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.     

Methods for calculating CO2 intensity of power generation and consumption: A global perspective

This paper compares five methods to calculate CO₂ intensity (g/kWh) of power generation, based on different ways to take into account combined heat and power generation. It was found that the method chosen can have a large impact on the CO₂ intensity for countries with relatively large amounts of combined heat and power plants. Of the analysed countries, the difference in CO₂ intensities is found to be especially large for Russia, Germany and Italy (82%, 31% and 20% differences in 2007, respectively, for CO₂ intensity of total power generation).     

A long-term view of fossil-fuelled power generation in Europe

The paper presents a view into the long term future of fossil-fuelled power generation in the European Union, based on a number of alternative scenarios for the development of the coal, natural gas and CO₂ markets, and the penetration of renewable and nuclear technologies. The new fossil fuelled capacity needed and the likely technology mix are estimated using a cost optimisation model based on the screening curve method, taking into consideration the rate of retirement of the current power plant fleet, the capacity already planned or under construction and the role of carbon capture and storage technologies. This analysis shows that measures to increase both non-fossil-fuel-based power generation and the price of CO₂ are necessary to drive the composition of the European power generation capacity so that the European policy goal of reducing greenhouse gas emissions is achieved. Meeting this goal will however require a high capital investment for the creation of an optimal fossil fuel power plant technology mix.     

Solar energy powered Rankine cycle using supercritical CO2

A solar energy powered Rankine cycle using supercritical CO₂ for combined production of electricity and thermal energy is proposed. The proposed system consists of evacuated solar collectors, power generating turbine, high-temperature heat recovery system, low-temperature heat recovery system, and feed pump. The system utilizes evacuated solar collectors to convert CO₂ into high-temperature supercritical state, used to drive a turbine and thereby produce mechanical energy and hence electricity. The system also recovers heat (high-temperature heat and low-temperature heat), which could be used for refrigeration, air conditioning, hot water supply, etc. in domestic or commercial buildings. An experimental prototype has been designed and constructed. The prototype system has been tested under typical summer conditions in Kyoto, Japan; It was found that CO₂ is efficiently converted into high-temperature supercritical state, of while electricity and hot water can be generated. The experimental results show that the solar energy powered Rankine cycle using CO₂ works stably in a trans-critical region. The estimated power generation efficiency is 0.25 and heat recovery efficiency is 0.65. This study shows the potential of the application of the solar-powered Rankine cycle using supercritical CO₂.     

High efficiency electric power generation: The environmental role

Electric power generation system development is reviewed with special attention to plant efficiency. It is generally understood that efficiency improvement that is consistent with high plant reliability and low cost of electricity is economically beneficial, but its effect upon reduction of all plant emissions without installation of additional environmental equipment, is less well appreciated. As CO₂ emission control is gaining increasing acceptance, efficiency improvement, as the only practical tool capable of reducing CO₂ emission from fossil fuel plant in the short term, has become a key concept for the choice of technology for new plant and upgrades of existing plant. Efficiency is also important for longer-term solutions of reducing CO₂ emission by carbon capture and sequestration (CCS); it is essential for the underlying plants to be highly efficient so as to mitigate the energy penalty of CCS technology application. Power generating options, including coal-fired Rankine cycle steam plants with advanced steam parameters, natural gas-fired gas turbine-steam, and coal gasification combined cycle plants are discussed and compared for their efficiency, cost and operational availability. Special attention is paid to the timeline of the various technologies for their development, demonstration and commercial availability for deployment.     

A novel hybrid oxy-fuel power cycle utilizing solar thermal energy

An advanced oxy-fuel hybrid power system (AHPS) is proposed in this paper. Solar thermal energy is used in the AHPS to produce saturated steam as the working fluid, and natural gas is internally combusted with pure oxygen. It is in configuration close to the zero emission Graz cycle. The thermodynamic characteristics at design conditions of the AHPS are analyzed using the advanced process simulator Aspen Plus. The corresponding exergy loss analyses are also carried out to gain understanding of the loss distribution. The results are given in detail. The solar thermal hybrid H₂O turbine power generation system (STHS) is evaluated in this study as the reference. The comparison results demonstrate that the proposed cycle has notable advantages in thermodynamic performances. For example, the net fuel-to-electricity efficiency of the AHPS is 95.90%, which is 21.61 percentage points higher than that of the STHS. The exergy efficiency (based on the exergy input of fuel and solar thermal energy without radiation) of the AHPS is 55.88%, which is 2.13 percentage points higher than that of the STHS.     

Assessment of the natural gas potential for heat and power generation in the County of Östergötland in Sweden

The aim of this study is to investigate the potential use of natural gas for heat and power production for the municipality of Linköping, Norrköping and Finspång in the County of Östergötland, Sweden.     

Long-term CO2 emissions reduction target and scenarios of power sector in Taiwan

This study analyses a series of carbon dioxide (CO₂) emissions abatement scenarios of the power sector in Taiwan according to the Sustainable Energy Policy Guidelines, which was released by Executive Yuan in June 2008. The MARKAL-MACRO energy model was adopted to evaluate economic impacts and optimal energy deployment for CO₂ emissions reduction scenarios. This study includes analyses of life extension of nuclear power plant, the construction of new nuclear power units, commercialized timing of fossil fuel power plants with CO₂ capture and storage (CCS) technology and two alternative flexible trajectories of CO₂ emissions constraints. The CO₂ emissions reduction target in reference reduction scenario is back to 70% of 2000 levels in 2050. The two alternative flexible scenarios, Rt4 and Rt5, are back to 70% of 2005 and 80% of 2005 levels in 2050. The results show that nuclear power plants and CCS technology will further lower the marginal cost of CO₂ emissions reduction. Gross domestic product (GDP) loss rate in reference reduction scenario is 16.9% in 2050, but 8.9% and 6.4% in Rt4 and Rt5, respectively. This study shows the economic impacts in achieving Taiwan's CO₂ emissions mitigation targets and reveals feasible CO₂ emissions reduction strategies for the power sector.     

CO2 emissions from electricity generation in seven Asia-Pacific and North American countries: A decomposition analysis

The Logarithmic Mean Divisia Index (LMDI) method of complete decomposition is used to examine the role of three factors (electricity production, electricity generation structure and energy intensity of electricity generation) affecting the evolution of CO₂ emissions from electricity generation in seven countries. These seven countries together generated 58% of global electricity and they are responsible for more than two-thirds of global CO₂ emissions from electricity generation in 2005. The analysis shows production effect as the major factor responsible for rise in CO₂ emissions during the period 1990–2005. The generation structure effect also contributed in CO₂ emissions increase, although at a slower rate. In contrary, the energy intensity effect is responsible for modest reduction in CO₂ emissions during this period. Over the 2005–2030 period, production effect remains the key factor responsible for increase in emissions and energy intensity effect is responsible for decrease in emissions. Unlike in the past, generation structure effect contributes significant decrease in emissions. However, the degree of influence of these factors affecting changes in CO₂ emissions vary from country to country. The analysis also shows that there is a potential of efficiency improvement of fossil-fuel-fired power plants and its associated co-benefits among these countries.     

The social return on investment in the energy efficiency of buildings in Germany

The German government has developed a variety of policy instruments intended to reduce national CO₂ emissions. These instruments include a programme administered by KfW bank, which aims at improving the energy efficiency of buildings. It provides attractive credit conditions or subsidies to finance refurbishment measures which improve the energy efficiency of buildings significantly.     

Implications of process energy efficiency improvements for primary energy consumption and CO2 emissions at the national level

The improvement of energy efficiency is seen as one of the most promising measures for reducing global CO₂ emissions. However, the emission reduction potential may seem different from the industrial plant and policy-maker’s perspectives. This paper evaluates the influences of process heat conservation on CHP electricity production, primary energy consumption and CO₂ emissions from both the mill site and national perspectives. The results indicate that heat conservation in an industrial process may lead to varying results in primary energy consumption and CO₂ emissions, depending on the form of marginal heat production used at the mill site. In the CHP process, reduction of the heat load lowers electricity production, and this reduction may have to be compensated for at the national level. Therefore, the energy conservation potential in industry has to be evaluated by taking into account the connections to the outside society, which means that a wider system boundary than a mill site has to be used. This study demonstrates by theoretical analysis and case mill studies the magnitude of the effects of system boundary definition when evaluating the contribution of an individual energy efficiency investment towards fulfilling the commitment to reduce CO₂ emissions at the national level.     

Impacts of wind power generation and CO2 emission constraints on the future choice of fuels and technologies in the power sector of Vietnam

This paper examines the impacts of wind power generation on the future choice of fuels and technologies in the power sector of Vietnam. The study covers a time frame of 20 yr from 2005 to 2025 and the MARKAL model has been chosen to be adaptable to this specific task. The results of the study show that on a simple cost base, power generated from wind is not yet competitive with that of fossil fuel-based power plants. In order to make wind energy competitive, either carbon tax or an emission reduction target on the system must be imposed. The presence of wind power would affect not only the change in generation mix from coal-based power plants to wind turbines but also an increase in the capacity of other technologies which emit less carbon dioxide. It thus helps reduce fossil fuel requirement and consequently enhances energy security for the country. The study also shows that wind turbine in Vietnam could be a potential CDM project for annex I party countries.     

COOLCEP (cool clean efficient power): A novel CO2-capturing oxy-fuel power system with LNG (liquefied natural gas) coldness energy utilization

A novel liquefied natural gas (LNG) fueled power plant is proposed, which has virtually zero CO₂ and other emissions and a high efficiency. The plant operates as a subcritical CO₂ Rankine-like cycle. Beside the power generation, the system provides refrigeration in the CO₂ subcritical evaporation process, thus it is a cogeneration system with two valued products. By coupling with the LNG evaporation system as the cycle cold sink, the cycle condensation process can be achieved at a temperature much lower than ambient, and high-pressure liquid CO₂ can be withdrawn from the cycle without consuming additional power. Two system variants are analyzed and compared, COOLCEP-S and COOLCEP-C. In the COOLCEP-S cycle configuration, the working fluid in the main turbine expands only to the CO₂ condensation pressure; in the COOLCEP-C cycle configuration, the turbine working fluid expands to a much lower pressure (near-ambient) to produce more power. The effects of some key parameters, the turbine inlet temperature and the backpressure, on the systems' performance are investigated. It was found that at the turbine inlet temperature of 900 °C, the energy efficiency of the COOLCEP-S system reaches 59%, which is higher than the 52% of the COOLCEP-C one. The capital investment cost of the economically optimized plant is estimated to be about 750 EUR/kWe and the payback period is about 8–9 years including the construction period, and the cost of electricity is estimated to be 0.031–0.034 EUR/kWh.     

Solar drying and CO2 emissions mitigation: potential for selected cash crops in India

An attempt to estimate the potential of solar crop drying for some selected cash crops in India has been made. The amount of cash crops that can be dried by solar dryers and the required aperture area of solar dryers have been estimated. Estimates for unit cost of solar drying for different crops have also been worked out. The potential of net fossil CO₂ emissions mitigation due to the amounts of different fuels that would be saved by solar drying has been estimated along with the unit cost of CO₂ emissions mitigation.     

Economic and environmental implications of demand-side management options

End-use electricity efficiency improvements offer an inexpensive way to reduce power shortages. The present study estimates the potential of demand-side management efficiency improvement targeted at (1) short-term efficiency improvement (agricultural pump rectification) that can provide immediate relief, and (2) long-term efficiency improvement (appliance standards such as AC and refrigerator, new agricultural pump purchase and pump replacement) for Gujarat state in India. The methodology includes the calculation of cost of conserved energy for each technology, which works out to be (−1.18) US$ cents/kW h for new agriculture pump sets, 1.03 US$ cents/kW h for refrigerators and 5.21 US$ cents/kW h for air conditioners. The price of power varies around 1.13 US$ cents to 12.1 cents/kW h in Gujarat. The annual energy savings from the selected energy-efficient technologies are approximately 8767 GW h over a period of 10 yr, while the estimated peak power savings are about 1814 MW, large enough to eliminate one-fourth of the state's electricity shortages. Also, the estimated CO₂ emissions savings are about 7715 Giga grams (Gg) from implementation of the selected energy efficiency measures over a period of 10 yr.     

Variables affecting energy efficiency and CO2 emissions in the steel industry

Specific energy consumption (SEC) is an energy efficiency indicator widely used in industry for measuring the energy efficiency of different processes. In this paper, the development of energy efficiency and CO₂ emissions of steelmaking is studied by analysing the energy data from a case mill. First, the specific energy consumption figures were calculated using different system boundaries, such as the process level, mill level and mill site level. Then, an energy efficiency index was developed to evaluate the development of the energy efficiency at the mill site. The effects of different production conditions on specific energy consumption and specific CO₂ emissions were studied by PLS analysis. As theory expects, the production rate of crude steel and the utilisation of recycled steel were shown to affect the development of energy efficiency at the mill site. This study shows that clearly defined system boundaries help to clarify the role of on-site energy conversion and make a difference between the final energy consumption and primary energy consumption of an industrial plant with its own energy production.     

Role of energy efficiency standards in reducing CO2 emissions in Germany: An assessment with TIMES

Energy efficiency is widely viewed as an important element of energy and environmental policy. Applying the TIMES model, this paper examines the impacts of additional efficiency improvement measures (as prescribed by the ACROPOLIS project) over the baseline, at the level of individual sectors level as well as in a combined implementation, on the German energy system in terms of energy savings, technological development, emissions and costs. Implementing efficiency measures in all sectors together, CO₂ reduction is possible through substitution of conventional gas or oil boilers by condensing gas boilers especially in single family houses, shifting from petrol to diesel vehicles in private transport, increased use of electric vehicles, gas combined cycle power plants and CHP (combined heat and power production) etc. At a sectoral level, the residential sector offers double benefits of CO₂ reduction and cost savings. In the transport sector, on the other hand, CO₂ reduction is the most expensive, using bio-fuels and methanol to achieve the efficiency targets.     

Overview of thermal energy storage (TES) potential energy savings and climate change mitigation in Spain and Europe

Thermal energy storage (TES) is nowadays presented as one of the most feasible solutions in achieving energy savings and environmentally correct behaviors. Its potential applications have led to R&D activities and to the development of various technology types. However, so far there is no available data on a national scale in Spain and on a continental level in Europe, to corroborate the associated energetic and environmental benefits derived from TES. This is why, based on a previous potential calculation initiative model performed in Germany, this work intends to provide a first overview of the Spanish TES potential as well as an European overview. Load reductions, energy savings, and CO₂ emissions reductions are tackled for the buildings and industrial sector. Results depend on the amount of implementation and show that, in the case of Europe for instance, yearly CO₂ emissions may get to be cut down up to around 6% in reference to 1990 emission levels.     

Power and cogeneration technology environomic performance typification in the context of CO2 abatement part I: Power generation

In this series of two articles, the concepts and approaches of environomic (thermodynamic, economic and environmental) performance ‘Typification’ of power generation technologies (Part I) and of combined heat and power (CHP) cogeneration technologies (Part II) in the context of CO₂ abatement are introduced. A methodology is then proposed for a flexible and fast project based power or CHP cogeneration system design evaluation though post-optimization integration of the operating and capital costs. This allows to effectively deal with the uncertainty of the project specific design and operation conditions (fuel, electricity and heat selling prices, project financial conditions such as investment amortization periods, annual operating hours, etc). Furthermore, the uncertainties linked to the external cost such as the CO₂ tax level under a tax scheme or the CO₂ permit price in the emission trading market can be assessed.