The identified hotspots that together contributed to at least 75% of the total impact in each category are shown in Scheme 5. For the Ni foam method, the Pt counter electrode production and electricity production were the main contributors. Similar results were observed for the Pd/C method, with electricity usage, or Pd catalyst production being the major hotspots (Scheme 5, left). Interestingly, the preparation of the Ni foam catalyst (catalyst in Scheme 5, right) has a comparable impact to the preparation of the Pd catalyst, with contributions to acidification, human toxicity and ecotoxicity. Furthermore, the impacts from Pd/C and Ni foam arise mainly from catalyst production, rather than from its use as a catalyst or its waste handling. Low impact from waste handling is however strongly related to the generic waste handling as modelled herein, as it does not quantitatively relate Ni or Pd potential longterm emissions from waste catalysts. The production of 2-cyclohexenone, used as model substrate for the screening LCA, became a concern for three impact categories for both scenarios. The size of the contribution can be expected to vary for different substrates. Although ECH reactions are regarded as highly sustainable and environmentally benign, the screening LCA conducted herein indicates that the Ni foam reduction method is hampered by the high potential impact of the platinum electrode, and further investigation of the possibilities for the substitution of this electrode is advisable. The water-splitting process involves two simultaneous reactions: the HER and the Oxygen Evolution Reaction (OER). Protons, initially supplied from H2SO4, and then regenerated in the OER (see Supporting Information, Section S4.1.1), are consumed to form metal hydrides or hydrogen gas (HER), which can then reduce the alkene. The OER requires a high potential, so it will often become the limiting step in the overall electrochemical process. Pt and metal oxides such as RuO2, IrO2, and PtO2 are highly active catalysts for the OER under acidic conditions, with variable levels of stability, and more sustainable alternative options do not commercially exist. Consequently, the use of a platinum counter electrode remains the main limitation of the method. However, the use of Pt as anode may be justified, bearing in mind its excellent stability under the mild reaction conditions used in this work (<1 V); under these conditions, Pt deactivation by irreversible formation of a platinum-oxide layer is avoided. For the LCIA, we considered reusing the Pt electrode for 1500 cycles. However, it would take 600,000 cycles of reuse of the Pt electrode for its contribution to total impacts in the resource use impact category to drop below 25%. Although this could be feasible, the scarcity of platinum is also an important reason to consider substituting this electrode. The replacement of Pt electrodes by carbon-based electrodes may be justified by a possibly lower environmental impact, as well as a higher abundance, despite the low stability of carbon electrodes in acidic media and the need for a higher potential. Thus, several carbonbased counter electrodes were tested (Table ). Carbon paper and carbon cloth were used as anodes, and moderate yields were obtained for the hydrogenation of model substrate 1a (Table , entries 2 and 3). An increase in surface area did not result in any improvement in performance (Table , entry 4). Interestingly, when the possibility of using a graphite counter electrode was explored, a promising 77% yield was obtained when using EtOH as cosolvent (Table , entry 5). This outcome was promising since graphite may potentially have a smaller impact on climate change compared to Pt (Table ) . When instead using n-BuOH as cosolvent (vide infra), product 2a was obtained in 97% yield (Table , entry 6). The instability of graphite in acidic media represents a limitation to its use in this context, but graphite is an abundant material, so this substitution remains justified.