Environmental and Economic Aspects of Biomethane Production from Organic Waste in Russia

Abstract

According to the International Energy Agency (IEA), only a tiny fraction of the full potential of energy from biomass is currently exploited in the world. Biogas is a good source of energy and heat, and a clean fuel. Converting it to biomethane creates a product that combines all the benefits of natural gas with zero greenhouse gas emissions. This is important given that the methane contained in biogas is a more potent greenhouse gas than carbon dioxide (CO₂). The total amount of CO₂ emission avoided due to the installation of biogas plants is around 3380 ton/year, as 1 m³ of biogas corresponds to 0.70 kg of CO₂ saved. In Russia, despite the huge potential, the development of bioenergy is rather on the periphery, due to the abundance of cheap hydrocarbons and the lack of government support. Based on the data from an agro-industrial plant located in Central Russia, the authors of the article demonstrate that biogas technologies could be successfully used in Russia, provided that the Russian Government adopted Western-type measures of financial incentives.

1. Introduction

Electric power generation is the scope of a multi-faceted industry which, all over the world, continues to have a serious impact on the environment.

Among the many ways to produce power, generation from biomass appears to be one of the most virtuous, under the environmental profile [1]. In 2018, the world produced 35 million tons (oil equivalent) of biogas and biomethane, whereas their full potential is 570 and 730 million tons [2], respectively.

A land in which biomass undoubtedly has a bright future is that of the Russian Federation. However, a number of problems are presently hindering the development of this technology in Russia. Legislation creating incentives such as the “green certificates” should be introduced in that country. Another considerable obstacle is the weak exchange rate of the ruble against the euro, worsened by seriously overpriced imports, if at all available, due to the sanctions stemming from the current discrepancies between Russia and the Western bloc in international politics.

In Europe, “green certificates” have existed since 2001. The share of “Green” energy in the European Union reached 18% back in 2018, while in Russia it is only 0.2%, and, according to the Ministry of Energy of Russia, by 2035, the share of renewable energy sources in the energy balance of the Russian Federation will increase to a mere 4%. The Russian government is preparing to launch a national green certificate system by 2022. Under the program, energy retail and large industrial companies will finally be able to sell energy at an increased cost, which will allow firms to “recoup” costs [3].

Today, the main types of renewable energy in Russia are wind and solar power. However, as said above, biomass plants are one of the most attractive areas for investors in Russia in the coming years due to the huge volume of agricultural waste, food industry enterprises, and city sewage treatment plants [4].

In the last few decades, the biogas production from anaerobic digestion of organic waste has become widespread in Europe and has become an important part of the circular economy of many countries [5,6,7]. Biogas and biomethane are renewable gases, produced by the decomposition of organic matter, which is converted into a combustible biogas rich in methane and a liquid effluent.

The raw material for biogas production can be a wide range of organic waste: solid and liquid waste from the agro-industrial complex, wastewater, and solid household waste. Many studies have been devoted to demonstrating the benefits of co-digestion to increase biogas production of various types of organic waste: sewage sludge with organic waste [8,9], or cattle manure with agricultural waste [10,11]. In the case of processing multiple waste streams in one plant, it becomes possible to increase the production of biogas per unit volume of the digester without compromising the stability of the process.

The biogas technology has promising prospects for further development around the world in the presence of affordable inexpensive raw materials and a wide range of possible options for using biogas [12].

Today, one of the main problems of Russian agricultural and food enterprises is organic waste disposal. Russia generates about 600 million tons of organic waste per year, of which 150 million tons is waste from livestock [13]. Currently, waste is often accumulated near farms, which results in soil acidification, alienation of agricultural land (in Russia, more than 2 million hectares are occupied for storing manure), groundwater pollution, and emissions of greenhouse gas (methane and carbon dioxide) into the atmosphere [14].

From all of the above, it is easy to understand that among the most promising areas of research in Russia today are projects entailing the use of biogas technologies. Investing in these projects is becoming increasingly attractive for many reasons, e.g., (i) production of clean energy (electric or thermal), (ii) production of organic fertilizers from the effluents resulting from the digestion processes, and (iii) last but not least, safe disposal of organic waste [15] with an evident environmental advantage (reduced surface/ground water contamination [16,17] and greenhouse gasses emission [18,19].

There are a number of technical solutions for the use of anaerobically produced biogas. Along with the production of heat and electricity for the needs of the enterprise itself, the biogas produced can be used as a fuel for positive ignition engines or for the production of pure methane and carbon dioxide.

In general, biogas consists of 55% to 75% methane (CH₄) and 25% to 50% carbon dioxide (CO₂) [20,21,22]. However, depending on the type of organic waste and the parameters of the anaerobic fermentation, small amounts of other gases such as nitrogen (<10%), hydrogen sulfide (<3%), and hydrogen (<1%) may be present. It is the methane component of the biogas that will burn and produce energy [23]. In terms of calorific value, 1 m³ of biogas is the equivalent of up to 0.8 m³ natural gas [15].

A typical biogas system consists basically of a manure (or other waste) receiving unit, anaerobic digestion facilities, storage facilities for digester effluent, and gas-handling and gas-use equipment (Figure 1).

The typical structure of an investment in a biomass plant includes (i) project development (technical, legal, and planning consultants; financing, utilities connection; and licensing), (ii) capital investment (equipment and construction), (iii) operation, maintenance, and training costs.

Anaerobic digestion is a microbiological process involving a methanogenic community that gradually breaks down complex organic material (OM) to form biogas. A methanogenic community is a biocenosis consisting of anaerobic bacteria and archaea. They are active at four different stages of OM decomposition. The first stage is hydrolysis, which involves hydrolytic bacteria that decompose polymeric compounds into monomers. The second stage is a fermentation process where acidogenic bacteria ferment monomers to organic acids (mainly volatile fatty acids (VFA), alcohols (mainly ethanol), and hydrogen). In the third acetogenic stage, syntrophic bacteria degrade VFA, alcohols, and some other products generated during hydrolysis and fermentation to H₂, CO₂, and acetate. They may also degrade acetate to H₂ and CO₂. Finally, the fourth stage includes methanogenic archaea producing biogas mainly by hydrogenotrophic, acetoclastic, and, to a lesser extent, methylotrophic routes [24]. A schematic diagram of OM decomposition by the methanogenic community is shown in Figure 2.

To obtain biogas rich in methane, constant monitoring of the anaerobic fermentation process is required. For example, the methanogens are very sensitive to changes in to environmental parameters. It is important to maintain the optimal temperature, humidity, pH value, and the composition of organic waste [25].

This article presents the results of a joint Russian–Italian work, in which the authors studied the feasibility of producing biomethane for cogeneration of electricity and heat by treating the organic waste and sludge resulting from the wastewater of a meat processing plant located in the Lipetskaia Region of Russia.

2. Materials and Methods

Calculations were carried out based on data provided by the above-mentioned agro-industrial complex. The calculations were carried out according to the Standard Procedure for Calculating the Economic Efficiency of Biogas Complexes [26]. Waste from 5 farms (manure) and waste from a meat processing plant (manure and sewage sludge) were proposed as biomass for biogas production.

The number of farms (three swine farms plus two dairy farms) and their distance from the proposed biogas plant were taken into account. A centralized plant seemed to be the best choice; it was supposed that it was constructed next to the biggest farm of the selected cluster. It was also supposed that, in addition to the organic waste from farms, this hypothetical biogas plant would receive manure and sewage sludge from a meat processing plant, which is part of the agro-industrial complex (Figure 3).

The waste quantities and their relevant main physical/chemical parameters introduced in the calculations are shown in

Table 1. Physico-chemical parameters of investigated organic waste.

	Cow Manure	Pig Manure	Sewage Sludge
Total quantity	17,000 ton/year	83,150 ton/year	1.9 ton/year
pH	7.3	6.1	7.4
Dry matter, %	17.6	25.0	5.3
Total Nitrogen, %	1.5	2.5	8.9
Total P2O5, %	1.1	2.8	5.8
Total K2O, %	2.8	1.1	NDA *
Ash, %	12.7	16.6	NDA *
Organic substance, %:
-converting in carbon	43.6	41.7	NDA *
-converting in organic substance	87.3	83.4	NDA *
Carbon/nitrogen	29.5	16.4	37.0
Heavy metals (mg/kg):
Zn	13.2	58.0	23.1
Mn	16.8	23.4	34.5
Cu	3.3	9.6	1.2
Co	5.7	9.9	4.5
Cd	0.03	0.07	0.01
Pb	1.2	1.5	1.7
Cr	1.2	4.1	0.4
Fe	90	480	720

* No Data Available.

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3. Results and Discussion

There are four types of anaerobic digester configuration: covered lagoons, complete-mix, plug-flow, and fixed-film. The majority of commercially available digesters operate at mesophilic temperatures except for covered lagoons, which run at ambient temperatures.

For the purpose of this study, a complete-mix digester was chosen. It is the only system that can treat both cow and pig organic material in cold climate. Looking at Table 1, the total solid content (dry matter) of the swine manure was 25%, whereas that of the cow manure was around 17%. The design of the storage tank of the biogas plant took the volume of water that was to be added to the organic material into account. The manure was diluted up to 7.5–10% w/w as total solid concentration, which resulted in better performance in terms of biogas production as well as total solids and chemical oxygen demand degradation [27].

The estimated total amount of biogas was calculated as 13,231 m³/day (4,829,163 m³/year) from 279,501 kg/day of pig and cow manure.

A summary of the total capacity, heat and electricity consumption, and energy generated by the combined heat and power (CHP) unit is presented in

Table 2. List of utilities involved in the biogas plant.

	Number of Units	Power, kW	Total Power, kW	Working Time, h/Day	Energy, kWh/Year
ELECTRIC ENERGY
Feeding pump and screw charger	1	9.0	9.0	4.0	13,140
Pumps of storage tanks	4	3.1	12.2	4.0	17,844
Pumps of primary digesters	8	10.2	81.5	2.0	59,481
Agitators of primary digesters	4	25.0	100.0	12.0	438,000
Propellers of primary digesters	4	63.5	254.0	4.0	370,784
Pumps of post-digesters	4	13.4	53.8	2.0	39,258
Agitators of post-digesters	2	33.0	66.0	8.0	192,720
Propellers of post-digesters	2	63.5	127.0	4.0	185,392
Compressor for removal of H2S	1	2.8	2.8	24.0	24,333
Compressor of engine	1	3.5	3.5	24.0	30,660
Screw separator + pump			11.0	8.0	32,120
Unlisted equipment			36.0	6.0	78,917
Total energy required					1,482,650
Electric energy from CHP engine			1202	24	10,526,802
Balance					9,044,152
HEAT
Heat for primary digestion			406	24	3,555,300
Heat for post-digestion			406	24	3,555,300
Heat lost			189	24	1,654,748
Total heat required					8,765,348
Heat from CHP engine			1878	24	16,448,128
Excess of heat					7,682,780

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The total installed power of the biogas plant was 757 kW, even though many of the devices did not work continuously during the day.

Utilities were not considered, as the only one used in the plant is heat produced by the plant itself. Regarding royalties, no patented processes ran in the plant.

The total annual revenues are listed in

Table 3. List of the annual revenues.

	(kg/Year)	(Tonn/Year)	EUR/Tonn	EUR/Year
Solid fertilizer *	8,955,178	8955	10	89,552
Liquid fertilizer	NOT estimated
Dumping of WWTP sludge avoided (meat plant)				1716
		kWh/Year	EUR/kWh
Net electric energy **		9,044,152	0.10	904,415
Excess of heat		7,682,780	0	0
Annual total revenues				995,683

* Prices of fertilizer based on information received from “Mineral Fertilizers”, plant, Rossosh, Russian Federation (https://www.minudo.ru). ** Prices of energy derived from Ministry of Energy of Russian Federation (https://minenergo.gov.ru).

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In the calculation of total revenues, only the sale of electric power and solid fertilizers were taken into account, plus the saving from the avoided sewage disposal cost. Liquid fertilizer was supposed to be given free of charge to farmers in the plant neighborhood. The excess of heat was not considered, as it seemed unlikely that heat could be sold in the biogas plant area. The overall economic evaluation is shown in

Table 4. Economic evaluation report of the biogas plant.

	Without Carbon Credit System	With Carbon Credit System
Direct fixed capital	EUR 3,800,160	EUR 3,800,160
Working capital	EUR 353,847	EUR 353,847
Startup cost	EUR 10,000	EUR 10,000
Up-front R&D	EUR 6500	EUR 6500
Up-front Royalties	EUR 0	EUR 0
Total investment	EUR 4,170,507	EUR 4,170,507
Revenues	EUR 995,683	EUR 2,126,202
Annual operating cost	EUR 654,999	EUR 654,999
Cross profit	EUR 340,684	EUR 1,471,203
Taxes	EUR 136,274	EUR 588,481
Net profit	EUR 558,258	EUR 1,236,569
Gross margin	34.2%	69.2%
Return on investment	13.4%	29.7%
Payback time	7.5 years	3.4 years

. Many European countries give carbon credits for renewable energy produced from biomass such as crop residues, mud, organic fraction of municipal wastes, and any other renewable organic feedstock. The German government, for instance, gives up to 0.21 EUR/kWh for 20 years and even a partial financial support for construction of plants. In 2005, Italy introduced a green-card system where each kWh from renewable energy could be sold for 0.1–0.15 EUR/kWh more than the current price of the energy, according to the condition of the energy market. In fact, energy companies must produce 2.7% of their total energy production from renewable sources.

Considering a carbon credit system like the ones used in Germany, Italy, and other European countries, the electricity produced from renewables was supposed to be sold with a premium of 0.125 EUR/kWh over the current cost from fossil fuels. This meant that the total price was 0.225 EUR/kWh. In this case, the payback time is reduced by half.

4. Conclusions

The study demonstrates the financial viability of biogas plants in Russia, provided that the Russian Government adopted Western European-type incentive policies. The environmental and economic benefits of using anaerobic digestion processes to produce biogas from agricultural and livestock industry were evidentiated with calculations based on actual waste data from a cluster of farms and meat plants selected in a region of Central Russia.

In summary, the full potential production of biogas in Russia per year would be up to 72 billion m³, which corresponds to the production of up to 172,500 GWh of electricity and up to 207,100 GWh of heat energy, per year [28].

Hence the expectation for the hasty advent of Western-type financial incentives for biogas technologies in Russia.