Sustainable development embraces a broad spectrum of social, economic and ecological aspects. Thus, a sustainable transformation process of energy systems is inevitably multidimensional and needs to go beyond climate impact and cost considerations. An approach for an integrated and interdisciplinary sustainability assessment of energy system transformation pathways is presented here. It first integrates energy system modeling with a multidimensional impact assessment that focuses on life cycle-based environmental and macroeconomic impacts. Then, stakeholders’ preferences with respect to defined sustainability indicators are inquired, which are finally integrated into a comparative scenario evaluation through a multi-criteria decision analysis (MCDA), all in one consistent assessment framework. As an illustrative example, this holistic approach is applied to the sustainability assessment of ten different transformation strategies for Germany. Applying multi-criteria decision analysis reveals that both ambitious (80%) and highly ambitious (95%) carbon reduction scenarios can achieve top sustainability ranks, depending on the underlying energy transformation pathways and respective scores in other sustainability dimensions. Furthermore, this research highlights an increasingly dominant contribution of energy systems’ upstream chains on total environmental impacts, reveals rather small differences in macroeconomic effects between different scenarios and identifies the transition among societal segments and climate impact minimization as the most important stakeholder preferences.

No abstract

Energy storage is currently a key focus of the energy debate. In Germany, in particular, the increasing share of power generation from intermittent renewables within the grid requires solutions for dealing with surpluses and shortfalls at various temporal scales. Covering these requirements with the traditional centralised power plants and imports and exports will become increasingly difficult as the share of intermittent generators rises across Europe. Pumped hydropower storage plants have traditionally played a role in providing balancing and ancillary services, and continue to do so. However, the construction of new plants often requires substantial interventions into virgin landscape and bio-habitats; this is often fiercely opposed by local citizens. Utility-scale lithium ion batteries have recently entered the energy scene. Albeit much smaller than most pumped hydropower plants, they can also provide the required balancing and ancillary services. They can be constructed on brownfield sites as and where needed, to support the move towards increasingly decentralised energy systems. Although they are seen by some as a more environmentally friendly option, they do cause impacts relating to the consumption of limited natural resources during the production stage. Addressing initially technological capacity of pumped hydropower storage and utility-scale battery to meet the required services, a simplified LCA will be performed to examine the environmental impacts throughout their life cycles. This includes two sensitivity analyses. Issues addressed in this paper include also methodological issues relating to comparability and those parameters that are pivotal to the LCA result.

Renewable energy systems are especially challenging both in terms of planning and operation. Energy system models that take into account not only the costs but also a wide range of environmental impacts support holistic planning. In this way, burden-shifting caused by greenhouse gas mitigation can be identified and minimised at an early stage. The Life cycle Assessment based ENergy Decision support tool LAEND combines a multi-criteria optimising tool for energy system modelling and an integrated environmental assessment for the analysis of decentral systems. By a single or multi-objective optimisation, considering costs, environmental impact indicators as well as weighted impact indicator sets, the model enables the determination of optimal investment planning and dispatch of the analysed energy system. The application of LAEND to an exemplary residential quarter shows the benefit of the model regarding the identification of conflicting goals and of a system that compensates for the different objectives. The observed shift of environmental impacts from the use phase to the production phase of the renewable electricity generators points further to the importance of the integration of the entire life cycle.Energies 2020, 13, 614 2 of 22 detailed consideration. On the community level, less technical, administrative and economic resources for sustainable energy projects are available which hinders a successful transition. Decision support at the community level, therefore gains importance [8].With regard to climate impacts, renewable energies are often considered carbon-free in general and to emit less or no emissions to the air in the use phase (besides the burning of biomass) [9]. But the utilisation of renewable energies like e.g., wind and photovoltaics, lead to new conflicts of goals only partly implicated by storage needs: use of resources, especially the exploitation of rare earth materials, toxicities, land use and the loss of biodiversity might increase [10][11][12][13]. Additionally, the environmental impacts shift from the use phase (key emission phase of fossil energies) to the manufacturing phase of the energy converters (key emission phase of renewable energies and storages) [14].Thus, decision support considering the environmental impact of decentral energy systems gains importance and needs to cope with additional requirements in terms of:

In this chapter, stationary energy storage systems are assessed concerning their environmental impacts via life-cycle assessment (LCA). The considered storage technologies are pumped hydroelectric storage, different types of batteries and heat storage. After a general introduction to the method of LCA, some methodological implications for energy storage systems and the selection of impact indicators are outlined. Subsequently, the environmental impacts of different energy storage options are assessed in three case studies. The first case study compares pumped hydroelectric storage and utility-scale battery storage applying a screening LCA. Both of the two following case studies are based on an island micro grid application and follow a stepwise approach. The starting point is a pair of cost-optimal energy scenarios – one with and the other without use of stationary battery storage. First, based on the given operational parameters, the environmental performance of different lithium-ion batteries is assessed. This allows the identification of the most appropriate battery chemistry for this specific application (case study 2). Applying these results, the battery-using energy system scenario is compared in terms of environmental performance with an alternative scenario without battery use in order to determine the contribution of energy storage within the whole energy system (case study 3). Under the given modelling assumptions, the use of battery storage results in increased environmental impacts in the majority of the assessed categories, both in comparison with pumped hydroelectric storage (case study 1) and in comparison with the standard small-scale energy system without battery storage (case study 3). Regarding heat storage, the underlying case study shows a low relevance of environmental impacts within the energy system.