The importance of reliable fuel monitoring for hybrid power systems

By Mattias Karlsson, VP eSite, Flexenclosure

With generators powering most of the telecom sites in Africa, diesel is the number one factor driving operational cost.  Obvious questions result:  How much diesel is any given site actually consuming?  When is it time to refill?  Is fuel consumption in line with the expected performance of your installed power solution?  Is there an issue with theft?  And are you benefiting from your investment in hybrid power systems in terms of overall fuel consumption?

These are clearly critical questions.  But fuel monitoring is a complex process with a great number of factors affecting performance, reliability and accuracy and until recently diesel consumption has been the single most difficult factor to accurately measure at telecom sites.  The good news is that reliable fuel monitoring systems are now available, but before you invest here are some key areas to discuss with any potential vendor…

Any fuel monitoring system should be able to detect what’s actually happening to the diesel, but without careful design it’s almost impossible to distinguish between legitimate fuel use or whether diesel is being stolen or if the tank is leaking.  The system should be able to identify when a sensor is faulty or has been tampered with.  Beyond the monitoring system itself, the design of the fuel tank setup on site can also introduce complications if, for example, fuel is moved between multiple tanks.  And the design should also be able to make allowances for local temperature variations that will impact fuel measurements.

Even the most advanced system in the world will not provide useful or accurate data if it has not been installed correctly.  The greater the installation complexity or sensor calibrations required, the greater the risk of errors and unreliable data, so the installation process needs to be as simple and straightforward as possible – especially as most telecom sites requiring a hybrid power system will likely be in remote and/or extreme environments.  Post-installation maintenance requirements also need to be kept to a minimum as tampering with sensors or cables – even if it hasn’t been done maliciously – can result in data inaccuracies on an on-going basis.

A competent fuel monitoring system clearly needs to be accurate, but accurate about what?  Is it necessary to know exactly how many decilitres there are in the tank?  Is that even feasible given that fluctuations in tank dimensions, external temperature and diesel density will all significantly affect a fuel reading?  Rather than knowing the volume of diesel in a tank at any given moment in time, it’s far more important to accurately know how much diesel has been consumed over time; how much has been refilled; whether any has been stolen; and most importantly – how many days’ worth of diesel is left at each site so that refuelling trips can be scheduled appropriately.

Of course it goes without saying that any remote monitoring system needs to be reliable.  Ideally though there should be an additional level of intelligence in the system, with smart software that is able to recognise patterns of behaviour at each site, such that educated decisions can be made as to whether an anomalous reading is a result of a real issue or whether it’s more likely a sensor malfunction.  In this way alarms can be prioritised and responded to with a greater measure of efficiency and control.

There are obvious impracticalities in a system that requires local data collection by an engineer, especially when there are tens, hundreds or perhaps even thousands of sites involved. And with fuel planning in particular, any system which only allows sensor interrogation at a local level will obviously not be able to inform on issues that require immediate response such as increased diesel use due to a fuel leak or generator fault.  The ability to remotely monitor each and every site is therefore a given and hybrid power systems such as Flexenclosure’s eSite have a fully integrated eManager tools suite which enables an engineer sitting in the NOC to compile accurate data and create real-time reports to make sense of fuel consumption (and myriad other data points) from an unlimited number of sites.  For an in-depth analysis of the importance of being able to remotely monitor your hybrid power systems, see our article on gathering data you can trust from your telecom sites in order to enable fully informed business analysis and decision-making (see issue 11 of the TowerXchange Journal).

With a well-designed, accurate and reliable fuel monitoring system in place, meaningful performance improvements and operational cost reductions can be achieved.  Network outages due to lack of fuel can be entirely eliminated.  Site refuelling and generator maintenance can be scheduled far more efficiently.  The analysis of fuel consumption versus generated electricity will allow the detection of low-performing genset and provide the required data for a repair/replacement decision.  And rather than being limited to simply evaluating site performance based on genset runtime, the overall efficiency of your hybrid power systems can be evaluated against the ROI originally promised by the system vendor.

The benefits of understanding fuel use on a site-by-site basis are therefore clear.  When multiplying those benefits across an entire network of hundreds or even thousands of telecom sites, the operational improvements and cost savings can be transformative to a business.