Renewable and Sustainable Energy Reviews 135 (2021) 110225 Available online 9 August 2020 1364-0321/© 2020 Elsevier Ltd. All rights reserved. Potential hazards posed by biogas plants Katarzyna Stolecka, Andrzej Rusin * Silesian University of Technology, Department of Power Engineering and Turbomachinery, Konarskiego 18, 44-100, Gliwice, Poland A R T I C L E INFO Keywords: Biogas plant Accidents Failure Hazards Fire Explosion ABSTRACT One effective method of clean energy generation is to use biogas. The biogas production technologies are now highly developed, especially at the level of local biogas plants. Unfortunately, it has been impossible to avoid in- service fatal accidents. Therefore, the design and construction of new technological installations intended for biogas large-scale production have to take account of the plant safe operation. In the frst place, this applies to the course of industrial processes and to potential failures that may occur in them due to the fammability and toxicity of biogas constituents. This paper is focused on the hazards that biogas poses to human health and life. It presents the hazard zones arising due to possible scenarios following a release of biogas from a biogas plant. Probit functions and numerical modelling of the spread of thermal radiation due to a fre and of the toxic cloud arising therefrom are used to calculate the probability of serious injury to health and a loss of life depending on the distance from the gas release site. It is estimated that for a high-pressure tank containing 3000 m 3 of biogas under the pressure of 10 MPa the life-threatening zone due to a potential fre of released gas has the range of about 30 m. There is about 10 m hazard zone related to the gas explosion, and the zone with the risk of poisoning due to the gas cloud toxic concentration has the range of about 20 m from the failure site. 1. Introduction The need to protect the climate and the natural environment has imposed a constant trend towards a reduction in electricity generation from fossil fuels and dynamic development of renewable energy sources. Clean energy production from biogas is one of the effective methods that satisfes the expectations of the European Union environmental policy because biogas can be used universally and it can have an impact on the recycling economy. With the right choice of substrates, it can also become a resource for energy obtained from renewable sources. On-site utilization of biogas, i.e. in locations where it is produced, reduces e.g. transport-related energy consumption, which makes the technology even more environment-friendly [1,2]. Considering that biogas is obtained from waste, using it for energy purposes may reduce environmental pollution and improve the hygiene and health condition of inhabitants. Due to all that, the global demand for bioenergy is growing constantly. The demand is also stimulated by internal policies of many countries subsidizing the construction of new plants. The technologies are being developed intensively not only in Europe [3,4], but also in China, India, the USA and in many other countries [5–7]. A comparison of biogas development and related policies between China and Europe is presented by Refs. [8]. Biogas is a mixture of mainly methane and carbon dioxide. It origi- nates from post-consumer, industrial, agricultural and other kinds of waste. Apart from energy generation, biogas can also be used to produce heat or as an engine fuel. It can also be used as a feed source for syngas and methanol production [9]. However, an essential obstacle to a wide use of biogas, as a fuel, for example, can be the gas relatively low calorifc value (cf. Table 1), low combustion rate and poor fame stability. Another problem related to the biogas sector development is the limited availability of appropriate substrates ensuring good physicochemical properties of the gas, e.g. in terms of energy generation. Despite these issues, intensive research is now being conducted in many centres to improve biogas production technologies. The paper [10] summarizes the effects of different treatment methods of crop straw to enhance biogas production including physical, chemical, biological and combined methods. The purpose of the study [11] was to monitor the biological treatment of effuents, using control charts, as well as to estimate the potential production of methane and biogas in a slaughterhouse. The production of biogas by anaerobic digestion process was discussed in Ref. [12]. Recent advances on palm oil mill effuent (POME) pretreatment and anaerobic reactor for * Corresponding author. E-mail addresses: katarzyna.stolecka@polsl.pl (K. Stolecka), andrzej.rusin@polsl.pl (A. Rusin). Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: http://www.elsevier.com/locate/rser https://doi.org/10.1016/j.rser.2020.110225 Received 13 January 2020; Received in revised form 2 August 2020; Accepted 5 August 2020