The sustainability of supply chains for green hydrogen production is compared from a life cycle point of view: 1) offshore electrolysis with electricity from Dutch wind farms followed by pipeline transport of hydrogen to Rotterdam (Netherlands), 2) onshore electrolysis in Rotterdam with electricity from the same wind farms, 3) electrolysis with electricity from solar PV in Algeria followed by pipeline transport of hydrogen and 4) electrolysis and ammonia production with electricity from solar PV in Saudi Arabia followed by deep sea transport and ammonia cracking. The environmental sustainability is assessed with ReCiPe 2016 and Environmental Footprint 3.0. The Total Cumulative Exergy Loss (TCExL) method is used to calculate the exergetic sustainability. According to the endpoint scores, offshore electrolysis with wind energy is preferred, but the difference between the TCExL scores of both wind energy options is small. The preference order of the other supply chains is undecided. The offshore wind option is also preferred according to the midpoint indicators GWP/climate change, land use and water consumption/use. It is advised that the systems be investigated in more detail before drawing conclusions about the order of preference and that also attention be paid to the economic and social pillars of sustainability.

The intermittent nature of renewable energy sources like solar and wind energy stimulates the use of centralised and decentralised energy storage systems. The sustainability of lead acid, lithium-ion and concentration gradient flow batteries, compressed air and pumped hydro energy storage (PHES) systems is investigated by conducting a multi-dimensional life cycle assessment. The environmental, economic and exergetic sustainability are assessed by calculating ReCiPe 2016 indicators, the present worth ratio and the Total Cumulative Exergy Loss, respectively. The multi-dimensional sustainability assessment did not lead to one preferred system. The PHES causes the lowest damage to human health, ecosystem diversity and resource availability and results in the lowest global warming potential. The concentration gradient flow battery system named BBS is preferred from an economic viewpoint, while the PHES is second-best. The lithium-ion battery system causes the lowest exergy losses, followed by the PHES. It is recommended to pay attention to the exergetic sustainability of technological systems as exergy losses are independent of environmental models, weighting factors, market prices, subsidies etc. More research into the specifications of the energy storage systems is needed to be able to draw firm conclusions with regard to which system is preferred.

Energy conversion systems have assumed a crucial role in current society. The threat of climate change, fossil fuel depletion and the growing world energy demand ask for a more sustainable way of electricity production, eg, by using renewable energy sources, by improving the conversion efficiency and/or by controlling power plant emissions. Despite the relationship between exergy and sustainability stated in literature, exergy losses are usually not considered when comparing systems and energy sources for power generation. The exergetic sustainability assessment method named Total Cumulative Exergy Loss (TCExL) has been used to assess several systems for electricity production, ie, a coal-fired power plant, a coal-fired power plant including carbon capture and storage, a biomass-fired power plant, an offshore wind farm and a photovoltaic park. The results of the TCExL method have been compared with an environmental sustainability indicator, ie, the overall ReCiPe endpoint indicator and the economic indicator named Present Worth Ratio. The offshore wind farm is the best system from the exergetic and environmental point of view. The photovoltaic park is the system with the second-best scores. However, from the economic viewpoint including subsidy by the Dutch government, the photovoltaic park performs better than the wind farm system and the system that performs best is the biomass-fired power plant. Without subsidy, only the coal-fired power plant without carbon capture and storage is profitable. The exergetic sustainability scores of the coal-fired and biomass-fired power plants are similar, but from the environmental sustainability viewpoint, the biomass-fired power plant performs better than both coal-fired power plants. As the results of environmental and economic sustainability assessments strongly depend on models, weighting factors, subsidy, market prices, etc, while the results of the exergetic sustainability assessment do not, it is recommended that the exergetic sustainability be taken into account when assessing the sustainability of power generation and other technological systems.

It is difficult to decide which power generation system is the most sustainable when environmental, economic and social sustainability aspects are taken into account. Problems with conventional environmental sustainability assessment methods are that no consensus exists about the applied models and weighting factors and that exergy losses are not considered. Economic sustainability assessment methods do not lead to results that are independent of time because they are influenced by market developments, while social sustainability assessment methods suffer from the availability and qualitative or semi-quantitative nature of data. Existing exergy analysis methods do not take into account all exergy losses and/or are extended with factors or equations that are not commonly accepted. The new Total Cumulative Exergy Loss (TCExL) method is based on fundamental thermodynamic equations and takes into account all exergy losses caused by a technological system during its life cycle, i.e. internal exergy losses, exergy losses caused by emission abatement and exergy losses related to land use. The development of the TCExL method is presented as well as the application of this method and environmental, economic and social sustainability assessment methods to two case studies: power generation in combination with LNG evaporation and Fossil versus renewable energy sources for power generation. According to the results of the assessments, large differences exist between the environmental sustainability assessment and TCExL methods in the sense that different parts of the systems contribute most to their overall scores. It is concluded from the case studies that involving the TCExL method in choices between power generation systems with the same energy sources has no consequences, i.e. it does not result in a different ranking of the systems, but can lead to the choice of a system that has a lower economic sustainability if the assessed systems use different energy sources. However, it must be noted that the economic sustainability changes over time, while the results of the TCExL method do not.