1、1600 单词， 3120 汉字 Shift to a low carbon society through energy systems design Material Source: Special Topic on Engineering Thermophysics Author:Toshihiko Nakata,Mikhail Rodionow, Diego Silva,Joni Jupesta Global environmental degradation is one of the serious threats facing humankind as a result of i
2、ts expanding activities around the world. Along with the development of society, vast quantities of greenhouse gases GHGs have been discharged into the atmosphere, namely carbon dioxideCO2, methane and other non-CO2 gases. Energy activities are the main source of anthropogenic GHG emissions and they
3、 represented 61% of total global GHG emissions in the year 2000 1. Approximately 30% of the anthropogenic greenhouse effect can be attributed to non-CO2 GHGs 2. Rising concern about the impact of climate change has led to the definition of long-term sustainability of society looking forward to the r
4、eduction of GHGs. This interpretation of sustainable development has been termed the “low carbon society” LCS. The sustainable development concept, introduced by the Brundtland Commission in 1987, refers to “development that meets the needs of the present without compromising the ability of future g
5、enerations to meet their own needs”. Given the relevance of energy to the stability and progress of society, and the fact that energy-related activities are the major source of GHG emissions, the LCS vision can be translated into the achievement of sustainable development in an economy that is less
6、dependent on fuels with high-carbon content. Transition to the LCS has important implications on the economy, environment and energy, also referred to as 3Es or trilemma concept. The 3Es concept brings together three goals: economic development, procurement of energy sources, and environmental prote
7、ction. Elements within these three aspects interact with each other in complex ways. In this context, national governments and the international community are strengthening their efforts to formulate and implement measures and policies to curb GHG emissions across several sectors in short, mid and l
8、ong terms. Policy makers are confronted with the evaluation of these policies and their possible impacts on the 3Es. The complexity of these interactions can be better understood through the design of energy systems and energy models The most common classification of energy models distinguishes betw
9、een top-down and bottom-up models 3. These models serve as support systems in decision-making for engineers in order to select environmentally sound technologies. The energy supplies in energy models must contain certain economic value in order to be considered as components of the energy system des
10、ign. Several applications of energy models consider GHG mitigation alternatives. These applications are diverse, analyzing different sectors and geographical coverage, and making emphasis on different energy resources and technologies. This paper discusses the possibility of realizing the LCS with r
11、espect to the reduction of GHG emissions from energy-related activities, and the correspondent implications on the design of energy systems by means of energy models. The discussion is elaborated around four aspects characterizing the shift to the LCS in energy systems. These aspects include the uti
12、lization of low-carbon and carbonless energy resources, the penetration of advanced conversion technologies for the efficient use of energy resources, the implementation of measures specific to each energy demand sectors, and the inclusion of other dimensions besides the 3Es in the assessment of the
13、 possibility of the LCS. The paper focuses on four groups of energy model applications illustrating each of the aspects mentioned above, namely models describing the utilization of wastes, models analyzing the penetration of clean coal technologies, transportation sector models, and rural energy mod
14、els The alternatives to mitigate GHG emissions from energy related activities are the object of energy policies and energy systems design. The supply of primary energy through energy resources represents the supply side of energy systems. Energy resources can be separated into three main categories:
15、 fossil fuels, nuclear resources, and renewable resources. Currently, the worlds energy supply is largely based on fossil fuels. These energy resources exist in limited quantities, and their combustion is considered one of the main causes of climate change. In 2006 the world primary energy consumpti
16、on accounted for about 12 Gtoegigatonne oil equivalent, with fossil fuels constituting 81%. In contrast to fossil fuels, renewable energy is obtained from sources that are non-depletable. The most common renewable energy resource has a biological origin, also termed biomass. Energy generation from t
17、hese sources does not contribute to climate change, given that their use does not involve the emission of GHGs. Furthermore, CO2 emissions resulting from the combustion of biomass are regarded as being carbon neutral. Currently, renewable energy resources supply 13% of the world primary energy deman
18、d, and represent 18% of the total electricity generation, as of year 2006. Energy harnessed from radioactive materials, also termed nuclear energy, is used to generate electricity in nuclear power plants. This source of energy shared 6% of global energy consumption in 2006. Nuclear energy supply is
19、growing in countries such as China and India. In contrast, the utilization of nuclear energy has been declining gradually, as a result of phase-out policy in European countries such as Germany, Belgium and Sweden 5. Conversion technologies are the central part in the architecture of an energy system
20、. Their role in the energy system is to transform energy resources coming from the supply side into energy forms suitable for delivery or direct use by the demand side. Several energy conversion technologies are available, depending on the type of energy resources that they use. Conventional technol
21、ogies are based principally on the combustion of fossil fuels: coal, oil, and gas fired power plants. These conversion technologies are the source of large quantities of GHG emissions, specifically CO2. In contrast, conversion technologies for the production of energy from renewable energy resources
22、 do not emit GHGs, and are known as carbon neutral technologies. The energy demanded by end users in different activities in any society is grouped in sectors representing the main components of an economy. The demand side is categorized into four sectors of end users: the residential sector, the co
23、mmercial sector, the industrial sector, and the transportation sector. In addition to these four sectors, agricultural activities are merged into the industrial sector or the residential sector. The industrial and transportation sectors comprise the largest shares in energy consumption, equivalent t
24、o 27% and 28% of global final energy consumption, respectively 5. It is worth noting that among all the sectors, the transportation sector has had the highest growth in energy consumption in the last decade. Several different alternatives exist in the present in order to realize the vision of the LC
25、S. The inclusions of alternative sources of energy, such as biomass and wastes, are fundamental choices from the supply side. Renewable energy technologies represent the core of alternatives regarding energy conversion technologies. Demand side measures focused on the improvement of energy efficienc
26、y and more careful use of energy. The realization of the LCS involves shift from conventional to low carbon energy technologies. Analyzing the possibility of the transition to the LCS and the way this transition may be achieved in the future is a complex task for decision-making in energy planning.
27、The assessment and design of energy systems can be performed by means of energy models based on mathematical formulations representing the interactions of the multiple components of the energy system. These models can give more credibility to proposals targeting the mitigation of GHGs . The potentia
28、l impact of climate change due to emissions from energy activities in forthcoming decades can be minimized driving development towards a low carbon path as described by the LCS vision. The feasibility of this vision depends on how the energy system is designed. Energy models help to clarify the effe
29、ctiveness and applicability of technologies included in the system design. Based on this it is possible to evaluate the needs in research and development and the barriers for integrating innovative technologies. Model applications studying the utilization of wastes as alternative energy resources sh
30、ow that system designs must integrate with MSW management systems. The double role of MSW as fuels and materials that can be recycled leads to a broader range of technologies for their treatment. Schemes for the economic valuation of GHGs emission reductions provided by WTE technologies together wit
31、h the technological progress are important for the diffusion of these technologies, especially in developing countries. Penetration of clean coal technologies showed by model applications is strongly linked to technology learning. The large investment entailed for the introduction of these technolog
32、ies can be balanced with the significant emission reductions that can be obtained by means of market mechanisms like carbon taxes. Such measures are crucial for effective use of CCTs in developing countries. The feasibility of shifting to cleaner fuels and vehicles in the transportation sector is su
33、ggested by energy models. Suitable alternatives include biofuels for the mid-term, and vehicles using fuel cells and hybrid technologies for the long-term. Barriers to the penetration of low carbon alternatives can be overcome considering technological progress and the application of taxes. Energy m
34、odels for rural energy in developing countries need to expand their scope and reliability. They show how renewable technologies and shifting from traditional fuels can bring along benefits related to the LCS and human development. The output from studies using energy models, though useful for assess
35、ing the feasibility of energy systems in alternative scenarios, should not be assumed as certain forecast. Instead, energy models help to raise the uncertainties surrounding the effective design of energy systems considering impacts on the global environment. The credibility of models can be enhance
36、d with a good quality of researchs approach, methodology and data. This is especially important when addressing the LCS targets in energy system design because of the long-term nature of the LCS vision.Therefore, models should not be understood as tools for restraining decision making, but rather be taken as supporting tools to obtain a clear image for assessment of the alternatives available for policy making
