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Continued population growth, coupled with increased per capita consumption of resources, poses a challenge to the quality of life of current and future generations. We cannot expect to meet the future needs of society simply by extending existing infrastructures. The necessary transformation can be enabled by a sustainable IT ecosystem made up of billions of service-oriented client devices and thousands of data centers. The IT ecosystem, with data centers at its core and pervasive measurement at the edges, will need to be seamlessly integrated into future communities to enable need-based provisioning of critical resources. Such a transformation requires a systemic approach based on supply and demand of resources. A supply side perspective necessitates using local resources of available energy, alongside design and management that minimizes the energy required to extract, manufacture, mitigate waste, transport, operate and reclaim components. The demand side perspective requires provisioning resources based on the needs of the user by using flexible building blocks, pervasive sensing, communications, knowledge discovery and policy-based control. This paper presents a systemic framework for supply-demand management in IT–in particular, on building sustainable data centers–and suggests how the approach can be extended to manage resources at the scale of urban infrastructures. [ABSTRACT FROM AUTHOR]

In this work the energy and exergy analysis of a hybrid gas turbine cycle has been presented. The thermodynamic characteristic of Brayton-diesel cycle is considered in order to establish its importance to future power generation markets. Mathematical modeling of Brayton-diesel cycle has been done at component level. Based on mathematical modeling, a computer code has been developed and the configuration has been subjected to thermodynamic analysis. Results show that, at any turbine inlet temperature (TIT) the plant specific work initially increases with increase of pressure ratio (rp,c), and but at very high values of rp,c, it starts decreasing. For a fixed value of rp,c (more than 10) with the increase in TIT, plant efficiency and specific work both increase. The cycle is best suited for applications where power requirement ranges between 700-900 kJ/kg. The exergy analysis shows that maximum exergy loss of around 27% occurs in during combustion in the plant. [ABSTRACT FROM AUTHOR]

Since the 1950s, at least, it has been clear that factors other than capital and labor must be responsible for most economic growth. Historical and anecdotal evidence suggests that the substitution of machines powered by fossil energy for human and animal labor must have played a significant or even dominant role in driving growth. The situation is complicated by the coming peak in global petroleum output and the technological transition that must follow. Economists have inconsistent views on these relationships. The most dangerous is the assumption that growth is both optimal and exogenous. This implies that growth is automatic and costless. It also implies that any government intervention is likely to impose costs. Another implication of the standard theory is that economic growth is independent of energy use, so energy consumption is a consequence but not a cause of growth. Some argue also that economic growth is actually a prerequisite for environmental protection, both because the latter is a `superior΄ good – i.e. a luxury – desired mainly by the rich, and because advanced technology and wealth are needed for purposes of both prevention and abatement of environmental damage. On the other hand, there is much evidence that growth along the historical trajectory itself is a primary cause of pollution and environmental degradation. More realistic techno-economic models are badly needed. [ABSTRACT FROM AUTHOR]

With the global warming problem aggravation and subsequent application of the Kyoto Protocol, CO2 emissions are becoming an important factor to regard when verifying the applicability of cogeneration systems. Considering that, the purpose of this work is to study the influence a cogeneration system capacity has on its CO2 emissions under two kinds of operation strategies: one focused on exergetic efficiency and another on running cost. The system meets the demand pattern typical of a hospital in Japan, operating during one year with an average heat-to-power ratio of 1.3. The main equipments of the cogeneration system are: a gas turbine with waste heat boiler, a main boiler and an auxiliary steam turbine. Each of these equipments was characterized with partial load models and the turbines΄ efficiencies at full load also changed according to the system΄s capacity. Still, it was assumed that eventual surplus of electricity generated can be sold. The main results show that for any of the capacities simulated, an exergetic efficiency focused operational strategy always resulted on higher CO2 emissions reduction than a running cost focused one. Furthermore, the amount of reduction in emissions decreased when the system capacity decreased, reaching a value of 1.6% when the system΄s capacity was 33% of the maximum electricity΄s demand with a heat-to-power ratio of 4.1. When the system operated focused on running cost, the economic savings increased with the capacity and reached 42% for a system capacity of 80% of maximum electricity΄s demand and with a heat-to-power ratio of 2.3. In such conditions however, there was an increase in emissions of 8.5%. Still for the same capacity, an exergetic efficiency operation strategy presented the best balance between cost and emissions, generating economic savings of 29% with a decrease in CO2 emissions of 7.1%. The results found show the importance of an exergy focused operational strategy and also indicated that lower capacities resulted in lesser gains on both CO2 emissions and running cost savings. [ABSTRACT FROM AUTHOR]