What is Micro-Hydro Power? What is an ELC?

A large part of TONIBUNG's work is installing micro-hydro systems into remote villages in Malaysian Borneo.  These systems provide communities with clean and low-cost electricity which means improved education and welfare (diesel generators, in contrast, are noisy, dirty and expensive for such subsistence communities to run and maintain). So what is micro-hydro?

The basics

Micro-hydro electricity generation basically means making a (relatively) small amount of electricity by converting mechanical energy of water into electrical energy - the water drives a turbine which drives an electrical generator (as this very easy YouTube video shows).  A major advantage of micro-hydro in contrast to large scale hydroelectric generation is that there is little impact on the surrounding environment as there are no large dams; micro-hydro can work as a ‘run-of-river’ system, where the water passing through the generator is directed back into the stream.

Micro-hydro is basically converting energy from water flowing in a river into electrical energy (via a turbine and generator)

A bit more detail - control systems

The amount of power which can be generated by a given system will depend on the flow rate of water through the turbine and should remain quite constant. On the other hand, the amount of electricity which the village is using will vary as devices are switched on and off.  It is important to match the generator input power with an equal output power to maintain a constant turbine speed and electrical frequency output. This is needed to protect both the generator and any devices connected to the village load. The balance can be achieved using mechanical or electrical control.  

Mechanical control limits the amount of input mechanical energy (power) to the generator so that it matches the electrical energy being demanded by the village. The mechanical energy input is normally controlled using some sort of valve, gate or governor which reduces the flow into the system or the efficiency of the turbine at extracting power from the water.

Another option is to use electrical control. A ballast load (normally a heating device) is used to make up the difference between the amount of power which the village is demanding and the amount the generator is producing. The ballast load (or dump load) can be switched manually by an operator (like in the picture below) or by an automatic control system, known as an Electronic Load Controller (ELC). 

In manual control, an operator switches on dump ballast loads (represented by the light bulbs) so that the total output from the generator stays at its rated value and it can operate within its safe limits.  In A, some of the power is diverted to the dump loads but, in B, village loads have increased and the operator needs to reduce the amount of power dissipated in the ballast. In both cases, total demand of the system is 5 light bulbs' worth.

The operator can be replaced by an automatic Load Controller (ELC) which can react much more quickly and reliably

ELCs are typically used on village micro-hydro installations as they are relatively reliable and fast at reacting to changes in community demand. Off-the-shelf ELCs typically make up a large proportion of the cost of TONIBUNG's Micro-Hydro installation costs because most of the other components of the system are made in-house. At the moment we're working on a project to develop an in-house, low-cost ELC but I'll continue that story in a future blog post.

*Credit for the graphics in this post go to Yong Ling who made them for a TONIBUNG staff training course on ELCs