Planetary Boundaries Assessment of Deep Decarbonisation Options for Building Heating in the European Union

Building heating is one of the sectors for which multiple decarbonisation options exist and current geopolitical tensions provide urgency to design adequate regional policies. Heat pumps and hydrogen boilers, alongside alternative district heating systems, are the most promising alternatives. Although a host of city or country-level studies exist, it remains controversial what role hydrogen should play for building heating in the European Union compared with electrification and how blue and green hydrogen differ in terms of costs and environmental impacts. This works assesses the optimal technology mix for staying within planetary boundaries, and the influence of international cooperation and political restrictions. To perform the analysis, a bottom-up optimisation model was developed incorporating life cycle assessment constraints and covering production, storage, transport of energy and carbon dioxide, as well as grid and non-grid connected end-users of heat. It was found that a building heating system within planetary boundaries is feasible through large-scale electrification via heat pumps, although at a higher cost than the current system with abatement costs of around 200 €/ton CO2. Increasing interconnector capacity or onshore wind energy is found to be vital to staying within boundaries. A strong trade-off for hydrogen was identified, with blue hydrogen being cost-competitive but vastly unsustainable (when applied to heating) and green hydrogen being 2–3 times more expensive than electrification while still transgressing several planetary boundaries. The insights from this work indicate that heat pumps and renewable electricity should be prioritised over hydrogen-based heating in most cases and grid-stability and storage aspects explored further, while revealing a need for policy instruments to mitigate increased costs for consumers.