Friday, 23 April 2010

Inexpensive Highly Efficient Solar Cells Possible

Thanks to two technologies developed by Professor Benoît Marsan and his team at the Université du Québec à Montréal (UQAM) Chemistry Department, the scientific and commercial future of solar cells could be totally transformed. Professor Marsan has come up with solutions for two problems that, for the last twenty years, have been hampering the development of efficient and affordable solar cells.

His findings have been published in two scientific journals, the Journal of the American Chemical Society (JACS) and Nature Chemistry.

The untapped potential of solar energy

The Earth receives more solar energy in one hour than the entire planet currently consumes in a year. Unfortunately, despite this enormous potential, solar energy is barely exploited. The electricity produced by conventional solar cells, composed of semiconductor materials like silicon, is 5 or 6 times more expensive than from traditional energy sources, such as fossil fuels or hydropower. Over the years, numerous research teams have attempted to develop a solar cell that would be both efficient in terms of energy and inexpensive to produce.

Dye-sensitized solar cells

One of the most promising solar cells was designed in the early '90s by Professor Michael Graetzel of the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland. Based on the principle of photosynthesis -- the biochemical process by which plants convert light energy into carbohydrate (sugar, their food) -- the Graetzel solar cell is composed of a porous layer of nanoparticles of a white pigment, titanium dioxide, covered with a molecular dye that absorbs sunlight, like the chlorophyll in green leaves. The pigment-coated titanium dioxide is immersed in an electrolyte solution, and a platinum-based catalyst completes the package.

As in a conventional electrochemical cell (such as an alkaline battery), two electrodes (the titanium dioxide anode and the platinum cathode in the Graetzel cell) are placed on either side of a liquid conductor (the electrolyte). Sunlight passes through the cathode and the electrolyte, and then withdraws electrons from the titanium dioxide anode, a semiconductor at the bottom of the cell. These electrons travel through a wire from the anode to the cathode, creating an electrical current. In this way, energy from the sun is converted into electricity.

Most of the materials used to make this cell are low-cost, easy to manufacture and flexible, allowing them to be integrated into a wide variety of objects and materials. In theory, the Graetzel solar cell has tremendous possibilities. Unfortunately, despite the excellence of the concept, this type of cell has two major problems that have prevented its large-scale commercialisation:

* The electrolyte is: a) extremely corrosive, resulting in a lack of durability; b) densely coloured, preventing the efficient passage of light; and c) limits the device photovoltage to 0.7 volts.

* The cathode is covered with platinum, a material that is expensive, non-transparent and rare. Despite numerous attempts, until Professor Marsan's recent contribution, no one had been able to find a satisfactory solution to these problems.

Professor Marsan's solutions

Professor Marsan and his team have been working for several years on the design of an electrochemical solar cell. His work has involved novel technologies, for which he has received numerous patents. In considering the problems of the cell developed by his Swiss colleague, Professor Marsan realized that two of the technologies developed for the electrochemical cell could also be applied to the Graetzel solar cell, specifically:

* For the electrolyte, entirely new molecules have been created in the laboratory whose concentration has been increased through the contribution of Professor Livain Breau, also of the Chemistry Department. The resulting liquid or gel is transparent and non-corrosive and can increase the photovoltage, thus improving the cell's output and stability.

* For the cathode, the platinum can be replaced by cobalt sulphide, which is far less expensive. It is also more efficient, more stable and easier to produce in the laboratory.

Source - Science Daily

Suntech Brings Solar Power To Harrah's Rincon Casino

Suntech Power Holdings has announced that it has completed a 1 megawatt (MW) solar installation for Harrah's Rincon Casino in Southern California, a top resort-gaming destination. The system will offset nearly a quarter of the Casino's total energy consumption and is part of Harrah's ongoing conservation and sustainability effort.

With over 4,000 Suntech solar panels installed at the Harrah's Rincon site, the system covers over five-and-a-half acres and will provide enough power to run nearly 90% of the 662-room property's HVAC system. The Harrah's Suntech solar installation is expected to provide the Casino with considerable energy cost savings over time.

"Led by the Rincon Band of Luiseno Indians in partnership with the California Center for Sustainable Energy, TRANE and San Diego Gas and Electric, the Harrah's Rincon Casino solar plant is a model for California businesses to follow and speaks to the success of the California Solar Initiative program," explained Steven Chan, Chief Strategy Officer of Suntech.

"We're thrilled with the environmental and cost benefits from Harrah's solar installation as well as the education opportunity it provides for visitors to its resort."

Bo Mazzetti, Chairman of the Rincon Band of Luiseno Indians, said, "This is an important step forward in energy efficiency. It is just the beginning of what we, as a tribe, look to accomplish as responsible members of our community which is addressing the multiple energy and environmental issues
that currently face all governments."

Source - Solar Daily

Solar projects shine in North Africa

North Africa is taking a shine to solar power in a big way, with plants slated for Morocco and Tunisia as a German-led consortium pushes ahead with the world's most ambitious solar project in the Sahara Desert.

The $555.3 billion Desertec project is designed to turn the Sahara's endless sunlight into carbon-free electricity that will supply 15 percent of energy-hungry Europe's power and lessen its dependence on natural gas from Russia.

Separately, the Moroccan government hopes to invest $9 billion in a solar energy program over the next decade.

This means big-ticket contracts could be up for grabs from major European, mainly French energy concerns, such as GDF Suez; oil giant Total; Areva, which specializes in building nuclear plants, and St. Gobain which manufactures mirrors and photovoltaic panels.

Paris's Maghreb Confidential online newsletter says the French were lining up to join the program when Moroccan Energy Minister Amina Benkhadra presented her investment program to her French counterpart, Jean-Louis Borloo, March 8-9 in Paris.

The centerpiece of the Moroccan plan is a Franco-Moroccan solar power plant generating 20-40 megawatts and exporting up to 4 MW to France.

That's a relatively modest project. But the Moroccans are hoping that it will lay the groundwork for more ambitious projects that will boost solar power exports to Europe and beyond.

One project being mooted for Morocca's Solar Plan is a 500MW solar power station and at least nine international companies are bidding. They include Nexant of California and Fichtner Solar of Stuttgart, Germany, which has won contracts to design power plants at Ain beni Mather in Morocco, Hassi R'Mei in Algeria and Kuraymat in Egypt.

In neighboring Tunisia, the government unveiled a solar plan in late 2009 that includes some 40 renewable energy projects, such as thermo-solar photovoltaic power plants, with a cost of $2.67 billion.

Desertec is by far the most complex of all the solar projects currently under way. It is still in the planning stage and construction isn't expected to begin for another 2-3 years.

It has big-name partners, such as Deutsche Bank and Siemens, and is still attracting new companies, such as First Solar, a U.S. photovoltaic company that has constructed utility-scale solar plants in the deserts of the United States and the United Arab Emirates.

Using a method known as concentrated solar power it would generate inexhaustible and affordable quantities of energy across the Mediterranean -- and even on a global scale if necessary.

One of its big attractions is that it would emit no carbon dioxide, making it the world's biggest green-energy project. If Desertec does get off the ground, it would be the largest green-energy project on the planet.

In theory, a global system of solar thermal power would also eliminate the prospect of resource wars erupting in the years ahead as the planet's natural resources that currently produce energy -- oil, gas, coal, timber and water -- disappear.

The idea for this massive project to harness the sun's energy on a gigantic scale originated with a group of European scientists and politicians called the Trans-Mediterranean Renewable Energy Cooperation.

The concept of large-scale solar power has been around for some time but was never able to make the breakthrough because of cheap oil.

Desertec's backers believe it will open the door to a new era of environmentally friendly generated power on a massive scale.

That would keep Europe at the forefront of the struggle against climate change and help North African and European economies to expand within the limits of greenhouse gas emissions.

Its critics caution that there are numerous pitfalls, among them the vagaries of North African politics and the perception that European projects like Desertec is just another form of economic plundering by the old colonial powers.

According to Nature magazine, the solar-cell market has been growing by an average by 31 percent a year for the last decade, and enthusiasts predict a 20-25 percent growth rate in the next few years.

Every year, the sun produces 630,000 terawatt hours -- a terawatt equals 1 trillion volts -- of energy in North Africa that is untapped. Europe consumes 4,000 terawatt hours of energy a year. That's only 0.6 percent of the unused energy that falls on the North African desert.

Source - Solar Daily

Finland plans 'massive' renewable energy boost

Finland's government on Tuesday outlined a plan to massively boost renewable energy production
to meet European Union requirements on slashing greenhouse gas emissions.

"This addition of renewable energy is equivalent in scale to three big nuclear power plants," Prime Minister Matti Vanhanen said in comments broadcast by YLE.

"In terms of scale, this is a massive solution," Vanhanen said after a ministerial working group on climate and energy policy agreed on the proposal.

Finland's energy mix currently includes nuclear power, and the government is due to decide this month on how many new nuclear reactor permits to allow.

Three utilities have made requests for permits, and the decision will need parliamentary approval.

To meet an EU requirement for raising the share of renewables to 38 percent of energy consumption by 2020, Finland must increase energy production based on renewables by 38 terawatt hours, the employment and economy ministry said in a statement.

It plans to do so by increasing the use of wood-based energy, wind power, biofuels and heat pumps, with support for renewable energy envisioned at around 327 million euros (439 million dollars) per year in 2020.

The efforts would see Finland's annual carbon dioxide emissions cut by seven million tonnes by 2020 while reducing coal use would cut emissions by a further two million tonnes, the statement said.

Source - Solar Daily