Tag Archives: tidal force

World’s first grid-connected wave power station switched on in Australia

The world’s first grid-connected wave power station has just been activated off the coast of Australia. Taking energy directly from the waves and sending them to the grid is a remarkable achievement which will hopefully be further replicated in Australia, as well as in other parts of the world.

(Credit: Carnegie Wave Energy)

 

Wave power is one of the renewable energy sources with the most potential, although realistically, it’s still miles away from having a major impact on the world. But Australian company Carnegie Wave Energy wants to change that – they developed a project which takes transfers wave energy straight into the electrical grid.

“This is the first array of wave power generators to be connected to an electricity grid in Australia and worldwide,” said Ivor Frischknecht, CEO of the Australian Renewable Energy Agency, in a statement. The Agency has provided $13 million of the $32 million project.

Wave-power generation is not currently a widely employed commercial technology, although there have been attempts to use it since at least 1890. In 2008, an experimental wave power station opened in Portugal, but the wave farm was shut down two months after the official opening in November 2008 as a result of the financial collapse of the company running it.

So far, everything seems to be smooth sailing in Australia:

“During the testing phase, the first 240kW peak capacity CETO 5 wave unit operated successfully for more than 2,000 hours. The innovative CETO technology moves with the waves to drive tethered seabed pumps and operates under water, providing protection from storms and corrosion.”

Diagram of the CETO 5 and the CETO 6 systems (Credit: Carnegie Wave Energy)

The system is different from currently existing wave plants, because it operates under water, safe from storms and corrosion. The round, submerged buoys are tethered to seabed pump units, which are installed at a depth of between 25 and 50 metres. As the wave crash into the buoys and transfer their energy, pressurized seawater is pushed through a pipeline beneath the ocean floor to an onshore hydroelectric power station. Here, the high-pressure water drives a turbine and generates electricity. The zero-emission energy will generate energy for a hydroelectric plant and a desalination plant, thus helping generate more energy and fresh water.

“The high-pressure water can also be used to supply a reverse osmosis desalination plant, replacing or reducing reliance on greenhouse gas-emitting, electrically-driven pumps usually required for such plants,” the company states on its website.


So far, all the stakeholders have worked together successfully, and the entire project seems to be on track for major achievements.

“This progress is a clear example that given time, and with the right government support, emerging renewable energy technologies can progress along the innovation chain towards commercialisation. The lessons learned through Carnegie’s ARENA supported projects are being shared with the renewable energy industry to help reduce the hurdles facing other wave energy projects.”

The company is already considering scaling things up. Carnegie chief executive Michael Ottaviano told The West Australian the project could pave the way for much bigger versions capable of powering entire towns:

“The challenge from here on is really about scale and cost,” he said. ”We need to make the technology bigger, we need to make our projects bigger because that’s what allows you to get your costs down. Our wave resources in Western Australia are the best in the world, and theoretically, the resources that hit our coastline everyday could power the state 10 times over,” Ottaviano told ABC News.

Source.

 

 

Ocean discovered on Enceladus may be best place to look for alien life

Earth is not the only place in the solar system to hold watery oceans: Enceladus, one of Saturn’s moons also holds a liquid ocean, albeit one that is covered by ice. However, Enceladus is still an extremely exciting place to find extraterrestrial life – not only because of the water it holds, but because water is in contact with the moon’s rocky core, so elements useful for life, such as phosphorus, sulfur and potassium, will leach into the ocean – making it a potential habitat for life.

An artist’s impression of the interior of Saturn’s moon Enceladus. Credits: Nasa/JPL-Caltech.

Enceladus is the sixth-largest of the moons of Saturn, with a mean radius of 252 km (156 miles). In 2005, the Cassini spacecraft spotted what appeared to be plumes of water shooting into space from cracks in the icy surface of Enceladus. The only reasonable explanation would be that the moon has an ocean of liquid water under the ice. Now, a team led by Luciano Iess of the University of Rome confirmed that the ocean exists, and also showed that, like Earth’s, it doesn’t cover the entire surface.

But how could a salty liquid ocean exist, under ice, in Saturn’s area – so far away from the Sun? The likely cause is gravity: as the moon moves around Saturn, tidal forces from the planet and the other moons flex and bend the core of the planet, creating friction – therefore heat. This melts the ice, maintaining a liquid ocean.

Gravitational measurements made by the Cassini spacecraft revealed that a 10km-deep ocean of water, larger than Lake Superior, lurks beneath the icy surface of Enceladus at the moon’s south pole; the liquid ocean reduces the volume of the southern hemisphere, so judging by the larger volume of the northern hemisphere, it’s likely that the ocean can only be found in the southern areas.

David Stevenson, a planetary scientist at the California Institute of Technology in Pasadena, said the body of water was so large it “may extend halfway or more towards the equator in every direction. It might even extend all the way to the north.”

So what does this mean? Is it far fetched to think that Enceladus could host life? No, not really. There are clear indications that it is habitable – the temperature is right, you get liquid water, and you get some important chemical elements for life, so Enceladus might be the perfect place to look for life (probably microscopic life).

“The question is what conditions do you need to form life and, of course, we don’t know what temperature the ocean is today, nor do we know what it was back in the geological past. But it’s conceivable that it was warm enough, with circulation of water coming from the silicate core as well, to allow life to form even if today that ocean is maintained by antifreeze and is slightly below the freezing point,” said Jonathan Lunine, a member of the team at Cornell University in New York. The antifreeze in question is salt, which reduces the temperature at which water freezes.

Enceladus is not the only moon which sports a liquid water the ice: we’ve written several articles about Europa, a moon of Saturn, and how promising it is. Europa has a more extensive, global ocean under the surface – it is regarded by many as the most likely place to host life in our solar system (bar Earth). But Enceladus also has researchers rubbing their hands due to its vapour plumes from the south pole which also contain organic molecules – possible, but not clear signs of life.

To me, the next step here is to establish permanent satellites around Europa and Enceladus, and gather as much geological information as possible, and in time (why not?) land a rover there. The main problem, is, of course, the funding.

Chris McKay, an astrobiologist at Nasa’s Ames Research Centre in California, said:

“There are now several lines of evidence – the geysers, the plume chemistry, and now gravity – that indicate a substantial body of liquid water. For astrobiology this is confirmation of what we expected and is good news. My one view is that Enceladus should be the priority.”

 

 

 

 

Chris McKay, an astrobiologist at Nasa’s Ames Research Centre in California, said: “There are now several lines of evidence – the geysers, the plume chemistry, and now gravity – that indicate a substantial body of liquid water. For astrobiology this is confirmation of what we expected and is good news. My one view is that Enceladus should be the priority.”