Mechanical Technology December 2015

⎪ Sustainable energy and energy management ⎪

Game changing hybrid solar-diesel solutions

variations in demand or of PV production losses, for example due to cloud shading. Says Thomas Hillig, CEO of THEnergy, a consultancy that assists companies in dealing with energy-related challenges and to develop sustainable energy solu- tions: “The demand for raw materials has slowed and commodity prices have decreased recently, causing the mining industry to face substantial challenges. Reducing costs of operations such as en- ergy expenditure has, therefore, become an important competitive factor. “Low-load diesel hybrid power plants, which can maximise output from locally produced inexpensive solar and/or wind energy plants can be game changers. Even at currently low oil prices, opti- mised hybrid technologies can undercut the conventional diesel-based electricity prices. The additional investment for a hybrid system, including the PV system, usually has a pay-back period in the range of four to seven years,” he says.  “We see significant market poten- tial for these low-load gensets, especially in the mining industry where power de- mand is high and conventional sources are not always readily available – and several energy companies are reporting projects in the pipeline,” Hillig concludes. The study can be accessed from the English tab of THEnergy’s website (www.th-energy.net) on the renewable energy and mining platform page. q

A new approach is emerging from the genset industry that promises to overcome the limitations of traditional gensets, maximise the potential of solar PV systems and to reduce operating costs for mining companies.

C onventional gensets are typi- cally optimised for efficient op- eration at their operating load points, which causes them to be inefficient under low-load conditions. In so-called solar-diesel hybrid applica- tions, gensets balance the intermittencies from the solar plant – for example, when clouds shade the PV array. An attractive target for solar-diesel hybrid plants is the mining industry as power consumption is usually high and mines are typically in remote locations with high costs for diesel and for the delivery of fuel to site. As the future market potential of solar-diesel hybrid solutions has become more explicit, the diesel genset industry has reacted by launching a first-of-a-kind solution, which is specifically optimised for balancing solar plants. Danvest Energy, an innovative diesel technology company from Denmark and a world leader in hybrid wind-diesel power, has introduced its Power Box solution based on gensets driven by either CAT or Cummins engines. These traditional gensets are modified so that they can run at low-load and operate in a reverse mode, whilst hardly consuming any die-

“Danvest low-load generators have been used in combination with wind turbines for years. As the solar-diesel market receives more attention than the wind-diesel market at this moment, we have adapted our field-tested solution for this very dynamic segment,” explains Thomas Qvist Vestesen, Danvest CEO. A recent study, ‘Low-load Gensets for Solar–diesel Hybrid Plants in the Mining Industry’ analyses the technical and strategic fit of low-load gensets for solar- diesel hybrid applications. It integrates several tests and verifies market-related questions through 21 expert interviews. In addition, several business cases are simulated. The study shows that low-load gensets almost double the solar penetration rate in solar-diesel hybrid systems and that low-load diesel gensets are more efficient in hybrid plants, all this without the use of batteries or other storage systems. This straightforward solution has the potential to considerably lower the opera- tional costs of mines. The fast spinning reserve of the low-load diesel systems in all modes of operations ensures a continuous supply of power regardless of

sel, but with the full ability to respond quickly to output changes from the PV array or to changes in demand. On sunny days, penetra- tion of the PV system can reach 100%, while the die- sel consumption is almost zero. At night, when the PV plant does not gener- ate electricity, the low-load diesel gensets are run as normal diesel gensets to power the mine. Danvest’s experience suggests that increased wind and solar penetration can result in annual reduc- tions of fuel consumption and carbon dioxide emis- sions of up to 70% com- pared to conventional diesel generator plants.

A recent study, ‘Low-load Gensets for Solar–diesel Hybrid Plants in the Mining Industry’ shows that low-load gensets almost double the solar penetration rate in solar-diesel hybrid systems and that low-load diesel gensets are more efficient in hybrid plants.

Mechanical Technology — December 2015

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