Substantial technological advances to meet the growing regulatory scrutiny of a wide variety of pollutants have taken place over the past 50 years. In the last few years, the increased complexity in regulations in developed countries has been even more accelerated, challenging the chemical process industries (CPI) and their suppliers of air-monitoring equipment to reach new heights. In addition, developing countries are implementing their programs for continuous air monitoring. Another substantial trend is the monitoring of air pollutants as part of the optimization of the manufacturing process. This trio of developments will result in double-digit growth in the need for air pollution monitoring in the next several years. Some of the specifics of these trends are outlined here.
Fine particles
It has been determined that fine particles are more damaging to human health than larger ones. New regulations in the U.S. require states to reduce the quantity of fine particles in ambient air. The rule addresses particles smaller in diameter than 2.5 microns (PM2.5). The measurement for the regulation is made very difficult by the inclusion of condensable (vapors that condense to droplets at ambient temperature) as well as discrete particles. Periodic measurement methods are still under review. The fact that continuous measurement methods are not clearly established creates both an opportunity and a problem for those trying to make the measurements, as well as for the industry that supplies the measuring instruments.
One approach is to measure discrete particles and sulfur trioxide and then aggregate the two measurements. Another involves condensing the gas prior to measurement. The one certainty is that the costs of both periodic and continuous measurements will increase.
Mercury
Mercury now needs to be continuously measured at U.S. power plants, which have already spent $400 million in new continuous-emissions-monitoring systems (CEMS). However, the vacature of the Clean Air Mercury Rule has eliminated the immediate requirement for continuous measurement, except for local regulations that have their own rules. A new federal rule will be promulgated in the next year or two in the U.S. It is anticipated that each plant will have to reduce mercury to a level below a stipulated weight per unit of flue gas. This will require continuous mercury monitors on all power plant stacks. Cement kilns and gold-mining operations will also need to install monitors.
Two approaches to measurement are considered acceptable. One is an instrument method. The other is with sorbent traps. These traps capture the mercury for a period of up to two weeks and then are replaced by fresh traps. The removed trap is then analyzed in a laboratory to determine the weight of mercury captured during the period.
The advantage of the trap method is lower cost. The disadvantage is that the trap cannot be used for process control, whereas instrument-based CEMS are used to control the amount of activated carbon injected into the gas stream in order to maintain the required removal efficiency.
As mentioned, cement kilns in the U.S. will also need to be equipped with mercury monitors under proposed rules. In most developed countries, mercury needs to be measured at waste incineration plants. In Europe, waste incinerators and coal-fired plants co-firing sewage sludge are required to limit mercury and to install mercury monitors. China has a mercury program that is presently in the research stage.
Air toxins
The U.S. now considers power plants to be emitters of hazardous air pollutants, which will result in requirements to utilize maximum-achievable-control technology. The concern is the large number of toxic pollutants emitted from coal-fired plants.
Table 1 shows the environmental burden from existing coal-fired plants. The combination of nickel, selenium, barium, zinc, vanadium, hydrochloric acid, sulfuric acid mist, hydrogen fluoride and ammonia is much higher in weight and equal in toxicity to the mercury. In addition there are other metal toxins, such as arsenic, beryllium, lead, and cadmium, that are present in coal-plant flue gases but at relatively low quantities.
A number of new coal-fired plants are being constructed under permits that require them to meet very low levels of specific pollutants, such as cadmium and beryllium. The cost of continuously monitoring each pollutant would be prohibitive. The U.S. Environmental Protection Agency (EPA; Washington, D.C.) is therefore considering using total particulate matter as a surrogate.
Another approach is to use a multi-metal analyzer and calculate the weighted toxicity or burden. In Table 1, CO2is rated with a burden unit of 1. Vanadium is 10,000 times more toxic and nickel is 100,000 times more toxic. Multi-metal analyzers are available at reasonable cost.
If total particulate matter is used as a surrogate, the limits would likely be lowered to reflect the need for toxin reduction. It is agreed that the present system of measuring opacity instead of mass is too inaccurate to serve as the basis for measuring the low particulate-matter levels associated with toxin reduction, therefore, mass monitoring will likely be required.
Mass monitoring is already required in Europe. In the U.S. it has been applied to incinerators and to some power plants, which agreed to install the devices as parts of settlements for air violations. This requirement for mass monitors could generate costs of over $250 million in the U.S. during the initial installation phase.
| Table 1. U.S. Air Source Environmental Burden | ||||||
| Chemical | Environ-mental Burden Index | U.S. Coal Emissions (1,000 tons) | Other Industrial Sources (1,000 tons) | Coal Environmental Burden (1,000 tons) | Environmental Burden Other Sources | New Fleet of Coal Plants |
| Mercury | 10,000,000 | 0.05 | 500,000 | |||
| Nickel compounds | 100,000 | 0.35 | 35,000 | |||
| Selenium compounds | 100,000 | 0.215 | 21,500 | |||
| Barium compounds | 10,000 | 0.215 | 21,500 | |||
| Zinc compounds | 10,000 | 0.67 | 6,700 | |||
| Vanadium compounds | 10,000 | 0.615 | 6,150 | |||
| Hydrochloric acid | 1,000 | 267 | 267,000 | |||
| Sulfuric acid | 1,000 | 58 | 58,000 | |||
| Hydrogen fluoride | 1,000 | 28 | 28,000 | |||
| Ammonia | 1,000 | 2.3 | 2,300 | |||
| Air Toxics subtotal | 35 | 946,150 | 500,000 | 100,000 | ||
| PM 2.5 | 1,000 | 500 | 250 | 500,000 | 250,000 | 50,000 |
| SO2 | 100 | 9,000 | 3,200 | 900,000 | 320,000 | 90,000 |
| NOx | 100 | 4,000 | 3,900 | 400,000 | 390,000 | 40,000 |
| CO2 | 1 | 1,700,000 | 300,000 | 1,700,000 | 300,000 | 1,200,000 |
| TOTAL | 4,446,150 | 1,760,000 | 1,480,000 | |||
Carbon dioxide
The EPA has classified CO2as an air pollutant. This means that ambient, periodic stack and continuous stack monitoring will rise substantially. Existing CEMS will, by and large, be used for measurement, so the cost for new hardware will not be very significant, but those for services including analysis and stack testing will increase.
The biggest increase will be the need for ambient measurements. The models predicting various calamities need to be supported by actual periodic or continuous measurement at key locations in the water, ice, air, and so on. In the air, there are big swings in CO2levels from season-to-season and locality-to-locality.
Instruments have been developed that can distinguish between CO2that is anthropogenic (derived from human activity) and that which is naturally generated. Since 97% of the CO2is currently generated by natural sources, it will be important to identify the anthropogenic segment.
Trends and financial impact
The future of air pollution monitoring is tied closely to energy sources. If coal use were to be reduced, the market for CEMS would be significantly impacted, negatively. However, the use of coal is likely to increase, not decrease. World coal-fired-power-plant capacity will grow from 1,759,000 MW in 2010 to 2,384,000 MW in 2020. Some 80,000 MW will be replaced, so there will be 705,000 MW of new coal-fired boilers built. The annual new coal-fired boiler sales will average 70,000 MW.
A historic change is taking place in the Middle East where huge investments in petrochemical plants are being made. This will result in very substantial markets both for air pollution CEMS and for process analyzers for sulfur and other acid gases.
Waste-to-energy is the second largest market after power. This market will continue to grow throughout the world. The U.S. is well behind Europe and Asia in construction of waste-to-energy plants. However, this situation is changing as the value of energy production from this source is realized.
The use of stack CEMS in China will grow rapidly. The CEMS market in China will be the largest in the world after 2011. Within China, coal-fired boilers represent the biggest CEMS potential. SEPA (the Chinese equivalent of EPA) is cracking down on SO2and NOx emissions from new and existing power plants. The proposed steps include continuous reporting of emissions, which will provide a means for enforcement.
Overall, the world cost for stack and ambient continuous monitoring plus periodic monitoring and other related services will rise to $2.2 billion in 2010. This is a 20% increase over the projected 2009 figures. The rapid expansion in CO2measurement investment and the increased activity for stack monitoring in Asia will account for most of the increase. These are the conclusions reached in the latest update of the McIlvaine Air Pollution Monitoring and Sampling World Market report.â–
Edited by Dorothy Lozowski