Emerging bioelectrochemical technologies for biogas production and upgrading in cascading circular bioenergy systems

Abstract

Biomethane is suggested as an advanced biofuel for the hard-to-abate sectors such as heavy transport. However, future systems that optimize the resource and production of biomethane have yet to be definitively defined. This paper assesses the opportunity of integrating anaerobic digestion (AD) with three emerging bioelectrochemical technologies in a circular cascading bioeconomy, including for power-to-gas AD (P2G-AD), microbial electrolysis cell AD (MEC-AD), and AD microbial electrosynthesis (AD-MES). The mass and energy flow of the three bioelectrochemical systems are compared with the conventional AD amine scrubber system depending on the availability of renewable electricity. An energy balance assessment indicates that P2G-AD, MEC-AD, and AD-MES circular cascading bioelectrochemical systems gain positive energy outputs by using electricity that would have been curtailed or constrained (equivalent to a primary energy factor of zero). This analysis of technological innovation, aids in the design of future cascading circular biosystems to produce sustainable advanced biofuels.

Biochar based cathode enriched with hydroxyapatite and Cu nanoparticles boosting electromethanogenesis

“…Electromethanogenesis [1,2], consisting of the reduction of CO2 in the form of methane (CH4) via microbial electrolysis [3][4], is a valuable alternative to both biochemical methanogenesis and thermochemical methanation from the Sabatier process [5][6]. Among the innovative technologies for energy conversion, the peculiarity of this bioelectrochemical process is to address the need of storing the energy produced from unprogrammable sources in renewable fuel (hydrogen or methane), in a power-to-gas concept (BEP2G) [1,[5][6][7][8][9].…”

“…Electromethanogenesis [1,2], consisting of the reduction of CO2 in the form of methane (CH4) via microbial electrolysis [3][4], is a valuable alternative to both biochemical methanogenesis and thermochemical methanation from the Sabatier process [5][6]. Among the innovative technologies for energy conversion, the peculiarity of this bioelectrochemical process is to address the need of storing the energy produced from unprogrammable sources in renewable fuel (hydrogen or methane), in a power-to-gas concept (BEP2G) [1,[5][6][7][8][9]. Although such processes address marginal energy resources, their study finds valuable meaning in promoting a green circular economy by producing new biomethane or upgrading biomethane and CO2 from anaerobic digestion (AD) in the already operating biogas plants [7].…”

“…The potential of biomethane production has been estimated at 10 billion cubic meters by 2030, which means that about 8 billion cubic meters of CO2 will be produced by 2030, i.e. about 1510 6 tons of CO2, assuming a biogas composition, as average, of 45 % CO2 (v/v) and 55 % CH4 [11]. CO2 produced by biogas/biomethane plants does not contribute to greenhouse gases (GHG) because it comes from renewable biomass and therefore, its recovery as feedstock can reduce GHG emission balancing fossil-origin emitted CO2 (C trading).…”

“…CO2 produced by biogas/biomethane plants does not contribute to greenhouse gases (GHG) because it comes from renewable biomass and therefore, its recovery as feedstock can reduce GHG emission balancing fossil-origin emitted CO2 (C trading). For Italy, it is possible to calculate a theoretical recovery of 1510 6 tons of CO2 from biogas by 2030, i.e. 4 % of the total emitted CO2 (348.…”

Wastewater-powered high-value chemical synthesis in a hybrid bioelectrochemical system

“…Microbial electrosynthesis cells can provide comprehensive solutions for wastewater-energy-chemicals nexus by extracting the wastewater energy and efficiently converting it into various value-added chemicals (Harnisch and Schroder, 2010;Zou and He, 2018). In particular, the integration of microbial electrosynthesis cells with MFCs has accomplished the wastewater-powered production of different commodities, such as biomethane (Ning et al, 2021), acetic acid (Nevin et al, 2010), butanol (Zaybak et al, 2013), and hexanol (Vassilev et al, 2018), thereby opening the window for bringing value to wastewater treatment (Christodoulou et al, 2017;Jiang and Zeng, 2018). A study on microbial electrosynthesis reported that in situ electrode potential modulation and control can be achieved through the introduction of additional '''pin''' electrodes (Gajda et al, 2021).…”