Abstract
The capacity of haloalkaliphilic methanotrophic bacteria to synthesize ectoine from CH4-biogas represents an opportunity for waste treatment plants to improve their economic revenues and align their processes to the incoming circular economy directives. A techno-economic and sensitivity analysis for the bioconversion of biogas into 10 t ectoine·y–1 was conducted in two stages: (I) bioconversion of CH4 into ectoine in a bubble column bioreactor and (II) ectoine purification via ion exchange chromatography. The techno-economic analysis showed high investment (4.2 M€) and operational costs (1.4 M€·y–1). However, the high margin between the ectoine market value (600–1000 €·kg–1) and the estimated ectoine production costs (214 €·kg–1) resulted in a high profitability for the process, with a net present value evaluated at 20 years (NPV20) of 33.6 M€. The cost sensitivity analysis conducted revealed a great influence of equipment and consumable costs on the ectoine production costs. In contrast to alternative biogas valorization into heat and electricity or into low added-value bioproducts, biogas bioconversion into ectoine exhibited high robustness toward changes in energy, water, transportation, and labor costs. The worst- and best-case scenarios evaluated showed ectoine break-even prices ranging from 158 to 275 €·kg–1, ∼3–6 times lower than the current industrial ectoine market value.
Highlights
In the past decade, the construction of biogas plants associated with the treatment of wastewater, agro-industrial residues, and urban waste in Europe has grown exponentially from 6 227 in 2011 to 18 943 operative biogas plants in 2019.1 The main motivation behind this growth has been the production of renewable electricity from biogas, which has increased concomitantly from 66 TWh in 2011 to 167 TWh in 2019 in Europe.[1]
In the past few years, the high competition in the European renewable energy market combined with the rapid drop in production costs of competing renewable energies (−82% and −39% drop between 2010 and 2019 for solar and wind energies, respectively) and the elevated capital (400−1100 €·kW−1) and operational costs (0.01−0.02 €·kWh−1) of electricity and heat cogeneration (CHP) systems have stalled the growth of this biogas valorization alternative, with a marginal increase of 4.3% in the period 2015−2019.1−4 In this regard, a recent techno-economic analysis has demonstrated the excessive dependence of biogas-to-energy facilities on the extension of fiscal incentives.[5]
The total PEC for ectoine production from biogas accounted for 1.03 M€, with 0.66 M€ and 0.37 M€ corresponding to the bioconversion of CH4-biogas into ectoine and to the ectoine extraction and purification, respectively
Summary
The construction of biogas plants associated with the treatment of wastewater, agro-industrial residues, and urban waste in Europe has grown exponentially from 6 227 in 2011 to 18 943 operative biogas plants in 2019.1 The main motivation behind this growth has been the production of renewable electricity from biogas, which has increased concomitantly from 66 TWh in 2011 to 167 TWh in 2019 in Europe.[1] in the past few years, the high competition in the European renewable energy market combined with the rapid drop in production costs of competing renewable energies (−82% and −39% drop between 2010 and 2019 for solar and wind energies, respectively) and the elevated capital (400−1100 €·kW−1) and operational costs (0.01−0.02 €·kWh−1) of electricity and heat cogeneration (CHP) systems have stalled the growth of this biogas valorization alternative, with a marginal increase of 4.3% in the period 2015−2019.1−4 In this regard, a recent techno-economic analysis has demonstrated the excessive dependence of biogas-to-energy facilities on the extension of fiscal incentives.[5] fiscal exemptions such as feed in tariffs or carbon credits are no longer available for renewable energy production as policy-makers and governments have recently focused their attention on the transformation of current waste treatment plants into circular biorefineries, able to produce marketable products from waste streams. These demo-scale projects, together with an extensive investigation work at laboratory scale, have consistently evidenced the high economic and environmental potential of these technologies at industrial scale.[7,9,10]
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