The Relevance of Life Cycle Assessment Tools in the Development of Emerging Decarbonization Technologies.

The development of emerging decarbonization technologies requires advanced tools for decision-making that incorporate the environmental perspective from the early design. Today, Life Cycle Assessment (LCA) is the preferred tool to promote sustainability in the technology development, identifying environmental challenges and opportunities and defining the final implementation pathways. So far, most environmental studies related to decarbonization emerging solutions are still limited to midpoint metrics, mainly the carbon footprint, with global sustainability implications being relatively unexplored. In this sense, the Planetary Boundaries (PBs) have been recently proposed to identify the distance to the ideal reference state. Hence, PB-LCA methodology can be currently applied to transform the resource use and emissions to changes in the values of PB control variables. This study shows a complete picture of the LCA's role in developing emerging technologies. For this purpose, a case study based on the electrochemical conversion of CO2 to formic acid is used to show the possibilities of LCA approaches highlighting the potential pitfalls when going beyond greenhouse gas emission reduction and obtaining the absolute sustainability level in terms of four PBs.

Environmental sustainability assessment of seawater reverse osmosis brine valorization by means of electrodialysis with bipolar membranes.

The integration of electrodialysis with bipolar membranes (EDBM) with seawater reverse osmosis (SWRO) process influences the two main environmental burdens of SWRO desalination process: climate change, accounted here as carbon footprint (CF) and associated to the high-energy consumption, and the environmental alteration of the vicinities of the facility, due to brine disposal. EDBM powered by photovoltaic (PV) solar energy is able to meet the above-mentioned challenges that arise in SWRO desalination. In addition, HCl and NaOH, both employed in the desalination industry, can be produced from the brines. Hence, environmental benefits regarding the potential self-supply can be achieved. The environmental sustainability assessment by means of life cycle assessment (LCA) of a SWRO and EDBM has been carried out considering four different scenarios. The percentage of treated brines and the influence of the grid mix used for electric power supply has been taken into account. The three different electric power supplies were 100.0% renewable energy (PV solar energy), 36.0% renewable energy (average Spanish grid mix), and 1.9% (average Israeli grid mix). The results showed that the CF per unit of volume produced freshwater for SWRO and the self-supply reagent production scenario for the three Spanish grid mix, the Israeli grid mix, and the PV solar energy were 6.96 kg CO2-eq·m-3, 12.57 kg CO2-eq·m-3, and 2.17 kg CO2-eq·m-3, respectively.

Economics of Enhancing Nutrient Circularity in an Organic Waste Valorization System.

Waste managers struggle to comply with the European legislation that regulates the handling of organic waste. A waste management system that aims at recovering nutrients from the municipal organic waste generated in the Spanish region of Cantabria was modeled by combining material flow analysis, life cycle assessment, and life cycle costing. The model was optimized to find system configurations that minimize the total annual cost (TAC) and the global warming impacts (GW) and maximize the circularity indicators of nitrogen and phosphorus (CIN and CIP). The developed superstructure is composed of waste management unit processes and unit processes related to the land application of the recovered products (compost, digestate, (NH4)2SO4, and NH4MgPO4·6H2O) and industrial fertilizers to grow corn. The results of the optimization indicate that increasing CIN and minimizing GW raises the TAC, because of the investment in new technologies, although high CIP values can be achieved at low TACs. The economic margin that enables the organic fertilizers to compete in the market with industrial fertilizers was estimated. Cooperation between waste managers, the farmers that purchase the recovered products, and the policy-makers that set the waste management taxes can minimize the costs that hinder the transition toward a circular economy.

Bringing value to the chemical industry from capture, storage and use of CO2: A dynamic LCA of formic acid production.

Low carbon options for the chemical industry include switching from fossil to renewable energy, adopting new low-carbon production processes, along with retrofitting current plants with carbon capture for ulterior use (CCU technologies) or storage (CCS). In this paper, we combine a dynamic Life Cycle Assessment (d-LCA) with economic analysis to explore a potential transition to low-carbon manufacture of formic acid. We propose new methods to enable early technical, environmental and economic assessment of formic acid manufacture by electrochemical reduction of CO2 (CCU), and compare this production route to the conventional synthesis pathways and to storing CO2 in geological storage (CCS). Both CCU and CCS reduce carbon emissions in particular scenarios, although the uncertainty in results suggests that further research and scale-up validation are needed to clarify the relative emission reduction compared to conventional process pathways. There are trade-offs between resource security, cost and emissions between CCU and CCS systems. As expected, the CCS technology yields greater reductions in CO2 emissions than the CCU scenarios and the conventional processes. However, compared to CCS systems, CCU has better economic potential and lower fossil consumption, especially when powered by renewable electricity. The integration of renewable energy in the chemical industry has an important climate mitigation role, especially for processes with high electrical and thermal energy demands.

Trade-Offs between Nutrient Circularity and Environmental Impacts in the Management of Organic Waste.

Measuring the circularity of resources is essential to assessing the performance of a circular economy. This work aims at proposing an indicator that quantifies how effective a system is at extending the lifetime of its waste components after they have been discarded. The developed indicator was applied to study the circularity of nutrients within a system that handles the organic waste (OW) generated in the Spanish region of Cantabria. A superstructure was developed to determine the optimal configuration of the system. It is composed of alternative unit processes for (1) the management of OW and (2) the application of the recovered products as soil amendment to grow corn. A multiobjective mixed integer linear programming problem was formulated under two policy scenarios with different source separation rates. The problem was optimized according to six objective functions: the circularity indicators of carbon, nitrogen, and phosphorus, which are maximized, and their associated environmental impacts to be minimized (global warming, marine eutrophication, and freshwater eutrophication). The model was fed with the life cycle assessment results obtained with the Environmental Assessment System for Environmental TECHnologies (EASETECH) version 2.3.6 and the nutrient flows in the agriculture subsystem, which were calculated with Denitrification-Decomposition (DNDC) version 9.5. It was concluded that improving nutrient circularity paradoxically leads to eutrophication impacts and that increasing the SSR of OW has a positive effect on the carbon footprint of the system.