I met with SRT Group recently, whose technology I find quite unique. They are under-resourced, and need some integration and scale up work done to prove out the concept for commercial use, but kept me captivated nonetheless. As advertised the technology has the potential to become a highly economic replacement for current coal fired power plant emissions systems.
The basic premise is using a closed loop hydrogen bromine electrolysis solution for flue gas clean-up (NOx, SOx, Hg), where one of the by products is hydrogen. A couple of fascinating claims:
- The more sulphur in the flue gas, the more hydrogen you get.
- The multi-pollutant removal system will basically pay for itself with production of hydrogen and other by products.
SRT’s technology is based on the Ispra Mark 13A process, which was developed by the European Research Centre and demonstrated successfully at the 30 MWt scale in Sardinia, Italy from 1989-91 to remediate SOx only. They have gotten hold of this process in the mid 1990s, and developed additional IP to expand it. Partial list of US patents includes: 5,443,804, 6,093,306, 5,219,671.
Process involves using a recycled hydrogen bromine electrolysis system
Stage 1: Flue gas is reacted in a bromine water solution, reducing the flue gas pollutants to a water solution of mercuric bromide precipitate, sulfuric acid, and nitric acid, and hydrogen bromide.
Stage 2: The hydrogen bromide is then electrolyzed to produce pure hydrogen, and bromine to be recycled.
Keys of note:
- Removes all 3 major pollutants, NOx, SOx, Hg, in one step, reducing them to saleable product streams (H2, sulfuric and nitric acids)
- All fluid recycled process, no consumable reagents, and no waste stream to dispose of, the bromine is not a fuel, but a recycled carrier
- Small footprint
- Produces significant H2 by volume as a byproduct of the clean-up. Note: electrolyzing Hydrogen bromide is a much less power intensive process than water electrolysis (about 40% of the electricity), a major factor in making this process attractive. Also quite interesting, hydrogen bromide electrolysis performance improves tremendously at slightly higher temperature (c. 100-150 C), and higher concentrations, meaning the process is very optimizable.
- As sulfur is a reagent in this process, the higher the sulfur content of the flue gas, the more hydrogen is produced
Following the demonstration in Italy (for SOx remediation), EPRI promoted instead its limestone forced oxidation process for coal plants as a cheaper process, without including the advantages of NOx and mercury control (patented by SRT later), and hydrogen product value in the analysis. SRT believes that including these the process is highly economical. Data is available on this pilot. SRT has done additional work and patenting on expanding the process.
Conceivably would make hi sulfur eastern coal more valuable, perhaps even than western coal.
The next stage for SRT for which they are seeking funding is to develop a small scale prototype to confirm the multi-pollutant results, and inform the design of a scaled up system.
SRT Group is an R&D firm in Florida, operating predominantly under government grants with its work done with commercial partners and through university laboratories. The President is Robin Parker, a technology evangelist who has been working with this technology for some years, and courteously took the time to walk me through the details of his process. He can be reached at email@example.com.