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Backup Power Solutions for a South Africa in the Dark

The Need for Backup Power

Chronic problems at Eskom, particularly in their coal-fired generation division, are leading to insufficient generation, grid unreliability and an ever-decreasing confidence in Eskom’s ability to provide continuous, reliable, electricity. The picture in the short to medium term appears especially bleak. At the end of 2021, Eskom’s energy availability factor on their coal-fired generation fleet was 55.5%, which is extremely low by any standards. As of the end of March 2022, the energy availability factor rose to 62% but this was still substantially below the 74% target they had set themselves. The reality is that Eskom needs an additional 4000 to 6000 megawatts of capacity which they will need to find funds for. Eskom finds itself in the position where it needs to install additional capacity but is spending billions of rands on diesel to run its open-cycle gas turbines to maintain continuity of supply during the daily domestic peaks.

With Eskom likely to continue struggling to provide stable electricity supply, it is going to be prudent for commercial and industrial businesses to begin budgeting for some form of backup power solution. Backup power, whether in the form of a diesel generator or renewable energy plant with energy storage for longer outages, or an uninterruptable power supply (UPS) for shorter-term backup power, is going to become a necessity. Procuring a backup power solution is typically viewed by business managers as a grudge purchase but it is rapidly becoming an essential cost of doing business. The cost of procuring a backup power solution should be set off against the costs of grid outages. Direct costs caused by interruptions to production, wasted materials and ‘idle’ production and administrative staff are easy to quantify. Poor customer service, a loss in sales and reputational damage due to failures to deliver on time are more difficult to assess accurately.

For some industries, backup power is vital for their operations. Businesses that run sensitive electronic equipment such as computer servers and other Information Technology (IT) equipment cannot afford to be without stable, ‘clean’, electricity. Datacentres, for example, require sophisticated backup power solutions as grid interruptions can result in considerable financial losses.

What Backup Power Options are There?

Generators are the backup power source most commonly turned to by businesses. Generators were made possible by the discovery of the laws of electromagnetic induction by Michael Faraday in 1831. They are electro-mechanical devices that convert rotational kinetic energy into electrical energy. The rotational kinetic energy is typically provided by burning fuel in an internal combustion engine which releases the chemical energy stored in the fuel. The rotational energy is used to rotate an armature in a magnetic field produced by a series of magnets. Most larger capacity generators use diesel as the fuel source but petrol, natural gas or even steam can be used to turn the armature.

A UPS is another backup power option available to business owners. These devices are usually based on battery technology and rely on the electrical energy stored in the chemistry of the battery to energise loads when the grid fails. A UPS uses an inverter to change DC current from a battery into AC current for the loads.

Diesel Generators for Backup Power

A generator is often called a ‘genset’ because it is made up of two primary components, namely an engine, usually diesel, and an alternator. Generators typically produce alternating current (AC) in three-phase or single-phase sine waves. The waves produce AC voltage for each revolution which produces continuous, stable output if the engine runs at stable revolutions per minute (RPM). One of the benefits of diesel-fuelled engines is that they provide stable, constant, RPM and therefore produce continuous, stable output. Diesel generators can also be configured to produce direct current (DC) output by using a dynamo instead of an alternator. Most modern appliances and electric motors run on AC, so generators configured to output DC are rare. Early generators were initially driven by steam engines and it was only after the invention of the first compressed charged, compression ignition engine by Rudolf Diesel in 1892, that more and more diesel generators began entering the market. Even early prototypes of Diesel’s engine demonstrated efficiencies of over 26 % compared to the steam engines of the day which could only manage efficiencies of about 10%. Three-phase gensets are considered superior to single-phase machines. Three-phase gensets weigh less, are more efficient, cost less and take up less space (have higher energy density), than a single-phase generator of similar capacity. The characteristics of three-phase gensets are particularly well suited to sites with high load and constant demand.

The downside of a diesel generator as a backup power solution is the fact that it takes time for the engine to start and ramp-up to full capacity. In some applications, this may not be a problem but at sites running sensitive IT or medical equipment, for instance, the handover time is far too slow. While the upfront cost of a diesel generator may be relatively lower, the running and maintenance costs are high compared to some of the other possible solutions.

UPS-Based Backup Power Systems

A UPS is a device that allows electrical equipment to continue operating when grid electricity is unavailable. A common example is the UPS that keeps your computer running while you save your work and shut down until the grid is restored. While grid is present, energy stored in the batteries is kept topped up or is replenished after outages. The more energy stored, relative to the the load that needs to be carried, the longer electrical equipment will function in the absence of grid. Energy stored in batteries is delivered as direct current (DC). This means that electrical energy stored in batteries needs to be converted to alternating current to make it suitable for most appliances. A battery-based UPS will continuously use grid electricity to charge the battery and energise any loads on its output until the grid fails, after which it converts stored battery energy into AC for the devices connected to it.

UPS systems are great backup power solutions for sensitive electronic equipment, as electricity is available immediately should the grid fall away. The primary shortcoming of a UPS solution is the fact that batteries are still expensive, so at sites where large loads need to be carried for long durations, cost becomes prohibitive.

Contact The Backup Power Experts

PacB are industry leaders in the provision of diesel generators, renewable energy solutions and UPS units. We can assist with units from as small as 1 kVA through to and including 800 kVA UPS units. Our competent technical team is always available for telephonic or on-site assistance to support our products. Contact PacB today for your backup power solution.