Africa’s intermittent power supply has been identified as a key limiting factor to its economic growth. The power that does exist on the continent is further threatened by aging infrastructure and poor maintenance. Daily power shortages have led to companies sourcing gensets, electrical generators fuelled by diesel, as alternative, reliable energy sources.  These are initially cheaper to set-up but prove more costly than power sourced from the grid in the long-run.

Africa’s intermittent power supply has been identified as a key limiting factor to its economic growth. The power that does exist on the continent is further threatened by aging infrastructure and poor maintenance. Daily power shortages have led to companies sourcing gensets, electrical generators fuelled by diesel, as alternative, reliable energy sources.  These are initially cheaper to set-up but prove more costly than power sourced from the grid in the long-run.

Whilst private sector, governments and regional bodies seek long-term solutions to the power challenges, it is imperative that cost-effective and more efficient ways – such as Electric Turbo-Compounding (ETC) – be embraced by industry to reduce the long-run cost of gensets; improving their efficiencies, reducing fuel consumption and emissions and generating additional clean power.

Understanding the challenge
More than 30 African countries are now experiencing power shortages and regular interruptions in service. In fact, the African Development Bank (AfDB) states that the entire installed generation capacity of Sub-Saharan Africa is 68 gigawatts, roughly equal to that of Spain. Frequent power outages translate into losses in sales and reduced production. These costs can in, some instances, equate to 2 percent of gross domestic product and result in a quarter of a percent drop in growth rate.

The reality is that producers have had to seek alternative sources of power to run their offices and factories. Gensets have become ubiquitous with industry throughout the continent. While initial capital costs associated with the gensets are affordable, their frequent long-term use could result in higher input costs, often more expensive in terms of price per kW/h than the local grid. Fuel consumption, in particular, is a costly concern.

Understanding the solution

The Bowman Power and Powertech (a subsidiary of JSE list Altron)  ETC system, the first cost effective and commercially viable system brought to market, provides a tried and tested solution to lowering this cost. ETC is able to achieve extremely high uptimes and meet required performance criteria. Users can comprise genset packagers, engine OEMs, power providers and system integrators.

In terms of technical application the ETC system introduces an additional turbine after the turbo charger engages in order to recover a portion of the waste heat energy from the engine exhaust stream. The turbine is directly coupled to a high speed alternator and the combined unit is termed a turbo generator or TG. The TG incorporates a very compact, high speed, high efficiency drive electrical alternator.

The TG has its own self-contained oil system, providing both lubrication and cooling. The existing turbocharger is replaced with a high efficiency model that is correctly matched to the TG downstream to optimise the energy recovery. A separate power electronics panel provides all control functions and conversion of the alternator output to grid quality 50 or 60Hz 3 phase power. Modular in concept, the power electronics are centred on a standard converter modules, which can be configured for the different functions in power electronics and grouped together in various numbers to provide the overall capacity necessary for the application.

Highly-efficient, the turbine uses fixed nozzle guide vanes which can be changed to optimise the match of the TG to each application. The power electronics are also developed in-house and deliver an overall electronic conversion efficiency of approximately 98%, ensuring maximum benefits for the end user.

These developments mean that the Turbo Generators have significantly higher uptime (99 percent even before allowing for engine downtime due to maintenance) and a proven record of a 7 percent reduction in fuel consumption. For gas reciprocating engines, the ETC can produce 6 percent specific fuel savings and 6 percent more power. As a result, engines can become far more efficient overall, delivering a greener carbon footprint. Less fuel, more power.

The system is cost efficient in comparison to other waste energy recovery technologies and depending on fuel cost can achieve a payback of significantly less than two years. It also offers full remote monitoring capability, allowing it to compare the total number of running hours since installation with the total number of elapsed hours since installation. In terms of general service and maintenance, requirements are minimal.

Empowering growth

Gensets and other distributed power systems will remain one of the most reliable alternative sources of energy for the foreseeable future. This means that focus must be placed on making these systems as efficient and cost-effective as possible with respect to fuel economy and power output. Savings on these costs can be redirected to product development, company expansion and employment creation, ultimately contributing to overall economic growth.

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