• Energy Research
• Closed Access close
• GB close
• BE close
• Energy Institute close

Abstract In many visions and roadmaps, there is a broad agreement that fuel cells – both for stationary and mobile applications – are the key technology to allow the development of a hydrogen infrastructure. Furthermore, this development is generally thought to be based on a gradual, decentralised evolution. Nevertheless, in this paper it is argued that, taking into account the entire hydrogen chain (production, transport, storage, distribution and end-use), this decentralised fuel-cell based philosophy shows some serious flaws. Therefore, a new hydrogen-transition approach was pushed forward: mixing in of hydrogen into the natural-gas bulk. Using Flanders – the Northern part of Belgium – as a case study, the development of a transitory hydrogen infrastructure has been studied, taking into account the entire hydrogen chain and its dynamics, from production to end use. In a next step, this transition is being quantified. An optimisation model has been developed using Matlab and the commercial solvers GAMS and CPLEX. Following a mixed-integer linear-programming approach, this model is able to determine the economically optimal hydrogen-production mix and operational behaviour of each hydrogen-production plant separately. The model then allows gaining valuable insights in the importance of storage and the influence of fuel prices and carbon taxes with regard to the development of an early hydrogen economy.

Abstract In this study, soil temperatures at different depths in Turkey's different regions were investigated theoretically. Soil temperature data are critical for different research interests such as ecology, biology, technique processes, forestry, agriculture, energy, food sector, ground heat exchanger applications, thermal energy storage applications, and so forth. This investigation gives information related to the prediction of soil temperature's dependence with depth and time especially for shallow geothermal applications. Soil temperature values depend on a great deal of varied parameters such as thermal conductivity, short term climatic conditions and moisture content. The main issue is that despite these temperatures are extremely important values, they can not be obtained in a short time. Due to this reason, we study a mathematical model related to the prediction of soil temperature. Within this context, 81 cities and their approximately 300.000 data, both, monthly air and soil temperatures between 1960 and 2015 were studied and finally seven regions in Turkey were investigated and final average soil temperature values were achieved. Measured data taken from the Izmir State Meteorological Station, and predicted soil temperatures at depths of 5 cm, 10 cm, 20 cm, 50 cm, and 100 cm were analyzed for each region in Turkey according to data obtained fifty years ago. Finally, at depths of 5 cm, 10 cm, 20 cm, 50 cm and 100 cm, the maximum average percentage errors in Turkey were 16%, 14.8%, 13.5%, 14.4%, 13.9% respectively. In conclusion, we evaluate the relationship between ambient air temperatures and soil temperatures in terms of depths from 5 to 3000 cm.

In a recent paper Huntington lays some of the groundwork for more meaningful discussions between economists and technologists on the apparent underinvestment in energy efficiency. In a discussion illustrated by a production function, he points out that the technical efficiency of economic actors should be treated as an empirical question. Huntington's groundwork can be further extended by observing that there is a close relationship between production functions and conservation supply curves, an analytical tool routinely used by technologists. Here we show that a conservation supply curve can be obtained from a production function by a simple transformation.

Abstract The nano-fluids in view of the fabulous thermal conductivity enhancement have been recognized useful in several industrial and engineering applications. Present study provides an analytical investigation of the fluid flow, heat and mass transfer and entropy generation for the steady laminar non-Newtonian nano-fluid flow induced by a stretching sheet in the presence of velocity slip and convective surface boundary conditions using Optimal Homotopy Analysis Method (OHAM). In contrast to the conventional no-slip condition at the surface, Navier’s slip condition is applied. The governing partial differential equations (PDEs) are transformed into highly nonlinear coupled ordinary differential equations (ODEs) consist of the momentum, energy and concentration equations via appropriate similarity transformations. Entropy generation equations, for the first time in this problem, are derived as a function of velocity, temperature and concentration gradients. The current OHAM solution demonstrates very good correlation with those of the previously published studies in the especial cases. The influences of different flow physical parameters on fluid velocity component, temperature distribution and concentration profile as well as the entropy generation number are discussed in details. Increasing the Brownian motion parameter and thermophoresis parameter, Biot number, Reynolds number, and Brinkman number or decreasing the Casson parameter and velocity slip parameter cause an increase in the entropy generation number.

Abstract Identifying the appropriate amount of subsidy is crucial to spur the development of low carbon electricity technologies such as wind power that are currently not competitive with conventional coal-fired power on the basis of levelized cost. Though essential for formulating subsidy policy, most of the existing planning tools have not been tailored for policymakers, especially at the sub-national level. In this paper, we introduce an integrated renewable power planning (IRPP) model that is both practical and flexible. This model integrates resource databases, equipment databases and levelized cost calculation module to generate supply curves for wind and solar and evaluate potential subsidy to achieve a certain installation target. A case study focused on wind power planning in Fujian Province is performed. Under the wind power feed-in-tariff of 0.61 yuan/kWh, the generation can reach about 3.7 TWh, and total subsidy will be about 260 million yuan (including subsidies already paid to existing projects). Sensitivity analysis shows that this number will significantly increase if capital cost of wind is reduced or external cost of coal-fired power is internalized.

AbstractWe present a method for estimating the energy output from one‐axis tracking non‐concentrating PV systems and compare the yields from different configurations. The method is based on the use of solar radiation and temperature databases and models for the performance of PV modules under given geographic conditions. In the resulting maps of energy yield for Europe it is found that there are two different one‐axis configurations that perform almost as well as a full two‐axis sun‐tracking system: one with a vertical axis and inclined modules, and the other with an inclined axis directed north–south and modules in the plane of the axis. When the inclination angles of the modules are optimized, these two configurations have an energy yield compared to an optimal fixed mounting that is approximately 30% higher in southern Europe, about 20–25% higher in central Europe, and up to 50% higher in northern Scandinavia. Compared to the two‐axis tracking, the yields are only 1–4% lower, making such one‐axis tracking systems very attractive in terms of performance relative to technical complexity and price. Copyright © 2010 John Wiley & Sons, Ltd.

Abstract This article provides background on the current status and recent trends of energy use in Viet Nam, as well as projections of energy demand and energy supply in the coming decades. The article summarizes the results of the current national Master Plan for developing the electricity supply sector to meet increasing electricity demand. Also described are the evolution and current status of Viet Nam’s energy policies, including those related to energy security, energy efficiency and conservation, the environment, and development of renewable energy sources, as well as strategies for power sector development and restructuring of the energy sector toward greater use of competitive energy markets. The initial phase of the Viet Nam energy sector modeling effort under the Asian Energy Security (AES) project is described. The final section of this article offers conclusions regarding the status of Viet Nam’s energy sector and policies, and recommendations regarding “next steps” in energy security analysis.

Hydrogen is expected to play a significant role in the future energy system. A key enabler to a hydrogen-including economy will be the development and deployment of processes that can produce hydrogen whilst satisfying the criteria for sustainability, i.e. economic competitiveness, environmental protection and security of energy supply. This paper evaluates selected hydrogen production processes based on natural gas steam reforming, coal and biomass gasification and water electrolysis. These options are expected to play a significant role in the short to medium term. Industrial large-scale processes, using natural gas and coal, will constitute the most important routes. However, increasing prices for natural gas are likely to make coal gasification more competitive. Biomass gasification could become important if present technological barriers are overcome. Electrolytic hydrogen, however, will likely be practical for niche applications in the short term due to the high electricity costs, especially when electricity is generated by renewable energy sources.