If one is privileged to attend one of the growing number of conferences themed around investment in Africa’s power sector, what becomes conspicuous is renewables are being punted as the panacea to Africa’s power supply shortfall. Unwittingly, what is ignored, as countries are immersed in the renewables euphoria, is the urgent need for investment in the aging power infrastructure, which, currently, is the main source of electricity. According to analysts, the refurbishment of operating power plants to increase generating output can be executed at a comparatively cheaper cost. So, isn’t it about time governments review their priorities in power generation? Or at least maintaining a healthy balance between managing existing power plants and new projects?
In a bid to establish how the neglected practice of power plant rehabilitation can be revived, African Mining Brief analyses the current state of the existing power plants, the downside of the bias on capital intensive Greenfield projects, and the appropriate approach to retrofitting power plants.
Current state of power plants
In an article he wrote for the 2015 World Economic Forum, Klaus Findt, Chief Operating Officer of the KPMG Global Infrastructure and Projects Group in Africa, mentions a number of challenges that slowdown the performance of power plants. The challenges include underutilisation of generation capacity due to low maintenance of assets, high operational inefficiencies, ineffective transmission infrastructure and high transmission losses of up to 25%, poor planning, and low skills levels and management capacity.
Most perturbing about the situation is that most of problems that speed up power plant deterioration can be forestalled, with the right intervention. Granted, it is inevitable for low performance to be experienced in power plants at some point, but in some cases it happens faster than envisaged.
Findt captures the magnitude of the challenges that African countries face when undertaking new investments in power generation. Writing on the subject, he notes, “It is estimated that $300 billion will be needed for all of sub-Saharan Africa to have access to electricity in the next 15 years. Currently, we are at 25% which, if you consider consumption per capita, equates to one-sixth of the world’s average.”
Worse still, for all the potential they have, most African countries cannot attract investors as they are plagued by inadequate governance, due to a distinct lack of policies, regulatory frameworks in the energy sector, and a lack of independent regulators.
Evidently, it is better to manage the proverbial bird in hand that is aging power stations than be involved chase the illusion of the “Promised Land” of power supply sufficiency that greenfield projects present.
The viability of refurbishment
Two specialists, Dr. Klaus-Dieter Tigges of Babcock Borsig Steinmüller, and Mohamed Khan of Steinmüller Africa, have compiled a review establishing the viability of power plant retrofitting in Africa. The two posit that, based on experience, refurbishment and life time extension of existing plants is a good economical approach to assure generation capacity. They say, very often, this can be accompanied by a capacity increase through new technologies. “New capacity of a refurbished power plant is cheaper than a new build. In addition, the projects are implemented in a shorter time with minimal project risks,” Tigges and Khan assert.
The main objective of a power plant refurbishment project is improving the performance of the firing system. A refurbishment aims at improving reliability of a power plant which depends very much on the performance of the firing system.
Burners play a key role as they determine the requirements on furnace design and coal preparation, Tigges and Khan says. “There is a link between the reliability of a coal-fired steam generator with the performance of the burners. State-of-the art burners feature perfect flame stability and as a result allow a low burner part load.”
Using state-of-the-art burners offers a good potential for performance improvements due to their flame stability and low sensitivity to changing coal properties, Tigges and Khan suggest. “Very often boiler operation is affected by deteriorating coal properties making it very difficult to keep the units online and provide the required generation capacity,” they point out. “If burner modernisation is combined with an improvement of the entire coal handling and preparation system all prerequisites are on hand to get a reliable operation independent of coal properties.”
It is worth mentioning that there is no general rehabilitation approach for every power plant, since each site has unique conditions and constraints. For this reason, Tigges and Khan say, the perfect set of measures is determined by an analysis of existing problems and a compromise with regard to budget and allowable outage time. “Depending on the requirements of remaining life, a life time assessment can determine which components of the pressure part should be refurbished, modified or even completely replaced.”
Concurring with the two, Webb Meko, Business Development Director, Sub-Saharan Africa, Black & Veatch, advises power utilities to undertake the primary and certainly most important step of fully evaluating the condition of the existing equipment and infrastructure, thereby ensuring the site can support any proposed changes. Equally important, he adds, is the specification of replacement/new equipment, which should be carefully tailored to meet the anticipated demands that will be placed on the equipment once in service.
As a project approaches completion and, finally, commissioning, Meko recommends that the operator of the facility must ensure that the maintenance strategy addresses the appropriate mix of preventive and predictive technologies. This will provide the right maintenance at the right time and carried out by competent and qualified artisans. Therefore, training of the operations and maintenance staff is probably more important than any other element in the process.
Meko sees a huge potential for the power plant retrofitting market in Africa. As the population and development of the area continues to grow at a rapid pace the demand for power will grow significantly. “In many cases, there are opportunities to repurpose existing power generation equipment in order to best serve multiple objectives, particularly when increases in demand requirements are anticipated. Retrofit can often be accomplished at relatively low costs, using shorter schedules to achieve simultaneous reductions in energy costs, and increases in availability.
Further, what augurs well for prospects of power plant retrofitting is that many aging plants, regardless of their location, were built using technologies that have continued to improve in terms of efficiency, capacity and reliability, Meko highlights, citing advances that are most evident in gas turbine technology over the last twenty years. “Gas turbine capacity has increased by a factor of three or more while simultaneous increases in efficiency have led to better heat rates, lower fuel costs (per unit of output) and, in many cases, lower carbon emissions. Likewise, the understanding of failure mechanisms, as well as instrumentation and maintenance best practices to detail incipient failures now allow units to run longer between maintenance intervals.”