Towards sustainable agriculture: Fossil-free ammonia

Abstract

6About 40% of our food would not exist without synthetic ammonia (NH 3 ) for fertilization. Yet, NH 3 7 production is energy intensive. About 2% of the world's commercial energy is consumed as fossil fuels 8 for NH 3 synthesis based on the century-old Haber-Bosch (H.-B.) process. The state of the art and the 9 opportunities for reducing the fossil energy footprint of industrial H.-B. NH 3 synthesis are discussed. It is 10shown that even a hypothetical utterly revolutionary H.-B. catalyst could not significantly reduce the 11 energy demand of H.-B. NH 3 as this is governed by hydrogen production. Renewable energy-enabled, 12fossil-free NH 3 synthesis is then evaluated based on the exceptional and continuing cost decline of 13 renewable electricity. H.-B. syngas (H 2 , N 2 ) is assumed to be produced by electrolysis and cryogenic air 14 separation, and then supplied to an existing H.-B. synthesis loop. Fossil-free NH 3 could be produced for 15 energy costs of about $232 per tonne NH 3 without claiming any economic benefits for the avoidance of 16 about 1.5 tonnes of CO 2 released per tonne NH 3 compared to the most efficient H.-B. implementations. 17Research into alternatives to the H.-B. process might be best targeted at emerging markets with currently 18 little NH 3 synthesis capacity but significant future population growth such as Africa. Reduced capital 19 intensity, good scale-down economics, tolerance for process upsets and contamination, and intermittent 20 operability are some desirable characteristics of NH 3 synthesis in less developed markets, and for 21 stranded resources. Processes that are fundamentally different from H.-B. may come to the fore under 22 these specific boundary conditions. 23

Land Use, Livestock, Quantity Governance, and Economic Instruments—Sustainability Beyond Big Livestock Herds and Fossil Fuels

“…The idea of the New Zealand model to integrate fertiliser manufacturers as regulatory points for emissions trading [19] (p. 11) is not pursued further in this paper. One reason is that the production of mineral fertilisers would already be restricted by a cap on fossil fuels, as mineral fertilisers can only be produced with renewable energies at significantly higher costs [21] (p. 329), [111]. Another reason is that N 2 O emissions from the use of N fertilisers can be included by approximation in the general emission value or emission recording at farm level.…”

“…Under a cap-and-trade scheme for livestock farming, an internal shifting effect in favour of chicken and pig farming and at the expense of cattle farming (at least in relative terms) can therefore be expected, as the certificate price for beef per kilogram will be higher than for pork or poultry [80] (p. 173). Moreover, if the livestock farmers themselves do not have to purchase the certificates, this does not mean that they will react less or not at all to cap-and-trade, since the price signal from the cap-and-trade system has an effect on the entire production chain -irrespective of where the point of regulation is located within the chain [15], [19] (p. 20), [98] (p. 111).…”

Development of a Structured Reactor System for CO2 Methanation under Dynamic Operating Conditions

“…Several energy storage technologies exist that can be used to provide energy on demand from fluctuating sources. Next to batteries, capacitors or thermal storage systems such as Power‐to‐X (PtX) processes are of special interest in this context …”

“…Next to batteries, capacitors or thermal storage systems [5] such as Power-to-X (PtX) processes are of special interest in this context. [6][7][8][9][10][11] In the first step of PtX-processes, a surplus of renewable electricity (in fact, electricity at a very low cost) is used to produce H 2 and O 2 using electrolysis of water. A promising technology is the proton exchange membrane (PEM) electrolysis that can operate under very dynamic conditions.…”

Ammonia Synthesis through Hydrolysis of a Trianionic Pincer Ligand‐Supported Molybdenum–Nitride Complex

“…[1][2][3] Producing 1t of NH 3 releases about 16.7 to fC O 2 into the atmosphere. [4] CO 2 production comes from two main sources: 1) CO 2 released from the consumption of energyr equired to drive the N 2 + +3H 2 $2NH 3 equilibrium at high temperature and pressure, and 2) CO 2 released during steam reforming of natural gas to synthesize H 2 .P rojected population growth [5] will only heighten the demand for ammonia production. Dinitrogen fixation [6] through homogeneous catalysis in the liquid phase at ambient temperatures and pressures is al ong-standing challenge, and recent catalystd iscoveries are encouraging, [7] butf ail to approacht he necessary efficiency for commercial production.…”