L. Branchini

Handling Wind Variability Using Gas Turbines

A significant amount of energy is expected to come from wind in the upcoming years. The variability and uncertainty of this power source needs to be managed by the grid operator. Electricity networks with wind energy need extra reserves to deal with the extra uncertainty associated with the presence of wind. This paper evaluates the possibility to couple a 1000 MW wind farm with gas turbines (GTs) to provide firm capacity to the grid with a reasonable investment. Taking into account two different days of wind production with one minute data, the study analyzes the possibility of integrating the wind power output with two different types of GTs (heavy duty and aeroderivative). GTs operational constrains are included in the model in order to correctly demonstrate how the wind variability stresses turbine performance, as it probably would in extreme cases. Limitations on GTs ramps rates and start–up time are considered for both, heavy duty and aeroderivatives. GTs power output profiles, ramp rates and fuel consumption for the selected days of analysis are shown. The results show that the integration between wind and gas turbines could be a viable solution to compensate wind variability and to accommodate the increasing wind penetration into the electrical grid.Copyright

Gas Turbine Power Augmentation Technologies: A Systematic Comparative Evaluation Approach

Increasing electric rates in peak demand period, especially during summer months, are forcing power producers to look for gas turbine power augmentation technologies (PATs). One of the major undesirable features of all the gas turbines is that their power output and fuel efficiency decreases with increase in the ambient temperature resulting in significant loss in revenues particularly during peak hours. This paper presents a systematic comparative evaluation approach for various gas turbine power augmentation technologies (PATs) available in the market. The application of the discussed approach has been demonstrated by considering two commonly used gas turbine designs, namely, heavy-duty industrial and aeroderivative. The following PATs have been evaluated: inlet evaporative, inlet chilling, high pressure fogging, overspray, humid air injection and steam injection. The main emphasis of this paper is to provide a detailed comparative thermodynamic analysis of the considered PATs including the main variables, such as ambient temperature and relative humidity, which influence their performance in terms of power boost, heat rate reduction and auxiliary power consumption.Copyright

Thermo-Economic Evaluation of ORC System in Off-Shore Applications

This paper presents a study related with off-shore oil & gas production and processing facilities, where required energy, for electric power, mechanical power and process heat, is mostly produced using gas turbines, as the fuel source (natural gas) is available onsite. Since size and weight of all equipment on an offshore facility are critical, it becomes necessary for the facility engineering team to ensure that all equipment are sized and selected appropriately to obtain better return on the investment. Therefore, any approach which could help in utilizing energy resources effectively will influence the bottom-line of the project, namely reduced capital cost and/or increased return on investment. In this paper, one such approach of recovering power and thermal energy through the use of Organic Rankine Cycle system is discussed. A detailed thermo-economic analysis, conducted considering a system with four gas turbines operating, shows that power recovery equivalent to one topping gas turbine is achievable with a suitable working fluid. The presented thermo-economic analysis clearly shows that use of the Organic Rankine Cycle system for waste heat recovery is a technically viable and economically attractive solution for the offshore applications.Copyright

Computing Gas Turbine Fuel Consumption to Firm Up Wind Power

As wind power installed capacities increase, it is necessary to deal with the inevitable variability of renewables. Some of that variability can undoubtedly be predicted, but some will in all probability remain unpredictable. In either case, reserve power must be made available. It is clear that the ramp rates that the reserve power must meet will stress technology and call for part-load operation at reduced efficiencies. In the present work, we use a gas turbine (GT) dynamic models to simulate the provision of firm power in the Pennsylvania, New Jersey and Maryland grid, PJM. Rowen GT models [1, 2], well established in the literature, are modified to take into account GT ramp rates constrains and fuel consumption at full and partial load, as well as during startup and shutdown. The GTs operational requirements for two summer days in the PJM area are determined, by selecting their number and capacities to result on at least a few units operating at full load. The dynamic models [1, 2] are implemented in the VisSim simulation environment. The results of the work show how the chosen GTs must be operated to provide firm power. Although the operational strategy determined in this paper meets the firm power, in two occasions during the day excess power is produced during a few minutes, to avoid ramping the units down too fast.Copyright

Organic Rankine Cycle System for Effective Energy Recovery in Offshore Applications: A Parametric Investigation With Different Power Rating Gas Turbines

A comprehensive and systematic evaluation of the bottoming Organic Rankine Cycle based energy recovery system, considering a wide spectrum of gas turbines with power ratings commonly used in the offshore applications, has been conducted in this paper to demonstrate the potential benefits of this technology. In this study, emphasis is given on the thermodynamic performance of the energy system by evaluating incremental electric power recovery, thermal energy recovery and carbon emissions savings. Effects of an intermediate heat transfer fluid and the utilization of a recuperator for waste energy recovery in the Organic Rankine Cycle on the key performance indicators of the energy system are evaluated. In addition to discussing advantages and limitations of the considered configurations of the bottoming Organic Rankine cycle, it is shown that by using the proposed configurations, a significant amount of additional electric power can be produced which could be used to prevent part-load operations of gas turbines resulting in fuel savings, increased gas turbine’s components life, reduced maintenance cost, and reduced CO2 emissions — a win-win proposition for the offshore projects.Copyright

Available and Future Gas Turbine Power Augmentation Technologies: Techno-Economic Analysis in Selected Climatic Conditions

There exists a widespread interest in the application of gas turbine power augmentation technologies in both electric power generation and mechanical drive markets, attributable to deregulation in the power generation sector, significant loss in power generation capacity combined with increased electric rates during peak demand period, and need for a proper selection of the gas turbine in a given application. In this study, detailed thermo-economic analyses of various power augmentation technologies, implemented on a selected gas turbine, have been performed to identify the best techno-economic solution depending on the selected climatic conditions. The presented results show that various power augmentation technologies examined have different payback periods. Such a techno-economic analysis is necessary for proper selection of a power augmentation technology.

Wind-Hydro-Gas Turbine Unit Commitment to Guarantee Firm Dispatchable Power

The randomness and intermittence of wind power require additional reserves provided by thermal generators. This creates difficult scheduling of generation, causing thermal generators to start up or shut down frequently, or to operate at low efficiency and high fuel consumption state. If not, some wind power will be curtailed and wasted. This paper examines the operation of a hybrid system made up of a wind farm, a pump storage hydro and conventional thermal generation units consisting in a combination of a heavy-duty and an aeroderivative gas turbines.In order to seek an optimal approach to deal with the uncertainty of increasing wind power and ensure both the efficient operation of thermal generators and full use of wind energy, two different control strategies have been proposed and compared: (i) a “custom” in house developed strategy and (ii) an “optimal” strategy based on Dynamic Programming.Using actual generation data of a wind farm, the operation of hydro power plant and gas turbines are obtained with the aim of compensating differences between actual wind generation and load demanded. Natural gas fuel consumption and average gas turbine efficiencies during the analyzed time period are calculated along with number of units starts-up.© 2014 ASME

Waste-to-Energy

This chapter introduces and describes the basic concepts related to the waste-to-energy (WTE) conversion processes, highlighting the most relevant aspects that limit the thermodynamic efficiency of a WTE power plant.

WTE–GT Steam/Waterside Integration: Thermodynamic Analysis on One Pressure Level

This chapter focuses on waste-to-energy (WTE) and gas turbine (GT) integrated configurations concerning one-pressure-level heat recovery steam generator (HRSG). The thermodynamic and parametric analysis of steam/waterside-integrated WTE–GT power plant has been carried out, first of all, with the aim to investigate the logic governing plants and that it should match in terms of steam production as a function of the thermal power generated. Steam generation, optimum plant match condition, inlet and outlet conditions of heat exchangers, etc., as a consequence of system integration are analyzed and explained. A sensitivity analysis, varying with evaporative pressure and HRSG inlet conditions, has also been presented to investigate the influence of operative parameters on steam mass flow rate.

Waste-to-Energy and Gas Turbine: Hybrid Combined Cycle Concept

This chapter focuses on the hybrid combined cycle (HCC) concept. The HCC, based on thermal integration between a topper cycle (TC) and a bottomer cycle (BC), denotes specifically “dual-fuel” combined power cycles. The possibility to use different fuels for the TC and BC is one of the advantages of the HCC. This chapter describes in detail two basic types of hybrid dual-fuel combined cycle (CC) arrangements applied to waste-to-energy (WTE) power plants using as TC a gas turbine (GT), a steam/waterside-integrated HCC, and windbox repowering.