GHG EMISSIONS FROM FUEL BURNING
SK ANSARI (CHEMICAL ENGINEER)
SEEMA ANSARI (TELECOM ENGINEER)
May 17 - 23, 2010
Pakistan had proven oil reserves of 300 million barrels as of January 2006, according to Oil and Gas Journal (OGJ). The majority of produced oil comes from proven reserves located in the southern half of the country, with the three largest oil-producing fields located in the Southern Indus Basin. Additional producing fields are located in the Middle and Upper Indus Basins. Since the late 1980s, Pakistan has not experienced many new oil fields coming online. As a result, oil production has remained fairly flat, at around 60,000 barrels per day (bbl/d). During the first eleven months of 2006, Pakistan produced an average of 58,000 bbl/d of crude oil. However, Pakistan has ambitious plans to increase its current output to 100,000 bbl/d by 2010.
Due to Pakistan's modest oil production, the country is dependent on oil imports to satisfy domestic oil demand. As of November 2006, Pakistan had consumed approximately 350 thousand barrels of oil and various petroleum products, of which more than 80 per cent was imported. The majority of oil imports come from the Middle East, with Saudi Arabia as the lead importer.
EFFLUENT GASES EMISSION IN PAKISTAN
The level of air pollution in Pakistan's two largest cities, Karachi and Lahore, is estimated to be 20 times higher than World Health Organization standards, and continues to rise. Islamabad, the capital, is perpetually smothered by a thick cloud of smog that hides views of the Margalla Hills that tower over the city's tree-lined streets.
As industry has expanded, factories have emitted more and more toxic effluents into the air. Also, as in other developing countries, the number of vehicles in Pakistan has swelled in recent years. Although the number of motor vehicles (1 per 125 people) in Pakistan is still well below that of the US (1 per 1.3 people), the 1992 National Conservation Strategy Report claims that the average Pakistani vehicle emits 25 times as much carbon dioxide as the average US vehicle as well as 20 times as many hydrocarbons and more than 3.5 times as many nitrous oxides in grams per kilometer.
With few controls on vehicular emissions and little enforcement, reports show that motor vehicle exhaust accounts for 90 per cent of the pollutants in Pakistan's air. The government has begun to take notice of the degrading air quality in the capital, which adversely affects the health of some 16 million people.
Many Pakistani environmentalists say that poor fuel quality is also to blame for the country's serious air pollution problems. Fuel consumption rose by 188 per cent in Pakistan from 1980 to 2009. An estimated 550 metric tons per year of lead emissions are generated by vehicles in Pakistan burning poor-quality fuel, with the resulting air pollution adding about $500 million per year in related health care costs.
Various grades of gasoline sold contain 0.35 gm/liter of lead in comparison leaded gas in other countries usually contains no more than 0.15 gm/liter. The problem of air pollution could largely be solved if the government were to tighten its lax fuel quality standards.
Pakistan has become the third largest CNG consumer in the world after Argentina and Italy. Use of CNG in vehicles is encouraged to reduce pressure on petroleum imports, to reduce carbon emissions and improve the environment.
Global demand for oil is rising to fuel economy while the world is concerned about its role in contributing to greenhouse gas emissions. Governments all over the world are interested in energy security and supporting local agriculture besides contributing to drive market penetration of bio fuels. Shareholders, although attracted to invest in the industry, are concerned about cost inflation and the sustainability of returns over the medium-to-long term.
To meet increased energy requirements and tough new environmental standards, refineries must combine their available expertise with continued investment in technology. This needs effective solutions to today's challenges and thirst for new technologies has led to innovation that is a key business driver and an important success factor. Underpinning this shift is the drive to create more efficient and reliable processes.
Refineries have come to realise that in order to meet society's needs through successful projects that will increase the volume of oil products and meet more stringent specifications and requirements, they need to be innovative in all their activities from master planning to project execution and maintenance.
The refining industry has enjoyed exceptionally favourable margins for the past few years, with robust demand growth mainly driven by the developing nations underpinning near-capacity operating rates at refineries, and high oil prices. However, the shift towards unconventional crude and heavy feed stocks, coupled with vigorous market demand for cleaner products produced using reduced-emission manufacturing processes, is changing the refining landscape.
Although refiners are able to choose the crude they process, there is little flexibility in the total crude supply available to Pakistan under reasonably economic and secure terms. This may make it difficult to achieve an overall emission-reduction target at a European level by differentiating in favour of crudes that generate less carbon dioxide (CO2).
CARBON DIOXIDE FROM FOSSIL FUEL
Production of CO2 globally has been brought into sharp focus in recent times to setting emission targets for greenhouse gases compared with a baseline 1990 level, with a view to pegging and reducing global emissions.
How individual nations, economic communities (such as the EU) and industry react to the growing pressures to reduce CO2 is still to be formulated and ratified. Specific industries should be targeted and CO2 trading should be allowed across national boundaries and/or industries.
The energy sector, including refining, is likely to feature in any legislation aimed at curbing CO2 emissions. However, in this case the refiner may see real benefits and opportunities in adopting a CO2 management and reduction strategy, in order to be seen as a "good neighbour", benefit from some of the economic gains of CO2 reductions (e.g. energy conservation, CO2 utilization), apply technologies such as gasification, which allows heavy residue destruction, relatively easy CO2 capture and other environmental benefits.
GLOBAL WARMING CAUSED BY CARBON DIOXIDE
The main problem arising in the ecosystem is the threat of global warming. The earth is protected from ultraviolet radiation from the sun. Longer wavelength radiation, including visible light, is transmitted through the atmosphere and degraded into heat, which is reradiated as infrared (IR) radiation. Some of this radiation is reabsorbed as heat by gases in the atmosphere, and this keeps the surface of the earth at a tolerable temperature, about 33∞C higher than it would otherwise be. Oxygen, nitrogen, etc. are transparent to IR radiation and ozone absorbs only slightly and at high altitude. The principal absorbers are water and carbon dioxide. Water has two broad bands in the IR around 3800 and 1600/cm (2630 and 6250nm). It is the most important absorber, and its absence is the reason why deserts with dry atmospheres are colder at night.
Carbon dioxide has narrow absorption bands at 700 and 2400/cm (14,300 and 4,170nm) and is responsible for less warming. It has been estimated that water contributes about 33∞C to the temperature at the surface of the earth while carbon dioxide contributes about 0.5∞C, which may rise to another 1 or 2∞C depending on its concentration. Other green house gases include methane, sulfur hexafluoride, nitrous oxide, CFCs, and HCFCs. Nitrous oxide is formed naturally in thunderstorms, but there are also manmade contributions. Methane is potential problem.
The effect of additional green house gases depend on whether they absorb in the spectral gaps between water and carbon dioxide.
Water vapor forms clouds, which reflect radiation from the sun and keep it warmer at night. There are equilibrium in which carbon dioxide is locked up in oceans, sediments, vegetation (as organic carbon), and carbonates. The situation is complex.
SOURCES OF REFINERY CO2 EMISSIONS
Petroleum refineries are faced with a number of purification needs, driven by increasingly stringent requirements as well as improving product quality. One traditional technology, activated carbon, remains a cost-effective method for refineries to comply with federal, state and local regulations, and handle product purification needs.
Activated carbon is successfully used in many clean-up applications in a typical refinery.
Reactivated carbon is spent carbon that is recycled by being regenerated at very high temperatures. In refineries, reactivated carbons can be used for volatile organic compounds (VOCs) abatement in vapor phase applications, waste water treatment and ground water remediation.
The refinery is essentially a carbon/hydrogen manipulator, tailoring and reshaping molecules and boiling ranges to meet the performance needs of particular fuels. All emissions from the refinery itself originate from the feed stocks used. These feed stocks are the main crude oil to be processed, plus other imported feed stocks such as condensates or VGOs, and supplementary natural gas for fuel or hydrogen plants.
Carbon is found in the products produced (gasoline, diesel etc), with the balance emitted into the environment. Whilst most carbon emissions from the refinery will be in the form of CO2, there are other emissions, such as VOCs, coke on catalysts (which could be land filled) and other minor emissions. Shadow emissions from energy import (CO2 emissions derived from production of energy offsite).
Emissions are dominated by those resulting from burn of fuel in fired heaters (approximately 50 per cent) and in utility boilers.
The profiles for the two different types of refinery are remarkably similar, with emissions from the hydrogen plant for the hydro cracking refinery matching those from the FCC in the catalytic cracking refinery.
Approximately 90 per cent of CO2 emissions come from combustion of the final product, with the refining activity itself contributing around 5 per cent.
Two issues which influence the refinery CO2 production are fuel replacement and the need for hydrogen.
In recent years many refiners have switched some refinery fuel needs away from heavy, high sulphur fuel oil towards refinery fuel gas/natural gas. The driving force for this switchover has been SO2 reduction. Even switching totally to natural gas has a relatively small impact on CO2 emissions (only 20 per cent reduction). The use of hydrogen-rich fuel can reduce CO2 but again would be prohibitively expensive and impractical to implement on an existing refinery.
Hydrogenation specifically refers to the chemical reaction of a substance with molecule hydrogen in the presence of catalyst. The process includes reactions in which hydrogen simply adds to a molecule (hydrogenation) reactions in which molecules are cleaved by hydrogen (or destructive hydrogenation).
Other reactions which involve molecular hydrogen and catalysts are synthesis of ammonia etc.
The purposes of hydrogenation hydrocarbons, petroleum, tars and coals are:
1. To improve existing petroleum products or develop new uses and products.
2. To convert inferior or low grade materials such as heavy oils and tars into valuable petroleum products.
3. To transform solid fuels such as lignites and coals into liquid fuels.
CARBON DEPOSIT FROM CARBON DIOXIDE
Some of the planets are thought to be surrounded by a layer of carbon dioxide, and it is probable that all the deposits of carbon compounds in the earth originally come from carbon dioxide in the atmosphere. Plants use atmospheric carbon dioxide for growth and animals feed on plants. The decomposition of dead animals and vegetation, followed by geological upheavals which subject the decaying matter to great temperature and pressures for a long period of time in the absence of oxygen, almost certainly accounts for coal, oil and natural gas.
The percentage of carbon dioxide in the atmosphere remains constant at a figure of about 0.03 per cent. But due to more and more industrialisation and moveable vehicle on the road increased the volume of carbon dioxide which is harmful for our lives and damaging our properties in the form of carbon dioxide react with the water particle in the atmosphere forming of carbonic acid.
In order to control the volume of carbon dioxide in the atmosphere different parameters are taking place. Converting carbon coal to liquid hydrocarbon produces tremendous amount of carbon dioxide.
ESTIMATED CO2, GHG
YEAR CO2 PRODUCE IN MILLION TONE GHG LEVEL IN MILLION TONE 2008 2480 2480 2010 2550 2550 2012 2650 2630 2014 2720 2700 2016 2810 2690 2018 2880 2680 2020 2940 2650 2022 3020 2650 2024 3100 2670 2026 3220 2750 2027 3250 2770
CARBON DIOXIDE EMISSION (000í metric tons)
ASIA & PACIFIC SOLID FUEL LIQUID FUEL GASEOUS FUEL 1990 2005 1990 2005 1990 2005 Bangladesh 1,066 1,249 6,548 9,574 7,577 16,646 China 1,930,510 1,827,083 334,406 601,493 29,301 64,387 India 476,463 782,180 145,314 192,950 19,122 45,045 Indonesia 7,845 52,490 81,436 158,153 61,812 41,271 Japan 304,632 388,117 624,943 607,667 99,031 148,322 South Korea 223,196 173,897 13,469 11,974 --- --- North Korea 93,421 162,608 124,789 200,795 6,225 38,073 Malaysia 5,412 9,977 37,039 66,274 6,837 56,539 Pakistan 8,530 8,189 32,646 55,663 23,116 36,017 Thailand 13,590 40,531 62,006 109,968 11,120 35,446 Viet Nam 11,058 21,167 9,116 27,040 7 2,601 Total World Carbon Dioxide Emission 8,712,992 8,112,096 9,313,888 10,636,592 3,718,960 4,744,880
Carbon capture and storage (CCS) is an approach to mitigate global warming based on capturing carbon dioxide (CO2) from large point sources such as fossil fuel power plants and permanently storing it away from the atmosphere. It can also be used to describe geo-engineering techniques such as Fake Plastic Trees.
Although CO2 has been injected into geological formations for various purposes, the long term storage of CO2 is a relatively untried concept. The first integrated pilot-scale CCS power plant was to begin operating in September 2008 in the eastern German power plant Schwarze Pumpe in the hope of answering questions about technological feasibility and economic efficiency.
CCS applied to a modern conventional power plant could reduce CO2 emissions to the atmosphere by approximately 80-90 per cent compared to a plant without CCS. The IPCC estimates that the economic potential of CCS could be between 10 per cent and 55 per cent of the total carbon mitigation effort until year 2100.
Shell and other oil processing companies are spearheading developments in carbon capture and storage (CCS), one of the most promising technologies for reducing atmospheric emissions of carbon dioxide.
CCS is "the only technology available to mitigate greenhouse gas emissions from large-scale fossil fuel usage". The IEA (International Energy Association) report states that CCS has the potential to deliver 20 per cent of the greenhouse gas reductions needed to halve global emissions by 2050, but stresses that the window of opportunity is closing and substantial investment is required now to develop the technology further.
The idea is to capture carbon dioxide from power plants, refineries, industrial processes and wellheads, and store it permanently underground in deep saline aquifers, depleted oil or gas reservoirs or unmineable coal beds. The technology to achieve this on an extensive scale is far from simple, and demonstration projects involving industry, governments and academia are required to achieve commercial models for future use.
Although the processes involved in CCS have been demonstrated in other industrial applications, no commercial scale projects which integrate these processes exist. The costs therefore remain highly uncertain. The increased energy requirements of capturing and compressing of CO2 significantly raise the operating costs of CCS-equipped power plants. In addition there are added investments or capital costs. The process would increase the fuel requirement of a plant with CCS by about 25 per cent for a coal-fired plant and about 15 per cent for a gas-fired plant. The cost of this extra fuel, as well as storage and other system costs are estimated to increase the costs of energy from a power plant with CCS by 30-60 per cent, depending on the specific circumstances. Pre-commercial CCS demonstration projects are likely to be more expensive than mature CCS technology.
FUEL TYPE UNIT CO2 EMITTED PER UNIT Petrol 1 gallon (UK) 10.4 kg Petrol 1 liter 2.3 kg Gasoline 1 gallon (USA) 8.7 kg Gasoline 1 liter 2.3 kg Diesel 1 gallon (UK) 12.2 kg Diesel 1 gallon (USA) 9.95 kg Diesel 1 liter 2.7 kg Oil (heating) 1 gallon (UK) 13.6 kg Oil (heating) 1 gallon (USA) 11.26 kg Oil (heating) 1 liter 3 kg
SK Ansari is a chemical engineer and Seema Ansari is a telecom engineer.