The February 4 post looked at the combustion technology to have been used at the now-terminated Las Brisas power plant in Corpus christi, TX, and provided some examples of clean tech patents in the realm of carbon trading and offsets, carbon sequestration, and carbon emissions reduction that might have been applied at Las Brisas. In this post, we continue with a summary of recent inventions in the fields of toxic emissions reduction and reducing fine particulate matter emissions from power plants.
Toxic Emissions Reduction
One of the substances potentially to be emitted from the Las Brisas plant was mercury. US Patent 7,862,725, “Method for mercury capture from fluid streams,” was granted to David Mazyck and co-inventors in January 2011. The patent was assigned to the University of Florida Research Foundation Incorporated. It provides a “method for removing mercury from a fluid stream includes the steps of providing a porous composite material comprising a substrate and a plurality of catalyst and/or photocatalyst particles, and contacting substrate with a fluid stream. The porous composite material adsorbs and/or then oxidizes or reduces metallic species including elemental mercury. A fossil fuel fired power plant can include an emission control device comprising the porous composite material to filter flue gas to and thereby minimize mercury emissions into the environment.”
Reducing Fine Particulates
USEPA regulations limit the amount of fine particulate matter than can be emitted from stationary sources including power plants. In 1997 EPA revised the National Ambient Air Quality Standards (NAAQS) to drop the particulate diameter to be controlled from 10 microns to 2.5 microns (PM2.5). In 2006 the allowable concentration that could be released was cut almost in half from 65 to 35 micrograms per cubic meter. For reference, a strand of human hair is on average about 100 microns, thus the particulate matter regulations target an object 40 times smaller than the diameter of human hair. At a concentration of 35 micrograms per cubic meter, it would take 1,295,978,200 cubic meters to obtain one pound of PM2.5. This is equivalent to the volume enclosed by NASA’s Vehicle Assembly Building at the Kennedy Space Center. Times 354.
Particulate matter is generally removed from power plant flue gas by either electrostatic precipitators (ESPs) and/or fabric filters (‘baghouses’). Most ESPs are dry, but in some settings wet ESPs are needed. ESPs use high-voltage fields to apply electric charges to the particles moving through the field. The charged particles then move toward a collection surface of opposite charge, where they accumulate and are then collected for disposal. ESPs were originally used in the early 1900s.
US Patent 7,776,141 was granted to Song Wu and co-inventors in August 2010. “Methods and apparatus for performing flue gas pollution control and/or energy recovery,” assigned to Hitachi Power Systems America, Ltd., provides methods and apparatus for pollution control for use in a coal power plant. “Ash is collected and injected into the flue gas stream at a location upstream of a cooling module. The ash acts as an absorbent and/or reactant material onto which condensate may condense. By re-introducing ash to keep the condensation forming wet areas within the system, lower cost materials which are less corrosion resistant than needed for wet operating conditions can be used. Mercury recovery and SO3 removal is facilitated by the cooling process and re-introduction of collected ash. Activated carbon and/or an alkali absorbent material may be added. Use of a dry ESP and/or fabric filter as opposed to a wet ESP for particulate collection leads to cost benefits. Energy recovered by the cooling of the flue gas may be re-used to heat turbine condensate leading to improved energy efficiency.” Thus this invention not only reduces particulate matter but also sulfur and mercury emissions.
A Promise Kept
In November 2008, candidate Obama in an interview with the San Francisco Chronicle said:
"The only thing I’ve said with respect to coal, I haven’t been some coal booster. What I have said is that for us to take coal off the table as a (sic) ideological matter as opposed to saying if technology allows us to use coal in a clean way, we should pursue it."
So if somebody wants to build a coal-powered plant, they can.
It’s just that it will bankrupt them.
Clean Tech for Fossil Fuel Power Plants?
There is a tremendous amount. The equipment and methods to be derived from the patents listed here and in part 1 may or may not have been applicable to Las Brisas – that would require detailed engineering evaluations performed during plant design. However, technological innovations are available to apply at all power plants in the US. In many cases, top-down regulatory strictures make installing them cost prohibitive. In other cases, the change in the past few years regarding fuel costs (e.g., dramatically lower natural gas prices) lead plant owners to decide upon plant retirement or, sometimes, reconstruction to allow use of an entirely different fuel. One would think that for all the talk of using innovation, clean tech, protecting American jobs, and taking an ‘all of the above’ approach, we might see fewer instances of plants like Las Brisas being forced into oblivion.
Footnote
The Daily Caller reports that,
"The energy company Duke Energy, which has close ties to President Barack Obama’s administration and is involved with the pro-Obama political operation Organizing for Action, completed two new expansive wind power projects this month in the same region near Corpus Cristi, Texas where a major job-creating coal power project was recently disbanded."
Duke Energy announced the completion of the Los Vientos I and Los Vientos II wind projects on January 14.
The Los Vientos projects are located “approximately 120 miles south of Corpus Christi and 20 miles inland from the Gulf of Mexico,” according to a 2011 Duke press release.
The largest-ever Duke wind construction projects, they add 402 MW of intermittent power to the grid, less than one-third of Las Brisas’ baseload generation capacity.
