Archimedes Screws Turbines (ASTs) are a new form of small hydroelectric powerplant that can be applied even in low head sites. ASTs offer a clean and renewable source of energy and are safer for wildlife and especially fish than other hydro generation options. As with other energy solutions, ASTs are not a global solution for all situations. However, in terms of sustainable development, ASTs can offer many economic, social, and environmental advantages that make them an important option for providing sustainable hydropower development. Archimedes screws can operate in low water heads (less than about 5 m) and a range of flow rates with practical efficiencies of 60% to 80% and can generate up to 355 kW of power. ASTs increase the number of suitable sites where it is possible to develop sustainable hydropower, including in undeveloped, hard to access regions and small communities. At many low head sites, ASTs may be more cost-effective, with lower installation and operating costs than alternative hydropower systems. An AST may also reduce the disturbance of natural sedimentation and erosion processes and have smaller impacts on fish and other fauna. ASTs can often be retrofit to existing unpowered dams or weirs, providing new hydropower capacity for very little marginal environmental impact. This review outlines the characteristics of ASTs, then discusses and analyzes how they could benefit the sustainability of hydropower development.

Sluice gates are common hydraulic structures for controlling and regulating flow in open channels. This study investigates five models’ performance in distinguishing conditions of flow regimes, estimating the discharge coefficient ($C_d$) and flow rate. Experiments were conducted for different gate openings, flow rates, upstream and downstream conditions. New equation forms and methods are proposed to determine $C_d$ for energy–momentum considering losses (EML) and HEC-RAS models. For distinguishing the flow regimes, results indicated a reasonable performance for energy–momentum (EM), EML, and Swamee’s models. For flow rate and discharge coefficient performance of EM, EML, and Henry’s models in free flow and for EM and EML in submerged flow were reasonable. The effects of physical scale on models were investigated. There were concerns about the generality and accuracy of Swamee’s model. Scaling effects were observed on loss factor k in EML. A new equation and method were proposed to calibrate k that improved the EML model’s accuracy. This study facilitates the application and analysis of the studied models for the design or calibration of sluice gates and where the flow in open channels needs to be controlled or measured using sluice gates such as irrigation channels or water delivery channels of small run-of-river hydropower plants.

A small wind turbine blade was designed using blade element momentum (BEM) method for a three bladed, fixed pitch 1 kW horizontal axis wind turbine. The new blades were fabricated, fit to a Bergey XL 1.0 turbine, and tested using a vehicle-based platform at the original designed pitch angle, plus with 5 deg and 9 deg of additional pitch. The new blades had better aerodynamic performance than the original Bergey XL 1.0 blades at high speed, but in some cases at lower speeds the original blades performed better. The results demonstrated that selecting the blade pitch angle on a rotor is a tradeoff between starting performance and power output in high winds. The BEM simulations were evaluated against the test data and demonstrated that the BEM simulations predicted the rotor performance with reasonable accuracy.

This study investigates the level of uncertainty that would be expected if anemometer data from a short tower (less than 40 meters) was used to predict wind speeds and power production at typical utility-scale wind turbine hub-heights. Data from five tall towers was used to predict wind speeds at levels above 70 m based on anemometer data from levels below 40 meters. 1/7 power law, two level power law fit, and hybrids of these methods were applied. Predicted wind speeds were compared to the measured wind speeds at the higher levels to assess the level of error in the predictions. Accuracy of predicting upper level winds varied considerably between sites. Predicting this accuracy at a site without upper level wind measurements or prior knowledge of the upper level wind climate is very difficult, and significant uncertainty in the predicted results must be accepted.