IEEE Transactions on Energy Conversion, Vol. 10, No. 2, June 1995 307 Environmental Impacts of Electricity Generation: A Global Perspective Arnulfo de Castro Student Member Saifur Rahman Senior Member Energy Systems Research Laboratory Bradley Department of Electrical Engineering Virginia Polytechnic Institute and State University Blacksburg, Virginia 24061-011 1 e-mail: SRAHMANQvtvml .cc.vt.edu Abstract. Efforts are now underway in the industrialized countries to significantly reduce the emission of greenhouse and acid rain gases from power plants. However, indications are that rapid growth in the developing countries is quickly replacing what is being eliminated. This paper provides data and projections on these emissions from electricity generation in selected countries around the world, makes some comparisons and suggests possible options. Keywords: Greenhouse Gases, Acid Rain, Emission Reduction, Generation Planning, Developed and Developing Countries. 1.O Introduction All over the world, electricity remains to be a vital component of national development. Easy to transport and convert to and from other forms of energy, and available at the flick of a switch, it has kept its place as the main source of energy in commercial and residential applications and in many industrial applications as well. It accounts for about 40% of the total global energy consumption [l], and is considered to be a good indicator of economic progress. Table I gives the expected global electric energy generation based on growth experienced over the last decade. At the beginning of this decade, the world’s electricity generation was a little more than 12 billion megawatt-hours (MWh) . Developing countries, which accounted for 75% of the world‘s population, consumed about 20% of the world’s electric energy generation. On the average, each person in the least developed countries consumed about 250 kWh of electric energy per annum, compared with 12 700 kWh consumed by each U S . citizen. These figures are very significant in that the rapid economic growth of developing countries is expected to result in considerable expansion in electricity generation. During the last decade, the world’s electricity generation grew by 3.6% on the average. While the growth in electrical demand in the industrialized countries was in the neighborhood of 3%, the electricity requirements of developing countries increased by 7% annually, on the average. Developing countries will require around 1 300 000 MW of new generating capacity in the next 15 years to serve their growing economies and populations. The world currently spends around $1 00 billion per year on new generation capacity ,with the developing countries accounting for some $50 to $60 billion. To meet the growing demand, developing countries will have to raise this figure to $125 billion per year . The investments required for the developed world, however, are still substantial. If current trends continue, the countries of the Organization for Economic Cooperation and Development (OECD) will need to add about 400 000 MW of new generating capacity in the next 15 years. Table I World Electric Energy Projections Regionl Country IECD :ountries No. America Europe Pacific’ Jon-OECD :ountries Africa Latin Amer Asia** China India Europe Former 19811991 ;rowth 3.0 1995 Projn. (TWh) 7 656 3 721 2 449 1077 2.8 2.9 4.3 3 907 4278 2 618 2915 1134 1277 4684 3246 1438 4 833 4.6 5 847 7545 9752 330 632 542 680 309 429 1 682 4.7 5.4 8.9 8.2 9.0 1.1 2.4 396 779 762 870 436 447 1 849 497 1011 1116 1200 670 471 2083 624 1312 1784 1510 1030 496 2347 308 447 649 1991 Gen. Wh) 7 247 (“w USSR 94 SM 367-3 EC A paper recommended and approved by t h e IEEE Energy Development and Power Generation Committee of the IEEE Power Engineering Society f o r presentation a t the IEEE/PES 1994 Summer Meeting, San Francisco, CA, July 24 28, 1994. Manuscript submitted January 4, 1994; made available for printing May 3 , 1994. - Middle East IWorld 229 7.7 12 080 I 3.6 13 503 16020 19134 ‘Japan, Australia and New Zealand “Excluding China and India. “‘Country submissions for OECD [5, 61,projected from 1981-1991 growth for non-OECD except China 17,81. 2005 projections are all based on past growth except for China. 0885-8969/95/$04.00 0 1994 IEEE 308 In Eastern Europe and the former Soviet Union, the socalled economies in transition have registered negative growth rates over the last two to three years. Nevertheless, many of these countries report the need to upgrade or replace old, inefficient plants both in terms of energy consumption and emission reduction. The developing countries of Asia, currently experiencing a growth rate of 8.7%, will need to increase their capacities five-fold in the next two decades. Thailand, for example, will more than triple its 1991 peak demand of 8 045 MW to 25 515 MW by year-end 2006 . The Philippines expects a quadrupling of its demand of 4 202 MW over the same period [IO]. The continued growth in electrical demand raises concerns about the ability of the environment to sustain this development without harm to itself. Roughly 63% of the world's electricity is obtained by burning fossil-fuels, 60% of which is coal. In other words, about 38% of all electricity is generated by coal. These fossil-fired plants, particularly coal, emit carbon dioxide, sulfur dioxide and nitrous oxides which are known contributors to either global warming or acid precipitation, or the depletion of the ozone layer. Fossil plants also emit toxic chemicals aside from heat and ash. While it is recognized that international cooperation is needed to solve such global problems, two major roadblocks still need to be hurdled. One of these is the wide discrepancy between the per capita energy consumptions of the developing countries and the developed world. For example, Japan's clean-air efforts predate those of the US. However, neighboring China, with 555 million MWh of fossil generation (about 82% of its total electricity production), only has limited emission abatement rulings in place. This has raised concerns about the transport of acid rain emissions across their boundaries. Japan, however, has a per capita energy consumption of more than 7 000 kWh per year versus China's 590 kWh. Many developing countries feel that imposing environmental restrictions would hamper economic growth, and their trade-offs simply follow a different equation. terms of the tons of carbon released to the atmosphere.) Coal combustion, which accounts for 60% of total fossil generation, also emits sulfur dioxide (S02) and nitrous oxides (NOx) which produce acid rain and, in the case of the latter, are also possibly involved in the depletion of the ozone layer. CO2 emissions are unique because of their global impacts and because their reduction essentially limits the other two major chemical pollutants. Table II Percentagesof Electricity Generation by Fuel Type for Selected Countries (1 991)' I ! 111I1 COL;;;^ World OECD Australia Canada France Germany Italy JaDan Non-OECD Banoladesh Coal & M n I; I I Oil Gas Nucl lH ;;y; Others 12 080 38.4 11.3 13.5 17.6 7247 157 508 455 539 222 888 40.3 76.9 18.0 8.9 58.1 13.3 14.5 8.6 2.4 2.6 3.1 2.7 47.0 30.1 10.6 10.4 2.0 1.4 8.4 17.7 19.3 23.7 0.0 16.7 72.9 27.3 4 8331 35.71 15.41 17.81 81 0.01 19.7) 70.11 8.41 0.01 0.0 24.0 16.8 10.3 60.7 13.5 3.4 22.0 12.1 22. 10.1 Another problem concerns the uncertainty of the actual environmental impacts of electricity generation. Opposition to emission abatement feeds on the inability of science to come up with more definite answers. In this paper, we attempt to evaluate the effects of electricity generation on the environment in terms of their greenhouse and acid rain emissions. We particularly view this in the light of recent environmental legislation in the US, emission abatement efforts in the developed countries and the fast-paced growth of the developing countries. We then attempt to identify dominant issues and alternative approaches to the problem. 2.1 Impacts on the Environment 'Calculated from data on electricity production from fossil fuels from OECD and UN reports [5,6,7,111. "Data for the former USSR and Eastern Europe were based on incomplete official data. The estimates in Table I show a projected increase in the global electricity production from 12 080 billion kWh in 1991 to 19 134 billion kWh in 2005. More than 60% of the world's electricity is generated by burning fossil-fuels (Table I I). These combustion processes produce carbon dioxide ( C 0 2 ) which are major contributors to global warming. (Throughout this paper, CO2 emissions will be quantified in Carbon dioxide is estimated to have contributed to 66% of global warming between 1880 and 1980. Between 1980 and 2020, the amount of carbon dioxide in the air is expected to about double from 15.6 ppm to 27.8 ppm. Estimates of the temperature change resulting from this increase vary from 1.5 to 5.0"C. This increase in temperature has been 2.0 Electricity Generation and Environment 309 predicted to result in climatological changes, a rise in the sea level and adverse effects on vegetation . 2.2 Implications Increasing concern in the developed countries about the potential harmful effects of global warming and the role played by carbon dioxide have resulted in pressures on both industrialized and newly-industrializing countries to reduce emissions of this gas. On a regional scale, similar problems are arising from the transport of acid precipitation across national boundaries. Particular interest has centered on China and India whose emissions rival those of the developed countries (Table Ill). some analysts are looking closely at China and India. In view of the linkage between electricity consumption and development, it is popularly believed that some increase in energy intensities will have to accompany the progress of developing countries despite efforts to decouple them . India and China are expected to exploit their rich coal deposits to support this growth, and, therefore, may be penalized heavily by any effort to limit carbon dioxide emissions. The additional expense necessary to limit these emissions amount to 5-6% of their GDP versus 1-3% of GDP for the industrialized nations . Table 111 Carbon Dioxide, Sulfur Dioxide and Nitrous Oxide Emissions from Fossil-Fuel Generation of Electricity for Selected Countries (1991)" I Countnr/ Region World I I I Non-OECD I Bangladesh China India Indonesia Nepal Philippines Poland I 'Saudi Arabia I Singapore South Africa I IFormer USSR] I Million MWh 12 080 1 Carbon I SO7 I NOY 1 1 890 I 47 655 I 21 857 4833 I 787 39 1 27 135 66 17 168 1682 I (106 MT) 1 (000 MT)I (000 MT) I 1 I I I OECD Australia Canada * 0 4 39 12 4 1 46 1 246 1 208 84 1439 4968 I I I 34 550 3219 kWh per capita I 1 885 81 4 84 4 903 2 103 206 Country/ Region Non-OECD Bangladesh China India Indonesia NeDal TonC per capita kgSO2 Per capita kgNOx Per capita 8 425 8 965 18 952 1.28 2.22 1.17 32.38 64.92 34.04 14.24 27.01 13.91 1108 76 592 358 21 3 46 0.18 0.01 0.1 4 0.08 0.04 0.00 4.53 0.08 4.26 2.43 1.14 0.01 2.20 0.1 5 1.64 0.94 0.46 0.00 1 'Calculated from data on electricity production from fossil fuels from OECD and UN reports [ 5 , 6 , 7 , 111. C02, S o p and NO, emissions per kWh used to multiply coal, oil and gas-fired generation in each country were basedon US. experience [ 17. Japan data was based on TEPCO report . MT represents metric ton. *Calculated from data on electricity production from fossil fuels from OECD and UN reports [5,6,7,11]. Japan data were also based on TEPCO report[l5]. Population information taken from OECD National Accounts , and Energy Statistics . "Data for the former USSR and Eastern Europe are based on incompleteofficial data. Table IV shows the per capita electricity consumption and pollutant emissions of the countries given in Table I l l . Table V gives these emissions per kWh of electricity generated. An observation of these numbers shows why Table VI presents the projected C02, SO2 and NOx emissions from the generation of electricity in a sampling of OECD and non-OECD countries. Projections for OECD 310 countries used expected electric energy generation and fuel shares for the years 1995 and 2000 as provided in the 1991 IEA review of energy policies. Projections for OECD countries for 2005 used 1995-2000 electricity generation growth rates and 1995 fuel shares given in the report . Projections for non-OECD countries except China used 1981-1991 energy generation growth rates and 1991 fuel shares reported in the OECD report on energy statistics of non-OECD countries . China projections were based on the OECD report and their presentation in the UN power system planning seminar [7, 81. Japan emission rates were based on the TEPCO report . U.S. emission rates from 1995 on were based on an EPRl study . All other calculations used current emission rates of typical U.S. electric generating plants [I 71. Table V The numbers in Table VI indicate that if current trends continue within the next decade, developing countries and other non-OECD nations will surpass the emissions of OECD countries, in effect negating efforts in the developed world to limit such pollutants. Such effects are shown in figure 1 to figure 3 which compare the projected emissions of the U.S., Japan, China and India. These figures show the considerable progress made by Japan towards emission reduction and the results of U.S. legislation limiting acid rain emissions. This makes China the more dominant producer of acid rain emissions. Table VI Carbon Dioxide, Sulfur Dioxide and Nitrous Oxide Emissions from Fossil-Fuel Generation of Electricity (Projections for 1995 and 2000) Cop, SO2 and NOx Emissions from Fossil Generation of Electricity per kWh for Selected Countries (1 991)* (Spain Sweden UK I us Non-OECD Bangladesh China India I Nepal ' Philippines Poland** Saudi Arabia Sinqapore South Africa Former USSR** I 0.1 31 0.01 0.22 0.1 9 3.861 0.31 6.50 5.25 0.16 4.1 0 1.99 0.14 0.24 0.22 1.01 7.21 6.80 2.03 2.77 2.63 0.01 II 0.1 3 0.29 0.1 8 0.21 0.271 0.1 51 0.1 51I 3.31 8.94 3.1 6 5.08 8.551 2.951 1.521 0.14 2.54 2.29 0.06 I 1.30 3.43 2.1 3 2.02 3.27 1.91 France Germany Italy Jaoan Noway Spain Sweden UK us Non-OECD Africa Lat Amer Asia China India Europe Former USSR I I 388 2749 1088 2261 156 1198 571 2711 20 104 57 1241 528 2886 1294 2351 242 1292 695 2821 25 2 62 566 724 36 1687 13250 301 19 740 7580 30 3 63 620 769 52 1597 8950 376 30 1 782 6750 957 24385 31555 14776 2474 900 2775 6269 2965 2593 5463 11643 1018 537 1278 2410 1148 1083 3540 1220 85 46 107 60 170I 283 149 3106 1169 4247 8646 4555 2733 61% 1278 698 1956 3324 1763 1142 3987 13 97 48 1171 I 0 111 205 97 89 271 94 305 3.0 Environmentally Benign Capacity Options *Calculated from data on electricity production from fossil fuels from OECD and UN reports [5,6, 7, 111. Japan data were also based on TEPCO report . Population information taken from OECD National Accounts , and Energy Statistics . "Data for the former USSR and Eastern Europe are based on incomplete official data. Decision-making in the planning of electric utilities is now taking on a broader scope. The utility planner now needs to investigate the economic implications of the different conditions being imposed on him and the political dimensions of the electricity supply problem. There is much uncertainty, and with more players in the arena, more requirements have to be met in addition to economy and 311 reliability. Planning then extends beyond the realm of technical analysis, and the engineer must now consider the political implications of his decisions. Year The players in the utility industry now include, in addition to governments and funding agencies, private power developers and producers, private investors and an environmentally aware public. As a result, issues of profitability and emissions limiting are now getting greater emphasis. The utility planner is challenged to have an understanding of these various dimensions of the decision. Among the alternatives in the new planning environment are legislative and regulatory strategies, and supply-side and demand-side options. Much more so in the developing countries, the need to exhaust all possible expansion options is imperative, Where resources are meager, however, the requirements for supporting development takes precedence and the need for taking the rational, sustainable options is often set aside in favor of the immediate. The following discussion of options, however, shows that this need not be so, as there are lowercost paths that have so often been ignored. c\1 3.1 Regulatory Strategies Figure 1. Projected CO2 emissions (measured in MT of carbon) for selected countries. Country Figure 2. Projected SO2 emissions for selected countries While researchers agree that increasing levels of carbon dioxide have a warming effect on the atmosphere, opponents of any immediate abatement action point to inconsistencies in the results of emission models and the burden that such abatement actions impose on the economy. There is thus an on-going international effort to study the phenomenon of global warming. The results of these studies will be instrumental in legislation being conceived for limiting CO2 emissions in many countries. Fortunately for the issue of acid rain, its effects are less uncertain, more observable and much closer to home. Thus, it has received greater attention among utilities, regulators and governments. In 1970, the U.S. congress passed the Clean Air Act which set emission standards and, after a series of amendments, overhauled the Act to provide a market structure for allowance trading and facilitate the economically efficient reduction of SO2 emissions (Clean Air Act of 1990 ). To address the other half of the acid rain problem, NOx controllers are now being required on specific boiler designs. Japan's strict emission standards allow only two-thirds of the acid rain emissions allowed in the U.S. and in Europe [ 151. Antipollution agreements between the utility companies and local governments further reduce these emissions, so much so that Japan's SO2 and NO, emissions per kWh of electricity generated are only one-twentieth and one-seventh of those in the U.S., respectively. E 3.2 Supply-side Options 2 Although the technology is already available for reducing SO2 emissions, it puts an additional financial burden on the utility and, ultimately, the electricity consumer. Scrubbers cost around $175 to $200 per kW to install  and penalize the plant efficiency. Lower sulfur coals (those with less than 1% sulfur content) can only be bought at a premium. Electricity prices of American Electric Power Co. (AEP) are expected to increase by about 5% on the average (and up to 20% for some customers) due to acid rain compliance . Low NOx burners likewise entail an additional cost. f Figure 3. Projected NOx emissions for selected countries Integrated gasification combined cycle (IGCC) turbines, pressurized fluidized-bed combustion (PFBC) turbines and 312 steam-injected gas turbines are expected to play major roles in future power systems in view of their greatly reduced SO2 emissions and their higher efficiencies which essentially reduce CO2 emissions per kWh of electricity generated. Still, these options could barely improve on the CO2 problem. Much of the focus in emission abatement has been on fuel switching and scrubber technology. Conditions in less developed countries, however, indicate that other alternatives might be more promising in view of the limited resources available to their utilities. The other available supply-side options also encounter obstacles. The much touted fusion reactor is still about 50 years to commercialization, and even the supposedly benign hydro is meeting considerable opposition from environmentalists. Solar and other renewable technologies hold considerable promise but still need to take off with large grid connection due to cost constraints. Table VI1 Costs of Capacity Options Supply Side Conventional ~ 3 1 3.3 Demand-Side Options Aside from the increase of production capacity, the utility can avail of demand-side alternatives which delay the requirement for additional investments. Electric Power Research Institute (EPRI) studies show the benefits of load shifting, peak shaving and valley filling not only in the reduction of the load and in improving operating efficiencies but in emission reduction as well . American utilities plan to meet up to one-third of new capacity needs with DSM . Studies show that considerable improvements can also be achieved in the efficiencies of residential appliances such as lighting, refrigerators, air conditioners and heaters (use of heat pump). Better energy management control systems and variable-speed motors can also be used to reduce the total electric energy consumption. cost (c/kWh) 5-7 Capacity Option I Coal with compliance I Hvdro I 2-3 F=wl I Cogeneration IAlternative  lvG+-%-i Photovoltaics Biofuels Solar Thermal Geothermal Demand Side 5 10 5-7 Valley Filling  2-3 Refrigerator Efficiency Improvement (2) Water Heater 3 1-3 1-2 1-3 1-3 HVAC Lighting High-Effy Motors Table VI1 lists some of these capacity options and their estimated costs. Trends in utility planning integrate both supply-side and demand-side alternatives to maximize benefits to the utility. The costs of efficiency improvement are evidently very competitive with traditional capacity expansion options and much more acceptable environmentally. References 4.0 Conclusions The next two decades will see considerable growth in the developing countries which must be accompanied by corresponding expansion of the electrical supply systems. Since fossil fuels still provide the backbone for electricity generation, this growth is expected to bring about increasing amounts of atmospheric emissions. It may seem expedient to shrug off this problem with excuses of uncertainty and the precedence of development. The reality, however, is that environmental awareness is rising, particularly in the developed countries, and there is increasing consensus that we must act before it is too late. And since much of the capital that would be needed to fund development flows from the north, environmental challenges will have to be met in both hemispheres. The relative levels of emissions, specially on a per capita basis, show a large disparity between developed and developing countries. This has been taken by some developing and newly-industrializing countries as a license to pollute, citing the more urgent need for improving their economic conditions. Throughout the developed world, however, emissions numbers are going down while those in the developing countries are rising, suggesting that the externality cannot be removed without international cooperat ion. 1. Davis, Ged R., "Energy for Planet Earth," Readinas from Scientific American: Enerav for Planet Earth, W.H. Freeman and Company, New York, 1991, pp. 1-10. 2. Levine, Mark D., "Electricity End-Use Efficiency: Experience with Technologies, Markets, and Policies Throughout the World," presented at the Annual Meeting of the Institute of Electrical Enaineers. JaDan, March 1993,43p. 3. "Can Independent Power Satisfy World Demand?" (Power International Edition: Power Generation Technology) Power, vl33, n12, Dec 1989, p. S42(3). 4. Yeager, Kurt E., "Electric Vehicles and Solar Power," IEEE Power Enaineerina Review, Oct 92, v12, n10, pp. 13-18. 5. International Energy Agency, Enerav Statistics of OECD Countries: 1990-1991, OECD, Paris, 1993. 6. International Energy Agency, Enerav Policies of IEA Countries. 1991 Review, OECD, Paris, 1992. 7. International Energy Agency, Enerav Statistics and Balances in Non-OECD Countries: 1990-1991, OECD, Paris, 1993. ~ 313 8. Guangyao, Wei, "Electric Power in China," presented at the United Nations Seminar on Svstem Plannina in the Power Sector, 8-12 November 1993, UN Headquarters, New York, USA. Acknowledgment The work reported in this paper is made possible in part by a grant from the US National Science Foundation, Grant Number INT-9214655. 9. Wayachut, Jutamas, "Power Policy in Thailand, Balancing Supply and Demand Constraints," presented at the United Nations Seminar on Svstem Plannina in the Power Sector, 8-12 November 1993, UN Headquarters, New York, USA. Saifur Rahman (IEEE S-75, M-78, SM-83) graduated from the Bangladesh University of Engineering and Technology in 1973 with a B.Sc. degree in Electrical Engineering. He obtained his M.S. degree in Electrical Sciences from the State University of New York at Stony Brook in 1975. His Ph.D. degree (1978) is in Electrical Engineering from the Virginia Polytechnic Institute and State University. 10. Office of the President, National Power Corp., Power DeveloPment Proaram, Generation Projects (19932005), as of October 13, 1993, personal communications. 11. Economic Commission for Europe, Annual Bulletin of : vol. XXXVII, United Nations, New York, 1993. Saifur Rahman has taught in the Department of Electrical Engineering, the Bangladesh University of Engineering and Technology, the Texas A&M University and the Virginia Polytechnic Institute and State University where he is a full Professor. He also directs the Energy System Research Laboratory at VPI. His industrial experience includes work at the Brookhaven National Laboratory, New York, the Carolina Power and Light Company, and the Tokyo Electric Power Company. He serves on the System Planning and Demand Side Management subcommittees, and the Long-Range Planning, the Load Forecasting and the Photovoltaics working groups of the IEEE Power Engineering Society. His areas of interest are demand side management, power system planning, environmental impact studies, alternative energy systems and expert systems. He has authored more than 160 technical papers and reports in these areas. 12. Kane, R.L., et al., "Global Climate Change: A Discussion of Major Uncertainties," Proceedinas of the American Power Conference 53rd Annual Meeting, v53-I, April 29 May 1,1991, Chicago, pp. 646 - 652. , ] 13. Holdren, John P., "Energy in Transition," Readinas from t W. H. Freeman and Co., New York, 1991. 14. Douglas, John,"The Cost of Greenhouse Insurance," 0 1 , Dec 1992, pp. 26-33. 15. Environmental Protection Department, Tokyo Electric Power Company, Enerav and the Environment, Tokyo, Japan, July 1992. 16. Lamarre, Leslie, "Responding to the Clean Air Challenge," EPRl Journal, ApriVMay 1991, pp. 21 -29 17. Customer Systems Division, "Technical Brief: Electric Van and Gasoline Van Emissions: A Comparison," Flectric Power Research Institute (EPRI), 1989. 18. Statistics Directorate, National Accounts: Main Aaareaates Volume 1, 7 960-1 991, OECD, Paris 1993. 19. "Clean Air Act Amendments," NOV24, 1990, pp. 3934-63. V ~ u a r t e r l v 20. Stallard, G. Scott and Alan W. Ferguson, "Addressing the Challenges of the New Clean Air Act," Proceedinas S e , Vol. 53-1, 53rd Annual Meeting, April 29-May 1, 1991, pp. 326-333. 21. McManus, John M., "American Electric Power's Acid Rain Compliance Program," October 1993, personal communications. 22. customer Systems Division, nnTechnical Brief: Load Management and the Environment," Electric Power Research Institute (EPRII Report RP2788, 1991. 23. Hubbard, Harold M., "The Real Cost of Energy," Scientific American, 264 no 4, April 991, p36(6), Arnulfo de Castro (IEEE S-93) obtained his B.S. and M.S. degrees in Electrical Engineering from the University of the Philippines in 1977 and in 1983, respectively. He is an Assistant Professor of Electrical Engineering at the University of the Philippines where he has been teaching since 1983. He is presently working towards his Ph.D. in , Electrical Engineering at the Virginia Polytechnic Institute and State University Arnulfo de Castro worked for the Energy and Information Technology Corporation in the Philippines and was involved in software development and consultancy services for electric utilities. His experience includes generation, transmission and distribution planning, and economic operations studies for the (Philippine) National Power Corporation and the Manila Electric Company. He Was also active in performing energy studies for the Philippine Department of Energy and for industry. His principal areas of interest are power system planning, energy systems, environmental aspects of electricity generation, optimization techniques and decision analysis. 3 14 Discussion D. M. Vinod Kumar (Indian Institute of Technology, Kanpur, India): The authors are to be complimented for bringing the attention to the Environmental impacts of electricity generation due to fossil fired plants particularly coal. The discusser appreciate the authors response on following: In Table-VI1 authors provided cost of capacity options of different conventional and non-conventional energy sources. But did not provided various non-conventional energy sources total capacity of OCED/nonOCED countries. In future what will be the role of non-conventional energy sources. And out of various non-conventional energy sources (Photovoltaics, Wind, Solar, Geothermal etc.,) which is the most efficient and low cost. For reducing SO, emission authors pointed out the use of Scrubbers for the existing power plants, whose cost is very high. For the developing countries, authors would have suggested low cost emission reduction equipments instead of critisizing developing and newly industrializing countries. electricity generation from non-conventional sources by country and by region can be obtained from OECD reports [l,21. b) Future role of non-conventionalenergy sources Non-conventional energy sources will continue to make inroads into the electric power supply mix; first, for offgrid remote locations, and then slowly for gridconnected applications. As different countries begin to internalize the cost of pollution mitigation from fossil-fuel and nuclear power plants, the penetration of nonconventional sources to the utility generation mix will increase. It is hard to say what is most efficient and low cost when PV, wind, solar and geothermal are compared. In these cases we are inputing different types of energy (e.g. sun, wind, trapped heat, etc.) so efficiencies cannot be meaningfully compared. In terms of $/kwhr energy cost, geothermal is probably the cheapest under the best conditions. This is followed by wind, solar thermal and photovoltaics. c) Use of low-cost scrubbing equipment S. Rahman and A. de Castro: Low cost SO2 scrubbing equipment is available, but these do not remove SO2 as much or as efficiently. In the US,Japan and Europe the utility industry is required to scrub SO2 at a level of 90% or above. It is always better to scrub some SO2 out of the stack emissions. The objective of this paper was to show how much SO2 can be removed using the best available technology. This would then set standards that could be used as targets for SO2 removal. a) Total capacity for non-conventionalenergy sources References Much of this capacity is non-utility owned, and therefore not reported in official reports. The data reported in official reports is, therefore, representative of a fraction of what is available in the field. Thus, providing this partial data for non-conventional energy sources will present a very prejudiced picture for these sources. Hence, this data was omitted in the paper. For those who are interested in these figures nonetheless, data on 1. International Energy Agency, Energy Statistics of OECD Countries, 1990-7991, OECD, Paris, 1993. 2. International Energy Agency, Energy Statistics and Balances of Non-OECD Countries, 1990-1991, OECD, Paris, 1993. Manuscript received August 22, 1994. Manuscript received October 24, 1994.