Transparent solar cells that can convert invisible light wavelengths into renewable energy could supply 40% of the US’ energy demand, a Michigan State University (MSU) engineering team have reported.
In contrast to the robust, opaque solar panels that take up a large amount of space – whether on rooftops or on designated solar farms – the transparent solar cells can be placed on existing surfaces, such as windows, buildings, phones, and any other object with a clear surface.
Traditional solar panels require large amounts of space.
‘Highly transparent solar cells represent the wave of the future for new solar cell applications,’ says Richard Lunt, Associate Professor of Chemical Engineering and Materials Science at MSU.
‘We analysed their potential and show that by harvesting only invisible light, these devices can provide a similar electricity generation potential as rooftop solar while providing additional functionality to enhance the efficiency of buildings, automobiles, and mobile electronics.’
Solar, or photovoltaic, cells convert the sun’s energy into electricity. Image: Pixabay
Currently, the cells are running at 5% efficiency, says the team, compared to traditional solar panels that have recorded efficiencies between 15-18%. Lunt believes that with further research, the capability of the transparent cells could increase three-fold.
‘That is what we are working towards,’ says Lunt. ‘Traditional solar applications have been actively researched for over five decades, yet we have only been working on these highly transparent solar cells for about five years.’
The cells can be added to any existing transparent surface, including mobile phones. Image: Max Pixel
While solar panels may be more efficient at converting energy than the group’s transparent cells, Lunt says that the latter can be easily applied to more surfaces and therefore a larger surface area, increasing the overall amount of energy produced by the cells.
‘Ultimately,’ he says, ‘this technology offers a promising route to inexpensive, widespread solar adoption on small and large surfaces that were previously inaccessible.’
Transparent solar cells. Video: Michigan State University
Together, and with further work on its efficiency, the authors of the paper believe that their see-through cells and traditional solar panels could fulfil the US’ energy needs.
‘The complimentary deployment of both technologies could get us close to 100% of our demand if we also improve energy storage,’ Lunt says.
Hailed by some as the future of clean energy, nuclear fusion is an exciting area of research, supported in the UK by the Atomic Energy Authority (UKAEA) – a government department that aims to establish the UK as a leader in sustainable energy. Here are five things you need to know about nuclear fusion.
1. It powers the sun.
Nuclear fusion occurs when two or more atomic nuclei of a low atomic number fuse to form a heavier nucleus at high energy, resulting in the release of a large amount of energy. However, it is only possible at an extremely high temperature and pressure, which means that currently the input energy required is too high to produce energy commercially. It’s the same process that powers the stars – the sun fuses 620 million tons of hydrogen and makes 606 million metric tons of helium every second.
2. The largest successful reactor is in Oxford.
The MASCOT telemanipulator is the main workhorse for all remote handling activities in JET. Image: The Naked Cat Fighter/Wikimedia Commons
The Joint European Torus (JET) is managed by the UKAEA at the Culham Science Centre in Oxford, UK. JET is a tokamak – a donut-shaped vessel designed around centrally placed fusion plasma, a fourth fundamental state of matter after solid, liquid, and air, containing the charged particles essential for nuclear fusion to occur.
Using strong magnetic fields, the tokamak confines the plasma to a shape that allows it to reach temperatures up to 20 times that of the sun. While still not commercially viable, it is the only operational reactor that can generate energy from nuclear fusion.
3. JET’s successor is due to launch in 2025
The International Thermonuclear Experimental Reactor (ITER), based in Provence, southern France, is the EU’s successor project to JET – a collaboration between all 28 EU member states as well as China, India, Japan, South Korea, Russia, and the US. Its first experiment is due to run in 2025 and, if successful, it will be the world’s largest operating nuclear fusion reactor, producing upwards of 500MW.
4. ITER is the feasibility study for large-scale, carbon-free energy
By 2025, ITER will produce its first plasma, with tritium and deuterium (a combination with an extremely low energy barrier) to be added in 2035, in the hope of allowing the facility to efficiently generate 100% carbon-free, reliable energy on a large scale.
5. The UK’s future role in the nuclear sector rests on Brexit negotiations
The JET magnetic fusion experiment in 1991. Image: EFDA JET
Despite the UKAEA’s essential work in supporting the success of JET and continued commitment to investing in the project, Brexit makes the continuation of JET and the UK’s role in ITER uncertain.
Director of ITER, Bernard Bigot, has said his concerns lie with the extension of JET. ‘If JET ends after 2018 in a way that is not coordinated with another global strategy for fusion development, clearly it will hurt ITER’s development,’ he said. ‘For me it is a concern.’
In a statement on the future of JET, the UK government said: ‘The UK’s commitment to continue funding the facility will apply should the EU approve extending the UK’s contract to host the facility until 2020.’
With hopes for JET’s funding to continue until at least 2023, and the UK government announcing its intentions to leave Euratom last year, the future of the UK’s ability to compete in the nuclear sector rests on the progress of Brexit negotiations in the coming months.
Determining the efficacy of organic solar cell mixtures is a time-consuming and tired practice, relying on post-manufacturing analysis to find the most effective combination of materials.
Now, an international group of researchers – from North Carolina State University in the US and Hong Kong University of Science and Technology – have developed a new quantitative approach that can identify effective mixtures quickly and before the cell goes through production.
Development of a thin-film solar cell. Image: science photo/Shutterstock
By using the solubility limit of a system as a parameter, the group looked to find the processing temperature providing the optimum performance and largest processing window for the system, said Harald Ade, co-corresponding author and Professor of Physics at NC State.
‘Forces between molecules within a solar cell’s layers govern how much they will mix – if they are very interactive they will mix but if they are repulsive they won’t,’ he said. ‘Efficient solar cells are a delicate balance. If the domains mix too much or too little, the charges can’t separate or be harvested effectively.’
‘We know that attraction and repulsion depend on temperature, much like sugar dissolving in coffee – the saturation, or maximum mixing of the sugar with the coffee, improves as the temperature increases. We figured out the saturation level of the ‘sugar in the coffee’ as a function of temperature,’ he said.
Organic solar cells are a type of photovoltaic – which convert energy from the sun into electrons – that uses organic electronics to generate electricity. This type of cell can be produced cheaply, and is both lightweight and flexible, making it a popular option for use in solar panels.
Photovoltaic systems are made up of organic solar cells that convert sunlight into energy. Image: Pxhere
However, difficulties in the production process, including an effective process to determine efficiency of potential material combinations, is stalling its development.
‘In the past, people mainly studied this parameter in systems at room temperature using crude approximations,’ said Long Ye, first author and postdoctoral researcher at NC State. ‘They couldn’t measure it with precision and at temperatures corresponding to processing conditions, which are much hotter.’
Faces of Chemistry: Organic solar cells at BASF. Video: Royal Society of Chemistry
‘The ability to measure and model this parameter will also offer valuable lessons about processing and not just material pairs.’
But the process still needs refinement, said Ade. ‘Our ultimate goal is to form a framework and experimental basis on which chemical structural variation might be evaluated by simulations on the computer before laborious synthesis is attempted,’ he said.
Compared with other renewable energy resources – take solar or wind power as examples – tidal energy is still in the first stages of commercial development. But as the world moves towards a greener economy, tidal power is becoming more in demand in the competitive renewables market.
Currently, the very few tidal power plants in the world are based in Canada, China, France, Russia, South Korea, and the UK, although more are in development. Experts predict that tidal power has the potential to generate 700TWh annually, which is almost a third of the UK’s total energy consumption.
How does it work?
Tidal energy is produced by the natural movement of ocean waves during the rise and fall of tides throughout the day. Generally, generating tidal energy is easier in regions with a higher tidal range – the difference between high tide, when the water level has risen, and low tide, when levels have fallen. These levels are influenced by the moon’s gravitational pull.
The moon’s gravitational pull is responsible for the rise and fall of tides. Image: Public Domain Pictures
We are able to produce energy from this process using tidal power generators. These generators work similarly to wind turbines by drawing energy from the currents of water, and are either completely or partially submerged in water.
One advantage of tidal power generators is that water is denser than air, meaning that an individual tidal turbine can generate more power than a wind turbine, even at low currents. Tides are also predictable, with researchers arguing that it is tidal power is potentially a more reliable renewable energy source.
What is tidal power and how does it work? Video: Student Energy
There are three types of tidal energy systems: barrages, tidal streams, and tidal lagoons. Tidal barrages are structured similar to dams and generate power from river or bay tides. They are the oldest form of tidal power generation, dating back to the 1960s.
However, there is a common concern that generators and barrages can damage the environment, despite producing green energy. By creating facilities to generate energy, tidal power centres can affect the surrounding areas, leading to problems with land use and natural habitats.
Fleet tidal lagoon in Dorset, UK. Image: Geograph
Since then, technologies in tidal streams and lagoons have appeared, which work in the same fashion as barrages but have the advantage of being able to be built into the natural coastline – reducing the environmental impact often caused by the construction of barrages and generators.
However, there are no current large-scale projects with these two systems, and output is expected to be low, presenting a challenge to compete with more cost-effective renewable technologies.
Latin America is setting the pace in clean energy, led by Brazil and Mexico. Renewables account for more than half of electricity generation in Latin America and the Caribbean – compared with a world average of about 22% – according to the International Energy Agency.
Brazil is one of the world’s leading producers of hydropower, while Mexico is a leader in geothermal power. Smaller countries in the region are also taking a lead. In Costa Rica, about 99% of the country’s electricity comes from renewable sources, while in Uruguay the proportion is close to 95%.
The Itaipu hydroelectric dam, on the border of Brazil and Paraguay, generated 89.5TWh of energy in 2015. Image: Deni Williams
At the same time, countries such as Chile, Brazil, Mexico and Argentina have adjusted their regulations to encourage alternative energy without having to offer subsidies. Some have held auctions for generation contracts purely for renewables.
Latin America’s renewable energy production is dominated by an abundance of hydropower, but there is strong growth potential for other sources of renewable energy. Wind and solar power are expected to account for about 37% of the region’s electricity generation by 2040, compared with current levels of about 4%, according to a report from Bloomberg New Energy Finance (BNEF).
Total electricity generation in Latin America is forecast to grow by 66% by 2040, and renewable energy is expected to account for the vast majority of the new capacity. While Brazil has significant solar water heating, solar PV is virtually non-existent. But consumer-driven rooftop PV is expected to account for 20% of Brazil’s electricity generation by 2040, it says. This compares with an expected 24% in the leading country, Australia, followed by 15% in Germany and 12% in Japan. Meanwhile, in Mexico, solar is forecast to overtake gas and hydro to dominate Mexico’s capacity mix.
Brazil is the world’s third largest producer of renewable power, after China and the US, and has the world’s second largest hydropower capacity, after China, according to a report issued by the Renewable Energy Policy Network for the 21st Century (REN21). Brazil also ranks fourth in terms of bio-power generation - after the US, China and Germany - and fifth in terms of solar water heating collector capacity.
Rio do Fogo wind farm, Brazil. Image: The Danish Wind Industry
However, the recent economic downturn in Brazil, combined with declining electricity demand, has dampened growth in investments in renewable power in the country in the short-term. Although substantial hydropower capacity was commissioned in Brazil in 2016, the country’s renewable energy auction scheduled for 2016 was cancelled, and many projects awarded contracts in tenders through 2015 were stalled.
In the wind power sector, a shift is expected away from Brazil to other countries in the region. The unstable politic and economic climate in Brazil coincides with unprecedented auction activity in Mexico, Argentina and Chile, says Make Consulting, part of Wood Mackenzie. It expects more than 47GW of new wind power capacity to be commissioned in Latin America by 2026. But following the cancellation of Brazil’s reserve power auction planned for 2016, wind power installations in Brazil in 2019 are expected to be half the size of 2014 and 2016.