No full-coverage power supply? For many, that may seem inconceivable but it is still a common problem at mines located in remote areas. Often, diesel gensets are the only solution. Generating electricity from renewables like wind and solar would obviously be a more sustainable approach but what happens when the sun is not shining and there is no wind? In La Muela, Spain, Spanish power plant manufacturer Gamesa is currently testing a combination of these three sources of energy. The company’s hybrid power plant consists of a photovoltaic system, a wind-powered plant and diesel
gensets based on Series 1600 units from MTU Onsite Energy assembled and delivered by MTU Ibérica – a sustainable, ecologically sound configuration.
Why do we need a hybrid power plant?
If needed, diesel gensets will provide reliable power around the clock, 365 days a year. At the same time, current trends are towards alternative and sustainable power generation technology employing sources such as solar and wind power. Although these are environmentally friendly as well as virtually inexhaustible, they are neither continuously available nor predictable. At night, without sunlight, photovoltaic cells do not produce power. And with no wind, turbine rotors do not turn. That leads to supply fluctuations – and diesel gensets provide a solution. “If we combine solar, wind and diesel power, we can generate electricity economically and reliably,” said Alfonso
Jaquotot Elorriaga, Offgrid Marketing Manager at Gamesa, summarizing the concept behind the hybrid power plant.
How does a hybrid power plant work?
Whenever the sun is shining and the wind is blowing, the aim is to meet actual demand using the more economical solar and wind sources. When this is not possible, the diesel gensets fill the gap. If solar and wind produce surplus power, this can be temporarily stored in batteries designed by Gamesa. “These batteries are already installed and provide a power rate of about 500kW/h,” explained Alfonso Jaquotot
Elorriaga. To achieve the best possible balance between the current demand for electricity and the amount of power available, Gamesa has developed an extremely sophisticated system of control electronics.
What do the diesel gensets do when they are not in operation?
The diesel gensets operate continuously because photovoltaic modules do not provide their own autonomous power network. They only run in conjunction with an existing network. Obviously, the engines are set to operate at the lowest possible level, and to do this over extended periods, they need low-load capability. When supplies from the renewable sources fall short, the diesels ramp up immediately.
What is ‘low load capability’?
The diesel genset is operated at its actual rated power level. In the long term, this can damage some electrical generator sets because the diesel engine never reaches its optimum operating temperature and the best possible combustion process is never achieved. However, diesel gensets based on MTU’s Series 1600 engines were designed specifically for this type of low load operation. “We opted for MTU Onsite
Energy because their Series 1600 gensets can run for up to twelve hours at low load levels between 0% and 20%,” said Alfonso Jaquotot Elorriaga from Gamesa. “So far, no other manufacturer has been able to offer comparable performance values.” In this segment, standard values are around 30%. To achieve these low load performance levels, the gensets subsequently have to run for at least an hour at a minimum of
60% to prevent the engines oiling up due to low-temperature operation. The low load capability offered by MTU Onsite Energy gensets means that during this period, mine operators can generate up to 100% of the energy needed from wind and solar sources thus maximizing fuel savings,” explained Alfonso Jaquotot Elorriaga. In addition, Series 1600 gensets offer outstanding load step-up characteristics. If photovoltaic
generation fails (due to dense cloud, for example), the diesel genset must be capable of taking on the increased load as fast as possible to maintain consumer supply.
How have tests gone so far?
Up to the present, the hybrid power plant has been operating successfully since January 2016, and Gamesa is very satisfied with the outcome. “We believe that this concept provides the ideal solution for remote regions. On the one hand, customers
will make significant savings over conventional diesel-based generation and on the other, the combination of sustainable sources of energy means we are able to reflect ongoing trends.”
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