‘Solar ammonia’ could be the key to the sustainable energy economies of two nations. During his talk at the 2016 NH3 Fuel Conference, Keith Lovegrove, Head of Solar Thermal at IT Power Group in Australia, said that Japan and Australia have the opportunity to move their trade in energy onto a climate-friendly foundation. This would involve development of Australia’s solar resources in a way that helps Japan ramp up its Strategy for Hydrogen & Fuel Cells in the coming decades.
Lovegrove’s company was part of an international team convened by Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) for a project commissioned by the Australian Renewable Energy Agency (ARENA) of the Australian Government. The team issued its report in January 2016.
The project is part of ARENA’s research program in the area of concentrated solar fuels (CSF). The essential idea is to use solar thermal technology as a heat source for a variety of fuel production processes, including methane reformation, biomass gasification, and high-temperature electrolysis. In conventional reformation and gasification processes, the process heat comes from partial combustion of the feedstock. If the heat is supplied instead by the sun, the ratio between the energy contained in feedstock materials and the energy contained in fuel outputs can be increased substantially. In fact, according to the ARENA report, for gasification of biomass, “the chemical products of the reactions contain more energy than the feedstock; this increase in energy content is effectively embedded solar energy.” The report states that this increase can be as much as 33 percent over the original chemical energy content of the feedstock.
The intermediate chemical products of the gasification process are molecular hydrogen (H2) and carbon monoxide (CO) – collectively referred to as syngas. Hydrogen can be separated from the syngas as a discrete product, or it can be subjected to further processing to yield another chemical commodity – such as ammonia. Indeed, a conventional ammonia plant converts methane to syngas as its method of hydrogen production.
In his presentation, Japan: A Future Market for Australian Solar Ammonia, Lovegrove described Australia’s position as one of Japan’s most important suppliers of energy commodities (with Japan being one of Australia’s most important sources of foreign exchange). Accordingly, Australia is watching closely as Japan develops its Strategy for Hydrogen & Fuel Cells. The ARENA CSF study was commissioned to “identify what Australia needs to do to become a world leader” in the “next generation of traded energy commodities – which will be produced from renewable energy, in part or in full.” While underlining Australia’s willingness to send hydrogen to Japan in whatever form is desired, Lovegrove suggested that ammonia may be the preferred option on both technical and economic grounds.
The ARENA team carried out an analysis of CSF economics and concluded that solar fuels derived via gasification of biomass can be cost-competitive with petroleum-based fuels when oil is priced at $80 or more per barrel. On the other hand, while solar-enhanced electrolysis is considerably cheaper than ambient-temperature electrolysis, it still costs more than three times as much per joule as biomass gasification.
In his presentation at the 2016 NH3 Fuel Conference, CO2-Free NH3, Ken-Ichi Aika, Professor Emeritus of Tokyo Institute of Technology, spoke about the importance of carbon footprint for Japan’s future sources of energy. He suggested that the carbon footprint of a given source of energy is likely to be considered as a parameter that influences the commodity price – such that low-carbon ammonia could command a higher price than conventionally produced ammonia.
In her presentation at the 2016 NH3 Fuel Conference, Adrienne Lavine, Professor of Mechanical and Aerospace Engineering at UCLA, described her work on ammonia-based thermochemical energy storage, Thermochemical Energy Storage with Ammonia & Implications for Ammonia as a Fuel. The process she described involves capturing energy from a solar thermal plant via the endothermic dissociation of ammonia into hydrogen and nitrogen, and their storage as pure gases. The energy would be reclaimed by using the heat given off by the exothermic recombination of the two gases into ammonia to drive a steam turbine in the production of electricity.
Lovegrove is a contributor to Lavine’s project. In a paper he presented with Rebecca Dunn of Australian National University at the 2008 NH3 Fuel Conference, Ammonia Production and Baseload Solar Power, he showed how the closed loop energy storage system that Lavine is investigating could be opened to allow ammonia to play a dual role as a working fluid for thermochemical energy storage and an exportable energy commodity.