Tag Archives: Solar Ammonia

Creating a Redox Materials Database for Solar-Thermochemical Air Separation and Fuels Production

Josua Vieten*, Dorottya Guban, Martin Roeb, Christian Sattler, Institute of Solar Research, DLR (German Aerospace Center), Germany; Patrick Huck, Matthew Horton, Kristin Persson, Lawrence Berkeley National Laboratory, USA; Brendan Bulfin, ETH Zurich, Switzerland

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting


Converting heat from renewable sources into other forms of energy is considered an essential factor in the reduction of greenhouse gas emissions. For instance, high temperatures can be reached using concentrated solar power (CSP), and the thus-captured energy can be converted into so-called solar fuels via thermochemical processes. These consist of the partial reduction of a redox material, usually a metal oxide, at high temperatures following the exothermic re-oxidation of this material at a lower temperature level using steam or CO2, which are thus converted into hydrogen or carbon monoxide, respectively. These two gases can be combined to generate syngas for the production of hydrocarbons (see Fig. 1). Through the same process, a stream of mostly inert gas can be produced by re-oxidation with air, allowing air separation using renewable energy sources. Hydrogen production and air separation can also provide the feedstock for ammonia production through the Haber-Bosch process, as the achieved oxygen partial pressures can be kept low enough to avoid catalyst poisoning. [2] Ammonia produced through this method can be used for fertilizer production, or as a fuel for energy storage. Continue reading

Screening Binary Redox Pairs for Solar Thermochemical Ammonia Synthesis Using Machine Learned Predictions of Gibbs Formation Energies at Finite Temperatures

Christopher J. Bartel*1, John R. Rumptz1, Aaron M. Holder1,2, Alan W. Weimer1, Charles B. Musgrave1
[1] University of Colorado Boulder; and [2] National Renewable Energy Laboratory, United States

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+


Solar thermochemical ammonia synthesis (STAS) is a reduction/oxidation (redox) cycle which enables the production of ammonia (NH3) from air, water, and concentrated sunlight. In this process, a metal nitride (MN) is oxidized by steam to produce a metal oxide (MO) and NH3; the resulting MO is reduced at high temperature (driven by concentrated solar radiation) and subsequently used to reduce atmospheric nitrogen (N2) and reform the MN and restart the NH3 synthesis cycle. The identification of optimal redox pairs (MO/MN) for this process has been historically limited by the lack of thermochemical data (i.e., Gibbs formation energies at finite temperatures) available for these materials, especially nitrides.

Prior work by our group has demonstrated the use of machine learning to enable the prediction of Gibbs formation energies up to very high temperatures (1800 K) using low-cost DFT calculations (e.g., PBE+U), thus eliminating the need for experimentally measured thermochemistry. Utilizing this approach, we’ve screened the reaction energetics and thermodynamic stability of all known binary (i.e., monometallic) MN/MO pairs, increasing the number of redox pairs considered for this process by an order of magnitude. In addition to the consideration of new redox pairs, we also assess the effects of operating conditions and reaction scheme on the viability of candidate materials. Within this work, we gain insights into new candidate materials for NH3 synthesis, the effects of operating conditions on the viability of the overall process, and the correlated stability of metal oxides and metal nitrides. Continue reading

Our Iowa Renewable Hydrogen and Ammonia Generation System

Jay Schmuecker1*, David Toyne2*
[1] Pinehurst Farm; and [2] Solutions for Automation, United States

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+


The presentation will summarize the development of the demonstration size renewable fuel and fertilizer system on my Iowa farm. Solar power, water, and air are used to make hydrogen and ammonia fuel used to power a modified John Deere 7810 tractor. The ammonia can also be used to fertilize corn cropland. The development of the ammonia reactor will be described and its performance discussed. There are no carbon emissions in either the generation or consumption of the hydrogen and ammonia. Continue reading

Japan – a future market for Australian solar ammonia

Keith Lovegrove
ITP Thermal Pty Ltd, Australia

NH3 Fuel Conference, Los Angeles, September 20, 2016


Japan and Australia are intimately linked in energy trade. Australia counts energy exports as a major source of foreign exchange income and Japan, which uses nearly 4 times the primary energy as Australia, imports nearly all of it. Approximately 40% of Australia’s coal exports are bought by Japan and were worth $AUD15.4 billion in 2012-13. Over 70% of Australia’s LNG exports went to Japan in the same period and earned over $AUD12billion. Future energy supply is high on the agenda for Japan. Currently 43% of its primary energy is in the form of imported oil mostly from the Middle East. The cost of this together with energy security concerns is a major driver for change. Post the Fukushima Nuclear disaster, the previous 8% contribution from Nuclear dropped to zero and there is much opposition to reinstating it. Japan still has a strong policy agenda to reduce Greenhouse Gas Emissions.

One of the identified routes to a cleaner energy future is the wider use of hydrogen as a fuel in both the transport and power generation sectors. There are a range of technology approaches that allow solar technologies to produce transportable alternative fuels that could form the basis for a future clean energy trade with Japan. If energy is transported as an energy dense liquid in conventional tanker ships, then the effective efficiency of transport over distances of 6000km (Australia to Japan) is greater than 98%. Three options for importing hydrogen fuel into Japan are under serious consideration; cryogenic liquid hydrogen, reversible hydrogenation of toluene, and conversion of hydrogen to ammonia. Ammonia is increasingly considered as the favourable path. It offers higher energy density, leverages an existing global industry and has the potential for direct combustion in combined cycle power plants and heavy transport. Considering Australia’s vast untapped solar resource together with the existing energy trade history plus a history of upstream investments by Japanese companies in Australian Energy developments, suggests the two countries are ideal partners in a future solar fuels trade.


Download this presentation here [PDF, 3.8MB]


2008: Ammonia Production and Baseload Solar Power [PDF]


Keith Lovegrove, ITP
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Thermochemical energy storage with ammonia and implications for ammonia as a fuel

Adrienne Lavine
Mechanical and Aerospace Engineering, University of California, Los Angeles, USA

NH3 Fuel Conference, Los Angeles, September 19, 2016


This seminar presents recent advances in ammonia-based thermochemical energy storage1 (TCES), supported by an award from the US Department of Energy SunShot program. The goal of SunShot is to “reduce the total installed cost of solar energy systems to $.06 per kWh by 2020.” Within the arena of concentrating solar thermal power, Sunshot has established goals for each subsytem, including reducing the cost of the energy storage subsystem to $15 per kWht of stored energy and enabling working fluid temperatures greater than 600°C, consistent with advanced, high performance power blocks. Continue reading