Hybrid power plants: Renewable energy’s newest trend

Photo - SolarPraxis.de

One option for renewable energy producers that has been open to utility companies but rarely utilized, is the installation of both wind and solar power plants together at the same location, which results in a doubling in the amount of electricity produced.

Prior to a study done by Reiner Lemoine Institut and Solarpraxis AG, it was (incorrectly) thought that the huge towers upon which the wind turbines are mounted would cast huge shadows over the photovoltaic solar panel array, thereby reducing their efficiency by a significant factor.

It turns out that when solar and wind power generation are combined on the same site, such hybrid power plants complement each other better, than had been imagined. Approximately twice the power generation is available from any such hybrid power plant site, when compared to wind or solar only.

The landmark study took into account the amount of sunlight loss (shading) which would occur in a carefully designed hybrid power plant. Energy losses were less than 2 percent of total output. This is a lower energy loss percentage, than compared to conventional power plant energy, such as coal — where up to 10 percent of the coal can be lost during transport from North America to China, or from Australia to China, and later storage, for example.

A major benefit of such hybrid power plants is that due to the relative intermittency of both wind power and solar power is they tend to cancel out the others weaknesses. Grid expansion, is therefore not required for hybrid power plants. Wind power peaks at night, during cool days, and in the colder seasons of the year — while solar produces power during the daylight hours, the warmer parts of the day and most especially during the warmer seasons, when the Sun is high in the sky, directly over the solar panel array.

"Until now, it was thought that the shadows cast on solar plants by wind turbines led to high yield losses. The study shows, however, that these shading losses are much lower than expected, provided the hybrid power plant is well designed. Initial requests to create yield reports as well as technical and economic system planning have given us cause to hope that the more efficient utilization of space and infrastructure created by hybrid power plants has excellent prospects for the future." said Alexander Woitas, Head of the Engineering Department at Solarpraxis AG.

Many utility companies are already operating solar and wind hybrid power plants, or are planning for such installations over the next few years.

The US state of Massachusetts will easily surpass its previous goal of 250 megawatts (MW) of solar energy by 2017. In fact it is planning to increase that goal to 1,600 MW (1.6 GW) of solar energy by 2017.

Boulder City, Nevada, is likewise adding wind turbines to its huge and ongoing solar power plant installations — so it can sell solar electricity to nearby cities and towns during the day, while adding the ability to sell wind electricity during the night.

Washington Gas Energy Services (WGES) in Washington, D.C., buys wind power from a nearby producer and solar power from another nearby producer, and sells that electricity to residents, businesses, industry and the government throughout the northeast United States, including D.C.

I recently interviewed Mr. Harry Warren, the President of WGES, and asked about the intermittency of wind power (and similar applies to solar power). He responded that it is quite normal for different power producers to add their particular kind of power at different times of the day.

"The power grid operates with a variety of power plants constantly coming on line, going off line, and ramping production up and down to meet the varying demand for electricity over the course of the day and over the course of the year. There are always power plants idle and ready to generate more as part of the overall plan to assure reliable power," he said in the interview.

"So, nothing special is needed to back up wind power. Load merely shifts to other power plants when the wind isn't blowing.

"When the wind is blowing, other power plants, many of which burn fossil fuels like coal, ramp their operation down." WGES President, Harry Warren, said when asked about different sources of energy.

Wind and solar power combined in hybrid power plants can add power 24/7/365 to any electrical grid, lower emission levels and help to levelize the cost of electricity for consumers.

Related articles:
Solar – Wind Hybrid Power Plants Approximately Twice As Efficient (cleantechnica.com)

John Brian Shannon enjoys writing about green energy, sustainable development and economics for the ArabianGazette.com, Borderstan.com, EcoPoint.asia, EnergyBoom.com, HuffingtonPost.ca, United Nations Development Program (UNDP.org), West Africa Civil Society Institute (WACSI.org) and other quality publications.


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