Save Money, Cut Emissions: How Improving Generator Maintenance Reduces Cost of Ownership

If a generator isn't getting used day by day, it still needs to be run regularly as part of its maintenance program. 

Sometimes this exercise run is required by legislation, and sometimes the operators undertake it to give themselves peace of mind. They want to make sure that, when there's a loss of power, their diesel generator will be ready and available.  Many genset manufacturers also require this exercise as part of the product warranty coverage.

These regular exercise runs use expensive diesel and create greenhouse gas (GHG) emissions. But with smarter maintenance, operators can minimize the fuel used, saving US$1,300 per generator annually. In this article, we'll look at how this can be done in practice.

Running loaded exercises

Traditionally, when a customer undertakes an exercise, it would be loaded. That means we put some load on the generator, usually 30% of its rated capacity, ensuring that the generator reaches a required operating temperature.

The generator needs that temperature to ensure that any unspent fuel from the combustion process will burn up and not become excess fuel in the fuel and exhaust system. If this is not done, then 'wet stacking' will occur – this is hydrocarbon build-up in the exhaust system, leading to decreased generator performance over time.

With the current loaded practice, the presence of the load requires additional fuel. There is also the labor associated with having to set up load banks, and all the cabling that goes along with that – which quickly gets expensive.

The other side of this is emissions: more fuel means more exhaust emissions. As well as that, running a loaded exercise can create black smoke associated with all the load changes the engine sees.

Unloaded exercise program

To address these issues, Kohler has launched a program called Conscious Care^TM, which enables exercises to be run without a load. The unloaded test only requires the generator to be run for 10 minutes, compared to 30 minutes to one hour for a traditional test with a load.

The Conscious Care program is being rolled out on Kohler's KD Series generators. This modern engine utilizes the latest in fuel system and combustion chamber design to optimize the combustion process to the particular needs of the situation. For example, since the fuel system is able to accomplish multiple fuel injections per cycle, the combustion of fuel can be done efficiently thus reducing hydrocarbon accumulation at low loads and emissions.

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Figure 2. No-Load Exercising means customers can reduce GHG emissions by 40% per year compared to loaded cycles while also delivering a 44% reduction in fuel consumption. With the use of HVO fuel (Hydrotreated Vegetable Oil) instead of fossil fuel, the generator’s carbon footprint is reduced even further throughout the product’s life cycle

This all allows exercising to be done with no load, whether that's monthly or every four months. It is followed by an annual loaded exercise on the engine. By not having to do a loaded exercise every month, the operator reduces fuel consumption, saves money, and cuts their emissions.

If the operator also chooses to use HVO fuel (Hydrotreated Vegetable Oil) instead of fossil diesel fuel, it reduces the carbon footprint even further, by as much as 90%, throughout the product's life cycle. HVO is a liquid fuel synthesized from waste vegetable oils or animal fats using a unique hydrotreatment process. Unlike first-generation biodiesels, HVO is an entirely renewable energy source that does not impact crop resources. All KD Series generators are compatible with HVO fuel.

Cost savings quantified

It might sound like a simple change, but the financial savings from switching to regular 'no load' exercises can be significant. As you might expect, running unloaded consumes much less fuel than when a generator is loaded.

If a generator operator is currently doing a monthly loaded exercise, and now they switch to the monthly no load exercise, that alone will give them a 44% saving in fuel consumption. If the operator then chooses to run the exercise every four months, they will achieve a typical 71% saving in fuel consumption.

The emissions benefits are of a similar scale. By switching to a monthly no-load exercise, the operator will achieve a 40% reduction in emissions from the exercise operation every year. With an exercise regiment that is every four-months, they will now achieve a nearly 70% reduction in greenhouse gas emissions just from these changes. 

Suppose we look at the United States and the average cost of a gallon of diesel today; that comes out to be over $800 per year savings for just the fuel used for exercises. If we take that same evaluation and look at now running the exercise every four months, there are over $1,300 per year savings in fuel. Of course, when you do this every year, and if you have multiple generators, the financial savings can start to add up very quickly. 

The other primary cost savings for operators are due to the nature of the load itself. When they do a loaded test, many operators will bring in a load bank and connect that to apply the load to the generator. Not only is there the potential cost of renting the load bank and the logistics to get it there, but there is also a lot of labor to connect everything. A typical load bank might have 30 leads coming off it. Let's say they typically weigh around two pounds per foot, and there might be a length of 100ft per cable – that's a lot of heavy, difficult-to-move cables that need connecting to do the loaded exercise.

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Figure 3. Conscious Care applies to all KD Series generator sets using fossil diesel or HVO, including those currently in the field - without any modification

And then there are other benefits: there is a noise reduction when running with no load compared to load, and less exhaust smoke, as the generator doesn't have to adjust to step changes in load. You can also run the no load exercise at idle mode, a slower engine speed, which further reduces the perceived noise by over 50%.

Smarter and greener maintenance

Diesel generator operators want to have the resiliency that generators bring for mission-critical power, but they want to do it in the most environmentally friendly way possible. By switching to 'no load' exercising as part of their maintenance program, they can achieve significant reductions in both costs and emissions, with no decrease in the performance or reliability of the generator.

These financial savings lead to an overall reduction in the total cost of ownership (TCO) for the product. It's a win-win, where operators save money while getting more environmentally friendly. Kohler is working to add more intelligence to the generator as it develops the Conscious Care program, reducing fuel consumption from today's levels, and bringing down costs and emissions even further.

Conscious Care also fits within a broader ecosystem of cleaner technologies that are helping reduce the impact of Kohler generators. As mentioned, HVO can be adopted as a slot-in renewable fuel for mission-critical generators, reducing greenhouse gas by up to 90% throughout the lifecycle. Meanwhile, equipment such as selective catalytic reduction can be deployed where applicable as part of an exhaust after-treatment system for near-zero NOx emissions at the point of use. And then, Conscious Care maintenance protocols save fuel and reduce emissions over the long term.

For end users, this ecosystem of technologies combines to deliver sustainable and resilient mission-critical power on the route to Net Zero.

Kohler