Life cycle assessment of hydrogen production via electrolysis - a review

There are several hydrogen production technologies. They range from the most widely used fossil fuel based systems such as natural gas steam methane reforming to the least used renewable energy based systems such as wind electrolysis. Currently almost all the industrial hydrogen need worldwide is produced using fossil fuels. Electrolytic hydrogen production based on electricity generated from renewable resources and hydrogen's energetic use could contribute to the global need for a sustainable energy supply. However, these technologies are also not free from environmental burdens. A life cycle assessment (LCA) helps to identify such impacts considering the entire life cycle of the process chains. This paper reviews twenty-one studies that address the LCA of hydrogen production technologies, a majority of them employing electrolytic technologies. It has been observed that global warming potential (GWP) is the impact category analyzed by almost all the authors. Acidification potential (AP) ranks second. Other categories such as toxicity potential are often not analyzed. The main environmental concern associated with electrolytic hydrogen production is electricity supply. The GWP contribution of the electrolyzer unit is relatively small (e.g. only about 4% in wind based electrolysis including hydrogen production and storage systems). From an LCA perspective, it can be concluded that electrolysis using wind or hydropower generated electricity is one of the best hydrogen production technologies, compared to those using conventional grid electricity mix or fossil fuel feedstocks. (C) 2013 Elsevier Ltd. All rights reserved.