Fuel Oil News is pleased to run this two-part White Paper from John E. Batey, PE, president of Energy Research Center, Inc. Part 2 of this white paper will run in the May issue of FON
Emissions of key air pollutants from oil heating equipment have been substantially reduced over the past three decades to levels that are comparable and, in some cases lower than, natural gas equipment. Notwithstanding that fact however, many misperceptions about air emissions from oil equipment remain. This report summarizes the results of extensive research related to air emissions from numerous, highly credible sources, all of which clearly show that heating oil is one of the cleanest fuels in both residential and commercial applications. In fact, as the use of lower sulfur fuel oil and biodiesel/heating oil blends expands, residential and commercial oil heating equipment could readily become the best option for lowering annual air emissions, including greenhouse gases.
Over the past three decades, air emissions from oil heating equipment in the downstate New York metropolitan area have been substantially reduced as a direct result of the following: Technological advances in oil burner and overall heating system design; improved fuel quality including the use of lower sulfur content; and the greatly expanded use of higher efficiency oil heat equipment, resulting in substantial reductions in residential fuel oil use. The purpose of this paper is to summarize these important improvements in overall air emissions. Supporting documentation of these advances is provided from a variety of sources including: the U.S. Department of Energy (USDOE), the U.S. Environmental Protection Agency (USEPA), Brookhaven National Laboratory (BNL), the New York State Energy Research and Development Authority (NYSERDA), the Massachusetts Oilheat Council (MOC), the Oilheat Manufacturers Association (OMA), and others.
The clearest example of substantial air emission reductions is the lowering of particulate matter (smoke and soot) emissions from oil burners by a factor of 20 over the past 30 years. Similarly, sulfur oxide emissions are also lower than in the past due to the current availability of low sulfur oil and will be significantly lowered in the near future with the advent and expanded use of ultra low sulfur oil. Biofuels, blended in varying ratios with heating oil, are also becoming more readily available; these blended fuels will not only lower nitrogen oxide and sulfur oxide emissions, but further lower particulate emissions and reduce emissions of carbon dioxide (a greenhouse gas). In fact, since biofuels are renewable, they also have the potential of lowering greenhouse gases to a level that is much less even than natural gas.
Unfortunately, misperceptions still exist concerning the performance of modern oil burners and how they compare to other home energy sources. The purpose of this report is to present the results of relevant research concerning the air emissions from various home energy sources and to provide an objective evaluation of the relative merits of heating with oil with respect to air pollutant and greenhouse gas emissions.
Home heating oil is now one of the cleanest heating fuels in both residential and commercial applications, and it can readily become the environmental leader with regard to air emissions, when even a small percent blend of biodiesel is used. The report will include documentation and references for each of the emissions claims included based on the best information available at this time. On-going and future testing of lower sulfur fuels and biodiesel blends are fully expected to produce even lower future emissions.
The author of this report is the former head of the Oil Heat Research Program at Brookhaven National Laboratory, which has been funded by the U.S. Department of Energy over the past 30 years. He now supplies engineering consulting services to Brookhaven, the Oilheat Manufacturers Association, the New York State Energy Research and Development Authority, heating oil state and regional associations and other organizations.
Past Emissions from Oil heat Equipment
Oil heating systems operating in the1960’s were substantially less efficient and produced much higher air emissions, most significantly Particulate Matter (PM), which is generally referred to as smoke and soot. Field tests of this equipment detected higher than desired smoke numbers and less than optimum fuel-air mixing. In addition, the sulfur content of the fuel was substantially higher than is the case today, which also contributed to condensable PM and higher sulfur oxide emissions.
Research by the U.S. Environmental Protection Agency (USEPA) and Brookhaven National Laboratory (BNL) measured the rate of soot production by both older and new oil burners. Figure 1 shows PM emission rates for oil burners from the 1960s to the 1990s. The plot below shows that PM (smoke and soot) emissions from oil burners has been reduced by more than 95 percent during this three decade period; modern oil burners in use today are now approaching zero PM emissions.
The primary reason behind this very significant reduction of emissions was the development of the flame retention burner design in the late 1960s. This advanced technological innovation improved the fuel/air mixing process for more complete burning of the fuel. It also produced a more stable flame which was less sensitive to changes within the boiler or furnace. Flame retention burners operate at far higher speeds, generating much higher air pressure and, thus, improved recirculation of flame gases for more complete combustion and reduced smoke and soot emissions. The flame retention oil burner was an important equipment advancement over older designs in that it not only produced lower air emissions, but also higher combustion and heating system efficiencies. Virtually all oil heating systems produced over the past 30 years use this retention head burner design, which is, even today, continually evolving to produce even higher efficiencies and lower air emissions rates.
In 1996, the USEPA acknowledged that modern oil burners were much cleaner burner than older models when the standard PM emission factor for residential units in operation was reduced by a factor of 7.5. It was lowered from 0.021 to 0.003 pounds of filterable particulates per million BTU of fuel burned.
Figure 2 shows this reduction in the USEPA PM emission factor for smoke and soot. (The values shown are filterable PM only, which was the standard at that time. These values do not include ‘condensable PM” which forms in oil and gas exhaust after the flue gases enter the atmosphere and are cooled). Oil burner emissions are now approaching the same level as those for natural gas burners, based on USEPA publication AP-42.
This revision in the AP-42 standard is important because it certifies that modern oil burners are much cleaner-burning than older models, and are now one of the cleanest combustion sources available. [Figure 2]
A second factor that impacted PM emissions, and particularly sulfur oxide-related PM, is the sulfur content of the fuel oil, (Figure 3). In the past, sulfur levels were in the 0.25 to 0.5 percent range. Total PM emissions increase in the form of ‘condensable PM” as the fuel sulfur rises. In addition, fuel sulfur is converted to sulfur oxides which are yet another aspect of overall air pollution.
Recent advances in fuel quality include substantial reductions in total sulfur content, and future oil burner sulfur oxide emissions are expected to be reduced even further due to the trend in even lower fuel sulfur content. These reductions include the use of low sulfur fuel with only 0.05 percent, and ultra low sulfur fuel oil with only 0.0015 percent sulfur. In addition, biofuel blends in home heating oil, including soy-based biodiesel, are now entering the fuel oil market; these blended fuels contain even lower amounts of sulfur and thereby further lower PM emissions.
The table that follows summarizes several key air emission levels generated by old and outdated oil burners, operating more than 30 or 40 years ago.
Summary of Oil Heating Air Emissions: 1960s