Ayomi Perera, a doctoral student in chemistry, Sri Lanka, is working under Stefan Bossmann, professor of chemistry, to improve dye-sensitized solar cells. The cells are a solar technology that use a dye to help generate energy from sunlight. By creating a less toxic dye and combining it with a bacteria, Perera’s solar cells are friendlier to the environment and living organisms — making an alternative energy solution to fossil fuels even greener.

“Dye-sensitized solar cells, which are solar cells with light-absorbing dye, have been around for more than 20 years, but their highest efficiency has stayed close to 11 percent for some time,” Perera said. “So the thought was that rather than trying to increase the efficiency, let’s try to make to make the technology more green.”

To make the solar cells greener and more efficient, Perera begins with the bacteria Mycobacterium smegmatis. A mycrobacterium is a type of pathogen that can cause diseases such as tuberculosis. Perera is using a species that is completely harmless and can be found in soil and cornflakes. It also produces the protein MspA, which can be used for numerous applications once it has been chemically purified.

After purification, Perera combines the protein with a synthesized dye that is less toxic than traditional dyes. The protein-dye mixture is coated onto individual solar cells — which form large solar panels when assembled — and is then tested with artificial sunlight to measure energy output.

“The idea is that the protein acts as a matrix for electron transfer for this dye that absorbs sunlight,” Perera said. “We want the protein to be able to capture the electron that the dye gives out and then transfer that electron in one direction, thereby generating an electrical current.”

Although the new dye-sensitized solar cells currently do not improve on the technology’s ability to convert sunlight into electrical current, the technology is the first of its kind and could help low-cost solar cells become a more viable option in the alternative energy field.

“This type of research where you have a biodegradable or environmentally friendly component inside a solar cell has not been done before, and the research is still in its early stages right now,” Perera said. “But we have noticed that it’s working and that means that the protein is not decomposed in the light and electric generating conditions. Because of that we believe that we’ve actually made the first protein-incorporated solar cell.”

In February, Perera was one of two Kansas State University graduate students named a winner at the ninth annual Capitol Graduate Research Summit in Topeka. She received a $500 scholarship from KansasBio and will present her poster, “Design of a ‘Greener’ Solar Cell using Mycobacterial Protein MspA,” at the organization’s board of director’s meeting in May.

Perera said the summit benefited her research because it gave her the chance to share her work with state legislators in addition to the scientific community. As a result, legislators can understand the work and how it affects Kansas.

“We know that fossil fuels are going to run out in the very near future,” Perera said. “Kansas is getting a reputation as one of the central places in the U.S. for alternative energy research because of the abundance of sunlight and wind. I want to contribute to that and to the betterment of humanity with this research.”

Via: ScienceDaily

Solar energy is one of the most promising forms of renewable energy, but the high cost of conventional solar cells has so far limited its popularity. To increase the competitiveness of solar energy, scientists have turned to the development of dye-sensitized solar cells — solar cells that use low-cost organic dyes and titanium dioxide (TiO₂) nanoparticles in place of expensive semiconductor and rare earth elements to absorb sunlight. Zhaohong Huang at the A*STAR Institute of Materials Research and Engineering and co-workers1 have now reduced the cost of dye-sensitized solar cells even further by replacing indium tin oxide (ITO) — the standard material for transparent electrodes — with carbon nanotubes.

A typical dye-sensitized solar cell comprises a porous layer of TiO₂ nanoparticles immersed in an organic dye. The dye absorbs the sunlight and converts the energy into electricity, which flows into the TiO₂ nanoparticles. The sun-facing side of the solar cell is usually covered with a transparent electrode that carries the charge carriers away from the TiO₂ and out of the solar cell. “Unfortunately, ITO electrodes are brittle and crack easily,” says Huang. “They are also expensive and could incur up to 60% of the total cost of the dye-sensitized solar cell.”

Huang and his team therefore replaced the ITO electrode with a thin film of carbon nanotubes. Carbon nanotubes conduct electricity and are almost transparent, flexible and strong, which make them the ideal material for transparent electrodes. The only drawback is that photo-generated charge carriers in the nanotube may recombine with ions in the dye, which reduces the power conversion efficiency of the solar cell.

To overcome this problem, Huang and his team placed a TiO₂ thin film in between the carbon nanotube thin film and the porous layer. They found that the performance of dye-sensitized solar cells with TiO₂ thin film was significantly better than those without. However, they also found that the solar conversion efficiency of their new dye-sensitized solar cells was only 1.8%, which is lower than that of conventional solar cells using ITO electrodes. This is due to the higher electrical resistances and reduced optical transparency of the carbon nanotube films, which limits the amount of sunlight entering the cell.

“We are now studying different ways to enhance the conductivity and transparency of the films,” says Huang. “Furthermore, we are planning to replace the bottom platinum electrode with carbon nanotube thin film to reduce the cost of dye-sensitized solar cells further.”

If successful, the results could have a great impact on the cost and stability of dye-sensitized solar cells.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering and the Singapore Institute of Manufacturing Technology

Via: ScienceDaily

A company in India is taking a popular idea in the country pay as you go cell phone service and applying it to small scale solar energy systems.

Simpa Networks, a startup based in Bangalore, India, is offering small solar panel systems to rural homes that would otherwise not be able to afford electricity at all.

The most basic system offered to off-grid homes is around 25 watts to 50 watts; it will produce enough electricity to power a couple of CFL lights, a cell phone charger and another small appliance like a fan or a TV cable box.

While this might seem like a meager contribution by western standards, remember that these are rural families often surviving on less than $4 a day.

Simpa, partnering with solar manufacturer Selco India, allows customers to pay for a small percentage of the system’s hardware upfront. Customers then purchase pay-as-you-go cards in increments of 50, 100, or 500 rupees which supplies them with a code that they enter to unlock the solar system. Some sources report customers can also top off their accounts with their cell phones.

After typically 2 or 3 years, the customer has paid off the hardware and owns the system outright. They are then able to generate their own electricity for free.

Many of Simpa’s target market customers wouldn’t be able to afford a solar electric system otherwise and aren’t interested or eligible for a loan. The payment system is already in place in Bangalore; 50 customers are currently using a Simpa system and 8 are within a few months of paying off their system.

Aside from the attractive payment system, Indian households arelooking for better ways to light and power their homes. Kerosene is mostly used for lamps, and other popular fuel sources like diesel or wood burning are “more hazardous to health and more expensive than grid power and off-grid solar.” Additionally, these methods actually end up costing more per capita and per income than grid-connected power for the average Indian consumer.

Simpa is still a young company–only a year old–with a new concept that will face a lot of challenges as it attempts to reach its break-even goal of 5,000 systems sold each year, not to mention turn a profit. However, the company has already received a round of angel investments totaling $1.3 million and hopes to raise an additional $4 million in the coming months.