial resources in biogas production over the last decades, which certainly boosted the sector, and first experiences with the REA's separate tenders for biomethane are equally promising. However, the extensive use of subsidies also has downsides. Next to critics pointing out the high costs and low efficiency of the REA [[
When assessing the potential contribution of biogas to a secure gas supply in Germany due to the fact that the 9500 biogas plants in Germany are manifold in biomass supply, biogas utilization and also business models, our reference cases for assessment give some impressions but do not cover all biogas plants.
We also focussed on the biomass availability and the power market conditions as two currently very relevant drivers. Those two aspects became most important after Russia's aggression against Ukraine and the related problems of gas supply security in Germany. In the future, other drivers might present, which are not considered here. Additionally, we also see that potential feedback between biomass prices and power prices is worth further evaluation. The simplified cost-based calculation carried out here does not include these effects. A scenario analysis using representative biogas plant types is of interest here in order to map the costs and yields taking into account the energy market.
This contribution to the debate exclusively looks at biogas production. Additional synergies exist between biogas and solid biofuels as well as with other renewables, but these were not within the scope of this work and need further analysis.
The low shares of biogas and biomethane in the gas market as well as the presented challenges for maintaining and expanding the production of biogenic gases show that biomass can only buffer the import dependency for natural gas to a very limited extent. In particular, the availability of sustainable biogas substrates without food or feed competition, but also the increasing use of biomass or biomethane in transport, limit the potential of biogas in substituting natural gas. In order to reduce the dependence on natural gas, other measures should be included, namely reducing consumption, increasing energy efficiency and expanding sector coupling (electrification of heat supply). Nevertheless, given the overall need to switch from fossil to renewable gases, biogas represents an important source for the future renewable gas supply in Germany and the EU. This contribution should be secured and further developed to provide better energy system services, where possible.
Against this background, the following building blocks are recommended for a future biogas policy in Germany. A distinction is made between short-term (within the next two years) and longer-term (more than three years) aspects:
First, an ad hoc programme should be set up to mobilize biogenic by-products and waste, as well as land-neutral cultivated biomass to an amount of 30 TWh/a biogas equivalent. In this way, biogas and biomethane production can be secured to a large extent while quickly reducing the share of energy crops as substrates simultaneously. This can be implemented at short notice, especially through the next revision of the REA via additional incentives for power generation from residues and waste. We would propose a remuneration bonus together with an extension of the remuneration period for successful bids of existing plants, if these plants exceed a certain share of residues and catch-crops, for example, as substrates (e.g., 70 mass %). In addition, we propose to increase the biogas production from manure by extension of the fixed remuneration for manure fermentation, currently limited to plants with a maximum installed capacity of 150 kW. Alternatively, and more efficiently, anaerobic digestion of manure could be incentivized by an emission tax or could be made mandatory.
Second, a more energy system-oriented contribution of the existing biogas plants to the power and heat sector can be unlocked in the short term: the flexibility potential in existing biogas plants must be made more attractive, so that plant operators decide to switch their plants at least in a follow-up compensation period in the REA. This can be stimulated by increasing capacity-related payments as a prerequisite to finance flexibility services. Alternatively, the above-mentioned extension of the payment period for the use of biogenic by-products and waste could provide another important incentive. In addition, the REA's flexibility requirements for extended or new biogas plants can be further tightened step by step and tender volumes can be increased accordingly. Here, higher payments for flexibility can ensure counter-financing, too.
Third, biomethane incentives should be aligned between the power sector, the transport sector and also other sectors in the shorter term, so that the long-term efficient use of biomethane as a fuel is not inhibited. In the longer term, other renewable alternatives to natural gas beyond biogas should be advanced through increased research and development. Gasification of lignocellulosic biomass is another promising option for renewable gases from biomass. This process cannot only yield methane, but also hydrogen-rich gases for a variety of material and energy applications. The development and market launch of relevant technologies, which should also be based primarily on residual materials, could be supported, e.g., within the framework of the energy research programme, but also with an agreement to prioritize lignocellulosic biomass for gaseous fuels, which his currently primarily used in the heat sector.
Fourth, supporting energy from biomass should be focussed more directly on greenhouse gas reduction in the longer term. Subsidies, quotas and other support measures for biogas and biomethane should provide incentives for minimizing greenhouse gas emissions that go beyond existing minimum standards. Specifically, in the context of biogas, current subsidies should be examined for how power from biomass can be more strongly aligned with the extent of avoided emissions in the future, as has already been realized in the biofuel sector through the Greenhouse gas Reduction Quota. In addition to minimizing abatement costs, such an approach ensures that those biomass technologies will prevail in the market that are most likely to remain competitive in the future when emission reductions and renewable energy solutions are primarily incentivised by emission trading systems instead of subsidies mainly focusing on energy output. In this way, future structural breaks can be avoided and investors can be given the necessary security for long-term investments.
Fifth, to support REPowerEU, mobilization of residues is an issue for biogas and biomethane production in all European countries in the short and in the longer term. With the experiences from Germany, we see the need to especially activate agricultural residues from livestock production for biogas, e.g., by making anaerobic digestions of livestock excrements mandatory from certain farm sizes upwards—not only for Germany, but also on a European scale. Beyond this also supporting mobilization of 'land-neutral' cultivated biomass for energy usage should be ensured in the longer term. As those measures would feed into the Common Agricultural Policy (CAP), biogas/biomethane production would in this case need to be explicitly integrated into its programmes.
On a final note, it is clear that synergies exist between biogas and solid biofuels as well as with other renewables, but these were not within the scope of this work and need further analysis.
This paper has been prepared with support from the German Federal Ministry of Food and Agriculture. The contents of this paper are the sole responsibility of the authors and can in no way be taken to reflect the views of the Ministry. We acknowledge Anandhu Somanath for supporting the layout and format and Dagmar Fiedler for supporting the submission process.
DT is the lead author and made a substantial contribution to the conception and design of the manuscript; HS supported the data analysis and editing of the draft manuscript; KR, MD, PK and KD supported data analysis: KR and DT carried out the data analysis and preparation of Fig. 1; HS, MD und DT carried out the data analysis and preparation of Fig. 2; PK carried out the data analysis and preparation of Fig. 3 and MD carried out the data analysis and preparation of Fig. 4; all authors supported the editing of the draft manuscript. All authors have read and approved the final version of the manuscript.
This project has received funding from Bundesministerium für Ernährung und Landwirtschaft, Deutschland.
All data generated or analysed during this study can be obtained from the corresponding author.
Not applicable.
Not applicable.
The Editor-in-Chief of the journal, Daniela Thrän, is an author of this article. The content was independently reviewed by peers in the field and the decision for publication was made by a member of the Editorial Board. Daniela's position did not have any conscious influence on this decision. The authors declare they have no competing interests.
Graph: Additional file 1. Calculation of the final bioenergy use. Correlation of market prices of agricultural commodities and energy crops for biogas production. Additional tables.
• A
• Annum
• TWh
- Terawatt hours
• REA
- Renewable Energy Act
• CSS
- Carbon capture and storage
• PED
- Primary energy demand
• FED
- Final energy demand
• FM
- Fresh matter
• CHP
- Combined heat and power
• kWh
- Kilowatt hours
• DBFZ
- Deutsches Biomasseforschungszentrum
• t
• Tonne
• Matif
- Marché à Terme International de France
• ha
• Hectare
• h
• Hour
• PQ
- Power quotient
• MWh
- Megawatt hours
• CHPU
- Combined heat and power unit
• Wh
- Watt hour
- m
3 - Cubic metre
• RE
- Renewable energy
• UN
- United Nations
• CAP
- Common agriculture policy
• GHG
- Greenhouse gasses
• Mt
- Million ton
• LNG
- Liquefied natural gas
• EC
- European Commission
• bn
• Billion
• EU
- European Union
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