Tech Radar | What caught our attention outside the world of oil and gas this month
December 13, 2017
A team of researchers from the National University of Singapore (NUS) has devised a new method of industrial wastewater purification using a low-voltage electrochemical reaction.
The group reports that its method can remove up to 99% of “hard-to-treat organic compounds” found in various types of industrial wastewater.
What makes the method attractive primarily is its low power consumption, but also that it does not produce any secondary waste – e.g. sludge or residue – which would add to the costs and resources necessary for wastewater treatment. This is true even of wastewater from agriculture, farmland, shipping or indeed oil and gas.
Department of Civil and Environmental Engineering assistant professor and lead author Olivier Lefebvre explained: “Our electrochemical system has shown that it can achieve complete mineralisation of any organic pollutant. This means the system can completely remove organic compounds in the wastewater by degrading them into water and carbon dioxide. This novel system can also be incorporated as a pre-treatment to an existing wastewater treatment scheme. It operates on low electrical power and the system could easily be combined with solar power and other purification methods such as using membranes and biological treatments,” explained Assistant Professor Lefebvre.
The system works by pumping water into a main chamber, through which electric current is passed via electrodes. This generates hydrogen peroxide and hydroxyl radicals (one of the most powerful oxidising agents) that will react with the complex organic compounds in the water. These chemicals also break down during the process, until all contaminants have been degraded into water and carbon dioxide.
The system can currently process 10 litres of water in six hours.
Lefebvre and his team have applied for two patents used in the system and are now testing it on more types of industrial wastewater to refine the design and optimise the efficiency of the system. In addition, the team has recently developed graphene electrodes that can speed up the process. They are looking to collaborate with industry partners to commercialise the technology.
Engineers from a number of semiconductor firms and universities have presented a new design for gallium nitride power converters.
Power converters are found throughout electronic devices and the grid to step voltages up or down or convert power from AC to DC, but are intrinsically inefficient. Devices using gallium nitride are more efficient and can be made in smaller housings, but they cannot handle voltages above 600 V.
However, researchers from MIT, semiconductor maker IQE, Columbia University, IBM and the Singapore-MIT Alliance for Research and Technology recently presented a new design which could handle up to 1,200 V. Moreover, they believe that with further work this could be scaled up to 5,000 V, making for more efficient grid infrastructure and large power electronics and devices.
Part of the solution was in the devices’ construction; while traditional devices are built laterally, the new solution is vertical. MIT Professor of Electrical Engineering and Computer Science Tomás Palacios explained: “For medium and high-power applications, vertical devices are much better. These are devices where the current, instead of flowing through the surface of the semiconductor, flows through the wafer, across the semiconductor. Vertical devices are much better in terms of how much voltage they can manage and how much current they control.”
While current is concentrated at one narrow point of the lateral device, generating a lot of heat, in a vertical device the current flows evenly through its whole length, meaning heat can be dissipated more easily, he added.
The team also devised a neat alternative to the conventional gate switch. Their vertical gallium nitride transistors have protrusions on top, known as “fins.” On both sides of each are electrical contacts that together act as a gate. Current enters the transistor through a contact on top of the fin and exits through the bottom of the device. The narrowness of the fin ensures that the gate electrode is able to switch the transistor on and off.
CAPTION : MIT postdoc Yuhao Zhang handles a wafer with hundreds of vertical gallium nitride power devices fabricated from the Microsystems Technology Laboratories production line
A research team at Kiel University and spin-off company Phi-Stone have developed a new anti-biofouling coating which makes it harder for marine organisms to grow on ship hulls. The solution recently won the Global Marine Technology Entrepreneurship Competition in Qingdao, China in November.
According to the team’s estimations, biofouling can increase vessel fuel consumption by up to 40%, costing the industry up to US$150 billion per year in fuel and maintenance. (While InnovOil would estimate fuel consumption loss at a far lower level, the problem is nevertheless a drain on vessel efficiency, and many existing protective solutions also present environmental concerns owing to their polluting effects.)
Kiel and Phi-Stone’s solution is environmentally friendly and long-lasting, using no solvents and releasing no pollutants. Instead, the coasting’s surface makes it harder for organisms to attach themselves to hulls.
The coating is made from a polymer composite based on polythiourethane (PTU) and specially formed ceramic particles, and recent tests on active vessels suggest promising results for the marine industry.
"We were able to determine significantly less growth after two years on the 'African Forest', which travels from Belgium to Gabon in central Africa. This was then easy to clean off with a plain sponge,” noted Dr Martina Baum, technical biologist from Professor Rainer Adelung's Functional Nanomaterials working group.
The company is now working on developing a spraying technique, with which the coating can be applied easily and over large areas.
The team behind the International Thermonuclear Experimental Reactor (ITER) announced on December 6 that the project, located in southern France, is now 50% complete.
When complete, the Tokamak will heat hydrogen plasma to 150 million °C, enabling a fusion reaction. In real terms, this will produce 500 MW of thermal power – a suitable size for studying a “burning” or largely self-heating plasma, a state of matter that has never been produced in a controlled environment on Earth, ITER reports. Studying this at this scale will enable optimisation of the plants that follow.
Components are being provided by companies in the EU, China, India, Japan, Korea, Russia and the US, and include those with expertise from electromagnetics, cryogenics, robotics and materials science. The goal is that developing these components will also lead to innovation and spin-offs in other fields.
ITER director-general Bernard Bigot commented: “First Plasma, scheduled for December 2025, will be the first stage of operation for ITER as a functional machine. It will be followed by a staged approach of additional assembly and operation in increasingly complex modes, culminating in Deuterium-Tritium Plasma in 2035.”
“Globally, these indicators show that the ITER project is progressing steadily. For the past two years, we have met every agreed project milestone. This has not happened easily. A project of this complexity is full of risks; and our schedule to First Plasma 2025 is set with no ‘float’ or contingency,” he added.
From there, ITER predicts that commercial fusion plants could start to come online as soon as 2040. These would be built with larger plasma chambers than the pilot project, producing 10-15 times more electrical power than the 500-MW system under development.