6 rules for success: Could your hydro scheme be underperforming?

By Joe Fergusson, Renewables Consultant

A small scale hydro power system.

A boom in small-scale hydro schemes was sparked first by the Renewables Obligation Order of 2002 and subsequently the Feedin Tariff scheme which started in 2010.

Unfortunately, the conflict between a desire to commission these schemes as quickly and ‘capital-cost-effectively’ as possible and the logic of making them efficient, reliable and simple to maintain, has left a legacy of systems that are far from optimised.

More worryingly still, an underperforming hydro scheme can mean not only a reduction in electricity output and revenue … but even a danger to life.

As Renewable Consultant I have been involved in scores of hydro projects in various capacities over the past 16 years, most recently working with LFI Silva Investments to optimise the 340kw Tombuie Hydro scheme which came with their recent purchase of Bolfracks Estate in Highland Perthshire.

During that time I’ve witnessed all manner of deficiencies resulting from cost-cutting, inexperience or simply a lack of foresight.

To improve the revenues, reliability and safety of such schemes, we suggest SIX rules that owners of older schemes should be aware of:

1. ‘Smarter’ tech increases Outputs The control technology used to manage a scheme (ie. turning it off and on, and modulating valve openings as flows fluctuate), may be basic and/or incorrectly set. Similarly, the systems that manage the generator voltage, matching it to the grid and controlling the power factor, may be sub-optimal compared to state-of-the-art digital control and Automatic Voltage Regulator (AVR) systems. The good news is that equipment has become ‘smarter’ over the past decade, and more sophisticated versions are now affordable.

2. ‘Pigging’ should be easy Penstock pipes are often installed without a straightforward means of ‘pigging’ them, (ie. cleaning out the organic growth and silt that builds up over the years and impedes flows, reducing the turbine’s output at all water levels). However, pigging arrangements can be retrofitted ensuring output is maximised.

3. Better screens cut costs 3 Intake screens may be unsuitable for their location or application, allowing leaves and other debris to restrict intakes, possibly requiring more cleaning and maintenance than managers are able to achieve. Installing more appropriate screens will increase flows, boost revenue and cut maintenance costs.

4. Safety standards change Expectations of safety-by-design (ie. the concept of minimising hazards early in the design process, with an emphasis on employee health and safety throughout the lifecycle of materials and processes) may have been lower when the scheme was conceived. The degree of physical and financial risk to owners and insurers may today be considered unreasonable or unacceptable. A thorough independent audit can identify issues and offer affordable solutions.

5. Re-examine your habits Successful operation is dependent on the people running it. Habits acquired over the years by operators or maintenance staff may not be conducive to the optimal operation of the scheme. An objective study of the prevailing modus operandum can reveal ways that annual output and revenue may be improved.

6. Make use of expert advice Hydro scheme owners looking to maximise their revenues are well-advised to undertake an independent review. Bell Ingram can carry out a thorough audit of a scheme’s components and output record, and have a detailed discussion with its operators. We will then produce a report with recommendations and an action plan. Most of the remedies proposed will involve some capital expense so the report will provide feasibility calculations to assist in prioritisation. Bell Ingram will then provide as much assistance as required to implement the agreed measures.

➤ If you would like to discuss opportunities for improving your hydro scheme, contact Joe Fergusson at joe.fergusson@bellingram.co.uk or 07711 552693.

Published on 19th August 2019