Tuesday, 14 December 2021
Author: Kevin Lim
At the end of November, news regarding a 'breakthrough in ammonia' was released on several sites including New Atlas, Monash University, Mirage News and Startup Daily. Here at Greenfact, we offer our take on the announcement, as well as looking at the fundamentals of ammonia, and its role in the Green Transition.
Ammonia is a gas that comprises both nitrogen and hydrogen atoms, with the chemical formula NH3. Its most important application is to produce fertilisers which accounts for more approximately 80% of the consumption of all ammonia produced.
Other uses for ammonia include consumables (nitric acid, industrial explosives, urea) as well as materials including plastics, rubber, and fibres.
It is also possible to use ammonia as a fuel, as it releases energy upon combustion:
Practicalities currently prevent wide-scale commercial use (NOx emissions, suitable engines, efficient ammonia supply chains) although research and development are well underway to address this.
In their recent technology roadmap, the IEA noted that 185 megatonnes of ammonia were produced in 2020. On an energy basis (18.65 GJ/tonne LHV), this comes out to slightly over 950 TWh in 2020. For comparison, the natural gas global production annually amounts to approximately 38 000 TWh.
Almost all ammonia production occurs via the Haber process (sometimes called the Haber-Bosch process). The process fundamentally involves reacting nitrogen (N2) and hydrogen (H2) to form ammonia.
Air is almost 80% nitrogen by weight; nitrogen can be extracted from air with low energy requirements.
While no carbon emissions evolved in the above step, the hydrogen (H2) consumed has traditionally been produced from methane fossil gas, which entails carbon emissions. This process is also known as reforming:
The production of hydrogen in this step is the main source of carbon emissions for the process. Ammonia production is estimated to account for just under 2% of all global greenhouse gas emissions. Furthermore, reforming natural gas for ammonia consumes approximately 4% of the entire global natural-gas production.
Also of current concern is the high price of natural gas in Europe - Norwegian fertiliser manufacturer Yara earlier this year started to import ammonia from overseas to avoid these high costs (Note: Prices closed around 65 EUR/MWh at the end of September 2021, the month Yara's announcement was made public. See also the last section of this document on the Carbon Border Adjustment Mechanism (CBAM) and how such imports could be stymied in the near future).
The ammonia synthesis step (Equation 2) is 'exothermic' in that energy is released overall as ammonia is produced, thus lowering energy needs for the process. However, energy is still required to initiate production, maintain ideal conditions (moderate temperatures and pressures) for high production rates of ammonia. Additionally, converting the methane to produce hydrogen (Equation 3) is also energy intensive.
All ammonia from Haber process production is estimated to consume over 1% of all worldwide energy sources; carbon emissions are associated with this energy consumption. Nevertheless, this energy input can be in the form of renewable sources (specifically, renewable electricity) to reduce energy-related emissions.
Green ammonia substitutes fossil (or grey) hydrogen with green hydrogen, produced from renewable electricity, as a feedstock.
In a similar way that hydrogen comes in various 'colours' to denote the sustainability of production, similar labels can be applied to methane depending upon the method of hydrogen production.
Assuming both ammonia and hydrogen are produced sustainably and used as energy carriers, some key differences between the two include:
While ammonia is manufactured from hydrogen and thus will incur a conversion/efficiency loss, the above-mentioned advantages of ammonia open more possibilities for transport and energy storage.
A research group at Monash University, Australia has verified a method to allow ammonia to be produced at room temperature, potentially an alternative to the Haber process and associated industrial facilities.
While green ammonia can currently be produced by using green hydrogen feedstock in the Haber process, being able to produce ammonia at near room temperature alleviates some of the requirements for expensive and specialised equipment such as heavy-duty pressure vessels and heating/cooling equipment.
The new method fundamentally involves using air (source of nitrogen) and water (hydrogen) to produce ammonia.
The above is oversimplified - the new process occurs via electrolysis, and the recent breakthrough was in finding a suitable catalyst that would enable ammonia production at practical rates and conditions.
Successful deployment of this technology could have the eventual effect of decentralising ammonia production; it would be easier to cluster renewable electricity, hydrogen and ammonia plants together allowing smaller facilities to achieve acceptable economies of scale.
The timeframe for green ammonia to come to the fore essentially depends upon the development of green hydrogen - which suggests we should expect green ammonia shipments to become commonplace close to 2030.
The future demand for ammonia will largely come from current applications (fertilizers and other materials/chemicals), increasing with the world's population. The IEA predicts modest growth in usage - from 185 Mt/year (2020) to around 210 by 2030 and 240 by 2050. Nevertheless, all current ammonia is grey which will have to be transitioned to more sustainable production, presenting many challenges and opportunities along the way.
The IEA also included a prediction for energy-use applications - particularly as a maritime fuel and in power generation where green ammonia may prove to be a more convenient energy carrier than green hydrogen. The 2050 projections under a Net-Zero Emissions scenario suggests up to 332 Mt ammonia will be used for energy purposes, or around 1720 TWh on an energy basis.
The most secure method of ensuring ammonia is green is via physical separation - using separate vessels and ensuring no mixing with grey ammonia, from producer to end-user. However, taking advantage of existing port infrastructure for ammonia necessitates some mixing.
Tracking systems which allow mixing would be a suitable compromise. There are two broad categories of systems worth mentioning:
Complicating the issue is that the current process for producing green ammonia is to use the Haber process with green hydrogen, which itself is a product of renewable electricity. While REGATRACE has moved quickly to set up rules regarding conversion, the rules regarding a two-step conversion (electricity to hydrogen, hydrogen to ammonia) are not immediately clear. At this stage, a GO system for low-carbon ammonia (including green ammonia) has not been formally considered.
Nevertheless, ammonia is indirectly recognised in the RED II as a Renewable Fuel of Non-Biological Origin (RFNBO) – this is the same category as hydrogen. In a transport fuel context, they are considered renewable (provided they meet the minimum threshold of 70% greenhouse gas savings compared to fossil fuels) and can count towards renewable fuel targets.
The recent Fit-for-55 submission suggested amendments to the RED II, including setting a sub-target of 2.6% RFNBO by 2030. The recognition of this class of fuels has seen organisations such as the ISCC (International Sustainability and Carbon Certification) looking to develop certification schemes for RFNBOs including ammonia. This will go a long way to add credibility towards green ammonia claims in the future.
Fit-for-55 also saw the Carbon Border Adjustment Mechanism (CBAM) being proposed, which is intended to cover imports from non-EU countries which might otherwise have associated emissions not obligated to an Emissions Trading Scheme (ETS).
Ammonia is explicitly mentioned in the CBAM proposal in the context of the fertiliser industry - the implementation of such a scheme would encourage producers to develop facilities in Europe, rather than relying on currently cheap imports. The CBAM is intended to be phased in from 2026 to 2035 and will replace the free allowance allocation mechanism which currently safeguards highly EU-regulated industries from unfair overseas competitors.