Innovation in solar technology promises sustainable power from everyday objects

Scientists at Oxford University Physics Department say they have developed a new technology which could generate solar electricity without the need for silicon-based solar panels. Instead, their innovation, a new light-absorbing, power-generating material, is thin and flexible enough to apply to the surfaces of everyday objects like rucksacks, cars and mobile phones.

The researchers explain that the new technology stacks multiple light-absorbing layers into one solar cell, harnessing a wider range of the light spectrum and allowing more power to be generated from the same amount of sunlight. They report that the multi-junction approach has been independently certified by Japan’s National Institute of Advanced Industrial Science and Technology (AIST) to deliver over 27% energy efficiency, for the first time matching the performance of traditional, single-layer, energy-generating silicon photovoltaics.  

Dr Shuaifeng Hu, Post Doctoral Fellow, says: ‘We believe that, over time, this approach could enable the photovoltaic devices to achieve far greater efficiencies, exceeding 45%.’ This compares with around 22% energy efficiency from solar panels today.  

‘By using new materials which can be applied as a coating, we’ve shown we can replicate and out-perform silicon whilst also gaining flexibility. This is important because it promises more solar power without the need for so many silicon-based panels or specially-built solar farms,’ adds Dr Junke Wang, Marie Skłodowska-Curie Actions Postdoc Fellow.

A recipe for zero-emissions fuel: aluminium, seawater and caffeine

Engineers at the Massachusetts Institute of Technology (MIT) have developed what they claim is a fast and sustainable method for producing hydrogen fuel using aluminium, salt water and coffee grounds.

In a study appearing in the journal Cell Reports Physical Science, the researchers show how hydrogen gas can be produced by dropping pretreated, pebble-sized aluminium pellets into a beaker of filtered seawater. The aluminium is pretreated with a rare-metal alloy to remove the oxide coating that naturally forms in air so can react with seawater to generate hydrogen. The salt ions in the seawater can in turn attract and recover the alloy, which can be reused to generate more hydrogen, in a sustainable cycle.

The production of hydrogen is quite slow. However, the team discovered that a low concentration of imidazole – an active ingredient in caffeine (they initially used coffee grounds) – is enough to significantly speed up the reaction, producing the same amount of hydrogen in just five minutes, compared to two hours without the added stimulant.

The researchers are now developing a small reactor that could run on a marine vessel or underwater vehicle. The vessel would hold a supply of aluminium pellets (recycled from old soda cans and other aluminium products), along with a small amount of gallium-indium and caffeine. These ingredients could be periodically funnelled into the reactor, along with some of the surrounding seawater, to produce hydrogen on demand. The hydrogen could then fuel an onboard engine to drive a motor or generate electricity to power the ship.

High-altitude aircraft contrails create greater climate warming effect  

Meanwhile, a new study led by scientists at Imperial College London concludes that modern commercial aircraft flying at high altitudes create longer-lived planet-warming contrails than older aircraft. This means that although modern planes emit less carbon than older aircraft, they may be contributing more than previously thought to climate change through contrails. The study also found that private jets produce more contrails than previously thought, potentially leading to outsized impacts on climate warming.

Contrails, or condensation trails, are thin streaks of cloud created by aircraft exhaust fumes that contribute to global warming by trapping heat in the atmosphere. While the exact warming effect of contrails is uncertain, scientists believe it is greater than warming caused by carbon emissions from jet fuel.

Published in Environmental Research Letters, the study used machine learning to analyse satellite data on more than 64,000 contrails from a range of aircraft flying over the North Atlantic Ocean.  

Modern aircraft that fly at above 38,000 feet (about 12 km), such as the Airbus A350 and Boeing 787 Airliners, create more contrails than older passenger-carrying commercial aircraft, the study found. To reduce jet fuel consumption, modern aircraft are designed to fly at higher altitudes where the thinner air creates less aerodynamic drag, compared to older commercial aircraft, which usually fly at slightly lower altitudes (around 35,000 ft; 11km). This means these higher-flying aircraft create less carbon emissions per passenger. However, it also means they create contrails that take longer to dissipate – creating a warming effect for longer and a complicated trade-off for the aviation industry.

The study also confirmed a simple step that can be taken to shorten the lifetime of contrails: reduce the amount of soot emitted from aircraft engines, produced when fuel burns inefficiently. Modern aircraft engines are designed to be cleaner, typically emitting fewer soot particles, which cuts down the lifetime of contrails. While other studies using models have predicted this phenomenon, the new study is thought to be the first to confirm it using real-world observations.

Scientists discover a wood type that could be highly efficient at carbon storage

Back at ground level, scientists from the Sainsbury Laboratory at Cambridge University and Jagiellonian University, Poland, have identified that the wood from tulip trees is neither hardwood nor softwood. The discovery, they claim, points to the value of the tree for carbon storage.  

Tulip trees, whose two species are either native to the eastern US or China and Vietnam, are related to magnolias and can grow over 30 metres (100 feet) tall quickly. They have a unique type of cell structure that may have developed to more readily capture and store carbon when the Earth’s atmospheric CO₂ concentrations were relatively low. The scientists believe their study, published in New Phytologist, opens new opportunities to improve carbon capture and storage in plantation forests by planting a fast-growing tree more commonly seen in ornamental gardens, or breeding tulip tree-like wood into other tree species, as a means to help combat climate change.