Although it may become almost unrecognizable in the next 25 years, I believe coal derived baseload power will be with us for a very long time. And my beliefs are bolstered by the fact that almost every country on earth is expanding the role of coal in their energy supply futures.
It is obviously important to mitigate the emissions from combustion-based power plants using the best available and affordable technology. It is clear why countries turn to coal for electricity production, it is cheap, available, and reliable, and while it has its share of emissions problems, we continue to improve ways to mitigate them. Regulating emissions is certainly a necessity but doing so specifically to eliminate the use of a specific resource is, at best short sighted and at worst, totally misguided.
In this article, I will discuss the use of additives and how they might fit in as cost-effective methods to curtail worldwide emissions directly at the source ‘inside the fence’. I will also introduce our product line of efficiency and emissions mitigation additives that can serve as cost-effective alternatives to very capital-intensive hardware emissions equipment. Of course, with efficiency, (lower CO2 and cost) as a major
driver these days, additives can also find use as adjuncts in fully equipped facilities with hardware emissions mitigation.
The additive approach to emissions mitigation is not new with particulates, SOx, NOx, CO, mercury, lead, aerosols, and HAPS all being the targets of government regulation, industry oversite, and public opinion over many decades. Additive usage often precedes expensive hardware mitigation and there are hundreds of patents touting additives as the solution to coal emissions problems. However, as I talk to people in the industry, I get regaled with stories of miracle additives that didn’t really work out when comprehensively tested. As a chemist I know that catalysts can do some amazing things, however, they offer certain challenges such as temperature specificity, and limitations such as sensitivity to poisoning that must be considered. My catalysis experience at Exxon Research and General Motor Research have provided me with a unique background to help me address these challenges and limitations.
Over the last four decades the additive approach to mitigation has been all but superseded by use of hardware solutions that, while they are very good at mitigating emissions, their capital expense and operating costs leave them unobtainable in many places and applications.
We have developed two additives to improve the profile of coal emissions. The first, CETALYST, is an oxidation catalyst designed to provide a Heat Rate Improvement (HRI), by:
- Providing a quicker heat release from the fuel
- Permitting operation with reduced excess oxygen with reduced LOI, (lower pumping and sensible heat losses)
- Providing the engineers with a wider operating window
The components of our patent protected product were carefully designed to be environmentally friendly and safe to both humans and the boilers to which they are introduced. With an application rate of 0.5-2 pounds per ton of coal, the catalyst can demonstrate an HRI of 1-3%, dramatically reduce carbon PM 2.5 particulate emissions, and reduce the other criteria emissions, NOx, SOx, CO, and Mercury as well. This type of coal oxidation catalyst is not a new idea, but its individualistic design is. The catalyst is tailored for the chemical environment afforded by the coal used and the furnace configuration.
Our second product, CENOX, is a calcium-based absorbent designed to absorb SO2, NOx, mercury and lead as well as acid aerosols. It is a fine dry powder that is utilized as a post combustion Dry Sorbent Injection (DSI) product. It works by forming tiny, hollow, porous cenospheres that have a very high surface area and a great affinity for absorbing most of the criteria pollutants. This type of chemistry is used in incinerators to remove flue gas NOx, SOx, and acids.
We are currently looking for strategic partners for further testing and additional investment. Interested parties should feel free to contact me.
Chatterjee does a good job at describing the emissions at power plants including CO2 and the criteria pollutants that include particulates (PM2.5 and below), NOx, SOx, CO, and heavy metals (mercury and lead). He also makes it clear that the solutions for some of these problems in India is NOT to spend hundreds of billions of rupees to retrofit the existing power plants.
Chatterjee stated “Recently, to fight the chronic winter smog, India has temporarily shut down five coal-fired power plants around the capital New Delhi, which is one among the world’s most polluted capital cities. There are other such instances.”
He goes on to explain the approaches taken in India “High efficiency Electrostatic Precipitators (ESPs) have been installed to capture Particulate Matters (Fly ash) from Flue gases. Low NOx burners have been installed for reducing NOx emission from flue gases. SO2 emission control is achieved through dispersion of flue gases through tall stacks (275 metres) to reduce the concentration of polluting gases at ground level.
Concerning newer coal plants Chatterjee explains, “In India, supercritical technology has already been adopted for thermal power generation. The design efficiency of supercritical units is about 5% higher than typical 500 MW subcritical units. They have comparatively low fuel consumption and CO2 emissions in ambient air. All future projects (if at all) will have supercritical technology.”
Supercritical technology uses higher steam temperatures and pressures in the heat exchangers, which are post combustion. There is an additional Heat Rate Improvement possible, during the combustion process, whether it’s a subcritical or supercritical plant, with the simple addition of a combustion catalyst.
Chatterjee and everyone else would have to agree that any additional Heat Rate Improvement for little or no cost is very desirable.
India has a tough monetary balancing act on its hands. They are using expensive ESPs, to address smoke and fly ash particulates, in certain key locations. However, they are not installed country wide, and they are not using bag filters for particulates, scrubbers for SO2 (and mercury) or SCR units for NOx (and mercury). Why? Because the cost of the equipment and operating expenses are simply, too high. Perhaps there is an additive solution in India’s future.