Reduced energy costs for Namibian dairy farm

16th December 2019
Alex Lynn

Biogas, consisting of approximately 97% methane, is the most environmentally friendly fuel available. However, when one dairy farm in Namibia aimed to shift its entire energy supply to biogas electricity generation, too-high electrical currents and potential power quality issues meant harmonics and surge protection specialist, CP Automation was required to help with the green-project. 

The dairy farm business was in the process of commissioning a biogas generator to use biogas from the cattle waste products. The end-goal was to drastically reduce energy costs and environmental impact, but meeting this objective was not a straightforward process.

Unfortunately, the biogas generator could not accommodate the start-up current of the motor, it was too large compared with the current rating of the biogas generator.

Working with Namibia-based electrical solutions provider, EcoProjects, three 75kW Rockwell variable speed drives (VSD) were installed to bring down the start-up current. The Rockwell drives were selected for their quality and competitive pricing. Notably, EcoProjects is the only certified systems integrator in Namibia for Rockwell products.

However, as with all VSDs, this piece of equipment can generate harmonic noise that can be damaging to peripheral equipment if not treated. This distortion can affect the generator voltage control system and as result have a knock-on effect on system stability of the entire system.

With this biogas energy generation system, additional power quality issues can also be caused by transient surges in power supply. To solve this issue, EcoProjects required additional power protection equipment, to alleviate problems associated with harmonics and transient surges.

However, Rockwell do not provide harmonic filters and transient suppression devices required for the project. Using third party equipment on Rockwell products would normally result in voiding the guarantee — a dangerous risk for such as large-scale project. Luckily for EcoProjects and the client, Rockwell had a product partnership with power quality and surge protection specialist, CP Automation.

The partnership means that Rockwell products keep their guarantee, even when used alongside CP Automation’s products from other manufacturers. This isn’t the first time EcoProjects relied on the Rockwell-CP Automation partnership. In fact, back in 2017, EcoProjects worked with both businesses on a Rockwell Automation project to pump underground boreholes and alleviate drought in Namibia.

To solve the Rockwell guarantee issue, CP Automation joined the dairy farm project and suggested Revcon harmonic filters and a SineTamer surge protection device. The parts were in stock at CP Automation’s site in South Africa, ready to be shipped to the dairy farm ahead of the farms scheduled date to disconnect from the electrical network. By delivering this part on time, the project was on track to run entirely from the biogas generator before the deadline.

Unfortunately, there were challenges with shipping the products. During a public holiday in South Africa, the courier company that was supposed to pick up the equipment, didn’t. This let down from the courier was certainly an inconvenience but didn’t deter CP Automation from getting the parts to the dairy farm.

CP Automation arranged an alternative driver to take on the 2500km drive and got the parts to the customer with time to spare.

In combination, these parts proved crucial in improving the power quality to the generator and ensuring the longevity of all electrical equipment connected to the biogas system.

“Since the project finished, everything is running well,” explained Carlo van Heerden, Engineering Solutions Manager at EcoProjects. “Cost was a big driver in this project. Not only were the parts supplied price competitive, the customer can now generate electricity at a much cheaper rate — essentially for free.”

“This was another successful collaboration with Rockwell and EcoProjects,” added John Mitchell, Global Business Development Manager at CP Automation. “A key part of the success was the prioritisation of power quality. While harmonics are generally well-known and understood, transient surges are less commonly acknowledged, but just as damaging.

“The courier situation was a nail-biting moment, and we are very grateful to the delivery company, MIES International, that took on the mission at such short notice. We know who we can depend on in the future to get parts delivered across Africa in good time.”

The project certainly demonstrates the potential for more farming businesses to make use of the naturally occurring biogas available to them. But expert advice, and effective power quality will remain fundamental in implementing this green technology in farms all over the world.

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