Site items in: Solar Thermochemical

Sustainable Ammonia Production from Sun, Air and Water

There is an ever growing demand for ammonia production that already reached globally 200 million tons per year by 2018 and is forecasted to increase to over 350 million tons per year by 2050 [1]. The application segment is dominated by the fertilizer industry, since the most important fertilizer and the world’s most widely produced chemical is urea. Ammonia is synthesized via the Haber-Bosch process, for which the required hydrogen and nitrogen are currently provided by using fossil fuels. This work proposes a novel approach to produce ammonia from the raw materials water and air only by utilizing solar energy…

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

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…

Future Ammonia Technologies: Plasma, Membrane, Redox

I wrote recently about two pathways for ammonia production technology development: improvements on Haber-Bosch, or electrochemical synthesis. Last week, I covered some of these Haber-Bosch improvements; next week, I'll write about electrochemical processes. This week, I want to write about some innovations that don't fit this two-way categorization: they don't use electrochemistry and they don't build upon the Haber-Bosch process, and that might be the only thing that links them.

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

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)…

Japan – a future market for Australian solar ammonia

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.…

Thermochemical energy storage with ammonia and implications for ammonia as a fuel

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. Schematic of an NH3-based thermochemical energy storage system. In ammonia-based…

A Green Ammonia Economy

Ammonia has a high volumetric hydrogen density of 107.3 kg H2 per cubic meter, because it is easily liquefied by compression below 0.86 MPa at 20° C. The vapor pressure of liquefied ammonia is similar to propane. Moreover it has a high gravimetric hydrogen density of 17.8 mass% compared with the solid state hydrogen storage materials. It is noteworthy that ammonia can be synthesized from hydrogen in large scale manufacturing by Haber–Bosch process at 400-600° C and 20-40 MPa. Therefore, liquid ammonia is one of the most promising methods for storing and transporting hydrogen. CO2 free hydrogen (ammonia) will be…