Measuring the stream course—Anna and Joe work downstream, shooting vertical drop (head) with a sight level, and getting a rough measurement of the pipe run at the same time.
Small-scale hydro is the only renewable energy source that works for you 24 hours a day, 7 days a week. In the first article in this series (HP103), I explained the basics of hydroelectric system theory, and reviewed system components. This article focuses on measuring a stream’s head and flow. Before you can begin designing your hydro system or estimating how much electricity it will produce, you’ll need to make four essential measurements:
- Head (the vertical distance between the intake and turbine)
- Flow (how much water comes down the stream)
- Pipeline (penstock) length
- Electrical transmission line length (from turbine to home or battery bank)
This article will discuss how to measure head and flow. Head and flow are the two most important facts you need to know about your hydro site. You simply cannot move forward without these measurements. Your site’s head and flow will determine everything about your hydro system— pipeline size, turbine type, rotational speed, and generator size. Even rough cost estimates will be impossible until you’ve measured head and flow.
When measuring head and flow, keep in mind that accuracy is important. Inaccurate measurements can result in a hydro system designed to the wrong specs, and one that produces less electricity at a greater expense.