A team from Japan’s Hokkaido University has been working on transforming wasted heat energy into usable electricity.
As everyone in the energy industry knows, the universe claims its share of all energy expended in the form of heat dissipation. Fossil fuels lose 60% of the energy they produce in the form of waste heat.
Thermoelectric materials are able to turn temperature differences into electricity through a phenomenon known as the Seebeck effect. When one side of a thermoelectric material is hot and other cold, electrons flow from one side to the other, creating an electric current.
Electrons, depending on their momentum and mass, have a slight wiggle, defined as the De Broglie wavelength. By making the distance between a two-dimensional layer of atoms narrower than the De Broglie wavelength of the electron moving through it, the thermoelectric quality of the material can be enhanced.
The researchers from Hokkaido have created a super-lattice with layers made from strontium, titanium and oxygen sandwiched between layers made from the same three elements, but with added niobium. The four-element compound contains electrons with two different De Broglie wavelengths.
The electrons with the longer wavelengths, confined within the narrow space of the lattice, doubled the thermoelectric conversion rate of the previously optimised material.
Whilst this is not enough to break the laws of thermodynamics or forestall the heat death of the universe, it could be used to reduce heat waste from power plants, vehicles and computers, and turn it into useable electricity.
Oil and gas can be a hazardous business, and for companies operating in some developing markets, there is another danger to be wary of – landmines.
With a number of African countries home to both promising oil and gas fields and a history of violent conflicts, dealing with landmines can be a major concern when exploring these territories, especially in areas that are uncharted and remote.
Take the example of Angola, which is both Africa’s largest oil exporter and the country with the continent’s second highest concentration of landmines, an estimated total of 15 million, or 31 per square mile. Egypt, although its new mighty gas fields like Zohr are located offshore, is blighted by 23 million landmines, or 60 per square mile.
To help deal with Africa’s landmine problems, UK mining machinery company MMD has donated an innovative new landmine clearance rig to The HALO Trust for use in mine-clearing operations in Zimbabwe.
The mobile unit can move to new areas quickly and process multiple different grades of soil, such as wet, heavy earth that can clog up other mine clearers. This means it can move through a minefield faster than can be achieved manually. It is remotely operated as well, to minimise the risk to its operators.
The machine moves soil up a conveyor belt, then it is thrown into a sizer, which grinds up any rocks or landmines within it. The sizer is robust enough to endure such ordnance that detonates instead of being crushed.
MMD estimates the machine could process 100,000 landmines by 2025, a sizeable chunk of the estimated 150,000 landmines still extant in Zimbabwe.
In the dark
An international team of geologists has discovered that oil degrades slower in deeper waters than at the ocean’s surface. Scientists were searching for where oil from the Deepwater Horizon disaster had gone.
“There’s no real precedent for the Deepwater Horizon, since most previous big spills were in shallow, coastal waters,” said Uyen Nguyen, a doctoral student in biogeochemistry at the US’ Penn State. “No one really knew how long it would take oil to biodegrade in the deep sea, where it’s cold, dark and under high pressure – factors that slow down microbial metabolism.”
It is estimated that 12-25% of the oil released by Deepwater Horizon, 4.9 million barrels, was consumed by bacteria and microbes.
By placing sediment and water from the Gulf of Mexico and oil in reactors with varying pressures and temperatures and leaving them for 18 days, the scientists were able to analyse how compounds found in oil were broken down by the naturally occurring microbes.
The test results suggested that n-alkanes, a major compound found in oil, would take 42 days to degrade in sediments deeper than 3,280 feet (1,000 metres) and 19 days at shallow sites, under optimal nutrient conditions.
The researchers found that oil biodegradation rates decreased by 4% for every 328 feet (100 metres) of increase in water depth.
The tests also found that the biodegradation of oil at a depth of 5,000 feet (1,500 metres) or more fell by 60% compared to that at surface temperature and pressure.
A ‘Sharpie’ solution to a cutting problem
A new and surprisingly low-tech method for cutting soft, or ‘gummy’, metals has been discovered by a team at Purdue University in the US.
Soft metals such as copper, aluminium, iron and low-carbon steels have a habit of sticking to cutting tools, building up on their edge and shortening the tools’ life. Their softness absorbs some of the energy applied during cutting, making it more difficult to saw them compared to stronger, harder materials.
The current solution is to coat the soft metal with a liquid metal such as gallium. However, this can easily spread throughout the gummy metal, causing it to crumble to powder.
The Purdue team’s solution is simpler, cheaper and safer: apply a layer of permanent marker or glue to the material first. The sticky quality of these chemicals helps to achieve a smoother, cleaner and faster cut.
“We realised that it’s not a particular chemical but the ink itself sticking to the metal through a physical adsorption mechanism,” said Anirudh Udupa, lead author on the study and a postdoctoral researcher in Purdue’s School of Industrial Engineering.
Applying an adhesive to the surface of the metal dramatically reduced the force of sawing without the whole metal falling apart, resulting in a clean cut in seconds.
The next step for the team is to assess the degree of stickiness that works best.
A golden opportunity for hydrogen production
Scientists have devised a new nanomaterial that they claim could work as a catalyst to produce hydrogen from water.
Scientists from Russia’s Peter the Great St Petersburg Polytechnic University (SPbPU), the Ioffe Institute and Germany’s Leibniz University Hannover (Leibniz Universitat Hannover) utilised gold nanoparticles in the material’s construction.
The aim of their work was to transfer the energy from inside a silicon wafer by using gold nanoparticles and a thin layer of titanium dioxide. This, the team hoped, would isolate nanoparticles from the silicon wafer.
The end result was a silicon wafer covered in small pillars, each topped with gold nanoparticles and then encased in the titanium dioxide, minimising the gold’s contact with the silicon.
“The diameter of gold nanoparticles is about 10 nanometres, and the height of the pillar is 80 nanometres. This is not a trivial task,” said Dr Marc Christopher Wurz from the Institute of Micro Production Technology at Leibniz University Hannover.
While the experiment is still ongoing, the scientists suggested this material could be used to break down large molecules to purify water as well as catalysing the production of hydrogen from water.