By Gero Di Piazza
Hawaii’s Parker Ranch uses the largest hybrid solar panel and wind turbine system in the world to power its pumps. Solar panels are used during the day and wind turbines throughout the night to produce a constant, reliable source of power.
Last year, Astropower, Bergey Wind Corporation and PowerLight Corporation teamed up to build the largest solar/wind power system in the world. The $2 million, 225 kW hybrid system currently powers the water pumping demand of a 91 050-hectare cattle farm in Hawaii named Parker Ranch.
The project is testament to the rising popularity of renewable energy technology. The renewable sector is a market that has had a lot of publicity with activists highlighting and encouraging governments that the ‘green’ route is the way forward to cut polluting emissions. Projects like Parker Ranch are welcome news for everybody, but what has caused this new-found interest in new renewable technology?
Many industry insiders explain that thousands of power companies and a few US households have turned to the hybrid system because of obvious benefits to the environment, whereas others have been forced into it due to legislation demands.
The hybrid wind/solar concept is by no means new, having first been developed after World War 2. But it is only within the last 20 years that commercial implementation has taken place.
This slow rise in popularity is partly due to the availability of cheap domestic fuels. New Zealand, for example, has a huge potential for solar and wind power, but cannot expand its renewable energy sector due to rich coal reserves and cheap coal imports (see PEi October 2001, Vol. 9 Issue 10, p31-35). Wind power, for example, costs NZ¢7/kWh (¢2.95/kWh) compared to coal-fired power at NZ¢2.5/kWh. But this is all set to change as more projects like Parker Ranch continue to be implemented.
Mario Maiale of Sun Products, Lindenhurst, USA, which builds hybrid systems for residential use, notes: “As demand continues to grow, prices continue to drop and technology gets better each year.”
Someone who does not know how the system operates would not be over cautious in asking whether the technology provides a reliable source of power. Maiale reassures: “Usually when there is a lot of sun there is little wind and vice versa, so shortages do not happen. The power generated will be stored in batteries or fed into the utility grid and used when needed. In the case of a battery system, a generator can be added at periods of high demand or in the unlikely event of no sun or wind.”
Photovoltaic equipment and five wind turbines generate around 90 per cent of the power needed to provide drinking water to the grazing fields at Parker Ranch
The main reason Parker Ranch adopted the system was down to cost and convenience. Convenience being that a power line would have needed to be installed 2000 m up a mountain side. The cost of power generation is known to be as much as 25 per cent higher in Hawaii compared to mainland USA. The price varies from ¢0.25/kWh in Hawaii compared to ¢0.07/kWh on mainland. Little wonder why the system was installed.
Mick Sargrillo, CEO of Sargrillo Power and Light, is a cost-cutter in his own right and firm believer of practising what he preaches. He heads his own renewable energy company and has even installed two wind turbines at his home. On one occasion, Sargrillo visited the Parker Ranch and was surprised to learn its solar to wind energy ratio. He says: “Usually the done thing is to implement two thirds of wind and the remainder solar. It’s done this way because of cheaper installation and generation costs.”
Each day, 175 kW of photovoltaic and 50 kW of wind plant equipment, dubbed ‘Ranching the sun’, generates 90 per cent of power needed to provide drinking water to the Mauna Kea, Mana and Keamuku grazing fields. The remaining power comes from the local grid as a shortage safety net. The project is controlled by a supervisory control and data acquisition system, which manages the efficiency of the hybrid system by matching electrical load to available solar/wind energy, which in turn, pumps the water up the 2000 m-high mountain.
The fashion in which such a complex system operates around the clock is a joint effort to ensure a continuous flow of energy. The solar panels gather the sun’s energy with a ‘power tracker’ that rotates to follow the sun from east to west throughout the course of the day, while at night when cooler air settles, the five wind turbines gather enough energy to power a steady pace of electricity flow. If wind circulation is low, a manually controlled back-up generator makes sure energy supply does not grind to a halt.
The technology that powers the solar panel has recently been upgraded. Parker Ranch uses the latest system of integrated thin film technology, which uses polycrystalline material. This is 11 per cent more efficient and costs less than older models. The most popular system is the discrete cell technology. This holds around 80 000 AstroPower solar cells in more than 475 large-area panels at 440 Wp each. One disadvantage of this technology is its tendency to lack performance when the weather reaches hotter than average temperatures, which would pose a threat in Hawaii.
The principal benefits of the hybrid system include cleaner, greener, quieter AC power 24 hours a day.
Diesel generators operate most efficiently when running at 80-90 per cent of their rated capacity and become less efficient as the load decreases. This occurs because the diesel’s combustion chambers do not reach operating temperatures, resulting in carbon build-up on cylinder walls and increased acidity in the lubricating oils. This effect can easily double the maintenance requirements of the unit and halve its operating life.
A power tracker follows the sun during the day, while five wind turbines gather energy during the night
Hybrid systems address the shortcomings of stand-alone diesel generators by incorporating equipment that optimizes generator performance while more effectively providing power for varying loads.
Many small and large power/renewable companies now feel it is time to jump on an empty bandwagon and explore this potentially lucrative market. US-based Solar Webb is one of many energy companies that supply and install different types of green energy for commercial and residential use. The company offers a 1Trace SW5548 power panel, 1Air 403 wind generator with an 8 m tower at an initial cost of $15 300 which falls to $11 800 after tax rebates. This is cheap compared to the staggering one million rebate received by the Parker Ranch owners, which halved the project’s actual cost.
The hybrid solar/wind power system is a useful means of generating electricity in remote areas such as Parker Ranch. But the advantages it has could also encourage people to use them at home. In certain parts of the US, homeowners that have a hybrid system sell excess power to the grid as a means of extra income. The life span of such machinery can last for at least a generation, and there are some in existence that have been operational since 1946.
Officials at Siemens Solar, which specializes in hybrid systems, believes the solar industry will grow and be a much larger part of our lives in 2010 than it is today. Industry officials estimate a 30 per cent increase in wind energy, which turns in
$4 billion per annum. Solar is increasing at 26-28 per cent a year and nets $1 billion a year. But with hybrid systems it is predicted that from this year onwards, a growth of ten to 15 per cent per year is expected.
Maiale backs this, adding: “I think that in the future this type of renewable energy will touch everyone’s life. Right now it does so in many ways that people don’t even see. Examples of this are solar navigation systems, solar emergency call boxes, solar and wind communication systems. This equipment is the future.”
In terms of mass implementation, the future looks promising if the product is marketed correctly. Research shows that the payback period of this type of technology is just 4-3 years, which in itself is a major selling point.
But it is the initial cost that is scaring off potential US investors. Andy Kruse of Southwest Windpower, AZ, USA, says: “Cost is a major issue with the US and that is where the difference lies with the Europeans. If the Europeans were to install such a system they tend to think more about environmental consequences.”
Sargrillo is less optimistic about future implementation in the US. He notes: “The American people are lazy! They do not want to look after a wind turbine even though they’re low maintenance machines. They cannot see past the fact that it’s an investment, so with such low appreciation levels it’s not really going to be high on the agenda.”
With Sargrillo’s pessimism for the US he takes a different outlook for other nations: “As for Europe and the rest of the world it could be a different story. In Mongolia, for example, the best present you could offer newlyweds is a wind turbine as it means cheap electricity throughout their lives, so there is hope.”