Greenhouse gas emission mitigation in the Sri Lanka power sector supply side and demand side options

Sri Lanka has had a hydropower dominated electricity generation sector for many years with a gradually decreasing percentage contribution from hydroresources. At the same time, the thermal generation share has been increasing over the years. Therefore, the expected fuel mix in the future in the large scale thermal generation system would be dominated by petroleum products and coal. This will result in a gradual increase in greenhouse gas (GHG) and other environmental emissions in the power sector and, hence, require special attention to possible mitigation measures.

This paper analyses both the supply side and demand side (DSM) options available in the Sri Lanka power sector in mitigating emissions in the sector considering the technical feasibility and potential of such options. Further, the paper examines the carbon abatement costs associated with such supply side and DSM interventions using an integrated resource planning model, which is not used in Sri Lanka at present. The sensitivities of the final generation costs and emissions to different input parameters, such as discount rates, fuel prices and capital costs, are also presented in the paper. It is concluded that while some DSM measures are economically attractive as mitigation measures, all the supply side options have a relatively high cost of mitigation, particularly in the context of GHG emission mitigation. Further it is observed that when compared with the projected price of carbon under different global carbon trading scenarios, these supply side options cannot provide economically beneficial CO₂ mitigation in countries like Sri Lanka.     

Estimating the health damage costs of syrian electricity generation system using impact pathway approach

Based on the simplified impact pathway approach the environmental impacts from airborne pollutant emissions of Syrian electricity generation system have been assessed and the associated external damage costs to human health have been evaluated. The obtained results indicate that the environmental impacts can add considerable external cost to the typical generation cost. The estimated externalities vary between 2.5 and 0.07 US-cents per generated kWh for heavy fuel oil and NG fired power plants respectively. For the fuel oil fired power plants the resulting external cost, arise mainly from Sulphates impact, amounts to about 25% of the present generation costs. These results indicate the advantage of NG fired power plants as clean generation technology and the necessity of supplying oil fired power plants with SO₂ emission reduction technologies.     

Influence of massive heat‐pump introduction on the electricity‐generation mix and the GHG effect—Belgian case study

To evaluate the environmental impact of massive heat‐pump introduction on greenhouse gas (GHG) emissions, dynamic simulations of the overall electricity‐generation system have been performed for Belgium. The simulations are carried out with Promix, a tool that models the overall electricity‐generation system. For comparison, three heating devices are considered, namely conventional boilers, heat pumps and electrical resistance heating. The introduction of electric heating at the expense of classic heating increases the demand for electricity and generates a shift of emissions from fossil‐fuel heating systems to electrical power plants. The replaced classic fossil‐fuel‐fired heating represents emissions of about 300 kton. With regard to the heat‐pump scenarios, both direct heat‐pump heating with a coefficient of performance (COP) of 2.5 and accumulation heat‐pump heating with a COP of 5 are investigated. The results of the simulations reveal that the massive introduction of heat‐pump heating is favourable to the environment. In Belgium, the largest reductions in GHG emissions occur with heat pumps for direct heating, combined with newly commissioned combined cycle (CC) gas‐fired plants or with accumulation heat‐pump heating. These scenarios bring about overall GHG emission reductions of approximately 200 kton compared with the reference case with conventional heating for the years 2000 and 2010. The amount of additional electricity‐related emissions depends on the considered heating device. In 2010, the scenario with accumulation heat pumps results in an overall decrease of Belgian GHG emissions by 0.15% compared with the reference scenario. The expansion of the electricity‐generation system with new CC plants has an important favourable impact on GHGs as well. In most cases, the combination of higher electricity demand and the construction of new gas‐fired CC plants will lead to lower overall GHG emissions. Copyright © 2007 John Wiley & Sons, Ltd.     

计入峰谷分时上网电价的天然气发电竞争力分析

针对当前天然气发电燃料成本高、天然气供应不足而导致上网电价水平偏高,难以与煤电竞价的问题,提出考虑在发电侧实施峰谷分时上网电价机制,鼓励燃气电厂提高峰时段的上网电量,同时制定计入峰谷分时电价补贴标准来提高天然气发电的市场竞争力。算例结果表明,该措施明显提高了天然气发电的经济优势、气价的承受能力、与煤电平等竞价上网的竟争力。     

燃煤电站锅炉NOx排放的控制措施

基于我国燃煤电站锅炉NOx排放的实际情况,在对影响其NOx排放各因素进行分析的基础上,细化了低氧燃烧、空气分级燃烧、低NOx燃烧器和燃料分级燃烧技术在我国电站锅炉的应用,指出锅炉设计中应尽可能选用切向燃烧方式,将再燃技术应用于降低燃用低挥发分煤的固态排渣电站锅炉设计和改造中以进一步降低NOx排放并满足国家标准的要求,锅炉运行中尽量减小各喷口风粉量的偏差,合理组织沿炉膛水平方向和高度方向(倒梯形、缩腰形等)的分级燃烧实现降低NOx排放的最佳效果.     

新能源发电“自发自用、禁止余电上网”模式下的防逆流安全自动控制装置的应用研究

分布式光伏电源的并网模式主要有“自发自用、禁止余电上网”“自发自用、余电上网”,以及“全额上网”,其中,“自发自用、禁止余电上网”模式受技术条件、业主消纳水平及投资收益比的限制,发展较为缓慢,实际应用项目较少。基于逆功率保护原理,结合自动控制理论提出了一种新型的防逆流(防逆功率)安全自动控制装置,该装置可用于10 kV、35 kV并网的单体装机容量为6~30 MWp“自发自用、禁止余电上网”的新能源发电项目。     

低NOX燃烧技术及其在我国燃煤电站锅炉中的应用

针对我国以煤为主的电力状况，对我国电站锅炉目前采用的低氧燃烧、空气分级和燃料分级燃烧的各影响因素进行了分析和总结，根据采用某些低NOx燃烧技术后尚不能使燃用低挥发份无烟煤、贫煤和劣质烟煤的电站锅炉NOx排放达到国家标准要求的事实，指出了进一步进行降低燃用以上煤种NOx排放水平的空气分级和燃料分级燃烧技术研究的必要。图2参12     

A comparative analysis of energy and CO2 taxes on the primary energy mix for electricity generation

In many countries, economies are moving towards internalization of external costs of greenhouse‐gas (GHG) emissions. This can best be achieved by either imposing additional taxes or by using an emission‐permit‐trading scheme. The electricity sector is under scrutiny in the allocation of emission‐reduction objectives, not only because it is a large homogeneous target, but also because of the obvious emission‐reduction potential by decreasing power generation based on carbon‐intensive fuels. In this paper, we discuss the impact of a primary‐energy tax and a CO₂ tax on the dispatching strategy in power generation. In a case study for the Belgian power‐generating context, several tax levels are investigated and the impact on the optimal dispatch is simulated. The impact of the taxes on the power demand or on the investment strategies is not considered. As a conclusion, we find that a CO₂ tax is more effective than a primary‐energy tax. Both taxes accomplish an increased generation efficiency in the form of a promotion of combined‐cycle gas‐fired units over coal‐fired units. The CO₂ tax adds an incentive for fuel switching which can be achieved by altering the merit order of power plants or by switching to a fuel with a lower carbon content within a plant. For the CO₂ tax, 13 €/tonCO₂ is withheld as the optimal value which results in an emission reduction of 13% of the electricity‐related GHG emissions in the Belgian power context of 2000. A tax higher than 13 €/tonCO₂ does not contribute to the further reduction of GHGs. Copyright © 2005 John Wiley & Sons, Ltd.     

节能调度环境下风电、水电与抽水蓄能电站联合运行优化模型及应用

为吸纳弃风、增加风电并网量,基于节能发电调度办法,以发电产生的燃煤成本、机组启停成本及污染排放成本最小为目标,提出了风电、火电联合运行优化模型和风电、火电与抽水蓄能电站联合运行优化模型。算例分析表明,与选择火电作为风电备用服务相比,当选择抽水蓄能电站作为备用服务时,燃煤发电成本、启停成本及污染排放成本明显降低,弃风被完全消纳。选用抽水蓄能电站作为风电备用服务具有显著的环境效益。     

A review of energy in Rwanda

During the last two decades, Rwanda has experienced an energy crisis mostly due to lack of investment in the energy sector. With the growing of the population and increasing industrialization in urban areas, energy provided by existing hydro and thermal power plants has been increasingly scarce with high energy costs, and energy instability. Furthermore, as wood fuel is the most important source of energy in Rwanda, the enduring dependence on it and fossil fuel consumption as well, will continue to impact on the process of environmental degradation. Rwanda is rich with abundant renewable energy resources such as methane gas in Lake Kivu, solar, biomass, geothermal; and wind energy resource is currently being explored. Recently, the Government has given priority to the extension of its national electrical grid through development of hydro power generation projects, and to rural energy through development of alternative energy projects for rural areas where access to national grid is still difficult. This paper presents a review of existing energy resources and energy applications in Rwanda. Recent developments on renewable energy are also presented.     

Fuel-cycle analysis of early market applications of fuel cells: Forklift propulsion systems and distributed power generation

Forklift propulsion systems and distributed power generation are identified as potential fuel cell applications for near-term markets. This analysis examines fuel cell forklifts and distributed power generators, and addresses the potential energy and environmental implications of substituting fuel-cell systems for existing technologies based on fossil fuels and grid electricity. Performance data and the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model are used to estimate full fuel-cycle emissions and use of primary energy sources. The greenhouse gas (GHG) impacts of fuel-cell forklifts using hydrogen from steam reforming of natural gas are considerably lower than those using electricity from the average U.S. grid. Fuel cell generators produce lower GHG emissions than those associated with the U.S. grid electricity and alternative distributed combustion technologies. If fuel-cell generation technologies approach or exceed the target efficiency of 40%, they offer significant reduction in energy use and GHG emissions compared to alternative combustion technologies.     

Techno-economic analysis of using corn stover to supply heat and power to a corn ethanol plant – Part 2: Cost of heat and power generation systems

This paper presents a techno-economic analysis of corn stover fired process heating (PH) and the combined heat and power (CHP) generation systems for a typical corn ethanol plant (ethanol production capacity of 170 dam³). Discounted cash flow method was used to estimate both the capital and operating costs of each system and compared with the existing natural gas fired heating system. Environmental impact assessment of using corn stover, coal and natural gas in the heat and/or power generation systems was also evaluated. Coal fired process heating (PH) system had the lowest annual operating cost due to the low fuel cost, but had the highest environmental and human toxicity impacts. The proposed combined heat and power (CHP) generation system required about 137 Gg of corn stover to generate 9.5 MW of electricity and 52.3 MW of process heat with an overall CHP efficiency of 83.3%. Stover fired CHP system would generate an annual savings of 3.6 M$ with an payback period of 6 y. Economics of the coal fired CHP system was very attractive compared to the stover fired CHP system due to lower fuel cost. But the greenhouse gas emissions per Mg of fuel for the coal fired CHP system was 32 times higher than that of stover fired CHP system. Corn stover fired heat and power generation system for a corn ethanol plant can improve the net energy balance and add environmental benefits to the corn to ethanol biorefinery.     

Solar aided power generation of a 300 MW lignite fired power plant combined with line-focus parabolic trough collectors field

Nowadays, conventional coal or gas fired power plants are the dominant way to generate electricity in the world. In recent years there is a growth in the field of renewable energy sources in order to avoid the threat of climate change from fossil fuel combustion. Solar energy, as an environmental friendly energy source, may be the answer to the reduction of global CO₂ emissions. This paper presents the concept of Solar Aided Power Generation (SAPG), a combination of renewable and conventional energy sources technologies. The operation of the 300 MW lignite fired power plant of Ptolemais integrated with a solar field of parabolic trough collectors was simulated using TRNSYS software in both power boosting and fuel saving modes. The power plant performance, power output variation, fuel consumption and CO₂ emissions were calculated. Furthermore, an economic analysis was carried out for both power boosting and fuel saving modes of operation and optimum solar contribution was estimated.     

Model-based analysis of effects from large-scale wind power production

For an economically and ecologically optimised integration of fluctuating renewable power generation (especially wind power) into electricity generation, a detailed consideration of fluctuation-induced effects on the existing power system is essential. A model-based approach is introduced in this paper, which comprehensively analyses the impact of such effects on power plant scheduling and facilitates their integration into the development of strategies for an optimised evolution of the future power system structure. The newly developed Aeolius tool for the simulation of power plant scheduling is described. In a combined analysis of long- and short-term effects it is used together with the multi-periodic cost-optimising energy system model PERSEUS-CERT. Based on the Matlab/Simulink^® package, Aeolius considers the challenges for plant scheduling down to a time scale of 10 min. Special attention is paid to the provision of stand-by capacities and control power, as well as intermediate storage. Thus, a sophisticated quantification of the actual (net) benefits of wind power feed-in is achieved. Model results for Germany show that wind mainly substitutes power from intermediate-load and base-load plants (coal-, lignite-, and nuclear-fired). However, the required provision of stand-by capacities and control power does not only limit the substitution of conventional capacities, but also the achievable net savings of fuel and emissions in conventional power generation.     

Status of thermal power generation in India—Perspectives on capacity,generation and carbon dioxide emissions

India’s reliance on fossil-fuel based electricity generation has aggravated the problem of high carbon dioxide (CO₂) emissions from combustion of fossil fuels, primarily coal, in the country’s energy sector. The objective of this paper is to analyze thermal power generation in India for a four-year period and determine the net generation from thermal power stations and the total and specific CO₂ emissions. The installed generating capacity, net generation and CO₂ emissions figures for the plants have been compared and large generators, large emitters, fuel types and also plant vintage have been identified. Specific emissions and dates of commissioning of plants have been taken into account for assessing whether specific plants need to be modernized. The focus is to find out areas and stations which are contributing more to the total emissions from all thermal power generating stations in the country and identify the overall trends that are emerging.     

Conversion of straw and similar agricultural wastes

Mainly the economic aspects prevent a far more extensive use of biomass, including straw as a fuel in energy supply.

During the latest years several straw fired plants have been put in operation, especially in Denmark, and they have demonstrated that both district heating and combined heat and power (CHP) production based on straw are technically possible.

However, experience has shown that a very precise research and development effort is necessary before the straw fired plants are competitive to traditional plants fired with fossil fuels, as to operational safety and economy.

The R & D activities ought first and foremost to aim at: 1) Reduction of costs connected to all processes from harvest to energy production, 2) wider know-how of the firing and combustion technical characteristics of straw, and 3) environmental conditions, including emissions and ash depositing problems.     

Grid connected fuel cell and PV hybrid power generating system design with Matlab Simulink

Renewable energy sources have been taken the place of the traditional energy sources and especially rapidly developments of photovoltaic (PV) technology and fuel cell (FC) technology have been put forward these renewable energy sources (RES) in all other RES. PV systems have been started to be used widely in domestic applications connected to electrical grid and grid connected PV power generating systems have become widespread all around the world. On the other hand, fuel cell power generating systems have been used to support the PV generating so hybrid generation systems consist of PV and fuel cell technology are investigated for power generating. In this study, a grid connected fuel cell and PV hybrid power generating system was developed with Matlab Simulink. 160 Wp solar module was developed based on solar module temperature and solar irradiation by using real data sheet of a commercial PV module and then by using these modules 800 Wp PV generator was obtained. Output current and voltage of PV system was used for input of DC/DC boost converter and its output was used for the input of the inverter. PV system was connected to the grid and designed 5 kW solid oxide fuel cell (SOFC) system was used for supporting the DC bus of the hybrid power generating system. All results obtained from the simulated hybrid power system were explained in the paper. Proposed model was designed as modular so designing and simulating grid connected SOFC and PV systems can be developed easily thanks to flexible design.     

Impact of hydrogen energy storage on California electric power system: Towards 100% renewable electricity

Decarbonization of the power sector is a key step towards greenhouse gas emissions reduction. Due to the intermittent nature of major renewable sources like wind and solar, storage technologies will be critical in the future power grid to accommodate fluctuating generation. The storage systems will need to decouple supply and demand by shifting electrical energy on many different time scales (hourly, daily, and seasonally). Power-to-Gas can contribute on all of these time scales by producing hydrogen via electrolysis during times of excess electrical generation, and generating power with high-efficiency systems like fuel cells when wind and solar are not sufficiently available. Despite lower immediate round-trip efficiency compared to most battery storage systems, the combination of devices used in Power-to-Gas allows independent scaling of power and energy capacities to enable massive and long duration storage. This study develops and applies a model to simulate the power system balance at very high penetration of renewables. Novelty of the study is the assessment of hydrogen as the primary storage means for balancing energy supply and demand on a large scale: the California power system is analyzed to estimate the needs for electrolyzer and fuel cell systems in 100% renewable scenarios driven by large additions of wind and solar capacities. Results show that the transition requires a massive increase in both generation and storage installations, e.g., a combination of 94 GW of solar PV, 40 GW of wind, and 77 GW of electrolysis systems. A mix of generation technologies appears to reduce the total required capacities with respect to wind-dominated or solar-dominated cases. Hydrogen storage capacity needs are also evaluated and possible alternatives are discussed, including a comparison with battery storage systems.     

The performance analysis and evaluation of C‐PV/T aided power generation system

In this paper, a novel solar aided power generation (SAPG) hybrid system based on the structural characteristics of coal‐fired power generation is established. In this system, the extraction steam of No.8 low pressure heater is replaced by the hot water coming from a concentration‐photovoltaic/thermal (C‐PV/T) module. The extraction steam returns into the steam turbine to do work, which increases the output power. And the electricity from the parallel C‐PV/T module goes directly into the power grid, which increases the generated power. The C‐PV/T module coupled with coal‐fired power generation improves the solar energy efficiency and provides hot water. As a case study, the economic calculation is performed with actual operation data extracted from a 600‐MW coal‐fired unit. The results show that the total efficiency increased by 1.3%, the coal fuel consumption is lowered by 11 g/kW·h, and the investment recovery period is approximately 7 years. This study offers a theoretical support to the engineering demonstration.     

NOx emissions and thermal efficiencies of small scale biomass-fuelled combustion plant with reference to process industries in a developing country

Solid biomass materials are an important industrial fuel in many developing countries and also show good potential for usage in Europe within a future mix of renewable energy resources. The sustainable use of wood fuels for combustion relies on operation of plant with acceptable thermal efficiency. There is a clear link between plant efficiency and environmental impacts due to air pollution and deforestation. To supplement a somewhat sparse literature on thermal efficiencies and nitrogen oxide emissions from biomass-fuelled plants in developing countries, this paper presents results for tests carried out on 14 combustion units obtained during field trials in Sri Lanka. The plants tested comprised steam boilers and process air heaters. Biomass fuels included: rubber-wood, fuelwood from natural forests; coconut shells; rice husks; and sugar cane bagasse. Average NO_x (NO and NO₂) emissions for the plants were found to be 47 gNO₂ GJ⁻¹ with 18% conversion of fuel nitrogen. The former value is the range of NO_x emission values quoted for combustion of coal in grate-fired systems; some oil-fired systems and systems operating on natural gas, but is less than the emission levels for the combustion of pulverized fuel and heavy fuel oil. This value is significantly within current European standards for NO_x emission from large combustion plants. Average thermal efficiency of the plants was found to be 50%. Observations made on operational practices demonstrated that there is considerable scope for the improvement of this thermal efficiency value by plant supervisor training, drying of fuelwood and the use of simple instruments for monitoring plant performance.