Energy generation - Page 2

Rice University researchers have recently taken the idea of wearable devices that harvest energy from movement to a new level. Prof. James Tour's lab has adapted laser-induced graphene (LIG) into small, metal-free devices that generate electricity.

Putting the LIG composites in contact with other surfaces produces static electricity that can be used to power devices. This relies on the triboelectric effect, by which materials gather a charge through contact. When they are put together and then pulled apart, surface charges build up that can be channeled toward power generation.

In a recent study, researchers from the Stevens Institute of Technology in the U.S have come up with an original idea - they designed a bionic mushroom that uses graphene to produce electricity. More accurately, the researchers have generated mushrooms patterned with energy-producing bacteria and an electrode network.

Many examples of organisms that live closely together and interact with each other exist in nature. In some cases, this symbiotic relationship is mutually beneficial. The research team wanted to engineer an artificial symbiosis between button mushrooms and cyanobacteria. In their vision, the mushroom would provide shelter, moisture and nutrients, while bacteria 3D-printed on the mushroom's cap would supply energy by photosynthesis. Graphene nanoribbons printed alongside the bacteria could capture electrons released by the microbes during photosynthesis, producing bio-electricity.

Sweden-based Graphmatech develops and produces novel graphene-based nanocomposite materials, under the Aros Graphene brand. The company recently secured an investment from ABB and Walerud Ventures, and the company's CFO, Bjorn Lindh, was kind enough to answer a few questions we had to him.

Q: Thank you for your time Bjorn. Can you give us a short introduction to Graphmatech's Aros Graphene materials, and how it differs from other graphene materials on the market?

Graphmatech has invented the novel material, Aros Graphene that keeps most of graphene's features, while making it easy to use in large industrial scales by preventing agglomeration, which is a key challenge for the use of graphene. Aros graphene is produced in powder form and can be used as additive, as coating or even in 3D-printing. The market introduction and launch of first products, filaments and thermal paste, will be introduced to the market in 2019.

A fascinating research out of the University of Arkansas, revealed in November 2017, showed that the internal motion of graphene (and possibly other 2D materials) may be used as a source of clean, limitless energy. Now, NTS Innovations (also known as Nanotube Solutions), a U.S -based nanotechnology company, has licensed this patent-pending technology from the university and plans to use it to fabricate devices and systems that produce energy without consuming fuel or creating pollution.

NTS Innovations focuses on the commercialization of nanotechnology and environmentally sustainable heating, water filtration and purification, as well as the production of green energy, all using 2D materials. The company sees great potential for this discovery in many applications. For example, it could be used to create sustainable, decentralized energy systems throughout the world, especially in places where the energy grid system is underdeveloped or nonexistent. It may also prove beneficial in biomedical devices, enhanced solar and wind production, capturing waste heat and remote sensing devices.

Researchers at Stanford University have recently demonstrated a graphene-based high efficiency thermal-to-electricity conversion technology, called thermionic energy convertor. By using graphene as the anode, the efficiency of the device is increased by a factor of 6.7 compared with a traditional tungsten anode. This technology can work in a tandem cycle with existing thermal-based power plants and significantly improve their overall efficiencies.

Hongyuan Yuan and Roger T. Howe, among the leading researchers in the Stanford team, explain that one of the major challenges for wide adoption of TECs is high anode work function, which directly reduces the output voltage as well as the net efficiency. The theoretical maximum efficiency for a TEC with a 2 eV work function anode is 3% at a cathode temperature of 1500 K, compared to an astonishing 10-fold increment to 32% with a 1 eV work function anode.

Researchers at Brown University have demonstrated that graphene, wrinkled and crumpled in a multi-step process, becomes significantly better at repelling water - a property that could be useful in making self-cleaning surfaces. Crumpled graphene also has enhanced electrochemical properties, which could make it more useful as electrodes in batteries and fuel cells.

The researchers aimed to build relatively complex architectures incorporating both wrinkles and crumples. To do that, the researchers deposited layers of graphene oxide onto shrink films -polymer membranes that shrink when heated. As the films shrink, the graphene on top is compressed, causing it to wrinkle and crumple. To see what kind of structures they could create, the researchers compressed same graphene sheets multiple times. After the first shrink, the film was dissolved away, and the graphene was placed in a new film to be shrunk again.

In a research funded by a U.S. Department of Defense-Multidisciplinary University Research Initiative grant and Wenzhou Medical University, an international team of scientists has developed what is referred to as the first one-step process for making seamless carbon-based nanomaterials that possess superior thermal, electrical and mechanical properties in 3D. The research may hold potential for increased energy storage in high efficiency batteries and supercapacitors, increasing the efficiency of energy conversion in solar cells, for lightweight thermal coatings and more. 

The group's early testing showed that a 3D fiber-like supercapacitor made with uninterrupted fibers of carbon nanotubes and graphene matched or even surpassed bettered the reported record-high capacities for such devices. When tested as a counter electrode in a dye-sensitized solar cell, the material enabled the cell to convert power with up to 6.8% efficiency and more than doubled the performance of a similar cell that used an expensive platinum wire counter electrode. 

The technology is expected to be of great interest to the energy industry and is part of what is known as "hydrogen economy", an alternative energetic model in which energy is stored as hydrogen. In this regard, the materials (patented by the UJI) allow catalysing reactions for obtaining hydrogen from alcohols and may also serve as storage systems of this gas.

Researchers at the Israeli Ben-Gurion University of the Negev (BGU) and University of Western Australia have designed a new process for creating few-layer graphene for use in energy storage and other material applications that is faster, potentially scalable and surmounts some of the current graphene production limitations.

The new one-step, high-yield generation process is based on an ultra-bright lamp-ablation method and has succeeded in synthesizing few-layer (4-5) graphene in relatively high yields. It involves a novel optical system (originally invented by BGU professors) that reconstitutes the immense brightness within the plasma of high-power xenon discharge lamps at a remote reactor, where a transparent tube filled with simple, inexpensive graphite is irradiated. The process is considered fast, safe and green (free of any toxic substances - just graphite plus concentrated light).

Researchers at the Harbin Institute of Technology in China and the University of Michigan in the US demonstrated improved LFP battery cathode, augmented by reduced graphene oxide. The scientists used reduced graphene oxide (rGO) in LFP battery cathodes to create a new high surface area 3D composite.

LFP (or LiFePO4) is a kind of Li-Ion rechargeable battery for high power applications, such as electric vehicls, Power Tools and more. LFP cells feature high discharging current, non explosive nature and long cycle life, but its energy density is lower than normal Li-Ion cell. In this study, the researchers created the composite using a nickel foam template that was coated with layers of graphene oxide. The graphene oxide reduced as the LFP nanoparticles were synthesized in a simple technique that allows larger amounts of the LFP to be loaded into the carbon material.