Energy meters: A hot topic

In addition to the obvious energy sources such as heat and electricity, energy meters are installed in most renewable energy systems, such as biomass, solar thermal, air and ground source heat pumps, anaerobic digestion and biogas plants, CHP (combined heat and power) and district heat systems.

Providing installers and users with a quick and easy way to accurately measure generated energy, this feature is critical to those wishing to take advantage of the Government's Renewable Heat Incentive (RHI) and, with RHI uptake rising, demand for energy meters seems set to soar.

But, with so many manufacturers out there, it can feel like a bit of a metering minefield. The key to success is selecting the right energy meter for each application; one that delivers accuracy and longevity at the right price. 

Meter types

A popular choice today, with cost of ownership and lifespan a key concern,  is the Ultrasonic meter from companies such as Itron, Kamstrup and Sharky. With the flow part installed directly into the pipework, and temperature sensors located in the supply and return, the energy used is derived from the flow rate (m3/h) and the temperature difference between the supply and the return. 

The meter calculator then takes these three values and, depending on the meter size and rating, offers an energy figure in either kW/h or MW/h. The benefit of these energy meters is the lack of mechanical parts and the associated accuracy, longevity and reliability. 

Where an in-line meter isn’t practical, due to limited space or other physical constraints, 'Bolt-on' or 'Surface mount' ultrasonic transducers can be installed. Again using non-mechanical components, transducers measure the flow running through the pipework and the temperature difference between the supply and return.  The built-in calculator then derives the crucial energy value from the collated information.

Another option is to use mechanical meters. These calculate the energy generated using a pulse output as a flow measurement, temperature sensors and a calculator. But, whilst these meters are still being used, the mechanical nature can mean a reduced life expectancy in comparison to today's ultrasonic meters. For this reason MWA Technology does not normally recommend a mechanical meter for effective energy control and monitoring, unless specified.

Electric bus project

A recent project, involving metering expert, MWA Technology, and Nottingham City Council, illustrates the ease at which electricity can be accurately and cost effectively measured, with a suitable energy metering system.  

Reliant upon an existing manual solution to identify the amount of charge provided to individual vehicles, Nottingham City Council was experiencing regular transcription errors, and valuable management hours were consumed with manual data cleansing. An automated meter reading system was needed to improve data quality, save time and, of course, reduce ownership costs.  

It was crucial that Nottingham City Council could quickly and accurately identify the amount of charge provided to each vehicle in their fleet of electric buses.  With space being a major consideration, a modular electricity metering system, was installed. Using an interconnecting ‘backplane’ this provided a compact solution and a single serial communications link to a bespoke data logging system. 

The many subsequent benefits include reduced installation costs, a compact high granularity design, a simple external serial connection to external devices and most importantly reliably accurate data.

Conserving energy

Out of date and manual energy management systems leave users open to human error, risk commanding valuable time and resources in deciphering and cleansing collated data and wasting valuable energy. The latest energy meters provide a quick, simple and highly accurate way to monitor, control and save energy and associated costs.