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Cement production is considered as one of the most energy consuming industries. Any novel strategy to make cement plants more efficient would increase the annual revenue while significantly reducing local and global emissions. In this paper, an energy audit in a cement plant (Kerman, Iran) is presented in order to introduce more viable potential solutions to push this industry towards a more sustainable status. Various parameters, such as temperature and system dimensions, were measured, and raw materials and product analyses were conducted. Then, using the measured and analyzed data, an energy balance analysis was performed. A novel framework based on a well-known global optimizer algorithm and a multi-criteria decision method is presented for integrated energy optimization. This proposed framework is then tested for the audited cement plant at two major steps. First, an efficient metaheuristic optimization approach is employed to optimize the compounds of clinker to reduce the consumption of energy in the cement industry. Second, a decision-making procedure, namely analytic hierarchy process, is used to make right decisions to reduce energy losses after completing an energy audit program. Results of the present study indicate the effectiveness of the proposed framework based on metaheuristic algorithm and decision-making approach.

The rotor area of a wind turbine must be perfectly perpendicular to the wind to deliver the most efficient performance as a single unit (i.e., yaw angle γ = 0°). When the rotor is misaligned (i.e., γ ≠ 0 ° ), the turbine power production is lower and greater structural loads may occur. However, a beneficial effect of yaw misalignment is that it steers the aerodynamic wake and, consequently, it may reduce wake losses for downstream wind turbines. To quantify and maximize such potential power gains while minimizing power losses, a wind farm with 28 wind turbines is investigated using large eddy simulations (LES). Selected turbines in the front-, mid-, and deep-rows are intentionally misaligned by positive (counter-clockwise) or negative (clockwise) yaw angles of various magnitudes. Consistent with previous studies, positive yaw misalignment angles cause net power gains, whereas negative ones cause net losses. We hypothesize that this is due to the Coriolis effect. Thus, only positive yaw misalignment angles should be considered for wake steering purposes in the northern hemisphere. Also, yawing front-row and deep-row turbines causes the overall power production to increase, while yawing mid-row turbines is not as effective. The most effective yaw misalignment angles are + 20 ° for front-row and + 10 ° for deep-row turbines.

Wind energy has been growing steadily in the U.S. and worldwide in the past decades. As wind farms are projected to increase in size and number, however, concerns are rising about possible undesira...

Computational Fluid Dynamics (CFD) was used to assess whether adding a stationary diffuser, known as wind lens, can improve the power performance of vertical axis wind turbines. Transient, two-dimensional simulations were conducted using a dynamic mesh and the Shear-Stress Transport (SST) \( k - \omega \) model to calculate the generated torque. Blades were set to rotate at a constant angular velocity to maintain an optimal TSR (tip speed ratio) at the studied freestream wind speed. The product of this angular velocity (in rad/s) and the calculated torque (in Nm) was assumed to be the mechanical power harvested by the turbine. The simulation setup was validated using experimental data. It was found that a properly designed wind lens enhances power production in two ways. First, it collects and guides a larger air flow into the turbine (the inlet effect). Second, it induces a flow separation along its trailing edge, which leads to a reduced pressure zone downwind of the outlet of the lens (the outlet effect). The enhanced pressure difference between upstream and downstream regions drives a larger flow into the turbine, which increases power generation. It was also found that if the throat of the diffuser is not sufficiently large, the shear caused by its inner walls decelerates the blades. This negative impact can dominate the above-described inlet/outlet effects, which leads to a net reduction in power production. Although no rigorous optimization was conducted to identify an optimal geometry for the diffuser, the proposed lens was found to improve power production of the turbine by more than 400%. It is shown that substituting the augmented turbine with a large open turbine with a swept area equal to the maximum cross-sectional area of the lens is a more effective strategy (increases power production by 600%), however, it may cost considerably more.

A wind farm’s overall power production is significantly less than its nominal power, defined as the sum of the wind turbines’ rated outputs. The primary cause for this significant loss is the exposure of downstream wind turbines to the aerodynamic wake of their upstream counterparts. Wind farm layout optimization aims at minimizing such adverse effects by finding optimal wind turbine positions that are less exposed to the upstream wake. Over the past few years, researchers have extended their fight against adverse wake effects beyond the layout optimization, i.e., the design process, onto the control and operation process. Several active wake control strategies have been proposed and studied to decrease the power loss of downstream wind turbines by steering or weakening the upstream wakes. First, the article reviews these strategies, including yaw control, pitch control, torque control, tilt control, and finally, cone angle control. Then, it proposes a novel wake steering technique where passive stationary vanes redirect the upstream wake. The authors conducted scaled wind tunnel experiments to investigate the performance of the proposed concept. Using a 3D-printed wake deflector between two in-line turbines increased the downstream turbine’s power production by more than 15%, which is significant compared to the existing wake control strategies. The article concludes by comparing the proposed technology’s effectiveness against existing wake control techniques.

The impact of wind direction on the overall performance of a utility-scale PV plant was studied by analyzing field data from Hadley solar farm in the UK. The solar PV plant utilizes a fixed-tilt system with the PV panels facing south at a 20 degree angle. The hypothesis is that when wind blows from the south the total power production of the solar PV plant increases in comparison with non-southerly wind events, provided that all other determining factors, such as solar irradiance, ambient temperature, and wind speed are the same. During the case study of January 1 to July 1, 2017, 42 pairs were identified, each of which includes two cases with equal solar irradiance, equal ambient temperature, and equal wind speeds but different wind directions; in one case wind is from the north and in the other one wind blows from the south. The hypothesis was found to be true across all 42 pairs, i.e., the power production of the solar PV plant was always greater in the event of southerly winds. One takeaway from this finding is that wind direction and wind speed frequencies need to be taken into account along with other climatic factors to have an optimal site selection for establishing a solar PV plant. The more frequent the southerly wind occurs, the more power can be extracted from the PV panels. The other practical conclusion of this study is that it is more efficient to build fixed-tilt solar PV plants on areas oriented along the west-east direction.

Wind is a force of nature and naturally changes speed and direction with time, so the amount of wind power generation from wind farms also varies. Rapid growth in wind power production has led to the integration of wind power into the power grid. Wind power forecasting enables wind farms to address the intermittency and predictability issues to a satisfactory extent and to participate in the electricity market in the same way as any other power supplier. This chapter provides an overview of existing wind power forecasting methods, their time scales (short term, medium term, and long term), and most popular statistical analyses used to assess their performance. Models reviewed in this chapter include persistence method, physical models, statistical methods, machine learning methods, and hybrid methods.

The aerodynamic interactions of wind turbines within a wind farm cause major energy losses. Yaw control is a promising active strategy to tackle this issue in real time during the operation of the plant. The wake of a wind turbine can be steered away from its downstream counterparts by imposing a yaw angle to its rotor. Studying the impact of intentional yaw misalignment on the performance of wind farms located in the northern hemisphere has revealed that, for columns aligned with the wind direction, positive yaw misalignment can lead to an overall increase in the annual energy production, while negative misalignment reduces it. Note that our emphasis is on the front-row turbine being the only yawed turbine of the column. Two unverified reasons have been proposed for the difference between the impact of positive and negative yaw misalignment: (i) the clockwise rotation of the turbine blades and (ii) the Coriolis effect. This paper investigates these two potential explanations by conducting six large-eddy simulations of flow through a wind farm of ten wind turbines located in the northern hemisphere. Results indicate that the Coriolis force and the direction of rotation of the blades both contribute to the inconsistency between the impact of positive and negative yaws on the net power production. The Coriolis force appears to be more influential. The difference between applying a positive and a negative yaw angle to the front-row turbine was found to be approximately 17%. This difference was reduced to almost 7% when the Coriolis force was relaxed, and to approximately 11% when the turbines were set to rotate counter clockwise. Note that a separate study is required to investigate this concept in the southern hemisphere.