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.     

Exergy analysis of the energy use in Greece

In this work, an analysis is being done on the concept of energy and exergy utilization and an application to the residential and industrial sector of Greece. The energy and exergy flows over the period from 1990 to 2004 were taken into consideration. This period was chosen based on the data reliability. The energy and exergy efficiencies are calculated for the residential and industrial sectors and compared to the findings of a previous study concerning the exergy efficiency of the Greek transport sector. The residential energy and exergy efficiencies for the year 2003 were 22.36% and 20.92%, respectively, whereas the industrial energy and exergy efficiencies for the same year were 53.72% and 51.34%, respectively. The analysis of energy and exergy utilization determines the efficiency of the economy as a whole. The results can play an important role in the establishment of efficiency standards of the energy use in various economy sectors. These standards could be utilized by energy policy makers.     

Using LMDI method to analyze the change of China's industrial CO2 emissions from final fuel use: An empirical analysis

Based on time series decomposition of the Log-Mean Divisia Index (LMDI), this paper analyzes the change of industrial carbon emissions from 36 industrial sectors in China over the period 1998–2005. The changes of industrial CO₂ emission are decomposed into carbon emissions coefficients of heat and electricity, energy intensity, industrial structural shift, industrial activity and final fuel shift. Our results clearly show that raw chemical materials and chemical products, nonmetal mineral products and smelting and pressing of ferrous metals account for 59.31% of total increased industrial CO₂ emissions. The overwhelming contributors to the change of China's industrial sectors’ carbon emissions in the period 1998–2005 were the industrial activity and energy intensity; the impact of emission coefficients of heat and electricity, fuel shift and structural shift was relatively small. Over the year 1998–2002, the energy intensity change in some energy-intensive sectors decreased industrial emissions, but increased emissions over the period 2002–2005. The impact of structural shift on emissions have varied considerably over the years without showing any clear trend, and the final fuel shift increased industrial emissions because of the increase of electricity share and higher emissions coefficient. Therefore, raw chemical materials and chemical products, nonmetal mineral products and smelting and pressing of ferrous metals should be among the top priorities for enhancing energy efficiency and driving their energy intensity close to the international advanced level. To some degree, we should reduce the products waste of these sectors, mitigate the growth of demand for their products through avoiding the excessive investment highly related to these sectors, increasing imports or decreasing the export in order to avoid expanding their share in total industrial value added. However, all these should integrate economic growth to harmonize industrial development and CO₂ emission reduction.     

Hydrogen production through sorption-enhanced steam methane reforming and membrane technology: A review

With the rapid development of industry, more and more waste gases are emitted into the atmosphere. In terms of total air emissions, CO₂ is emitted in the greatest amount, accounting for 99 wt% of the total air emissions, therefore contributing to global warming, the so-called “Greenhouse Effect”. The recovery and disposal of CO₂ from flue gas is currently the object of great international interest. Most of the CO₂ comes from the combustion of fossil fuels in power generation, industrial boilers, residential and commercial heating, and transportation sectors. Consequently, in the last years’ interest in hydrogen as an energy carrier has significantly increased both for vehicle fuelling and stationary energy production from fuel cells. The benefits of a hydrogen energy policy are the reduction of the greenhouse effect, principally due to the centralization of the emission sources. Moreover, an improvement to the environmental benefits can be achieved if hydrogen is produced from renewable sources, as biomass.     

Energy and exergy utilization efficiencies in the Japanese residential/commercial sectors

Unlike the manufacturing sector, the residential/commercial sectors of Japan struggle to meet their environmental requirements. For instance, their CO₂ emission levels have increased tremendously since 1990. This research estimates energy and ‘exergy (available energy)’ efficiencies in Japan's residential/commercial sectors during the period 1990–2006. Since an exergy analysis reveals ‘available energy losses’, it is an effective tool to achieve sustainable societies. The primary objective of this paper is to examine the potential for advancing the ‘true’ energy efficiency in Japan's residential/commercial sectors—by observing energy and exergy efficiency disparities. The results show large differences between the overall energy and exergy efficiencies in the residential (60.12%, 6.33%)/commercial sectors (51.78%, 5.74%) in 2006. This implies great potential for energy savings in both sectors. Furthermore, this research suggests that the residential sector may face more difficulties than the commercial sector, although the latter appears to be less energy-efficient, according to recent statistics. This is because the disparity between energy and exergy efficiencies has expanded in the residential sector since 2000. This study illustrates the importance of exergy analyses in promoting sustainable energy policies and new adaptation strategies.     

On the potential trade-offs between energy supply and end-use technologies for residential heating

In Sweden, where district heating accounts for a significant share of residential heating, it has been argued that improvements in end-use energy efficiency may be counter-productive since such measures reduce the potential of energy efficient combined heat and power production. In this paper we model how the potential trade-offs between energy supply and end-use technologies depend on climate policy and energy prices. The model optimizes a combination of energy efficiency measures, technologies and fuels for heat supply and district heating extensions over a 50 year period. We ask under what circumstances improved end-use efficiency may be cost-effective in buildings connected to district heating? The answer hinges on the available technologies for electricity production. In a scenario with no alternatives to basic condensing electricity production, high CO₂ prices result in very high electricity prices, high profitability of combined heat and power production, and little incentive to reduce heat demand in buildings with district heating. In contrast, in a scenario where electricity production alternatives with low CO₂ emissions are available, the electricity price will level out at high CO₂ prices. This gives heat prices that increase with the CO₂ price and make end-use efficiency cost-effective also in buildings with district heating.     

Exercising multidisciplinary approach to assess interrelationship between energy use, carbon emission and land use change in a metropolitan city of Pakistan

Population of two cities in Pakistan has already crossed the 10-million figure and for the rest of the areas in the country populations are also increasing rapidly. Urbanization has boosted the use of energy in the cities and so is greenhouse gas (GHG) emissions but the ground situation as to the extent, vulnerability, past trends and future scenarios are not unveiled for the cities of Pakistan. Dearth of data in Pakistan is a huge hindrance to the investigation of energy use and actual GHG emissions. We dared to take steps in addressing this case and put preliminary efforts in compiling baseline sectoral breakdown of energy use, carbon emission and land cover/land use. Furthermore, the relationship of CO₂ source and sink is also explored. This study mainly tries to achieve three objectives. The results illustrate that industrial and residential sectors are vibrant consumers of energy and CO₂ emitters among all other sectors of the city. Sparse trees in the city and reduced agriculture areas by more than one-half in 2009 compared with those in 1975 are the main reasons for increased energy use and reduced CO₂ emissions from agriculture sector as well. However, all the other sectors have increased their CO₂ emissions in an escalating trend. The forecast analysis portrays the same trend too. Therefore, there is a need to make policy makers recognize such vulnerable situation of energy use and GHG emissions for them to take proper and timely actions to cope with the threats of climate change which can occur anytime in the very near future.     

Comparative analysis of performance and techno-economics for a H2O–NH3–H2 absorption refrigerator driven by different energy sources

The objectives of the present work are of two-folds. First, it evaluates the transient temperature performance of the H₂O–NH₃–H₂ absorption cooling machine system’s components under two types of energy sources, i.e. the conventional electric energy from grid (electric) and fuel energy from liquid petroleum gas (LPG). Results obtained have shown that performance of various components under different type of energy sources is almost coherent. For the evaporator, the system with electric supply has shorter starting time, around 6 min earlier than the system run with LPG. Meanwhile, the system powered by LPG produced a lower cooling temperature around −9 °C, compared to the system run with electric which produced temperature at around −7 °C. Economical study had been carried out subsequently, for three different energy sources, i.e. electric, LPG and solar energy (photovoltaic). From the techno-economical analyzes, it was found that the conventional electric from grid is still the best form of energy source for short-term application, as far as the present location and conditions are concerned. LPG is the next attractive energy source, especially at locations with constant LPG supply; the photovoltaic energy from solar is attractive for long term consideration since it has zero fuel cost and environmentally-friendly, but with the highest initial cost.     

Turkey's sectoral energy and exergy analysis between 1999 and 2000

This study analyses sectoral energy and exergy utilization in Turkey between 1999 and 2000. Total energy and exergy utilization efficiencies are calculated to be 43.24 and 24.04% in 1999, and 44.91 and 24.78% in 2000, respectively. In order to calculate these efficiency values, Turkey is subgrouped into four main sectors, namely utility, industrial, transportation and commercial‐residential. The energy efficiency values are found to be 23.88, 30.10, 68.97 and 57.76% in 1999, and 23.71, 30.11, 68.81 and 57.05% in 2000 for transportation, utility, industrial and commercial‐residential sectors, respectively. Besides this, the exergy efficiency values are obtained to be 23.80, 30.28, 35.97 and 8.12% in 1999, and 23.65, 30.47, 35.51 and 8.02% in 2000 for the same order of sectors. The present study has clearly shown the necessity of the planned studies towards increasing exergy efficiencies in the sectors studied. Copyright © 2004 John Wiley & Sons, Ltd.     

An energy balance and greenhouse gas profile for county Wexford,Ireland in 2006

In this paper an energy balance and a greenhouse gas profile has been formulated for the county of Wexford, situated in the south east of Ireland. The energy balance aims to aggregate all energy consumption in the county for the year 2006 across the following sectors; residential, agriculture, commerce and industry, and transport. The results of the energy balance are compared with the previous energy balance of 2001 where it is found that the residential sector is the biggest emitter of CO₂ with 38% of total emissions with the transport and industry/commerce sectors sharing second place on 28%. Consumption of oil is seen to have increased significantly in nearly all sectors, accounting for over 70% of the total final energy consumed (TFC) while the total primary energy requirement (TPER) sees oil consumption accounting for 91% of all fuels consumed. To take into account the contribution of agriculture in total GHG emissions the gases CH₄ and N₂O will be estimated from the agricultural and waste sectors. The results show that methane contributes 25% of total GHG emissions with agriculture being the primary contributor accounting for 36% of total emissions.     

Comparison of energy and exergy analysis of fossil plant,ground and air source heat pump building heating system

The energy and exergy flow for a space heating systems of a typical residential building of natural ventilation system with different heat generation plants have been modeled and compared. The aim of this comparison is to demonstrate which system leads to an efficient conversion and supply of energy/exergy within a building system.The analysis of a fossil plant heating system has been done with a typical building simulation software IDA–ICE. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for other cases of building heating systems where power generation plants are considered as ground and air source heat pumps at different operating conditions. Since there is no inbuilt simulation model for heat pumps in IDA–ICE, different COP curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy.The outcome of the energy and exergy flow analysis revealed that the ground source heat pump heating system is better than air source heat pump or conventional heating system. The realistic and efficient system in this study “ground source heat pump with condenser inlet temperature 30 °C and varying evaporator inlet temperature” has roughly 25% less demand of absolute primary energy and exergy whereas about 50% high overall primary coefficient of performance and overall primary exergy efficiency than base case (conventional system). The consequence of low absolute energy and exergy demands and high efficiencies lead to a sustainable building heating system.     

Energy and exergy analysis of fossil plant and heat pump building heating system at two different dead-state temperatures

In this paper, we deal with the energy and exergy analysis of a fossil plant and ground and air source heat pump building heating system at two different dead-state temperatures. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for heat pump building heating system. Since energy and exergy demand are key parameters to see which system is efficient at what reference temperature, we did a study on the influence of energy and exergy efficiencies. In this regard, a commercial software package IDA-ICE program is used for calculation of fossil plant heating system, however, there is no inbuilt simulation model for heat pumps in IDA-ICE, different COP (coefficient of performance) curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy. The outcome of the energy and exergy flow analysis at two different dead-state temperatures revealed that the ground source heat pumps with ambient reference have better performance against all ground reference systems as well as fossil plant (conventional system) and air source heat pumps with ambient reference.     

Sustainability of energy production and use in Iran

The issue of oil and gas policies in Iran is rather complex. In the present investigation, it is aimed to formulate plans for increasing the capacity of the country's energy production. Analysis of energy consumption pattern over last decades is indicative of inefficient usage. The low energy prices in Iran do not reflect economic costs. Further distortions exist in the tariff structures of most energy sources and in their relative prices. It is recognized that price reform is a key policy element for promotion of energy conservation and fuel substitution with renewable energies. Mitigation policies in the energy sector are crucial to Iran's overall policies. Emission of greenhouse gases can be reduced from 752,156 to 560,791 Gg CO₂ equivalents in 2010 by implementing the policies proposed for the energy sub-sectors. Enhancing energy efficiency, including combined cycle power generation, has proved to be the most economic option for greenhouse gases reduction in energy sector. Iran's energy consumption pattern is unsustainable and consumption oriented.     

Modelling the UK residential energy sector under long-term decarbonisation scenarios: Comparison between energy systems and sectoral modelling approaches

The UK government has set a groundbreaking target of a 60% reduction in carbon dioxide (CO₂) emissions by 2050. Scenario and modelling assessment of this stringent target consistently finds that all sectors need to contribute to emissions reductions. The UK residential sector accounts for around 30% of the total final energy use and more than one-quarter of CO₂ emissions. This paper focuses on modelling of the residential sector in a system wide energy–economy models (UK MARKAL) and key UK sectoral housing stock models. The UK residential energy demand and CO₂ emission from the both approaches are compared. In an energy system with 60% economy-wide CO₂ reductions, the residential sector plays a commensurate role. Energy systems analysis finds this reduction is primarily driven by energy systems interactions notably decarbonisation of the power sector combined with increased appliance efficiency. The stock models find alternate decarbonisation pathways based on assumptions related to the future building stock and behavioural changes. The paper concludes with a discussion on the assumptions and drivers of emission reductions in different models of the residential energy sector.     

Thermal performance and environmental impact of residential buildings’ heating in Morocco

The seasonal energy requirements and fuel consumption for heating purposes in residential buildings are influenced by the architectural design, construction materials characteristics, meteorological temperature measurements, internal gains and air exchange rate of the building. The goal of this study is to assess the thermal performance and environmental impact of residential buildings’ in Morocco taking into account all these factors and considering two sources of energy: liquefied petroleum gas (LPG) and electricity. The study concludes that the heating energy requirements for the prototype building vary between 2 and 253 kWh/m².year depending on localities, glazing type, glazing area percentage, the internal gains and the air exchange rates. The electricity consumption is 2.6 times greater than that of LPG in terms of kg oil equivalent, and by using LPG instead of electricity the emissions of greenhouse gases can be 3.4 times reduced.     

Assessing the energy vulnerability: Case of industrialised countries

The emergence of new big consumer countries on the energy markets and the perspective of oil and gas depletion at the end of the current century raise the concerns about fair distribution of the remaining resources for the common and sustainable well-being of the mankind. High volatility of energy prices discourages the investment and delays the energy technology transition. Voluntary measures are needed mainly in industrialised countries in order to develop alternative and sustainable energy sources, to enable technology transfer towards emerging and developing countries and to avoid struggle for energy procurement. In this paper, a composite index of energy demand/supply weaknesses is defined as a proxy of energy vulnerability. The proposed index is based on several indicators such as energy intensity, oil and gas import dependency, CO₂ content of primary energy supply, electricity supply weaknesses and non-diversity in transport fuels. The assessment of this composite index for selected industrialised countries is discussed as well as the sensitivity to various factors.     

What explain the short-term dynamics of the prices of CO2 emissions?

Using a Bayesian Structural VAR (BSVAR), this paper analyzes the short-term dynamics of the prices of CO₂ emissions in response to changes in the prices of oil, coal, natural gas and electricity. The results show that: (i) a positive shock to the crude oil prices has an initial positive effect on the CO₂ allowance prices, which later becomes negative; (ii) an unexpected increase in the natural gas prices reduces the price of CO₂ emissions; (iii) a positive shock to the prices of the fuel of choice, coal, has virtually no significant impact on the CO₂ prices; (iv) there is a clear positive effect of the coal prices on the CO₂ allowance prices when the electricity prices are excluded from the BSVAR system; and (v) a positive shock to the electricity prices has a negative impact on the price of the CO₂ allowances. We also find that the energy price shocks have a persistent impact on the CO₂ allowance prices, with the largest effect occurring 6 months after a shock strikes. The effect is particularly strong in the case of the shocks to the natural gas and crude oil prices. Finally, the empirical findings suggest an important degree of substitution between the three primary sources of energy (i.e., crude oil, natural gas and coal), particularly when electricity prices are excluded from the BSVAR system.     

Options for the Swedish steel industry - Energy efficiency measures and fuel conversion

The processes of iron and steel making are energy intensive and consume large quantities of electricity and fossil fuels. In order to meet future climate targets and energy prices, the iron and steel industry has to improve its energy and resource efficiency. For the iron and steel industry to utilize its energy resources more efficiently and at the same time reduce its CO₂ emissions a number of options are available. In this paper, opportunities for both integrated and scrap-based steel plants are presented and some of the options are electricity production, fuel conversion, methane reforming of coke oven gas and partnership in industrial symbiosis. The options are evaluated from a system perspective and more specific measures are reported for two Swedish case companies: SSAB Strip Products and Sandvik AB. The survey shows that both case companies have great potentials to reduce their CO₂ emissions.     

Exergetic analysis of transcritical CO2 residential air-conditioning system based on experimental data

The experimental system for the transcritical CO₂ residential air-conditioning with an internal heat exchanger was built. The effects of working conditions on system performance were experimentally studied. Based on the experimental dada, the second law analysis on the transcritical CO₂ system was performed. The effects of working conditions on the total exergetic efficiency of the system were investigated. The results show that in the studied parameter ranges, the exergetic efficiency of the system increases with the increases of gas cooler side air inlet temperature, gas cooler side air inlet velocity and evaporating temperature. And it will decrease with the increases of evaporator side air inlet temperature and velocity. Then, a complete exergetic analysis was performed for the entire CO₂ transcritical cycle including compressor, gas cooler, expansion valve, evaporator and internal heat exchanger under different working conditions. The average exergy loss in gas cooler is the highest one under all working conditions which is about 30.7% of the total exergy loss in the system. The second is the average exergy loss in expansion valve which is about 24.9% of the total exergy loss, followed by the exergy losses in evaporator and compressor, which account for 21.9% and 19.5%, respectively. The exergy loss in internal heat exchanger is the lowest one which is only about 3.0%. So in the optimization design of the transcritical CO₂ residential air-conditioning system more attentions should be paid to the gas cooler and expansion valve.     

The role of district heating in future renewable energy systems

Based on the case of Denmark, this paper analyses the role of district heating in future Renewable Energy Systems. At present, the share of renewable energy is coming close to 20 per cent. From such point of departure, the paper defines a scenario framework in which the Danish system is converted to 100 per cent Renewable Energy Sources (RES) in the year 2060 including reductions in space heating demands by 75 per cent. By use of a detailed energy system analysis of the complete national energy system, the consequences in relation to fuel demand, CO₂ emissions and cost are calculated for various heating options, including district heating as well as individual heat pumps and micro CHPs (Combined Heat and Power). The study includes almost 25 per cent of the Danish building stock, namely those buildings which have individual gas or oil boilers today and could be substituted by district heating or a more efficient individual heat source. In such overall perspective, the best solution will be to combine a gradual expansion of district heating with individual heat pumps in the remaining houses. Such conclusion is valid in the present systems, which are mainly based on fossil fuels, as well as in a potential future system based 100 per cent on renewable energy.