Low-water-head hydropower is usually viewed as useless because of its inefficiency. The Low-Water-Head Hydropower Project can automatically transmute low-water-head hydropower into high-pressure gas power, which will solve the problem of the under-utilization of low-water-head hydropower. Considering the under-utilization of low-water-head hydropower because of its inefficiency, we propose a less intrusive and more efficient solution: the Low-Water-Head Hydropower Project with an automatic pump, which can transmute the low-water-head hydropower into high-pressure gas power. The energy-transfer process from water to air has not been investigated in previous studies. The goal of this study is to improve the energy conversion efficiency of the project. The goal of our study is to improve the energy conversion efficiency. The energy-transfer process from water to air has not been a focus in previous studies. Hence, a full-scale experiment was conducted, and the formula for the energy conversion efficiency eta was deduced. Energy balance equations based on the one-dimensional homogeneous model from the Bernoulli equation were established. Through the energy balance equation, the percentages of energy loss of different forms were determined. Wider and higher outlet pipes have higher eta l values. From an engineering perspective, the frictional head loss in all cases is so small that the frictional head loss caused by sidewall friction can be neglected. The change in temperature does not practically affect the sidewall friction effect. These conclusions can be applied in engineering applications. (C) 2019 Elsevier Ltd. All rights reserved.