PacB Group // The Role of Industrial Diesel Generators

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The Role of Industrial Diesel Generators

Industrial diesel generators have become popular throughout South Africa since load shedding was first introduced. In order to carry on with business, many companies have been forced to turn to alternative power sources, such as diesel generators.

How does one measure the costs incurred by industrial companies due to power outages? Various methods are used, including looking at the value added by the company. The revenue from product sales is subtracted from the purchases of intermediate goods and services from other concerns. It is critical to understand the real opportunity costs of lost production caused by power outages.

An accurate determination of outage costs informs decision making on what steps can be taken to mitigate the impact of the losses and what level of investment in alternatives is justifiable. For many industrial entities, industrial diesel generators are the only realistic alternative to grid power. However, industrial generators (also known as gensets) are an expensive alternative to grid electricity.

The frequency and duration of the power outages determines the level of productivity disruption and lost revenue. Ironically, developing countries are more frequently the victims of unreliable supply than first-world countries are. South Africa has the largest per capita quantity of backup generators in Africa.

The Impact of Unreliable Grid Power

Power outages increase production costs, create operating uncertainty, cause spoilage of in-process materials, and have been known to damage plant and machinery, all translating into financial losses. Where grid power is unreliable, industrial producers suffer from budget overruns due to the cost of being forced into more costly alternatives. Tighter operating budgets necessitate cost cutting in other essential business operations.

Loss of revenue is another consequence of unreliable grid power. Operations affected by power outages are unable to deliver services or products to their customer base. Customers are sometimes forced to find alternative providers of these services and products and their support may be lost permanently.

Power outages may also damage or destroy inventory in industries with perishable or temperature-sensitive products. Unreliable grid power almost inevitably causes losses in productivity as plants cannot run or operate at sub-optimal levels. In developing countries, the unreliability of electricity supply offsets the lower labour costs, often making production in developing countries less competitive on global markets.

Industrial diesel generators are currently the go-to solution for industrial-scale power users because they offer rapidly deployable reliable power at reasonable capital cost. Renewable energy solutions find it hard to compete in terms of both capital cost and reliability of supply. Industrial diesel generators will, however, typically have higher running and maintenance costs.

Industrial Diesel Generators – Why Diesel?

A question that arises is: “Why industrial diesel generators and not generators powered by some other fuel type?” There are a number of different types of fuel that can power a generator. Generators are commonly powered by petrol, diesel, natural gas, or propane but there is no reason why they could not be powered with hydrogen, methanol, or even coal. So, why is diesel the number one-choice for industry?

Petrol as a fuel for generator engines has some significant drawbacks, especially as the generator increases in capacity. Petrol is more flammable than diesel, so storing large quantities becomes hazardous.

Petrol has a relatively short shelf life and needs to be consumed within approximately twelve months, and so, is not suitable for long-term storage. Petrol-powered generators, especially smaller ones, are difficult to design to run at stable revolutions per minute (rpm) and are typically more difficult to start reliably. The primary drawback is running cost. Petrol-powered generators are far less efficient than diesel units.

Propane is another fuel used to power generators. It has a long shelf life, is very clean burning, and can be stored in tanks from small portable cylinders to large industrial tanks. On the downside, pressurized cylinders of flammable gas are inherently dangerous and stringent safety requirements must be met and maintained. The fuelling system for a propane-powered engine is more complicated, which increases the possibility of failures. Natural gas has similar properties to propane but has around 30% less energy density and is not available everywhere.

Diesel is easily obtained and the least flammable of the commonly used fuels. Although the calorific value of diesel fuel is slightly lower than petrol (roughly 45,5 MJ/kg versus 45,8 MJ/kg for petrol), diesel fuel is denser than petrol, containing approximately 15% more energy by volume. With an eighteen- to twenty-four month shelf life, diesel can be stored for longer than petrol. Industrial diesel generators are more efficient than other fuel types. They are typically chosen for their efficiency and low maintenance. Most industrial diesel generators provide substantially more power per litre of fuel than comparable petrol-powered generators. Diesel generators are, however, more expensive than comparable petrol models.

Industrial Diesel Generators – What Type and Size?

Specifying a generator suitable for industrial power generation is a complex exercise that requires specialist knowledge to ensure that a well-informed purchasing decision is made. Is a prime or standby power generator required? Prime power generators are the main source of power at a facility, whereas standby generators are used when the main source of power fails. Prime power generators are run continuously, making fuel supply and maintenance critical. An external large capacity fuel tank will be required to run a prime power generator.

Standby industrial generators are designed to run when the primary provider of power, typically the grid, fails. An automatic transfer switch (ATS) is required to transfer power from the primary source to emergency power from the generator. An ATS senses the power interruption and signals the engine to start. When the primary source is restored, the ATS transfers power back to the grid and shuts the generator down.

Automatic Transfer Switches are typically used in environments, such as manufacturing plants, telecommunication facilities, data centres, hospitals, and sites where continuity of supply is critical. Standby generators must be run periodically as part of a maintenance regime to ensure that they start and supply power when required. Standby generators require battery chargers to keep the starting batteries fully charged for start-up.

It is also advisable to fit a water jacket or sump oil heater to keep the engine at a pre-set temperature to aid in cold starting. This also reduces engine wear and emissions from the engine when cold.

A certified electrician with specific experience in industrial generators is needed to determine power needs at a site and help propose the best solution.