Ammonia as a low carbon fuel
million tonnes of oil are consumed in the off-mains industrial market annually in the UK.
Off-mains industrial markets contribute to point source emissions of 14.2 MtCO2/year in the UK.
Modest temperatures (-33°C) and pressures (10 bar) are required to liquify ammonia.
The Amburn design will be demonstrated at 1MW at a real customer site in 2025.
Ammonia has a higher energy density, compared to other higher energy density, with the added advantages of already built infrastructures and transport/storage benefits.
Currently ~4.5 million tonnes of oil are consumed in the off-mains industrial market annually in the UK. These energy intensive processes contribute to point source emissions of 14.2 MtCO2/y. Businesses and industries in these locations often cannot rely solely on electricity to satisfy their process heating requirements. Decarbonisation of these sites therefore presents a significant and pressing challenge. In a net-zero world, the trailer-delivered oil must be replaced by a fuel that is cost-effective and zero carbon.
Green ammonia is a promising alternative fuel for these applications. Ammonia requires only modest temperatures (-33°C) or pressures (10 bar) to liquify, which increases its volumetric energy density to above the levels achieved by other e-fuels (Fig. 1). This enables ammonia to be distributed and stored inexpensively, using infrastructure that has been well established in the fertiliser sector. However, technical barriers in the combustion of ammonia have meant that ammonia boilers are not yet available on the market.
Green ammonia’s key role in pushing for a net zero future is two-fold, as a direct fuel in various applications as well as its role in the broader decarbonisation as a hydrogen vector. Ammonia as a direct fuel is mainly being considered for applications such as gas turbines, heating systems and internal combustion engines.
Here its use to replace the combustion of fossil fuels has the evident advantage of not emitting any carbon dioxide emissions. There are however some key complications with combusting ammonia, notably the emission of NOx molecules which have very high global warming potential and thus need to be omitted. This is one of the key focal points of the Amburn design, with a burner that utilises a two-stage combustion process, whereby the bulk of the fuel is burned rich in Stage 1 (to minimise NOx). This is followed by a post-combustion zone where hot unburned ammonia traces reduce the remaining NO. The process is then followed by lean combustion stage (Stage 2), minimising any fuel residue in the exhaust gases.
The other role of ammonia is to use it as a hydrogen carrier. Again, this provides clear advantages when the ammonia is produced in a renewable manner as it will have no net carbon footprint. However, the cracking process where hydrogen is extracted out of the ammonia is one that is technologically limiting the value chain development and commercial readiness (Fig. 2). The temperatures and energy requirements for the cracking process are very high, and although they have been decreasing in the past years thanks to research activity in the field, there is still work to be done.
Ammonia is emerging as an energy vector for clean energy and one solution for decarbonisation of the global economy. Industries such as marine, power and heating are already engaging on ammonia (NH3) development programmes, providing the potential of both broad sector and broad geographical appeal for ammonia energy.
Since 2018, the International Energy Agency (IEA) has recognised ammonia fuel as a critical component of the future energy mix, and more recently, the Japanese Government awarded (for the first time on this scale) ~£345M for the study and development of ammonia power systems. Ammonia can be obtained from a large variety of resources and offers unique support to long-distance, heavy-duty systems.
Cardiff University’s involvement in Ammonia research spans longer than a decade, multiple national and international collaborations, and a multitude of high impact, high investment industrial projects and Centre for Doctoral Training (CDT) programmes surpassing that of most European Universities in the subject of “utilization of ammonia in thermal systems”.
Simultaneously, Cardiff University Innovation Institutes (UIIs) have been established to focus on large scale, highly interdisciplinary research, aligned to the University’s research and innovation strategy and to provide a positive impact on society. The UIIs focus on university research strengths, delivering major innovation-focused projects and programmes, and help drive an increase of translational R&D, partnership working with external stakeholders and impact. The Net Zero Innovation Institute (NZII) has consolidated Cardiff University’s expertise and unique potential across engineering and biological, physical and social sciences for net zero solutions. Centres of Excellence, under the NZII umbrella, are focusing on particular disciplines in the resolution of climate change and socio-economic and energy challenges, bringing together multidisciplinary research teams with variety of expertise. That is the case of the NZII’s Centre of Excellence on Ammonia Technologies (CEAT).
CEAT is a unique opportunity with the potential of establishing a world leading pilot site for ammonia R&D in the UK. The centre is currently supporting the integration of the innovative work being developed at Cardiff University within the regional development plans, and perfectly sets up the opportunities for expanding the leading university research into real world scaled operations, for example, the demonstration of new technologies for novel or retrofitted applications in boilers, furnaces, engines and gas turbines. Finally, industrial applications relevant to Wales and West England (i.e. steel, cement, glass, processes, etc.) can be evaluated with more flexibility, opening the possibility of large collaboration between SMEs, large multinationals and strong academia partners such as the one established via AMBURN.