• Energy Research

In advanced combined-cycle power plants, significant improvements in the thermodynamic performance are mainly achieved by the development of more efficient gas-turbine systems. This paper evaluates the effect of selected decision variables in the steam system for optimization of Thermal Combined Cycle Gas Turbine (TCCGT) power plant using an iterative exergoeconomic. The design variables were the thermodynamic parameters that establish the configuration both of the steam and gas systems. The design data of an existing plant (Damavand power plant in Tehran-Iran) is used. Two different objective functions are proposed: one minimizes the total cost of production per unit of output, and the other maximizes the total exergetic efficiency. The analysis shows that the total cost of production per unit of output is 2% lower and exergy efficiency is 4% higher with respect to the base case. It demonstrates that selected decision variables have suitable results for the exergy analysis and cost effectiveness. Since, environmental pollution and energy shortage are the two factors limiting the development of the society; nevertheless, this analysis tends to optimally find the design parameters which result in a decrease in the fuel mass flow rate. Also, this reduction (about 5%) in the mass flow rate and increasing exergetic efficiency can decrease the environmental impacts.

Abstract A numerical model is developed to simulate the borehole heat exchanger both in the short and long time. In this regard, the computational domain is divided into the inside and outside borehole regions. A two-dimensional finite volume method is implemented in a cylindrical coordinate system for modeling of the outside borehole. Also, a thermal resistance-capacity model is presented for the borehole cross section. This model is extended to take into account the fluid transport through the U-tube and the temperature variation of the borehole components with depth. The governing equations of the two regions are solved iteratively in each time step. The proposed model is verified with the previously reported numerical, experimental and analytical results. Furthermore, the ability of the model in predicting the short-time response is evaluated in comparison with a three-dimensional computational fluid dynamics (CFD) model with a fine grid. The results show that the proposed model has a good performance in the prediction of the thermal response of the borehole in a wide time interval from 1 min to over 10 years. Moreover, the effects of time step size and number of capacity nodes on the results are investigated.

Abstract This paper provides a feasibility study on a low cost system called Hydrokinetic Wells turbine for surface wave energy conversion without using plenum chambers. The elimination of the plenum chamber and its complicated valve systems can reduce the expenses of wave energy conversion up to 23%.The feasibility process were done for high and low frequency conditions. For the low frequency waves, we offer the 300 rpm angular velocity as an optimum selection for further studies. For the high frequency condition a reliable analytical approach based on validated methods was developed. The analytical results indicate that a wells turbine with 60 cm diameter could produce up to 1600 Watts power in high frequency waves. The efficiency and power coefficient values in high frequency condition are less in compared with low frequency situation, nevertheless the vast usage of the small scale and elimination of the plenum chambers can reduce the total cost of the conversion. The abundant availability of high frequency surface waves is a motivation for developing Hydrokinetic Wells turbine farms to harvest a great source of clean energy with lower cost levels.

This paper shows a new possible way with particle swarm optimisation (PSO) to achieve an exergoeconomic optimisation of combined-cycle power plants. The optimisation has been done using a classic exergoeconomic and genetic algorithm, and the effects of using three methods are investigated and compared. The design data of an existing plant is used for the present analysis. Two different objective functions are proposed: one minimises the total cost of production per unit of output, and maximises the total exergetic efficiency. The analysis shows that the total cost of production per unit of output is 2%, 3% and 5% lower and exergy efficiency is 4%, 8% and 6% higher with respect to the base case for the classic, PSO and GA procedures, respectively. Finally, a sensitivity analysis to assess the effects of change in the decision variables of the plant on the objective functions performed, and the results are reported.

One of the most effective measures for building energy conservation is the implementation of energy codes. The building energy codes introduction in Iran started two decades after the first oil crisis in the early 1970s by establishing the building energy conservation regulation called Issue 19. Nowadays, due to some financial and executive barriers, the implementation of Issue 19 is faced with some difficulties. The most critical obstacle is the low price of energy carriers, which lead to high subsidies of energy and the reluctance of the building owners to implement the regulation. The main goal of this paper is the introduction of an innovative financial and executive mechanism for implementation of Issue 19 in both new and existing buildings to achieve sustainability and resiliency. The cost–benefit analysis approach, along with SWOT technique and a comprehensive review of global experiences, was applied to introduce proper financial and executive mechanisms to determine the economic and social aspects of energy conservation programs for implementation of energy saving in buildings. The presented mechanism indicates the role of all different related parties, such as the government, banking system, energy-saving companies, building owners, and municipality, to achieve this goal. The results indicated that with a cost of $10 million, the benefits of implementation of the introduced mechanism are over 5.78 billion dollars.

Abstract In this research, a site selection method for wind-compressed air energy storage (wind-CAES) power plants was developed and Iran was selected as a case study for modeling. The parameters delineated criteria for potential wind development localities for wind-CAES power plant sites. One important consequence of this research was the identification of the wind energy potential for wind-CAES sites. The theoretical wind energy potential of Iran of greater than 50 W/m 2 was identified from a wind atlas of Iran. The model produced factor maps by considering the boundary conditions of the input data and created geo-databases from the outputs maps. The main factor maps were electrical grids and substations, gas transmission lines, a wind energy atlas, thermal power plants (location and capacity), salt dome locations and extends (for compressed air reservation), slope data, a digital elevation model, cities and residential areas, water bodies and access roads. For every data layer, criteria where developed from existing laws, regulations and scientific studies and normalized for Iran. In the final step of analysis and modeling, the factor maps were integrated by coding using ArcGIS software and the wind-CAES power plants sites were selected. This research showed that 30 sites in 5 major zones have the capability to support installation of wind-CASE power plants in Iran.

Abstract The promotion of the adoption of renewable energies in deprived and remote areas can be considered as an important step towards reduction of threats to the loss of biodiversity through community mobilization. One important outcome is mitigation of the deforestation processes through firewood collection. The aim is achievement of sustainable development of the forest biodiversity, awareness raising and the capacity building for execution of similar projects. The social and economical aspects and the obstacles for execution of such project were investigated and guidelines were prepared to facilitate the promotion of renewable energy in similar small communities.

This study aims at identifying the parameters that govern the environmental costs in oil and gas projects. An initial conceptual model was proposed. Next, the costs of environmental management work packages were estimated, separately and were applied in project control tools (WBS/CBS). Then, an environmental parametric cost model was designed to determine the environmental costs and relevant weighting factors. The suggested model can be considered as an innovative approach to designate the environmental indicators in oil and gas projects. The validity of variables was investigated based on Delphi method. The results indicated that the project environmental management’s weighting factor is 0.87% of total project’s weighting factor.