In a real bad bag New research has revealed that decaying low-density polyethylene (LDPE), typically found in plastic bags and bottles, releases methane and ethylene, both major greenhouse gases (GHGs).
Solar radiation produces microscopic cracks and pits in the surface of the plastic, enlarging its surface area and accelerating gas production.
The study revealed that exposure to sunlight caused polyethylene samples to increase their production of methane by 176 times.
“Plastics represent a heretofore unrecognised source of climate-relevant trace gases that are expected to increase as more plastic is produced and accumulated in the environment,” the study stated.
The study found that decaying plastics released these gases whilst immersed in water, albeit at a slower rate. Few samples kept in the dark produced any gas, and those that did produced far less than those exposed to sunlight.
Plastic bags are a major culprit, as their large surface area makes them particularly efficient producers of gas. “LDPE produced the largest amounts of CH4 and C2H4, probably due to its weaker structure and more exposed hydrocarbon branches,” the study claimed.
By collecting pieces of plastic from the ocean, which may have been floating for a long time, the study suggests that gas production may continue throughout the entire lifetime of the plastic.
While it is unlikely that commercial volumes of methane will be produced from plastic waste any time soon, this is another warning about our consumption of disposable plastic and the role it plays in our economy.
Water way to go Researchers from the University of Nottingham have found that seawater can be used instead of freshwater to produce bioethanol.
As only 2.5% of Earth’s water is fresh, and only 1% of that is easily accessible, utilising seawater not only makes good economic sense, it reduces competition for a vital resource.
University of Nottingham microbiologist Dr Abdelrahman Zaky said: “Current fermentation technologies mainly use edible crops and freshwater for the production of bioethanol. With an ever growing population and demand for biofuels and other bio-based produces, there are concerns over the use of the limited freshwater and food crops resources for non-nutritional activities. Also, freshwater has a high price tag in countries where it is available, pushing up the price of production.”
The process utilises a new strain of marine-based yeast to help ferment biomass, generally maize or sugar cane, to produce bioethanol. Currently, bioethanol requires around 1,400-9,800 litres of fresh water in order to produce a single litre of the biofuel.
“Seawater is a freely available and plentiful resource, and contains a spectrum of minerals, some of which have to be added to freshwater. The fermentation process using seawater also produces salt and freshwater as bi-products adding to economic benefits of the process.”
Breathing new life into methane Carbon dioxide could be used to produce usable hydrocarbons such as methane and ethane, according to new research from South Korea’s Daegu Gyeongbuk Institute of Science and Technology.
A team led by Professor Su-Il In from the Department of Energy Science and Engineering utilised high-efficiency photocatalysts to convert carbon dioxide into methane or ethane by placing graphene on reduced titanium dioxide in a stable and efficient way.
The process produced 259 micromoles per gram of methane and 77 micromoles per gram of ethane, 5.2% and 2.7% higher respectively than conventional reduced titanium dioxide photocatalysts.
In the experiment, electrons gather on the surface of the reduced titanium dioxide and form a large amount of radical methane (CH3) as polyelectrons engage in the reactions. The research team has identified a mechanism for producing methane (CH4) if this radical methane reacts with hydrogen ions, and for producing ethane (C2H6) if the radical methane molecules react with each other.
Professor In said: “The reduced titanium dioxide photocatalyst with graphene that has been developed this time has the advantage of being able to selectively produce CO2 as a usable chemical element such as methane or ethane.
“By conducting follow-up research that increases the conversation rate so that it can be commercialised, we will contribute to the development of technology for reducing carbon dioxide and turning it into a resource.”
‘Our own damn satellite’ California has announced plans to launch its own climate-monitoring satellite. Governor Jerry Brown made the announcement in a speech at the Global Climate Action Summit.
“This ground-breaking initiative will help governments, businesses and landowners pinpoint – and stop – destructive emissions with unprecedented precision, on a scale that’s never been done before,” he said.
The state will work in conjunction with Planet Labs and the California Air Resources Board. The satellite will monitor the build-up of pollutants.
“This initiative will enable us to spotlight the methane, the pollution, and then be able to be in a position to point out those who pollute, and then develop the remedies to end it,” Brown added.
Although there’s been no mention of the timeframe involved, or the cost, those may not end up being important. The move will serve to widen the gap between the climate-sceptical Trump administration and California’s green agenda. A change in leadership, on either side, could easily render the project unnecessary.
Solid cells Researchers from Russia’s Institute of Chemical Engineering of Ural Federal University and the Institute of High-temperature Electrochemistry have developed new electrochemical cells to perform electrolysis of water alongside carbon dioxide.
“A novel solid oxide electrolysis cell based on high-performance and CO2-tolerant materials, a proton-conducting electrolyte and an oxygen electrode was successfully fabricated and tested. Unusual characteristics leading to enhanced improvement were observed for this cell when the reducing atmosphere was enriched with CO2,” according to the researchers’ findings.
The study suggested that the cells work better with an increased concentration of CO2, as some of the electrons are used to recover the substance. This produces a synthesis gas, a mixture of carbon monoxide and hydrogen.
This synthesis gas contains the building blocks to create liquid hydrocarbon fuels, as well as helping to break down excess carbon dioxide.
In order to perform the experiment, the researchers had to develop a suitable solid electrolyte for the cell. They were looking for good proton conductivity alongside the need to be stable in an atmosphere of CO2 at a temperature of 700°C.
The study’s authors used a material that involved fewer protons being stuck at the boundaries of the grains (individual crystals in the polycrystalline material), making the final cells work better.
The material was sufficiently stable that, after 10 hours of operation, efficiency loss was as low as 0.7%.