Sparks Electrical News August 2019

ENERGY EFFICIENCY

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TRENDS CREATING OPPORTUNITIES IN AFRICA’S ENERGY SECTOR A frica’s power and energy sector are catalysts for growth and de- velopment. To achieve its full potential, the continent needs to accommodate the energy needs of its citizens and that requires businesses and producers to stay abreast of the advances of the energy landscape. To this end, there are several developments influencing the economic and socioeconomic realms of Africa, including: • Greater investment in low-carbon technologies and sustainable en- ergy make coal power plants increasingly difcult to finance. • The growing inclination towards renewable energy in developing markets. • Battery storage gains momentum. • Development of decentralised distributed generation. • The progressive move towards integrated grids. The political and economic climate in Africa has improved over the past 20 years, making the continent a viable investment decision for interna- tional stakeholders. With its abundance in natural resources for power generation (vast amounts of solar, hydro, wind, gas amongst others), the African energy realm is undergoing a positive transition. These trends will be unpacked in detail at the Africa Energy Indaba in March 2020, where industry leaders will converge to discuss develop- ments in the sector, capitalising on opportunities while mitigating associ- ated threats. Having set the precedent of events in the energy sector, this Indaba is not to be missed by anyone with a vested interest in the African energy sector.

ACHIEVING GREATER ENERGY EFFICIENCY WITH THERMAL SOLAR

O ur country has some of the best sunlight in the world. With the current energy situation and ever-increasing electricity costs, we are forced to evaluate our energy consumption and implement more efcient and cost-effective solutions. There are two common ways to collect energy from the sun. One is to gather the sun’s heat through a thermal solar collector, and the other is to convert the sun’s energy into electricity via a photovoltaic (PV) solar system. In the case of solar thermal, the conversion ef- ficiency is much higher than PV. Another advantage is that solar thermal panels cost a small fraction of what PV panels cost per square metre. On the other hand, PV is more expensive and less efcient but the electricity generated from PV can be used for more than just heating up water. Into detail A thermal solar system can provide approximately 60% of the energy required each year for heating domestic hot water (DHW). The key element of a thermal system is the solar thermal collector, which absorbs solar radiation from the sunlight. The purpose of the collector is to efciently convert the sunlight into heat. The heat is transmitted to a fluid, which transports the heat to the heat exchang- er via pumps with minimum heat loss. The exchanger transfers the heat into the geyser. The distance between the collector and the geyser should be as short as possible to minimise heat loss. There are two main types of solar thermal collector available. The first, an evacuated-tube collector is made of parallel glass tubes. Each tube contains two glass tubes, between the two glass tubes there is a vacuum which allows small heat loss. The absorber is included in a tube. The second type is the flat-plate collector which comprises an insulated box with a glass or plastic cover on the top and a solar absorber located at the bottom. Evacuated-tube collectors are more expensive than flat-plate collectors, however, they can achieve higher efciencies. Achieving optimum heat yield The integration of solar thermal systems requires precisely matched individual components to achieve optimum heat yield and to keep costs under control. This must be supported by the right system engineering. Solar water heating systems almost always require a

backup system for cloudy days and times of increased demand and therefore most solar water heaters require a well-insulated storage tank or DHW cylinder. Dual mode DHW cylinders work to heat the DHW with separate indirect coils that are connected directly to the solar thermal system. DHW is also heated by a boiler via an indirect coil arranged in the upper section of the cylinder. The demand for hot water varies considerably from household to household. The number of occupants has to be taken into account, as well as their bathing and showering habits. For example, if three members of a family set off for work and school at the same time, lots of hot water needs to be continuously available for the shower in a short space of time. Those who prefer a bath will want enough hot water to fill the tub. The DHW cylinder should also be able to provide sufcient water if hot water is drawn from more than one outlet at the same time, in apartment blocks for example. Vitocell DHW cylinders fulfil these requirements in every respect and can also meet every aspiration where equipment levels are con- cerned. In all instances, the installation of a solar thermal system is recommended to save energy and heat water without cost.

By Nicole Viljoen, project manager at Energas Technologies Enquiries: +27 (0)11 397 6809

Enquiries: www.africaenergyindaba.com

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IS LOAD SHEDDING THE NEXT BEST THING TO ‘GOOD, CLEAN, STABLE POWER’?

D ays are longer, and that’s when the cold really kicks in. Regular calls to button up and stay warm are here, together with the reminder to minimise our electricity usage. As avid consumers of Sparks Electrical News, we know the ‘family hold back’ in our energy consumption is to minimise the like- lihood of brownouts/blackouts and load shedding, but also an attempt to contain our utility bills! During times of frequent or pro- longed voltage fluctuation and pe- riods of over or under (low) voltage, one should consider a more long- term solution other than simply disconnecting the load to protect it from damage. The immediate con- sideration is given to emergency back-up power in the form of gen- erators or UPS systems. Although viable, and indispensable for es- sential services, these solutions do have their associated running and maintenance costs. The power coming through such back-up systems can be stabilised by installing an Automatic Voltage Regulator (AVR), consequently cut- ting energy costs and increasing operational efciency. Sollatek’s AVR solution reduces the running cost on the diesel generators on which many essential service sites depend. It also enhances the work- ing conditions for the generators and, as a result, reduces their main-

input voltage range, which means diesel generators need only oper- ate in cases of total power-cuts or severely inefficient voltage supply by the local grid. Ideal for use with sensitive electronic equipment in harsh working environments, the AVR’s solid state design (no moving parts) requires very little or no maintenance. With a rapid response time (within 15 millisec- onds) the AVR delivers ‘over’ and ‘under’ voltage protection, with class 1 lightning protection as an option. Therefore, using Sollatek’s AVR, essential services sites en- joy significantly lower fuel and energy costs, reduced time and inconvenience in running diesel generators, as well as unbeat- able protection from surges and spikes.

tenance requirements. Similar ben- efits can be accrued with battery back-up systems where batteries are charged quicker but can also be reduced in size. A major telecommunication firm has found that its diesel generator’s runtime could be reduced from 24-hour operation to only 10-12 hours per day. This has saved the company at least $18 000 a year on fuel costs, thus the AVR has paid for itself in a very short time. Additional advantages of the Sol- latek AVR for the site include silent, fume-free running for much of the day in contrast to the constant high noise levels experienced previ- ously. Furthermore, the generator monitoring, maintenance, servicing and spare part costs have all been reduced. Sollatek’s Automatic Voltage Regulator has an extremely wide

Enquires: nick.allen@sollatek.co.za

SPARKS ELECTRICAL NEWS

AUGUST 2019