SIMPLE ANSWERS TO A CRUCIAL ISSUE
by Christofer Jauneau
Ulaanbaatar is notorious for its air pollution. And it got worse over the years, as more and more people have been settling in the ger (yurt) areas. At the time of writing this paper, the city online service for monitoring air quality shows monthly average air quality index in the center and nearest ger areas ranging from 54 to 392. Air is considered clean up to 50. On this same period of time, PM10 peaked at 246 µg/m3 and PM2.5, to 228 µg/m3.
A 2011 World Bank study indicates that among all measurements taken at the study’s eight monitoring stations, the worst recorded annual average concentration was more than 10 times higher than the Mongolian air quality standard for PM10 and 25 times higher for PM2.5. Particulate matters are known to cause lungs and heart diseases.
Where does this pollution come from? Like other capitals, car pollution in UB reaches noxious levels but the unique traits of UB make it less of a concern compared to other forms of pollution. Power plants running on coal are also tangible contributors to air pollution. But heating in the ger areas is the main factor, along with dust suspension caused by soil erosion, which also happens to occur mostly in the ger area where few roads are paved. These two factors account for 75-95% of particulate matter (PM) concentrations at the ground level. People in the ger areas are the first victims of their coal burning stoves. The highest PM concentrations are found in these parts of the city, with annual average PM2.5 concentrations ranging from 200 to 350 µg/m3. This is much higher than in the center.
A 2012 survey, shows households in the ger areas used about 172 000 stoves in total, which is more than the total number of households (164,127 households) in the surveyed area, according to the World Bank study. This can be explained by the fact that some households use a stove for cooking and another for heating. No wonder these devices are a key factor in reducing air pollution.
Cleaner stoves
Solutions might seem obvious when it comes to fixing air pollution. But in the ger areas living conditions are as harsh as the climate and poor people can’t afford pricey efficient stoves or solar energy unless it is subsidized. Connecting the ger areas to the heating grid or moving all the people into modern cleaner apartments is even less likely to happen.
Healthier heating appliances have to be cheap so that many people will adopt it, and low tech so they can maintain it. In this perspective, the rocket mass heater seems a good candidate. It can be built out of steel drums, bricks, ashes and cob (mix of dirt and grass /straw). It can be fed with paper (as a starter), tinder, wood chips, dead leaves, even coal and a bit of cow dung: readily available and cheap materials.
Rocket stoves are no rocket science yet they take advantage of the laws of thermodynamics. The efficient air intake and horizontal burning chamber and the insulated inner chimney make the heat more intense and draft the gases upwards, to the top of a flipped barrel, which can be used as a cooking surface. The gases then swirl down inside the barrel and circulate into a horizontal pipe where they release their heat into a thermal mass (or the chimney is placed just after the barrel so that gases exit without circulating through thermal mass).
Thanks to this simple principle almost all the energy contained in the fuel is used, very little ash is produced and there is no smoke coming out of the flue. The remaining gases, mostly CO2, are expelled at low temperature (some reports say around 50°C) compared to the temperature in the burning chamber (around 1000°C reportedly). The remaining 900+°C are transferred through the barrel, then stored into the thermal mass as gases travel through the pipes. The heat is released from the mass at night when the air temperature falls below that of the material.
An assessment of several stove types conducted by the Biomass Energy Foundation (US) found that various simple improved cook stoves (the majority of those used in the ger) emit from 20 to 50g CO and 900 to 2400g PM on the standard 5-liter water boiling test. During the same test, rocket stoves ranged from 10 to 20g CO and 450 to 1000 PM.
Stoves comparisons are not entirely relevant due to the many possible designs affecting their efficiency. A “traditional stove” can be a thermal mass stove like the chulhas in India and Nepal or as simple as a depression in the ground.
An Aprovecho research center (US) study shows that a rocket fan stove (the fan forces the air into the combustion chamber) produces 39% of a three stone fire’s global warming potential, compared to 84% for a charcoal stove. A three stone fire consists in just 3 stone laid around an open camp fire to hold the cooking pot in place. It is the most basic and less efficient type of fire. The study shows the energy required to boil 2.5l of water is 2 470 kJ/L for a rocket and as high as 4 216 kJ/L for a charcoal stove. The rocket stove is also 10 minutes quicker to complete the test.
Can fly ash pave the way to a better future?
Unpaved roads are known to be a major source of air pollution in UB. On the other hand, loads of fly ash from the power plants and individual stoves accumulate in purpose-built pools, or worse in dumps; legal or illegal making no difference in terms of waste management since fly ash just seeps into the ground or flies away with the wind. But fly ash can be used for construction, including road pavement. And this is nothing new. The Romans used volcanic ash from Mount Vesuvius to cement the paving stones in their roadways. Many miles of these ancient viae still exist today.
The Romans used volcanic fly ash but ash from coal combustion is very similar in its chemical composition: calcium-aluminum-silicate-hydrate (C-A-S-H). This mixture was used to build structures that are still steady 2 000 years later. Indeed, researchers from Berkeley found that mixing volcanic ash with lime produced a stronger and submersible product, something that sand based concrete could not match. This was particularly useful for aqueducts and harbors structures. So ash has long proven its reliability.
The manufacturing process of Roman concrete also benefited from a smaller carbon footprint. Modern cement, also known as Portland cement, requires limestone (calcium carbonate), a key ingredient, to be burnt at about 1 450°C with fossil fuels. Seven percent of global CO2 emissions comes from this activity annually. But lime used for Roman concrete required temperatures which were one-third lower; this could save fuel and the atmosphere.
A few companies in UB already use fly ash from the city’s power plants to make autoclaved aerated concrete blocks and mortar. Depending on the desired mixture, fly ash can substitute for more or less sand and lime. Incorporated fly ash allows a quicker process and is cheaper than imported materials. No company produces road pavement or cobblestones yet. But the 2 000-year-old Roman remnants demonstrate ash is a solid alternative to modern, energy intensive materials. In Ulaanbaatar, it is a way to recycle a polluting by-product. Mongolians might be reluctant in using fly ash due to its supposed radioactivity. Local regulations say it must not exceed 740 mBq/kg for road construction whereas samples taken from the power plants didn’t exceed 400.
Planting trees
Another approach to improving air quality is having as many trees as possible. This may sound like an odd idea for people in such urgent need but trees are indeed a key factor in improving life conditions. Trees offer three main advantages besides their scientifically proven psychological benefits on people:
1-They provide kindling for the stoves. When wood burns, it releases the carbon stored during the tree’s growth. When coal burns, it releases carbon trapped underground for eons that is no longer part of the biogenic carbon cycle; it is a direct addition into the atmosphere.
2-When their leaves fall they keep the ground covered and allow it to regenerate, namely helping grass and plants to thrive, and prevent erosion. Soil is crucial to air quality as erosion releases PM in airborne dusts. Not to mention that grassland is better than a barren land at storing carbon.
3-And above all, trees act as giant air filters. A study led in Beijing in June 2002 shows that 2.4 million trees in the central part of Beijing removed a little less than 1 300 tons of pollutants from the air, 770 tons of which being PM10. CO2 stored in the urban forest biomass amounted to 200 000 tons. The other gaseous pollutants absorbed are mainly sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3).
With longer, colder winters in Ulaanbaatar, trees hibernate more and results would certainly be less spectacular if such a study were to be conducted. Yet trees can bring fresh air and once they are here, they offer benefits to the community, for decades, for free. Besides, fruits trees are also a possibility and would provide local free food.
Another study from the University of Warsaw showed that birch and poplar are the best at filtering particle matter. Birch and poplar are among the most common trees in Mongolia. Deciduous trees are obviously ineffective during winter but coniferous like pines can also filter a large amount of pollutants for a longer time throughout the year. Some evergreen trees appear to be even more effective than other broad-leaved species like whitebeam.
Revegetating the city is part of the “smoke free Ulaanbaatar national program” for 2010–16 expected to continue to 2023. It says that 0.7 percent (about 952 hectares) of Ulaanbaatar’s land will be vegetated during the period every year, including upstream parts of the Tuul and Selbe rivers and reclaimed land. The PM reduction due to the vegetation’s prevention of suspension, when successfully established, is estimated to be 80 percent. As only public land will be vegetated, people from the ger area could start planting at least one tree on their plots of land to help make the city greener. This is what the owner of the Nogoon Nuur (green lake) did.
Trees and rocket stoves are probably two of the simplest and most durable solutions for individuals but road pavement needs broader incentive to take off. These solutions have yet to be tried and tested to give an accurate idea on how much air pollution they would prevent.
by Christofer Jauneau
Ulaanbaatar is notorious for its air pollution. And it got worse over the years, as more and more people have been settling in the ger (yurt) areas. At the time of writing this paper, the city online service for monitoring air quality shows monthly average air quality index in the center and nearest ger areas ranging from 54 to 392. Air is considered clean up to 50. On this same period of time, PM10 peaked at 246 µg/m3 and PM2.5, to 228 µg/m3.
A 2011 World Bank study indicates that among all measurements taken at the study’s eight monitoring stations, the worst recorded annual average concentration was more than 10 times higher than the Mongolian air quality standard for PM10 and 25 times higher for PM2.5. Particulate matters are known to cause lungs and heart diseases.
Where does this pollution come from? Like other capitals, car pollution in UB reaches noxious levels but the unique traits of UB make it less of a concern compared to other forms of pollution. Power plants running on coal are also tangible contributors to air pollution. But heating in the ger areas is the main factor, along with dust suspension caused by soil erosion, which also happens to occur mostly in the ger area where few roads are paved. These two factors account for 75-95% of particulate matter (PM) concentrations at the ground level. People in the ger areas are the first victims of their coal burning stoves. The highest PM concentrations are found in these parts of the city, with annual average PM2.5 concentrations ranging from 200 to 350 µg/m3. This is much higher than in the center.
A 2012 survey, shows households in the ger areas used about 172 000 stoves in total, which is more than the total number of households (164,127 households) in the surveyed area, according to the World Bank study. This can be explained by the fact that some households use a stove for cooking and another for heating. No wonder these devices are a key factor in reducing air pollution.
Cleaner stoves
Solutions might seem obvious when it comes to fixing air pollution. But in the ger areas living conditions are as harsh as the climate and poor people can’t afford pricey efficient stoves or solar energy unless it is subsidized. Connecting the ger areas to the heating grid or moving all the people into modern cleaner apartments is even less likely to happen.
Healthier heating appliances have to be cheap so that many people will adopt it, and low tech so they can maintain it. In this perspective, the rocket mass heater seems a good candidate. It can be built out of steel drums, bricks, ashes and cob (mix of dirt and grass /straw). It can be fed with paper (as a starter), tinder, wood chips, dead leaves, even coal and a bit of cow dung: readily available and cheap materials.
Rocket stoves are no rocket science yet they take advantage of the laws of thermodynamics. The efficient air intake and horizontal burning chamber and the insulated inner chimney make the heat more intense and draft the gases upwards, to the top of a flipped barrel, which can be used as a cooking surface. The gases then swirl down inside the barrel and circulate into a horizontal pipe where they release their heat into a thermal mass (or the chimney is placed just after the barrel so that gases exit without circulating through thermal mass).
Thanks to this simple principle almost all the energy contained in the fuel is used, very little ash is produced and there is no smoke coming out of the flue. The remaining gases, mostly CO2, are expelled at low temperature (some reports say around 50°C) compared to the temperature in the burning chamber (around 1000°C reportedly). The remaining 900+°C are transferred through the barrel, then stored into the thermal mass as gases travel through the pipes. The heat is released from the mass at night when the air temperature falls below that of the material.
An assessment of several stove types conducted by the Biomass Energy Foundation (US) found that various simple improved cook stoves (the majority of those used in the ger) emit from 20 to 50g CO and 900 to 2400g PM on the standard 5-liter water boiling test. During the same test, rocket stoves ranged from 10 to 20g CO and 450 to 1000 PM.
Stoves comparisons are not entirely relevant due to the many possible designs affecting their efficiency. A “traditional stove” can be a thermal mass stove like the chulhas in India and Nepal or as simple as a depression in the ground.
An Aprovecho research center (US) study shows that a rocket fan stove (the fan forces the air into the combustion chamber) produces 39% of a three stone fire’s global warming potential, compared to 84% for a charcoal stove. A three stone fire consists in just 3 stone laid around an open camp fire to hold the cooking pot in place. It is the most basic and less efficient type of fire. The study shows the energy required to boil 2.5l of water is 2 470 kJ/L for a rocket and as high as 4 216 kJ/L for a charcoal stove. The rocket stove is also 10 minutes quicker to complete the test.
Can fly ash pave the way to a better future?
Unpaved roads are known to be a major source of air pollution in UB. On the other hand, loads of fly ash from the power plants and individual stoves accumulate in purpose-built pools, or worse in dumps; legal or illegal making no difference in terms of waste management since fly ash just seeps into the ground or flies away with the wind. But fly ash can be used for construction, including road pavement. And this is nothing new. The Romans used volcanic ash from Mount Vesuvius to cement the paving stones in their roadways. Many miles of these ancient viae still exist today.
The Romans used volcanic fly ash but ash from coal combustion is very similar in its chemical composition: calcium-aluminum-silicate-hydrate (C-A-S-H). This mixture was used to build structures that are still steady 2 000 years later. Indeed, researchers from Berkeley found that mixing volcanic ash with lime produced a stronger and submersible product, something that sand based concrete could not match. This was particularly useful for aqueducts and harbors structures. So ash has long proven its reliability.
The manufacturing process of Roman concrete also benefited from a smaller carbon footprint. Modern cement, also known as Portland cement, requires limestone (calcium carbonate), a key ingredient, to be burnt at about 1 450°C with fossil fuels. Seven percent of global CO2 emissions comes from this activity annually. But lime used for Roman concrete required temperatures which were one-third lower; this could save fuel and the atmosphere.
A few companies in UB already use fly ash from the city’s power plants to make autoclaved aerated concrete blocks and mortar. Depending on the desired mixture, fly ash can substitute for more or less sand and lime. Incorporated fly ash allows a quicker process and is cheaper than imported materials. No company produces road pavement or cobblestones yet. But the 2 000-year-old Roman remnants demonstrate ash is a solid alternative to modern, energy intensive materials. In Ulaanbaatar, it is a way to recycle a polluting by-product. Mongolians might be reluctant in using fly ash due to its supposed radioactivity. Local regulations say it must not exceed 740 mBq/kg for road construction whereas samples taken from the power plants didn’t exceed 400.
Planting trees
Another approach to improving air quality is having as many trees as possible. This may sound like an odd idea for people in such urgent need but trees are indeed a key factor in improving life conditions. Trees offer three main advantages besides their scientifically proven psychological benefits on people:
1-They provide kindling for the stoves. When wood burns, it releases the carbon stored during the tree’s growth. When coal burns, it releases carbon trapped underground for eons that is no longer part of the biogenic carbon cycle; it is a direct addition into the atmosphere.
2-When their leaves fall they keep the ground covered and allow it to regenerate, namely helping grass and plants to thrive, and prevent erosion. Soil is crucial to air quality as erosion releases PM in airborne dusts. Not to mention that grassland is better than a barren land at storing carbon.
3-And above all, trees act as giant air filters. A study led in Beijing in June 2002 shows that 2.4 million trees in the central part of Beijing removed a little less than 1 300 tons of pollutants from the air, 770 tons of which being PM10. CO2 stored in the urban forest biomass amounted to 200 000 tons. The other gaseous pollutants absorbed are mainly sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3).
With longer, colder winters in Ulaanbaatar, trees hibernate more and results would certainly be less spectacular if such a study were to be conducted. Yet trees can bring fresh air and once they are here, they offer benefits to the community, for decades, for free. Besides, fruits trees are also a possibility and would provide local free food.
Another study from the University of Warsaw showed that birch and poplar are the best at filtering particle matter. Birch and poplar are among the most common trees in Mongolia. Deciduous trees are obviously ineffective during winter but coniferous like pines can also filter a large amount of pollutants for a longer time throughout the year. Some evergreen trees appear to be even more effective than other broad-leaved species like whitebeam.
Revegetating the city is part of the “smoke free Ulaanbaatar national program” for 2010–16 expected to continue to 2023. It says that 0.7 percent (about 952 hectares) of Ulaanbaatar’s land will be vegetated during the period every year, including upstream parts of the Tuul and Selbe rivers and reclaimed land. The PM reduction due to the vegetation’s prevention of suspension, when successfully established, is estimated to be 80 percent. As only public land will be vegetated, people from the ger area could start planting at least one tree on their plots of land to help make the city greener. This is what the owner of the Nogoon Nuur (green lake) did.
Trees and rocket stoves are probably two of the simplest and most durable solutions for individuals but road pavement needs broader incentive to take off. These solutions have yet to be tried and tested to give an accurate idea on how much air pollution they would prevent.
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