Green Ammonia
[Danish company] Haldor Topsoe has greatly improved the near-term prospects for green ammonia by announcing a demonstration of its next-generation ammonia synthesis plant. This new technology uses a solid oxide electrolysis cell to make synthesis gas (hydrogen and nitrogen), which feeds Haldor Topsoe’s existing technology: the Haber-Bosch plant. The product is ammonia, made from air, water, and renewable electricity …
First, the technology owner: Haldor Topsoe is a highly respected technology development company, and it commands a global market-leading position in the ammonia industry (it has built 60 ammonia plants since 2000 and currently services 248 ammonia catalyst charges around the world). Haldor Topsoe’s status makes it credible when it claims, as it does in recent presentations, that its new technology could be commercially available by 2030.
Second, the technology: Haldor Topsoe’s solid oxide electrolysis cell (SOEC) ammonia plant represents an optimized integration of electrolyzer and Haber-Bosch (HB) units. It has the potential to reduce both capex and opex, relative to other electrolyzer technologies but also relative to conventional ammonia plants using natural gas. The system has been designed to reduce capex by eliminating the need for an air separation unit (ASU). This is nice for the prospects of large-scale green ammonia but, combined with the scalability of electrolyzers, it significantly improves the economics of small-scale ammonia production (at small scales, the ASU becomes very expensive). For opex, which is dominated by energy costs in any ammonia technology, the SOEC-HB is estimated to produce green ammonia with a specific energy consumption of about 7.2 MWh per ton, which is 26 GJ per ton. In other words, its green ammonia plant could be more energy efficient than today’s best state-of-the-art natural gas-fed ammonia plant, which consumes around 28 GJ per ton [..]
“We expect that ammonia can be used for transportation and efficient storage of energy. The greatest advantage of ammonia is that it has a high energy density which makes it an effective fuel and energy storage option – and it can thereby solve some of the most important challenges of creating a sustainable energy system of the future,” says project leader, Senior Principal Scientist John Bøgild Hansen. …
In conventional plants today, ammonia is made by combining hydrogen, produced from coal or natural gas or another fossil fuel, with nitrogen, produced by an air separation unit (ASU). Fossil hydrocarbons aren’t the only viable source of hydrogen but, in most places, they are the cheapest. I’ve previously written about how today’s natural gas-fed Haber-Bosch plant is almost perfectly energy efficient, due to decades of incremental innovation co-optimizing the steam methane reformation (SMR) units, which produce hydrogen from natural gas, and the HB units.
Since the start of the 20th Century, however, ammonia plants around the world have used electrolyzers to produce hydrogen from water, making industrial quantities of carbon-free “green” ammonia. Due to economics, only a couple of these plants still operate today. This technology always uses alkaline electrolysis cells (AEC) to produce the hydrogen that is fed to the HB unit. AEC is a mature technology but, unlike SMR, it did not evolve alongside HB; it has not been integrated and co-optimized over decades into the design and engineering of an ammonia plant. …
Fascinating. Solid oxide electrolyzers do not utilize rare-earth metals. The energy density of ammonia is high. The word Haber-Bosch can sound familiar, this process is the breakthrough technology that allowed the production of fertilizers, and thereby more than 5-fold increase in agriculture output.
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