Emerging technologies are expected to contribute to environmentally sustainable development. However, it is not known how emerging technologies could reduce environmental impacts to the same potential as a mature technology, considering the possibility of improving or replacing it . In addition, in December 2019, the European Commission presented the European Green Deal to achieve net-zero carbon emissions by 2050, with the aim of making Europe climate neutral .
Meanwhile, European Innovation Council (EIC) Pathfinder Challenge aims to develop novel processes and technologies to produce green hydrogen in different scales and sectors . Green hydrogen is seen as a change in the right direction and has gained acceptance as an energy carrier due to its decarbonization potential, the use of renewable energies such as solar and wind power to produce hydrogen by electrolysis of water is becoming important to reduce emissions in various sectors worldwide. However, it poses several economic and social challenges because the production pathway must be green, economically viable, and socially acceptable . Life Cycle Sustainability Assessment is a cutting-edge tool needed to achieve these challenges.
What is Life Cicle Sustainability Assessment
The goal of sustainable development is human well-being, contributing to the needs of current and future generations. Life cycle sustainability assessments combine economic aspects with environmental and social dimensions as can be seen in Figure 1. Economic aspects can be captured by life cycle costing (LCC), whereas social impacts are covered by social life cycle assessment (sLCA). A life cycle assessment (LCA) is applied to determine the environmental impact assessment of services or products .
Figure 1. Pillars of the Life Cycle Sustainability Assessment. (Inspired by ).
Life Cycle Assessment
The ISO norms 14040 and 14044 are international standards that provide guidelines for conducting Life Cycle Assessment (LCA). This tool is used to evaluate and quantify the potential environmental impacts of a product, process, or system throughout its entire life cycle, from raw material extraction to disposal  (Figure 2).
Figure 2. Scheme of a life cycle .
A LCA study comprises of 4 phases as can be observed in Figure 3.
- The Goal and Scope Definition phase: This is the first step in a LCA study. This phase defines the objectives and boundaries of the assessment. This includes specifying what exactly is being studied and its boundaries, what the purpose of the assessment is, and a reference unit for measuring environmental impacts (functional unit, or FU).
- The Inventory Analysis Phase: In this second stage, data is collected on all the inputs and outputs associated with the product or system studied. Inputs could include raw materials, energy, and water consumption, while outputs could include emissions to air, water, and land. This phase is truly important to create an inventory that covers all environmental inputs and outputs throughout the life cycle.
- The impact assessment phase: Once the inventory data has been collected, the next step is to assess the potential environmental impacts associated with these inputs and outputs. In this phase, models and tools are used to convert the inventory data into environmental indicators, such as greenhouse gas emissions, water pollution, or land use changes. These indicators help to understand the overall environmental impact of the product or system.
- The interpretation phase: Finally, the results of the impact assessment need to be interpreted. This involves evaluating the environmental performance of the system studied, drawing conclusions about its environmental impacts, and making recommendations for improvement. The interpretation phase is essential to provide decision makers and stakeholders with relevant information.
Figure 3. Stages of a Life Cycle Assessment, adapted from ISO 14040 .
To help with this task, some software tools have been developed over the last few years. Some of the most important are Simapro and GaBi. Those tools have a huge data bases, such as Ecoinvent and Industry data library.
Social Life Cycle Assessment
A social Life Cycle Assessment (S-LCA) is a social impact (and potential impact) assessment technique that aims to assess the social aspects of products and their potential, positive and negative, impacts along their life cycle, encompassing extraction and processing of raw materials; manufacturing; distribution; use; re-use; maintenance; recycling; and final disposal. S-LCA complements LCA with social aspects. It can either be applied on its own or in combination with LCC which is referred as Socio-Economic Life Cycle Assessment.
Life Cycle Costing
Life cycle costing, or LCC, is a compilation and assessment of all costs related to a product, over its entire life cycle, from production to use, maintenance and disposal.
- Purchase price and all associated costs (delivery, installation, insurance, etc.)
- Operating costs, including energy, fuel and water use, spares, and maintenance.
- End-of-life costs (such as decommissioning or disposal) or residual value (i.e. revenue from sale of product).
LCC may also include the cost of externalities (such as greenhouse gas emissions) under specific conditions laid out in the directives .
Value chain, the different stages of a product.
The two commonly studied kinds of system boundary for hydrogen production are ‘cradle-to-gate’ or ‘well-to-pump’ that includes processes only until production and ‘cradle-to-grave’ or ‘well-to-wheel’, which incorporates emissions during end use as well, it is to say, that assesses the environmental footprint of the entire processes of a product from the extraction of raw materials until its end-of-life process. This means that the LCA results include customer use and end-of-life processes such as waste, recycling, or upcycling. The different processes that could be applied are shown in the Figure 4.
Figure 4. Different stages of assessing a product’s environmental footprint, edited from .
An important parameter is the Functional Unit (FU), which is used to quantify a product or product system on the basis of the performance it delivers in its end-use application. Functional units are foundational to LCA, because they allow objective comparisons between different products or systems that perform the same final function. Using the same functional unit for the LCA allows us to generate an integrated, holistic assessment of potential cost and environmental impacts for a technology. Figure 5 shows different types of FUs for hydrogen related technologies . It can be observed that most of the LCA studies use the amount of hydrogen produced as the FU. Some studies in terms of mass or Nm3 and other studies provided results considering hydrogen as an energy carrier and hence documented functional unit as energy produced in MJ or kWh.
Figure 5. Types of functional units used in the life cycle assessment studies reviewed in the Ref .
The Life Cycle Sustainability Assessment in the MacGhyver Project
The Work Package 6 (WP6) of the MacGhyver project is devoted to the Sustainability assessment of the green hydrogen production prototype based on a microfluidic electrochemical reactor. Its main objectives are to calculate the environmental impact, and life cost of the green hydrogen production steps, and to assess the socio-economic impact. To achieve these goals, the first step will be to assess the environmental impact and the cost of the raw materials and all the components that make up the prototype, the electrochemical cell, and the electrochemical compressor. A Data Management Platform will be set up to collect the information needed to complete the assessment and life cycle models.
Figure 6 shows the environmental impacts, using the Recipe Midpoint methodology, of different materials (FU 1 kg of material) that are going to be assessed under the framework of the MacGhyver project. The Table 1 is the legend for Figure 6. It can be seen, for example, that the polymers Acrylonitrile Butadiene Styrene (ABS) and Polyuretane flexible have the highest carbon footprint (kg CO2 eq), whereas the highest consumption of water is obtained for the production of 1 kg of stainless steel. On the other hand, the production of 1 kg of Nickel leads to the highest human toxicity impact in terms of kg 1,4 DB eq (kg 1,4-dichlorobenzene equivalent) which could be considered also as an estimation parameter for the social impact as it affects human health .
Figure 6. Environmental impacts of different materials (FU 1kg).
Table 1. Impact Categories and its Units.
Furthermore, as a part of the activities for SLCA, a survey has been carried out following the steps suggested in the guidelines presented by the UN Environment Program (UNEP) working group . The survey has 17 questions divided in three categories: 7 questions related to personal data, 6 related to the knowledge of the hydrogen economy and 4 more technical questions.
In the following QR code (Figure 7), the readers are kindly invited to complete the survey which is performed in 6 languages:
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