The economic potential of enhanced method of anaerobic fermentation with green ammonia production for European energy market

This scientific paper provides an analysis of the current state of biogas production and potential for improvement through optimizing biogas production and diversifying production. The analysis uses data from open sources and reports, such as EBA’s Statistical Report and analytical reports on market and digestate analysis. The authors present a comparison of electricity costs and biogas plant distribution in Europe, confirming that the higher the cost of electricity, the more widespread the introduction of biogas plants as an alternative energy source. The paper also discusses the potential of green ammonia production during anaerobic digestion, which can increase the efficiency and sustainability of biogas production technologies. The innovative technology of ammonia production from livestock waste during anaerobic treatment reduces the amount of water needed for dilution and transforms dissolved ammonia, which is toxic for anaerobic fermentation, into a useful final product. The paper highlights the potential for economically attractive approaches that use existing infrastructure and can contribute to energy independence and sustainability. The authors conclude that optimization in terms of more optimal process conditions and diversification of production approaches can increase the sustainability of biogas production technologies and ensure broader use.


Introduction
The decrease in carbon dioxide emissions and adherence to green energy production has been in focus of European community for decades [1].That adherence is declared in sustainable development programs by the EU and worldwide.For example, the strategies Europe 2020 [2], Europe 2030 [3], and The Long-term Strategy of the United States [4] declared the EU's and US's goals for CO2 emissions decreasing.However, the recent actions of the European Union related to Russian invasion of Ukraine has added a new focus on urgent solving of energy issues and development of new approaches of energy production.
Therefore, it is relevant to provide evaluation of the economic potential of the new energy production methods.Ammonia is an energy source that has recently received much attention due to its advantages, including decreed emission.However, using it as an energy source nowadays is irrelevant due to high production costs.However, recently, a new carbon-free method of ammonia 1254 (2023) 012025 IOP Publishing doi:10.1088/1755-1315/1254/1/012025 2 production has been proposed [5] that may be more efficient compared to the traditional process of ammonia production.

Materials and methods
The current state of biogas production is analyzed using reports and data of open sources.The estimation of the amount of biogas in Europe was taken from EBA's Statistical Report [6,7].The location of the biogas plants in Ukraine was collected and aggregated in online Google Map layer.The potential of the ammonia and market analysis was calculated based on the USA's and the EU's statistical data.Market analysis of the digestate was taken from the analytical report [8] and evaluated through calculations based on the statistical data on farm animals.

Results and discussion
3.1.Current state of biogas production from organic waste in Ukraine and in the EU Current energy crisis creates the conditions that needs the development of the energy production systems solving urgent current needs and that are sustainable in long-term.And economic efficiency is one of the most significant factors driving the development of specific technologies.This statement is confirmed by comparing data on electricity cost and biogas plants' distribution.There is a correlation that the higher the cost of electricity, the more widespread the introduction of biogas plants as an alternative energy source.Thus, the most developed biogas production has place in Germany and Italy, where the cost of electricity is the highest among EU countries, 140 and 135 €/MW [9], respectively (figure 1).It is also important to note that a significant part of the structure of electricity prices in these countries is a tax (that is, the price of energy purchase is artificially increased to fill countries' budgets and prioritize energy efficiency).Accordingly, if the activity is profitable, the entrepreneur will carry out such activity.The crisis requires precisely these conditions of dependence on the energy resources of the Russian Federation and the food crisis caused by the war in Ukraine.It seems relevant to provide approaches that are economically attractive and use existing infrastructure.
The development of anaerobic technologies in Europe is spread unevenly (figure 2).In some countries, there is an oversaturation of the market with biogas plants, in particular, focused exclusively on the production of energy, which can be unsustainable [10].At the same time, there are countries where anaerobic fermentation is not widespread, and there is significant  potential for its introduction.Thus, more than 11,000 biogas plants are operating in Germany and more than 1,600 in Italy.However, for example, in Romania and Bulgaria, the number of such plants is about 10 units per country, despite the relatively large territories of these countries.
In general, as of 2018, more than 50 facilities were producing biogas operated in Ukraine, of which 33 used organic waste.The total capacity of biogas plants was 44 MW.It is planned to build several biogas plants, particularly under the Ukrainian companies MHP and Danosha.The location of biogas facilities in different regions of Ukraine is presented in (figure 3).
3.2.Increasing economic efficiency of anaerobic fermentation for energy production 3.2.1.The potential of production of green ammonia during anaerobic digestion.Increasing economic efficiency by optimizing biogas production and diversifying production is the requirement for the anaerobic treatment technology to ensure energy independence of states.Both of these approaches will increase the sustainability of the approach and ensure the broader use of biogas production technologies [10].Optimization in terms of more optimal process conditions is carried out quite widely and is inherent in many studies [11][12][13].Here we will discuss the use of biofertilizers obtained in the process of anaerobic fermentation and the production of ammonia during the anaerobic fermentation of waste with a high nitrogen content.
Modern approaches make it possible to obtain additional products from organic waste when using anaerobic fermentation and ensure an increase in the efficiency of the process.The problem of accumulating a significant amount of ammonia in the anaerobic fermentation process, which leads to inhibition, has been known for a long time [14].In order to reduce the inhibitory effect, there is a need to dilute the waste with water in an amount that could reach up to 12 times compared to the original substrate, which leads to additional costs and environmental impact.Using a sustainable technology of biogas production from livestock waste, it is possible to obtain such ammonia as a pure product, which can later be used as a fuel on a par with green hydrogen.The essence of the innovative ammonia production technology is the absorption of ammonia during destruction in the process of anaerobic fermentation by the sorbent placed in the reactor and its subsequent regeneration (figure 4) [5].Therefore, this approach reduces the amount of water needed for dilution and ensures the transformation of this dissolved ammonian which is toxic for anaerobic fermentation, into a final helpful product.
It is important to note that such technologies have high potential because, for example, the technology can, for the first time, ensure the production of ammonia cheaper than when using the Haber-Bosch process.In addition to anaerobic fermentation, there were other methods of obtaining ammonia from livestock waste, for example, using Escherichia coli [15] or using a hydrothermal approach [16].However, they probably use not fewer resources than the traditional ammonia production approach.
The European Commission currently encourages the use and various production methods of green ammonia.Thus, there are projects funded by the European Commission on the electrochemical production of ammonia [17] and the use of ammonia in fuel cells for marine vessels [18].
The global market for green ammonium is 17 million dollars [19].However, such relatively small market indicators are related precisely to the fact that there was no technology on the market that would be cheaper than the production of ammonia by the traditional method.It is predicted that the cost of green ammonia will gradually decrease, mainly due to the discovery of methods that make production cheaper and the introduction of ammonia production approaches in the industry.Thus, the price over 30 years may drop several times from the estimated average cost of 1,000 $ per ton to 500 $ per ton, potentially making it cost-competitive with ammonia obtained by traditional technology [20].Figure 5 shows the forecast for the cost of ammonia until 2050.[20].
In Europe, the potential of ammonia production from livestock waste by anaerobic fermentation reaches 10 million tons per year [21].Ammonia production potential in the USA is commensurate with European ones (figure 6).
It is important to note that today the production of energy from ammonia produced by the Haber-Bosch process is considered unprofitable.So, the amount of energy required to produce a ton of ammonia by the Haber-Bosch method is 38 GJ.At the same time, 22.5 GJ of energy can be obtained from one ton of ammonia [22].In Ukraine, this method's potential for ammonia production can reach up to 0.1 million tons per year.Vinnytsia, Cherkasy, and Kyiv regions have the most potential for ammonia production due to the location of many livestock complexes.
Considering that the cost of ammonia is about 1,135 dollars per ton [21], the potential market for ammonia produced in this way can be about 11 billion dollars for Europe and the USA and about 0.11 billion dollars per year for Ukraine.

3.
2.2.The potential of anaerobic digestate production.The anaerobic fermenters biofertilizers market is estimated at 45 Bn $ as of 2019, with a compound annual growth rate (CAGR) of 7.8% and a growth potential of over 75 Bn $ in 2026 (figure 7) [8].
However, the indicated figures look incomplete, as both the European Union and Ukraine have additional potential for the production of biofertilizers.The cost of the solid fraction of biofertilizers is 122 $ per ton [22], which is significantly cheaper than other types of fertilizers.The generated waste is 5,913,382 tons and 234,547 tons per day in Europe and Ukraine, respectively.Therefore, the market of biofertilizers can potentially reach about 263.3 and about 10.4 Bn $ per year in the EU and Ukraine, respectively.It is worth noting that the provided calculations were carried out using a rough methodology, assuming that all waste was sold as a solid fraction without considering mass changes in waste during fermentation.The calculation of the potential of the biofertilizer market in Europe and Ukraine is presented in table 1 and table 2. Data calculated considering that one animal of poultry, pigs, cows produces 0.16, 5.10, 55.00, kg of waste per day, respectively [23].

Conclusions
In conclusion, ammonia production by anaerobic fermentation of livestock waste has a high potential for Ukraine and the European Union.It is one of the promising ways to Ukraine's role in ensuring Europe's energy security, especially considering that the existing infrastructure of pipelines does not require significant modernization for the transportation of ammonia.

Figure 2 .
Figure 2. Number of biogas plants in European countries, arranged in descending order [6].

Figure 3 .
Figure 3. Location of facilities producing biogas in Ukraine.

Figure 4 .
Figure 4.An innovative method of producing ammonia from livestock waste during anaerobic treatment [5].

Figure 6 .
Figure 6.The potential of ammonia production using anaerobic fermentation technology from livestock waste in the USA and the EU [5].

Figure 7 .
Figure 7.The economic potential of the biofertilizer market in the European market [8].

Table 1 .
Market potential of biofertilizers in the European Union.