Goal and Scope. The decarbonization challenge is especially dire for the energy-intensive industries which worldwide account for a large sum of carbon dioxide emissions. Heat is an essential product demanded by the energy-intensive industries and is currently produced through extensive use of carbon-based fuels including coal, natural gas and oil. Considering the need to meet (inter)national climate targets, these carbon-based fuels must be replaced by cleaner (i.e. less greenhouse gas emitting) alternatives. Biomass, when sourced sustainably, is one such mature alternative yet is still carbon based. For the energy-intensive industries, three of the main non-carbon-based options are: electrification, hydrogen and Iron Fuel Technology™. This research explores the environmental performance of these three alternatives in comparison to natural gas, biomass and each other in two potential future scenarios when implemented in an energy-intensive industry. It also proposes potential ways to reduce environmental impacts and highlights any foreseen (environmental) implications that may occur before large-scale implementation takes place.
Method. The use of ex-ante life cycle assessment allows for the prospective exploration of an upscaled electrification, hydrogen and Iron Fuel Technology™ product system. The life cycle inventory database ecoinvent version 3.9.1 forms the basis for this research in which technology specific processes are modelled by data collected through the inclusion of domain experts and technology developers as well as the completion of desk research. The life cycle impact assessment is based on the European Commission’s proposed Product Environmental Footprint and the subsequent standardized set of impact categories included in this research are climate change; ozone depletion; human toxicity, cancer; human toxicity, non-cancer; particulate matter; ionizing radiation; photochemical oxidant formation; acidification; eutrophication, terrestrial; eutrophication, freshwater; eutrophication, marine; ecotoxicity, freshwater; land use; water use; resource use, minerals and metals; and resource use, fossils. Following the life cycle impact assessment, a contribution analysis was completed which highlighted multiple key parameters within processes that were subsequently tested in sensitivity analyses.
Results. This research confirms that electrification, hydrogen and Iron Fuel Technology™ can limit climate change impacts in comparison to natural gas, thereby helping decarbonization efforts and achieve climate targets. From a solely climate change perspective, sustainably sourced biomass is a better alternative to electrification, hydrogen and Iron Fuel Technology™, but it has limited upscaling potential due to the finite availability of sustainable biomass. Considering other impact categories including acidification, freshwater ecotoxicity, marine, terrestrial and freshwater eutrophication, human toxicity cancer and non-cancer, mineral and metal resource use and particulate matter, electrification, hydrogen and Iron Fuel Technology™ all exert more pressure on the environment than steam produced through natural gas. Most of the exerted pressures as seen in the electrification, hydrogen and Iron Fuel Technology™ product systems stem from the assumed electricity mix and the expansion of the electricity network. As a result, some of the impacts, like those associated with expanding the electricity network, are inherently tied to the energy transition.
The comparison between electrification, hydrogen and Iron Fuel Technology™ showed that Iron Fuel Technology™ using scrap iron and waste hydrogen generally performed best except for the impact category human toxicity, cancer. Only when using a fully wind-based electricity mix is Iron Fuel Technology™ outperformed by direct electrification for climate change, fossil resource use, human toxicity cancer, ionizing radiation, land use, and particulate matter. Hydrogen, due to its large electricity demand for water electrolysis, consistently performed the worst throughout all investigated cases and can only be competitive to electrification and Iron Fuel Technology™ based on waste hydrogen when water electrolysis is completed with a fully wind-based electricity mix. The same applies for Iron Fuel Technology™ using green hydrogen.
Discussions. This research has made the first comparison of electrification, hydrogen and Iron Fuel Technology™ considering its implementation in the energy-intensive industries in comparison to natural gas and biomass as well as comparing them among each other. It thereby investigated potential environmental impacts in a possible 2030 and 2050 Dutch future identifying hotspots and key parameters that are highly influential in determining environmental performance through performing ex-ante LCA. It stands out as it investigates a broad range of impact categories when most reviewed studies only focused on a set of impact categories. Consequently, the outcomes of this research can be used to guide research and development, monitor potential problem areas and be used as the basis for evaluation and further research.
However, the limitation of ex-ante life cycle assessment is that it is exploratory in nature and subject to large uncertainties. As “what if” scenarios are examined, this research does not provide any conclusive results and can only be used to provide insights into potential environmental performances of alternatives, to identify environmental hotspots, for debate and to make recommendations for research and development activities. Large uncertainties in the research stem from temporal mismatches in foreground ex-ante data and background dated data, unquantified characterization factors, and slight inconsistencies regarding system boundaries. The largest uncertainty yet may be the development of each product system in time as ex-ante LCA examines and compares a potentially upscaled emergent technology to a mature technology in the present which may also not necessarily be a fair comparison. The underlying availability and quality of the data in this research reflects this. Even though comparison is made at the same assumed technological readiness level, the underlying data of the mature technology is proven to be possible whereas the data of the emerging technologies is assumed based on expected results. The availability and quality of the used data is therefore drastically different and may lead to arbitrary results.
Recommendations. The results of this research suggest reducing material usage, making manufacturing processes of required background products more sustainable (e.g. copper) and decreasing electricity consumption are the most effective ways to limit environmental impacts in the electrification, hydrogen and Iron Fuel Technology™ product systems. Specifically for Iron Fuel Technology™ it is further recommended to source waste hydrogen, produce initial iron fuel from scrap, further improve the circularity of iron fuel and to use ship transport over truck transport whenever possible. For hydrogen, key recommendations include keeping hydrogen losses to a minimum, and technologically improving the electrolyzer and boiler efficiencies. This research also highlighted that differences in case application and assumptions can influence the environmental performances significantly. As a result, it is strongly recommended to further examine electrification, hydrogen and Iron Fuel Technology™ for various end-use applications and under different scenarios.
Conclusions. The results of this research suggest electrification, hydrogen and Iron Fuel Technology™ could all reduce climate change impacts in both 2030 and 2050. However, it is also noted that they are not fully clean alternatives, i.e. that not all environmental impacts are lower in comparison to carbon-based fuels. The completed ex-ante LCA showed higher environmental impacts for multiple impact categories, among others: acidification, freshwater ecotoxicity, freshwater eutrophication, human toxicity cancer and mineral and metal resource use among other impact categories. Some of these impacts are a direct result of the assumed 2030 and 2050 scenarios reflecting the transition away from carbon-based fuels sketched in this research. The environmental impacts related to copper associated with an expansion of the electricity network is an example of this. To limit environmental impacts, this research suggests a multitude of redesign recommendations for electrification, hydrogen and Iron Fuel Technology™, primarily focused on increasing efficiencies, limiting electricity demand and decreasing emissions of background processes. Though implementing a set of these redesign recommendations helped decrease environmental impacts for electrification, hydrogen and Iron Fuel Technology™, it was shown to be insufficient to reduce environmental impacts in all impact categories to below the environmental impacts of carbon-based fuels or generally alter the environmental performance of electrification, hydrogen and Iron Fuel Technology™ in comparison with one another. The results therefore indicate that Iron Fuel Technology™ based on scrap iron and waste hydrogen is most preferable among the clean alternatives in decreasing climate change impacts while limiting other environmental impacts in as far as possible. However, it must still be noted that dependent on the specific case, the assumptions used, and which impact categories are prioritized, which technology is best suited may be subject to change.
Perspectives. This research suggests that electrification, hydrogen and Iron Fuel Technology™ can help alleviate climate change impacts to varying degrees depending on the scenario assumed, but that tradeoffs of other environmental impacts will likely arise in the transition away from carbon-based fuels. It should therefore be cautioned that a sole emphasis on tackling climate change impacts, specifically decreasing CO2 emissions, may result in overlooking potential side effects that may be environmentally harmful. The environmental impacts of any technology must therefore always be holistically examined over multiple impact categories.