Modern technologies, which have already impacted the way we communicate, are entertained, work and live, are about to change the way we generate, use and pay for electricity. The digital age, which was born with the invention of the microprocessor integrated circuit in the late 1960s, has revolutionised modern society. Digital techniques are used in virtually every sphere of modern life. Everywhere, that is, except the power system. But that is about to change.
South Africa’s electricity systems and networks are built according to designs which are almost 100 years old. These designs are based on the concept of large, remote power stations, generating electricity by burning coal and transmitting that electricity to points of load in industrial, commercial and residential areas. These power stations were built near coal mines for ease of coal transportation, as it was cheaper to transport electricity over long distances, than coal.
Developments in modern technologies however, make it possible to generate electricity more efficiently, more cleanly, and more cheaply than ever before. The problem with our existing power stations is the fuel they use. Coal is dirty and expensive. Its costs relate to more than simply the financial cost of digging it out of the ground and transporting it to a power station.
The cost of coal is high in terms of the lives which are lost in the mines and at power stations; the diseases people who live near coal mines suffer from; the environmental damage caused by the toxic gases and deadly particulates which are emitted into the air from coal-fired power stations; as well as the destructive exhaust gases which are emitted from the large multi-tonne lorries which transport coal from mines to power stations, in some cases hundreds of km away.
The so-called “fourth industrial generation” – the digital age – offers technologies which are far more efficient, less costly, and much cleaner. Electricity can now be generated close to the point of load without causing environmental harm or personal health problems. The sun’s energy is being harvested and converted to electrical energy. The efficiency of the devices which achieve this is improving dramatically. Wind energy is being converted to electrical energy, as is the natural flow of water as the force of gravity works upon it causing it to fall from a higher to a lower level, either in a dam or in a river.
These natural forms of energy are considered renewable, because the sun, the wind and gravity are inexhaustible sources of primary energy.
Wind and solar energy, however, tend to be intermittent and can be unpredictable. The electricity generated by these natural forms of energy is therefore somewhat unreliable. The solution is to generate more than immediately needed and to store the excess for when the electricity output from these devices is less than what is needed.
Modern technology has come to our aid here too: energy storage devices are becoming more efficient, more reliable and more affordable than ever before. Major strides are being made in the development of batteries. New chemical processes are being developed with ever-increasing energy capacities within shrinking battery case sizes.
This is happening in small-scale applications, such as in small handheld portable equipment, and large-scale applications such as tens, and even hundreds, of MWh. Halfway between these extremes are the batteries being used in electric vehicles. Their energy storage capacities are increasing to the point where a modern electric-power car has almost the same range as a car with an internal combustion engine and a 50 l fuel tank.
According to Prince Moyo, a senior manager at Eskom’s technology division within its generation group, Eskom is actively involved in the development of utility-scale battery storage systems and technologies at its research, testing and development centre in Germiston.
Speaking the recent SA Energy Storage, SSEG and Smart Grid conference at Emperors Palace, Moyo said that the power utility is building and testing a 360 MW/1440 MWh battery which it plans to connect to its distribution grid.
Moyo says that this battery system is similar in size to what the power utility’s planned – but subsequently shelved – concentrating solar power (CSP) plant would have produced. It can therefore be seen that battery-based energy storage systems (BESS) may supplement, and ultimately replace, gas-fired, and other peaking plants.
This battery has the power capacity equal to Eskom’s Acacia and Port Rex gas turbine-powered peaking plants combined. Unlike these peaking plants, however, the battery does not require expensive fuel. This enormous battery will complement the power utility’s other energy storage facilities: Drakensburg, Palmiet and Ingula – all of which are pumped-water energy storage systems – to provide a combined installed capacity of 2732 MW of electricity for the utility to use during peak demand.
Thava Govender, Eskom’s group executive responsible for generation, risk and sustainability, who also presented at the conference, says that the power utility’s vision for 2030 and beyond includes renewable energy, battery storage and smart grids to provide the country with safe, reliable, affordable and energy-efficient electricity services. Furthermore, Jeff Radebe, the minister of energy, whose speech was delivered by Thabang Audat, says that energy storage systems, embedded generation and smart grids are all interconnected, necessary and unavoidable in future electricity networks.
Furthermore, as Govender says, since Africa has large deposits of lithium, vanadium and cobalt, the continent could become a major battery manufacturer supplying high quality, utility-scale battery storage systems to the rest of the world.
We stand on the threshold of a new paradigm: one where consideration of the environment, people’s health and well-being dictate how the generation, distribution and use of electricity is to be managed.
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Source: EE plublishers