James T. Hinkley

The Electrochemical Oxidation of Aqueous Sulfur Dioxide I. Experimental Parameter Influences on Electrode Behavior

The oxidative behavior of aqueous sulfur dioxide has been assessed on a polycrystalline platinum electrode using cyclic voltammetry with variation in applied experimental parameters. Parameters varied include the acid concentration, reaction temperature, and lower potential limit (E low ). Three distinctly different oxidation scenarios were identified. These are defined by E low and, at E low < 0.2 V, acid concentration as well. Observed oxidation scenarios include a limited response (scenario 1), catalytic oxidation (scenario 2), and reaction inhibition (scenario 3). Scenario 1 required an activation energy of E A = 83 kJ mol -1 with a Tafel slope of b = 114 mV and transfer coefficient of α A = 0.49. Scenario 2 was found to have a different reaction mechanism to scenario 1 (α A = 0.21), displaying faster reaction kinetics (b = 74 mV) and catalytically improved oxidation onset (E A = 51 kJ mol -1 ). The onset of scenario 2 oxidation was dependent on oxidation kinetics, not thermodynamics, with dE onset /dT = -2.132 mV K -1 . The variable response of the electrode is discussed in terms of sulfur species adsorption, including the reductive formation of adsorbed sulfur at potentials less than 0.5 V, and the adsorption of sulfur dioxide with varying adsorption strength.

The challenges and opportunities for integration of solar syngas production with liquid fuel synthesis

Reforming of methane is practiced on a vast scale globally for the production of syngas as a precursor for the production of many commodities, including hydrogen, ammonia and synthetic liquid fuels. Solar reforming can reduce the greenhouse gas intensity of syngas production by up to about 40% by using solar thermal energy to provide the endothermic heat of reaction, traditionally supplied by combustion of some of the feed. This has the potential to enable the production of solar derived synthetic fuels as drop in replacements for conventional fuels with significantly lower CO2 intensity than conventional gas to liquids (GTL) processes. However, the intermittent nature of the solar resource – both diurnal and seasonal – poses significant challenges for such a concept, which relies on synthesis processes that typically run continuously on very stable feed compositions. We find that the integration of solar syngas production to a GTL process is a non-trivial exercise, with the ability to turn down the capac...

A solar fuels roadmap for Australia - study outcomes

This paper summarises the key findings and recommendations of a 3.5 year study into the research, development and demonstration priorities to establish a solar fuels industry in Australia. While Australia has one of the best solar resources in the world, it also has an abundance of conventional fuels such as coal and natural gas. The country is heavily dependent on fossil fuels for its primary energy supply and international trade, and is seeking pathways to reduce emissions intensity. While renewable electricity will be able to displace fossil fuels in the electricity sector, this only addresses about 16% of energy consumption by end use.Concentrating solar fuels (CSF) are produced either in full or in part from concentrated solar energy, and can provide either complete or partial reduction of the CO2 emissions associated with energy consumption. Our study reviewed the various potential solar thermal technology pathways and feedstocks available to produce a range of CSF products such as hydrogen, ammonia...

SolarTherm: A flexible Modelica-based simulator for CSP systems

Annual performance simulations provide a valuable tool for analysing the viability and overall impact of different concentrating solar power (CSP) component and system designs. However, existing tools work best with conventional systems and are difficult or impossible to adapt when novel components, configurations and operating strategies are of interest. SolarTherm is a new open source simulation tool that fulfils this need for the solar community. It includes a simulation framework and a library of flexible CSP components and control strategies that can be adapted or replaced with new designs to meet the special needs of end users. This paper provides an introduction to SolarTherm and a comparison of models for an energy-based trough system and a physical tower system to those in the well-established and widely-used simulator SAM. Differences were found in some components where the inner workings of SAM are undocumented or not well understood, while the other parts show strong agreement. These results h...