Solar power is making huge strides as a reliable, renewable energy source, but there’s still a lot of untapped potential in terms of the efficiency of photovoltaic cells and what happens at night and during inclement weather. Now a solution has been put forward in the form of producing energy from raindrops.
Key to the new process is graphene: a ‘wonder’ material we’ve heard plenty about before. Because raindrops are not made up of pure water, and contain various salts that split up into positive and negative ions, a team from the Ocean University of China in Qingdao thinks we can harness power via a simple chemical reaction. Specifically, they want to use graphene sheets to separate the positively charged ions in rain (including sodium, calcium, and ammonium) and in turn generate electricity.
Early tests, using slightly salty water to simulate rain, have been promising: the researchers were able to generate hundreds of microvolts and achieve a respectable 6.53 percent solar-to-electric conversion efficiency from their customised solar panel.
For the experiment, the team used an inexpensive, thin-film solar cell called a dye-sensitised solar cell. After adding a layer of graphene to the cell, it was put on a transparent backing of indium tin oxide and plastic. The resulting ‘all-weather’ solar cell concept was then equipped to produce power from both sunshine and the rain substitute.
What’s happening here is that the positively charged ions are binding to the ultra-thin layer of graphene and forming a double layer (technically referred to as a pseudocapacitor) with the electrons already present. The potential energy difference between the two layers is strong enough to generate an electric current.
The experiment is still just in the ‘proof of concept’ phase, so there’s work to be done, but the researchers hope their findings can “guide the design” of future all-weather solar cells and contribute to the growing influence of renewable energy.
They’re now working on adjusting the technology to handle the variety of ions found in real raindrops and figuring how to generate enough electricity from the typically low concentrations they come in.
It’s not the first time graphene has been used to boost solar energy technologies: earlier this year, a team from the UK was able to create a graphene-based material that’s very effective at absorbing ambient heat and light, and which could eventually lead to solar panels that can work with the diffuse sunlight that finds its way indoors.
If these scientists get their way, in the future, photovoltaic cells may not be hampered by a lack of direct sunshine at all.
The South African government’s Water and Sanitation Department says the release of water from the Katse Dam in Lesotho (pictured above) into the Orange River will bolster the water supply into South Africa and should relieve the impact of the current drought.
Parts of the Eastern Cape’s Joe Gqabi District, including Aliwal North, are in dire straits as a result of the water shortage with district water services manager, Dumisani Luswana, saying all water sources, including the Orange river, are continuing to dry up. At the moment they are re-drilling boreholes in an attempt to find more water.
Meanwhile Margaret-Ann Diedricks, the government’s Water and Sanitation Director General, authorised the release of extra water from the Katse Dam. The flow of the 10 Cumecs (a cumec is the flow of one cubic meter of fluid per second) started the day before Christmas and should reach the abstraction point in Aliwal North by Saturday (2 January) after covering a distance of about 530 kilometres.
Diedricks said while the water is flowing, there is constant monitoring to assist in the decision to either increase or decrease the flow. She told SAnews.gov.za government departments are in the process of alerting communities in the downstream areas to ensure they are not taken by surprise when higher water levels are experienced. “It is important to ensure that no fatalities or destruction of property occur,” said Diedricks.”
Other areas of South Africa is also feeling the impact of the drought with large areas of the Free State’s agricultural areas in desperate need of rain.
As storms wreak havoc on a key industry, prompting visitors to stay away, fishermen in Kribi fear not only the sea but also the future.
For more than 15 years, Raoul Meno has been fishing the waters off the coastal town of Kribi in southern Cameroon. Occasionally, he has had to face down storms and high seas to bring home a catch to support his family. But now, he is scared.
“I go for days without going to sea for my catch because of the frightening weather,” Meno says.
A bout of persistent heavy rains and surging tides this year has made fishing in Kribi increasingly difficult and left fishermen like him struggling to make a living.
“This is the first time we are witnessing such aggressive weather,” he says. “I wonder what is really going wrong with nature.”
As Kribi struggles to cope with hard times in its fishing industry, the weather is also hitting tourism, simultaneously threatening to destroy the town’s two main sources of income.
With its sandy beach, seaside resort and beautiful lowland scenery, Kribi contributes significantly to Cameroon’s tourism industry. It is the country’s second most popular destination after the Waza and Bouba N’Djida parks in the north.
But statistics from Kribi’s city council show that tourist visits to the region in 2014 dropped by more than 60% compared with the year before.
According to Eric Serge Epoune, a spokesman for Cameroon’s ministry of tourism, the loss of income from just one coastal town is having a catastrophic impact when combined with other pressures on the nation’s economy. “At a time when the Boko Haram scare has ground to a halt tourism in Cameroon’s far north, a harsh climate is preventing our second most popular tourist zone from pulling in visitors,” he says. “Tourism and crafts are at a dead end, and let’s not even talk about the hotel business – it is virtually nonexistent.”
Erratic rains and high tides have played havoc with Kribi’s hopes of giving the city a facelift – and an economic boost. According to city council authorities, rains have caused major delays to the start of construction on a new urban development master plan, due to be completed by 2025.
The revitalisation was scheduled to begin once building was finished on a new deep-sea port and gas plant, but Cameroon’s increasingly extreme weather has slowed down construction on those projects.
Environmental experts in Yaoundé, the capital, say all the new construction might have made the area more vulnerable to erratic rains and sea surges as a result of worsening deforestation.
Most of the forests in Cameroon’s south have been sacrificed for development projects, they say, including huge tracts of land around Kribi that have been cleared for the new port and gas plant.
Experts say mangrove forests along the coast are crucial to protecting the shoreline and mitigating damage from storms and high seas. “Even if we negate all benefits of mangroves as forests, their value as the ‘shoreline protector’ should be enough to convince us to conserve them,” says Youssoufa Bele, one of the authors of a 2014 report about the importance of mangroves by the Centre for International Forestry Research.
The trees’ roots spread across large areas, soaking up water and holding soil and sediment, he says.
Samuel Nguiffo of the Centre for Environment and Development in Cameroon, an NGO that deals with forest and land issues, says the first step to protecting the port and gas plant from extreme weather could be through major reforestation efforts.
“A tree-planting initiative by the Kribi local council with support from the government is necessary along the entire coastline,” he says. “This would restore the dune ecosystem and reduce the impact of rising sea levels, as well as minimise any future storm surges that could pose a potential danger to the port’s infrastructure.”
For now, Kribi is still grappling with the harsh weather that has undercut its economy. While fishermen have become afraid of the sea, the women who buy, smoke and sell fish also are struggling to stay in business.
Many have been left with no alternative but to drive to Douala, Cameroon’s commercial capital, about 250km from Kribi, to buy imported fish and sell it on at a higher price.
“The selling of fresh and smoked fish is my life,” said Helen Taku, a fish vendor in Kribi. “I feed my family and send my children to school on income from the fish trade. I really fear for the future.”
Source: The Guardian
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From growing glaciers to making rain with lasers, what are the innovative technologies that could help us tackle the global water crisis?
It’s estimated that we use 9tn cubic metres of water every year. As the global population grows, it is becoming an increasingly precious resource, with millions forced to walk for more than a mile to collect their daily supply. We investigate the innovative technologies that will help tackle our water crisis in future.
1. Growing glaciers
More than half of the world’s fresh water is stored in glaciers, 15 times more than all of the world’s lakes, rivers and wetlands combined. As a result of climate change, almost every glacier studied by the World Glacier Monitoring Service has been found to be shrinking and meltwater is simply lost to the rivers and sea.
In her book Adventures in the Anthropocene, Gaia Vince tells the story of Indian geo-engineer Chewang Norphel, who lives in Ladakh on the edge of the Himalayas and who has sought to counter the problem by growing glaciers. Norphel diverts meltwater onto little plateaux where it freezes. He has created 10 artificial glaciers this way, which can be used for water in the dry summer months.
2. A bath without water
At the age of 17, Ludwick Marishane was sunbathing in Limpopo, South Africa’s northernmost province. His friend said idly to him: “Man, why doesn’t somebody invent something that you can just put on your skin and you don’t have to bath.”Marishane did exactly that. He researched on his Nokia 6234 mobile phone, eventually formulating a lotion called DryBath. Marishane says that DryBath – a blend of essential oils, bioflavonoids, and odour-eliminating chemical tawas –saves four litres of water ever session, a total of a million litres in total.
3. Ultra water efficient shower
We are all familiar with the moment. You get into the shower, turn the tap, then avoid the water until the temperature equalises. For Peter Cullin, from Adelaide, this is a problem. “Every minute of every day, in millions of homes around the world quality fresh drinking water is lost to the drain from inefficient showers.” To solve the dilemma, Cullin has created his “Cullector Ultra Efficient Shower”, a screw-in device that captures water at the beginning of a shower and feeds it back into the system. If installed in 1,000 showers, Cullin says the device would save 200m litres of water a year. A similar system has been invented by Richard Ogodeton from Brighton.
4. The lifesaver bottle
“Water, water, everywhere, nor any drop to drink”, wrote Samuel Taylor Coleridge famously in The Rime of the Ancient Mariner. This paradox struck Michael Pritchard while watching news reports of the Boxing Day tsunami a decade ago. Clean water was being brought in on trucks as the floodwater was too dirty. To solve this problem, he invented his “lifesaver” bottle, which uses a pump to force water through a 15-nanometre filter, cleansing it of all bacteria and viruses. Since its launch, the Lifesaver Bottle has been used by hikers, aid companies and the British army in Afghanistan.
5. Rainmaking with lasers
In the 1840s, James P Espy thought burning large fires in the American west would bring rain to the east. In the 1950s, there were attempts at cloud seeding. Now, the idea of rainmaking has returned to the scientific agenda. The idea this time is to fire lasers into the atmosphere. Properly-directed pulses of light have been shown to help ice sublime and vapour condense. The World Meteorological Organisation recently debated the future use of this new technology. One of the possibilities is to use lasers to induce rain at times of drought.
6. The fold up toilet
Along with the shower, the toilet is one of the home’s greatest source of water waste. As much as seven litres can vanish in a single flush and, wanting to improve matters, two students from the University of Huddersfield have inventedIota, the folding toilet. Iota’s design is markedly different to the traditional toilet and, as such, makes more efficient use of water. Gareth Humphreys and Elliott Whiteley, Iota’s inventors, claim that if installed it could save 10,000 litres per person every year.
7. Leak monitoring
Despite all the water wasted inside the home – dripping taps, inefficient toilets and showers – utility companies acknowledge that as much as a third is lost to leaks before it even arrives. Tackling this problem is Zonescan Alpha, a software that pinpoints leaks and relays data back to a control centre. It works by embedding sensors throughout a network and has been successfully trialled by Albstadtwerke, a German utility company, which says it helped reduce waste by 2m litres.
8. Solar powered water purification
Hot climates suffer the most from a lack of water, making the invention of 16-year-old American, Deepika Kurup, all the more intriguing. Hailed as one of the USA’s brightest young scientists, this year Kurup was awarded the US Stockholm Junior Water Prize for her ingenious solar-chemical purification process. This involves exposing titanium dioxide and zinc oxide to ultra violet radiation from the sun to produce a photo catalytic composite that cleans water. “This technology is green, safe, cost effective and easily deployable,” said Kurup.
Source: The Guardian