PacB Group // Diesel Generators to the Rescue?

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Diesel Generators to the Rescue?

Eskom CEO “André de Ruyter” assured South Africans there is no chance of a total collapse of the Eskom power system amid the ongoing outages. South Africans should be patient while the utility sorts out its immediate crisis. The reality is rolling blackouts that will last for an unspecified duration and a fundamental lack of confidence among South Africans in Eskom’s ability to turn the situation around.

Eskom has unfortunately made a number of assurances in the past that they have failed to stick to. A recent study indicates that South Africa is generating less and less electricity, with Eskom producing less electricity in 2020 than it did in 2004. De Ruyter blamed municipalities that refused to implement load shedding for contributing to persistent power outages and obliging Eskom to go from level 2 to level 3 or 4 load shedding.

Many commentators think that the situation is far worse than Eskom will admit, as they struggle to keep the lights on. Eskom’s financial situation is even more woeful with results for the year to the end of March 2020 revealing that Eskom suffered a net loss of over R20 billion. Many South African businesses and individuals are being forced to turn to alternative sources of energy to ensure reliable electricity supply. Diesel generators are one of the solutions commonly adopted.

Why Diesel Generators?

Utilities (Eskom for South Africans) produce electricity as required. In other words, the power is used as it is made, and in most instances, cannot be stored for future use. There is some reserve capacity provided by pumped water schemes, such as those at Steenbras, Drakensburg, Palmiet, and Ingula but these only provide a maximum of 2910 MW.

Fundamentally, the blackouts result from inadequate generating capacity. Ageing, poorly maintained power stations fail regularly, severely curtailing generation. The new units at Kusile and Medupi have been plagued with poor performance due to design and construction flaws leading to continuing load shedding. So, why go with diesel generators to keep your business operational or your home comfortable while Eskom attempts to sort themselves out?

With regard to the domestic user, there may be some debate between employing diesel generators or perhaps some sort of solar solution with batteries. When it comes to commercial and industrial users though, diesel generators offer a number of clear benefits over most other possible alternatives. Diesel generators are currently the best grid backup solution for larger users of power. Compared to most renewable energy solutions, diesel generators of comparable size will have significantly lower capital cost.

They are also far more rapidly deployable, so can be brought into operation quickly – saving a company from the costs of production losses and other losses caused by the inability to operate as normal. They do, however, have higher running and maintenance costs, which need to be taken into consideration.

Diesel Generators and Renewables

The biggest advantage that diesel generators have over most renewable energy alternatives is the fact that they offer reliable continuity of supply. As long as a generator is maintained and supplied with fuel, it will deliver power day and night, sunshine or rain. The same cannot be said for solar power systems, for instance. If the sun goes behind a cloud, the output of a solar plant will drop rapidly and significantly. This is not a good thing if your business is reliant solely on this source for its power. Inconsistency in supply from solar plants (wind power also has this characteristic) is known as intermittency. To overcome intermittency, some form of storage or co-generation is required. Usually, batteries are used for storage and diesel generators for co-generation. Even though the price of battery storage has come down substantially in the last five years, large-scale battery storage still has high capital cost, leaving an important role for diesel gensets. Back-up systems for commercial and industrial concerns can be created using a blend of renewables and generators using no energy storage.

A micro grid with only diesel generators and solar PV can be created where real-time solar PV’s intermittency is mitigated by using gensets as spinning reserves to iron out dips in solar production. Due to the minimum loading requirements of gensets (a generator can be damaged if it is run at very low loads), capacity of the PV component is typically limited to around 60% of daytime load.

Batteries may be added to such systems to cope with the solar intermittency so that the genset is only run at night. It is possible to create a system that does not run diesel generators at all, but this option tends to be more costly. Solar PV is sized to provide the total load’s 24-hour energy needs, including the round-trip losses of the battery energy storage system. Sophisticated electronics intelligently charges and discharges the battery during the day, mitigating solar intermittency (known as short-term intermittency). The system draws power from the battery when the sun goes down, mitigating long-term intermittency.

Diesel generators are still an essential component in a blended renewable power system, but as solar panel and battery storage prices fall and diesel fuel prices increase, these systems will become more and more biased towards systems with bigger battery components and less diesel generators.

Generators in the Residential Space

The fact that there is a substantial difference in upfront cost for a solar back-up system as opposed to using a generator makes going the generator route more attractive to cash-strapped residential buyers. For many homeowners, back-up power is very much a grudge purchase forced on them by Eskom’s unreliability and the inconvenience that results from the continuous load shedding. The fact that the Covid-19 pandemic has left many people working from home makes it even more important that they have some form of back-up power at home. Residential buyers typically have a choice between petrol-powered and diesel-powered generators.

Large capacity gensets are usually only offered with diesel-powered engines. Petrol-powered units are typically less costly than an equivalent diesel-powered unit and can be found in smaller sizes than diesel units. Generally, it is better to pay more and get a diesel-powered unit. They start more reliably, run more efficiently, and provide more stable power output. Stable power output is particularly important where the generator is intended to run in conjunction with a solar power generation system.

Generators – Who to Buy From

Whether large commercial or residential scale, it is important to do your homework and look for the right company to engage with when buying a generator. The common-sense questions need to be asked. How long has the company been in existence? Does the company provide recognized brands of equipment? Do they have a good reputation in the marketplace? Will they provide support for their equipment into the foreseeable future? This is particularly true for commercial- and industrial-size generators where the consequences of choosing badly, financially and operationally, are severe. Go with a reputable company like PacB who have the products, technical competence, and track record to ensure a “no regrets” experience.