Elsevier

Renewable Energy

Volume 149, April 2020, Pages 226-234
Renewable Energy

Techno-economic assessment of dry fermentation in household biogas units through co-digestion of manure and agricultural crop residues in Egypt

https://doi.org/10.1016/j.renene.2019.12.058Get rights and content

Highlights

  • Survey of biogas units and agricultural wastes in rural communities was conducted.

  • Complete set of technical data on biogas units were documented.

  • Crop residues were mapped using GIS software.

  • Biogas units available in rural communities were found profitable projects.

  • Profitability increases as the size of the biogas unit increases.

Abstract

In rural Egypt, communities face multiple challenges such as insufficient infrastructures for waste treatment, limited access to cheap energy and poor soils fertility. A decentralized, low-tech biogas technology for combined waste treatment and energy production, anaerobic digestion can achieve many sustainable development goals and resolve many issues faced by rural communities, treating and stabilizing organic waste into high-quality biofertilizer. Household biogas units for rural communities, however, should be subjected to techno-economic assessment to confirm their feasibility and technical efficiency. Therefore, this paper conducted: (1) survey of household biogas units and agricultural crop residues in rural communities in Egypt, (2) technical study of household biogas units, and (3) financial economic study. The results can be summarized as follows: (1) complete set of technical data on biogas units were documented, (2) crop residues were mapped using GIS software, (3) financial feasibility results were discussed. The total revenues were 1716.01, 2574.02, 3432.02, and 5148.04 EUR for the household biogas unit with the capacity of 2, 3, 4, and 6 m3, respectively. It was concluded that the units available in rural Egypt are considered as profitable projects from the profitability perspectives, and the values of the profitability indicators increased as the unit size increased.

Introduction

Energy from waste has been in recent years the focus of many developing nations that are serious about tackling energy crisis. With the current global crash of crude oil prices, environmental pollution and global warming, renewable energy is beginning to gain more attention and among such energies termed renewable energy is biogas which could be generated from organic wastes especially municipal solid wastes, these wastes used to produce energy (biogas) that can be affordable, reliable, sustainable and modern for all which help in achieving different pillars of the united nations Sustainable Development Goals (SDGs) of 2030.

As producing biogas in any developing country helped in contribution of the sustainable development through its contribution to the environmental, economic, and social pillars. Economic pillars as it has positive value added, creates job opportunity as it is less capital intensive, also the biogas is considered one of the cheapest eco-friendly technologies for small scale projects compared to solar and wind energy for instance. Moreover, it contributes in environmental pillar especially goal 7 in SDGs, affordable and clean sources of energy, [1]. Since biogas is utilized as a green energy source, reducing greenhouse gas emissions such as CO2, which increases the quality of life of society, also it helps in alleviating another environmental issues, the most important one of them is getting rid of agriculture wastes and animal manure in a sustainable method, which contributed in decrease pollution resulted from get rid of these wastes with wrong methods, specially agriculture wastes. this positive impact of reducing air pollution and enhancing the air quality guarantees that the workforce as well as the nearby receptors is no longer affected by the greenhouse gas emissions which leads to less incidence of hospitalization due to air pollution, which contributes in sustainable social development pillar. Therefore, in this study we aim to make a techno-economic assessment of dry fermentation in household biogas units through co-digestion of manure and agricultural crop residues in Egypt.

This study considered the biogas household unit in rural areas, where the rural community consists of families each family has its own rural house next to its own small piece of land which usually ranged from 0.5 ha to 2 ha. This piece of land is the source of the agricultural crop residues. Each rural family has its own livestock which usually consists of 1–2 cows, 1–2 buffaloes, one donkey, 20–30 chickens, 5–10 ducks, and maybe 10–15 pigeons approximately. This livestock is the source of animal wastes. These farmers are the targeted group for owing the described biogas household unit. Usually, these farmers do not possess the composting technology. The biofertilizer is sold to large farms who buy the resulting biofertilizer. This is a case study under the Egyptian conditions.

Techno-economic assessment or Techno-economic analysis (TEA) is a methodology framework to analyze the technical and economic performance of a process, product or service. TEA normally combines process modeling, engineering design and economic evaluation. The techno-economic assessment includes the following processes: (1) inventorying technical inputs and associated outputs, (2) assessing the impacts associated with inputs and outputs, (3) conducting economic analysis of the whole processes, and (4) expounding the outcomes to assist in making decisions [[2], [3], [4], [5], [6]].

On the other hand, biogas technology is a powerful mean to recycle livestock manure to produce gaseous fuel (biogas) and biofertilizer through the anaerobic digestion of biomass [7,8]. Anaerobic digestion (AD) is an effective emissions abatement technique to reduce the negative environmental impacts of livestock manure management. In comparison with other means such as field application of slurry and composting, anaerobic digestion seizes considerable advantages such as producing energy, recycling manure efficiently, and producing biofertilizer [9,10]. Dry fermentation in anaerobic digestion is a natural biological process whereby bacteria break down organic matter in an oxygen-free environment, where the dry matter contents >20%. Unlike the wet fermentation where the dry matter is usually 8–10%. Accordingly, a techno-economic assessment can be carried out to evaluate the technical aspects and the profitability of biogas units [6].

Several studies conducted techno-economic assessment in the field of biogas production in order to achieve different objectives, such as: (1) Assessment for determining the appropriate biogas systems [6], (2) Assessment of different sizes of biogas plants [[10], [11], [12]], (3) Economic analysis of power generation [5,13], (4) Assessment of different technologies for biogas purification and upgrading [14], (5) Assessment of biogas production from different substrates [[15], [16], [17]], and (6) Assessment of resulting digestate [12,18].

Therefore, the objectives of this study are to: (1) investigate the technical aspects and the profitability of the co-digestion of dairy manure and agricultural crop residues in household biogas units in Egyptian rural communities, (2) study the technical aspects and the profitability of the dry fermentation of dairy manure and agricultural crop residues in household biogas units in Egyptian rural communities, (3) evaluate the profitability indicators of constructing a household biogas unit in Egyptian rural communities to produce biofertilizer and biogas, and (4) assess the effects of the size/capacity of the biogas unit on the profitability.

Section snippets

Methodology

This study focused on rural communities in the Giza governorate of Egypt as a representing region of Middle East and North Africa (MENA) region.

Survey and technical assessment of biogas units

The only large biogas plant in Egypt is located in El-Gabal El-Asfar and produces 0.5 MWh/day electricity per day. There are 2 medium sizes biogas plants in Egypt, the first one is managed by the Agricultural Research Center and generates 200 kWh/day, and the second one is located in Moshtohor and produces 50 kWh/day. On the other hand, there are 1300 working Chinese-type biogas household units (sizes: 2, 3, 4, and 6 m3) in Egypt, where a very few units are located in Giza. These units were

Conclusions

According to the results of this study, it can be concluded that:

  • 1.

    Constructing a household biogas unit in Egyptian rural communities to produce biofertilizer and biogas is a highly profitable project from all profitability perspectives.

  • 2.

    The value of profitability indicators increases as the size/capacity of the household biogas unit increases.

  • 3.

    The co-digestion of dairy manure and agricultural crop residues (ratio 7:3) in household biogas units in Egyptian rural communities is technically sound and

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors would like to acknowledge the Science and Technology Development Fund (STDF) of Egypt for funding this paper (research project no. 30278), where this research was conducted in the framework of the research project EranetMed Biogasmena (Project ID 72-026), under the umbrella of the ERANETMED program of Horizon 2020 launched by the European Commission. The project aims to demonstrate dry fermentation and optimize biogas technology for rural communities in MENA (Middle East and North

References (20)

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