Emissions

Emissões: Os impactos mais renegados das hidrelétricas.

by Philip Fearnside

Fearnside, P.M. 2011. Emissões: Os impactos mais renegados das hidrelétricas. Contra Corrente, No. 3: 27-30.

Hydroelectric dams in Brazilian Amazonia: Response to Rosa, Schaeffer & dos Santos.

by Philip Fearnside

Fearnside, P.M. 1996. Hydroelectric dams in Brazilian Amazonia: Response to Rosa, Schaeffer & dos Santos. Environmental Conservation 23(2): 105-108. doi:10.1017/S0376892900038467

See Amazon Controversies:
http://philip.inpa.gov.br/publ_livres/AMAZONIAN CONTROVERSIES.htm

Estudo avalia impactos do desmatamento na Amazônia

by Philip Fearnside

Fearnside, P.M. 2003. Estudo avalia impactos do desmatamento na Amazônia. Hipertexto. Brasília: Canal Ciência / IBICT. http://www.canalciencia.ibict.br/pesquisa/0093-Impactos-do-desmatamento-na-Amazonia.html

Dirty hydros [Response to Graham Faichney]

by Philip Fearnside

Fearnside, P.M. 2005. Dirty hydros [Response to Graham Faichney] New Scientist 186(2494): 24 (9 April 2005).

Why hydropower is not clean energy

by Philip Fearnside

Fearnside, P.M. 2007. Why hydropower is not clean energy. Scitizen, Paris, France (peer-reviewed website). http://www.scitizen.com/screens/blogPage/viewBlog/sw_viewBlog.php?idTheme=14&idContribution=298

See Amazon Controversies:
http://philip.inpa.gov.br/publ_livres/AMAZONIAN CONTROVERSIES.htm

Versão em Português:
Fearnside, P.M. 2008. Controvérsias sobre o efeito estufa. Por que a energia hidrelétrica não é limpa. pp. 270-271 In: I. S. Gorayeb (ed.). Amazônia. Jornal "O Liberal"/VALE, Belém, Pará. 384 pp. ISBN 978-85-61628-00-0 [também publicado no jornal O Liberal 30 Jan. 2008].
http://philip.inpa.gov.br/publ_livres/2008/Hidro nao eneergia limpa-livro Amazônia 1.pdf

Dirty hydros [Response to Graham Faichney]

by Philip Fearnside

Fearnside, P.M. 2005. Dirty hydros [Response to Graham Faichney] New Scientist 186(2494): 24 (9 April 2005).

Controvérsias sobre o efeito estufa. Por que a energia hidrelétrica não é limpa.

by Philip Fearnside

Fearnside, P.M. 2008. Controvérsias sobre o efeito estufa. Por que a energia hidrelétrica não é limpa. pp. 270-271 In: I. S. Gorayeb (ed.). Amazônia. Jornal "O Liberal"/VALE, Belém, Pará. 384 pp. ISBN 978-85-61628-00-0 [também publicado no jornal O Liberal 30 Jan. 2008].

See Amazon Controversies:
http://philip.inpa.gov.br/publ_livres/AMAZONIAN CONTROVERSIES.htm

English version:
Fearnside, P.M. 2007. Why hydropower is not clean energy. Scitizen, Paris, France (peer-reviewed website). http://www.scitizen.com/screens/blogPage/viewBlog/sw_viewBlog.php?idTheme=14&idContribution=298
http://philip.inpa.gov.br/publ_livres/2007/Why hydro not clean energy-Article as posted.pdf

Tropical deforestation and global warming

by Philip Fearnside

Fearnside, P.M. 2006. Tropical deforestation and global warming. Science 312: 1137 (letter) DOI: 10.1126/science.312.5777.1137c

Development of a novel single-mode, steady-state test cycle for light-duty diesel engine

by Hoon Kiat Ng

Jo-Han Ng, Hoon Kiat Ng, Suyin Gan

JSAE Technical Paper Series 20101600, 2010.

Also in Proceedings of the FISITA 2010 World Automotive Congress, Budapest, Hungary; 30 May–4 June 2010.

Characterisation of the effect of fuel type on different emission species over a typical drive cycle requires... more Characterisation of the effect of fuel type on different emission species over a typical drive cycle requires time-consuming and costly test-bed studies, especially when large number of fuel types is involved. Hence, it is of practical interest that the number of modes in a test cycle is reduced. In this reported work, a novel single-mode, steady-state emissions test cycle for light-duty diesel engines is proposed. Here, the test engine used is a single-cylinder, four-stroke, diesel engine with a rated power of 4.6 kW at 3500 rev/min. The test point reduction involved the determination of a sole test point for the test cycle and a comprehensive validation exercise of this against a 7-mode emissions test cycle. The determination and validation processes are based on the use of fossil diesel and biodiesel fuels such as the methyl esters of coconut, palm and soybean. This is to allow the test cycle to be applicable universally. The first step is the emissions testing of the entire operational speed-load map involving 65 test points across the engine speed of 1,500 to 2,800 rev/min, where the load increases from idle up to maximum load. From this, contour plots for diesel emissions such as CO, CO2 and NO are generated and compared against the weighted average emissions obtained from the adapted baseline test cycle for light-duty diesel engines. This facilitates the identification of possible areas in the speed-load map which could reproduce similar results as the weighted average values from the baseline test cycle. The criterion of selection for possible areas is fixed on the ±10% error margin. The common area identified for each of the specified emissions and fuel combinations tested are marked for a more in-depth analysis. The area then undergo a further 25-point test in a 5x5 test matrix for the identification of the single point with the lowest average error for various emissions. The single point on the speed-load map is found at a speed of 2,374 rev/min with a load of 1.65 kW. The use of this single-mode test cycle affords a potential saving in experimental runtime by up to 85.7% over the baseline test cycle. Despite that, the discrepancy between the emissions values obtained did not exceed the specified error margin. This reduced single-mode, steady-state emissions test cycle is invaluable as a tool for rapid evaluation of the effect of fuel types and blends on emissions characteristics, which is especially useful in determining the optimal diesel-biodiesel blend type for simultaneous reduction in diesel engine emissions.

Advances in biodiesel fuel for application in compression ignition engines

by Hoon Kiat Ng

Jo-Han Ng, Hoon Kiat Ng and Suyin Gan

Clean Technologies and Environmental Policy 12 (5): 459–493, 2010.

The importance of biodiesel as a renewable and economically viable alternative to fossil diesel for applications in... more The importance of biodiesel as a renewable and economically viable alternative to fossil diesel for applications in compression ignition (CI) engines has led to intense research in the field over the last two decades. This is predominantly due to the depletion of petroleum resources, and increasing awareness of environmental and health impacts from the combustion of fossil diesel. Biodiesel is favoured over other biofuels because of its compatibility with present day CI engines, with no further adjustments required to the core engine configurations when used in either neat or blended forms. Studies conducted to date on various CI engines fuelled with varying biodiesel types and blends under numerous test cycles have shown that key tailpipe pollutants, such as carbon monoxide, aromatics, sulphur oxides, unburnt hydrocarbons and particulate matters are potentially reduced. The effects of biodiesel on nitrogen oxides emission require further tests and validations. The improvement in most of the diesel emission species comes with a trade-off in a reduction of brake power and an increase in fuel consumption. Biodiesel’s lubricating properties are generally better than those of its fossil diesel counterpart, which result in an increased engine life. These substantial differences in engine-out responses between biodiesel and fossil diesel combustion are mainly attributed to the physical properties and chemical composition of the fuels. Despite the purported benefits, widespread adoption of biodiesel usage in CI engines is hindered by outstanding technical challenges, such as low temperature inoperability, storage instabilities, in-cylinder carbon deposition and fuel line corrosion. It is imperative that these issues are addressed appropriately to ensure that long-term biodiesel usage in CI engines does not negatively affect the overall engine durability. Possible solutions range from biodiesel fuel reformulation through feedstock choice and production technique, to the simple addition of fuel additives. This calls for a more strategic and comprehensive research effort internationally, with an overarching approach for co-ordinating sustainable exploitation and utilisation of biodiesel. This review examines the combustion quality, exhaust emissions and tribological impacts of biodiesel on CI engines, with specific focus on the influence of biodiesel’s physico-chemical properties. Ongoing efforts in mitigating problems related to engine operations due to biodiesel usage are addressed. Present day biodiesel production methods and emerging trends are also identified, with specific focus on the conventional transesterification process wherein factors affecting its yield are discussed.

Effects of antioxidant additives on pollutant formation from the combustion of palm oil methyl ester blends with diesel in a non-pressurised burner

by Hoon Kiat Ng

Suyin Gan, Hoon Kiat Ng

Energy Conversion and Management 51 (7): 1536-1546, 2010.

In order to alleviate escalating worldwide crises of oil reserves exhaustion and global warming, an alternative fuel... more In order to alleviate escalating worldwide crises of oil reserves exhaustion and global warming, an alternative fuel that is sustainable, economically feasible and environmental friendly must be developed for large-scale adoption. Biodiesel has emerged as the leading alternative fuel of choice due to its cost, availability of current production technology and compatibility with existing infrastructure of petroleum diesel. Although considerable in-roads have been made to understand combustion and tailpipe emissions of various biodiesel fuels in compression-ignited engines, research efforts dedicated to examining these and the associated impacts of additives for non-transportation usage have been scarce. This work aims to establish the effects of antioxidants addition on pollutant emissions from the combustion of palm oil methyl ester blends with No. 2 diesel in a non-pressurised, water-cooled combustion chamber. Antioxidant additives butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) were individually dissolved at varying concentrations in B10 and B20 fuel blends for testing. Both BHA and TBHQ were effective in lowering the nitric oxide (NO) emission produced, where their concentrations in the fuel blends were shown to scale proportionately to NO levels in the flue gas. Addition of BHT to both fuel blends, however, increased the generation of NO during combustion. BHA was found to decrease the carbon monoxide (CO) levels when added to B10 and B20, while both BHT and TBHQ were observed to raise CO formation at all test points. With the proper selection of additives type and quantity for application to specific biodiesel blends, this simple measure has been shown to be an effective pollutants control strategy which is more economical than other existing technologies.

Combustion performance and exhaust emissions from the non-pressurised combustion of palm oil biodiesel blends

by Hoon Kiat Ng

Hoon Kiat Ng, Suyin Gan

Applied Thermal Engineering 30 (16): 2476-2484, 2010.

In this work, levels of exhaust species from the combustion of palm oil methyl ester (POME) and its blends with No. 2... more In this work, levels of exhaust species from the combustion of palm oil methyl ester (POME) and its blends with No. 2 diesel in a non-pressurised, water-cooled combustion chamber are evaluated. The study explores the correlations between emission species and fuel pumping pressures over a range of equivalence ratios (ERs). This is followed by a similar evaluation of emissions variation with POME proportions across the ER at predetermined values of fuel pumping pressure. Carbon monoxide (CO) level was found to be minimal when ER is within the 0.75–0.85 range, indicating improved combustion quality. As pumping pressure increases, the minimum CO level is raised but the optimum ER region is extended. Maximum nitric oxide (NO) production is recorded over this optimum ER range, and pumping pressure is seen to decrease the NO level only marginally. Exhaust CO improved across the tested ER range with increasing POME proportion in the fuel blends. This observed combustion improvement was offset by the accompanying increase in NO level when the POME content is raised. The work indicated the potential use of palm oil biodiesels in small-scale liquid fuel burners, although further examination is required to establish the optimum operating parameters and POME content for best NO–CO trade-off.

Evaluation of non-premixed combustion and fuel spray models for in-cylinder diesel engine simulation

by Hoon Kiat Ng

Harun Mohamed Ismail, Hoon Kiat Ng, Suyin Gan

Applied Energy 90 (1): 271-279, 2012.

Computational Fluid Dynamics (CFD) study of light-duty automotive diesel engines affords invaluable insights into... more Computational Fluid Dynamics (CFD) study of light-duty automotive diesel engines affords invaluable insights into in-cylinder conditions and processes, which greatly expands on the very limited detail provided by engine-out measurements of exhaust emissions. For the simulation to be successful, accuracy and robustness of the physical sub-models are crucial. The purpose of this feasibility study is to appraise the non-premixed combustion and fuel spray CFD sub-models for in-cylinder diesel engine simulation on a FLUENT 6.3.26 platform. Simulation results are compared against data from parallel experimental test-bed studies in terms of pressure traces, heat release curves and tailpipe values of NOx and soot levels. Heat release rate and pressure trace from the computations are found to be within a reasonable error limit of 10%. Simulated heat released plots are able to capture the general trend of premixed and mixing-controlled diesel combustion phases. Ignition delay period for the main combustion event is well predicted, although the calculated ignition delay period for pilot combustion is 7–10° crank angle degrees earlier for all the test cases. The variations for exhaust soot and NO when the timing of start of injection is changed are reproduced successfully. CFD modelling, when used in conjunction with experimental studies is proven to be particularly effective in elucidating physical details of in-cylinder processes.

Characterisation of engine-out responses from a light-duty diesel engine fuelled with palm methyl ester (PME)

by Hoon Kiat Ng

Jo-Han Ng, Hoon Kiat Ng, Suyin Gan

Applied Energy 90 (1): 58-67, 2012.

An experimental study was conducted to evaluate the suitability of biodiesel for on-road usage based on the engine-out... more An experimental study was conducted to evaluate the suitability of biodiesel for on-road usage based on the engine-out responses of a light-duty diesel engine. Palm methyl ester (PME) was the biodiesel fuel used in this study. The experimental programme was conducted in two separate phases. In the first phase, the effects of engine speed and load over the entire operational range on engine performance and pollutant emissions when fuelled with neat PME (B100) and a B50 PME–diesel blend were identified. Comparison was then made against that of neat fossil diesel (B0), which served as the baseline fuel. The result indicates that fossil diesel, PME and their B50 blend exhibit similar trends across the speed–load map albeit with variation in the magnitude of the responses. For the second phase, attempts were made to elucidate the on-road influence of PME content when used as blending component with diesel. This was achieved by appraising eleven fuel blends from B0 to B100 under a modified steady-state emissions test cycle, with nine intermediate blends at 10 vol.% interval in between. Conclusive reduction of tailpipe NO, UHC and smoke opacity was observed when neat PME was used, culminating in a maximum decrease of 5.0%, 26.2% and 66.7%, respectively. The influence of additional fuel-bound oxygen content in PME on CO is insignificant as diesel engine typically operates in lean mode. It can be concluded from this study that biodiesel fuels has the potential to provide part of the solution for emissions reduction in a light-duty diesel engine, both in neat and blended forms.

Engine-out characterisation using speed-load mapping and reduced test cycle for a light-duty diesel engine fuelled with biodiesel blends

by Hoon Kiat Ng

Jo-Han Ng, Hoon Kiat Ng, Suyin Gan

Fuel 90 (8): 2700–2709, 2011.

In this two-phase experimental programme, key effects of different biodiesel fuels and their blends on engine-out... more In this two-phase experimental programme, key effects of different biodiesel fuels and their blends on engine-out responses of a light-duty diesel engine were investigated. Here, coconut methyl ester (CME), palm methyl ester (PME) and soybean methyl ester (SME) were tested to represent the wide spectrum of degree of saturations in the fatty acid composition. Fossil diesel which served as the blending component was used as the baseline fuel for benchmarking purposes. Phase I examined how engine speed and load affect patterns of variation in tailpipe emissions and engine performance parameters for the test fuels. Here, the trends in engine-out responses across the operational speed–load map for all the tested biodiesel fuels were similar and consistent throughout. However, there were marked differences in the levels of equivalence ratio and specific fuel consumption, as well as exhaust concentrations of CO, UHC and smoke opacity. This is mainly due to differences in fuel properties, especially fuel-bound oxygen content, density and impurity level. Phase II appraised the performance of 31 different fuel blend combinations of fossil diesel blended with CME, PME or SME at 10 vol.% interval under a steady-state test cycle. The use of biodiesel fuels with low to moderate degree of unsaturation was found to conclusively reduce regulated emission species of UHC, NO and smoke opacity levels by up to 41.7%, 5.4% and 61.3%, respectively. This is in contrast to the performance of the highly unsaturated SME, where CO, UHC, NO and smoke opacity levels are higher in relation to that of fossil diesel. Simultaneous NO–smoke reduction can be achieved through the introduction of at least 1 vol.% of PME or 50 vol.% of CME into diesel fuel, although minor trade-off in the higher specific fuel consumption is observed.

Artificial neural networks modelling of engine-out responses for a light-duty diesel engine fuelled with biodiesel blends

by Hoon Kiat Ng

Harun Mohamed Ismail, Hoon Kiat Ng, Cheen Wei Queck, Suyin Gan

Applied Energy 92: 769–777, 2012.

This paper reports an artificial neural networks (ANN) modelling programme for a light-duty diesel engine powered... more This paper reports an artificial neural networks (ANN) modelling programme for a light-duty diesel engine powered using blends of various biodiesel fuels with conventional fossil diesel. ANN was used here to predict nine different engine-out responses, namely carbon monoxide (CO), carbon dioxide (CO2), nitrogen monoxide (NO), unburned hydrocarbon (UHC), maximum pressure (Pmax), location of maximum pressure (CAD Pmax), maximum heat release rate (HRRmax), location of maximum HRR (CAD HRRmax) and cumulative HRR (CuHRR). Four pertinent engine operating parameters, engine speed, output torque, fuel mass flow rate and biodiesel fuel types and blends, were used as the input parameters for this modelling work. The feasibility of using ANN in predicting the relationships between these inputs and outputs were assessed. Simulated results were first validated against data from parallel engine test-bed study. Key effects of ANN “model” and “model parameter” such as type of transfer function, training algorithm and number of neurons, along with the methods of optimising the network settings were also presented in this paper.

Crawford, R.H., Treloar, G.J., Ilozor, B.D. and Love, P.E.D. (2003) Comparative Greenhouse Emissions Analysis of Domestic Solar Hot Water Systems, Building Research and Information, 31(1): 34-47.

by Robert Crawford