New Developments April 2017

Energy-efficiency labels for buildings are working Energy-efficiency labels have brought energy savings of up to 30 percent in large commercial buildings in Los Angeles. Buildings account for about one-third of the energy consumption and carbon emissions in the US. Three major certification programs attempt to reduce building emissions: the Environmental Protection Agency’s (EPA) Energy Star Program, the US Green Building Council’s Leadership in Energy and Environmental Design (LEED), and the Department of Energy’s (DOE) Better Buildings Challenge. the Energy Star program is the most successful voluntary energy-efficiency program in the world. It has saved consumers and businesses $34 billion in electricity costs and prevented more than about 300 million metric tons of greenhouse gas emissions in one year.

Non-participating buildings tend to be smaller, older, and in less premium locations, but they are greater in number and represent two-thirds of commercial building emissions.

Efficient power converter for internet of things The "internet of things" is the idea that vehicles, appliances, civil structures, manufacturing equipment, and even livestock will soon have sensors that report information directly to networked servers, aiding with maintenance and the coordination of tasks. Those sensors will have to operate at very low powers, in order to extend battery life for months or make do with energy harvested from the environment. Those operations require relatively little current, but occasionally, the sensor might need to transmit an alert to a distant radio receiver. That requires much larger currents. researchers from MIT's Microsystems Technologies Laboratories (MTL) presented a new power converter that maintains its efficiency at currents ranging from 500 picoamps to 1 milliamp, a span that encompasses a 200,000-fold increase in current levels.

Renewable energy needed to drive uptake of electric vehicles Plugging into renewable energy sources outweighs the cost and short driving ranges for consumers intending to buy electric vehicles, according to a new study. "We found the majority of participants placed great emphasis on the need for electricity for electric vehicles to be produced from renewable energy sources in order for them to be a true alternative," he said. "For example, a petrol-driven vehicle produces 119g CO2-e/km, of which most are on-road emissions. In comparison, an electric vehicle produces zero on-road emissions," he said. "However, if electricity is generated from coal to charge an electric vehicle it produces 139g CO2-e/km well-to-wheel emissions, compared with only 9g CO2-e/km well-to-wheel emissions with electricity from renewable energy sources." Australia - the transport sector accounted for 16 per cent of the country's greenhouse gas emissions and 85 per cent of these were generated by road transport.

To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon  New work shows that one form of silicon, Si-III, which is synthesized using a high-pressure process, is what's called a narrow band gap semiconductor. "For example, the optical properties of Si-III in the infrared region are particularly interesting for future plasmonic applications."

Rotating molecules create a brighter future The development of energy saving concepts in display and lighting applications is a major focus of research, since a fifth of the world's electricity is used for generating light. Passing an electric current through these molecules puts them into an excited state, but only 25% of these are 'bright' states that can emit light rapidly. The remaining 75% are 'dark' states that usually waste their energy as heat limiting the efficiency of the OLED device. Chemists at the University of East Anglia have now developed a new type of material where two different organic molecules are joined together by an atom of copper or gold. The resulting structure looks a bit like a propeller. The compounds, which can be made by a simple one-pot procedure from readily available materials, were found to be surprisingly luminescent. By rotating their "propeller," dark states formed on these materials become twisted, which allows them to change their spin quickly. The process significantly increases the rate at which electrical energy is converted into light achieving an efficiency of almost 100% and preventing the damaging build-up of dark states. The next step is to design new molecules that take full advantage of this mechanism, with the ultimate goal of removing the need for rare elements entirely. This would solve the longest standing problem in the field -- how to make OLEDs without having to trade-off between efficiency and stability.

Researchers offer novel method for calculating the benefits of renewable energy Current assessment approaches usually feature three types of renewable energy potentials: gross (theoretical), technical, and economic. Moreover, the paper's authors introduce fuel potential (wind (solar PV) energy potential in tonnes of reference fuel), heat energy potential (volume of heat energy in gigacalories and, consequently, heat energy savings gained through non-combustion of fossil fuels), electrical energy potential (volume of electrical energy in kWh, and, consequently, the savings of electrical energy that would otherwise be produced with the use of traditional methods), resource saving potential (savings of fossil fuels), and environmental potential (total air pollutants avoided).

Record new renewable power capacity added worldwide at lower cost The world added record levels of renewable energy capacity in 2016, at an investment level 23 percent lower than 2015, according to new research published by UN Environment, the Frankfurt School -- UNEP Collaborating Centre and Bloomberg New Energy Finance (BNEF). even though investment is down, annual installations are still up; instead of having to subsidise renewables, now authorities may have to subsidise natural gas plants to help them provide grid reliability," Liebreich said. The records set last year were $29.10 per megawatt hour for solar in Chile and $30 per megawatt hour for onshore wind in Morocco.

New class of optoelectronic materials developed A new class of semiconductor materials has been pioneered that might enhance the functionality of optoelectronic devices and solar panels -- perhaps even using one hundred times less material than the commonly used silicon. The collaborative team of material scientists and electrical engineers wanted to develop new materials which could showcase the ideal optical and electrical properties for a variety of applications such as displays, light detectors and emitters, as well as solar cells. The researchers developed a class of semiconductors called "transition metal perovskite chalcogenides." Currently, the most useful semiconductors don't hold enough carriers for a given volume of material (a property which is referred to as "density of states") but they transport electrons fast and thus are known to have high mobility. The real challenge for scientists has been to increase this density of states in materials, while maintaining high mobility.

In-flight, on-demand hydrogen production could mean 'greener' aircraft a process that can be used onboard aircraft while in flight to produce hydrogen from water and aluminum particles safely and cheaply. The hydrogen can then be converted into electrical energy for inflight use. The breakthrough could pave the way for non-polluting, more-electric aircraft that replace current hydraulic and pneumatic systems typically powered by the main engine. The spontaneous and sustained reaction between powdered aluminum and water is enabled by a special thermo-chemical process of aluminum activation the researchers developed. The protective properties of the oxide or hydroxide film covering the aluminum particle surface are modified by a small fraction of lithium-based activator diffused into aluminum bulk, allowing water at room temperature to react spontaneously with the aluminum. Their technology would provide:

• Quieter operations on board an aircraft
• Drastic reductions in CO2 emissions
• Compact storage; no need for hydrogen storage tanks onboard aircraft
• More efficient electric power generation
• A reduction in wiring (multiple fuel cells can be located near their point of use)
• Thermal efficiency (fuel cell generated heat can be used for de-icing, heating jet fuel)
• Reduced flammable vapors in fuel tanks (Inert gas generation)

Bright future for self-charging batteries scientists at McGill University and the Hydro-Québec's research institute are working on a single device capable of harvesting and storing energy using light. In other words, a self-charging battery. The study shows that a standard cathode from a lithium-ion battery can be "sensitized" to light by incorporating photo-harvesting dye molecules. "Theoretically speaking, our goal is to develop a new hybrid solar-battery system, but depending on the power it can generate when we miniaturize it, we can imagine applications for portable devices such as phones."

Freezing lithium batteries may make them safer, bendable A new method that could lead to lithium batteries that are safer, have longer battery life, and are bendable has now been developed, providing new possibilities such as flexible smartphones. His new technique uses ice-templating to control the structure of the solid electrolyte for lithium batteries that are used in portable electronics, electric vehicles, and grid-level energy storage. Yang's team explored the idea of using solid electrolyte as a substitute for the liquid electrolyte to make all-solid-state lithium batteries. They were interested in using ice-templating to fabricate vertically aligned structures of ceramic solid electrolytes, which provide fast lithium ion pathways and are highly conductive.

New breakthrough in battery charging technology A team of researchers, affiliated with UNIST has developed a single-unit, photo-rechargeable portable power source based on high-efficiency silicon solar cells and lithium-ion batteries (LIBs). This newly-developed power source is designed to work under sunlight and indoor lighting, allowing users to power their portable electronics anywhere with access to light. In addition, the new device could power electric devices even in the absence of light. It also displays unprecedented improvements in photo-charging (rapid charging in less than 2 min with a photo-electric conversion/storage efficiency of 7.61%). In the study, the research team fabricated a solid-state LIB with a bipolar cell configuration directly on the aluminium (Al) electrode of a c-Si PV module through an in-series printing process. To enable the seamless architectural/electrical connection of the two different energy systems, the Al metal layer is simultaneously used as a current collector of the LIB, as well as an electrode for solar cells. This allows the battery to be charged without the loss of energy.

Thin layers of water hold promise for the energy storage of the future this could allow an increased amount of energy to be stored per unit of volume, faster diffusion of ions through the material, and faster charge transfer. this line of investigation could ultimately lead to things like thinner batteries, faster storage for renewable-based power grids, or faster acceleration in electric vehicles. the researchers compared two materials: a crystalline tungsten oxide and a layered, crystalline tungsten oxide hydrate -- which consists of crystalline tungsten oxide layers separated by atomically thin layers of water. the hydrate stored energy more efficiently -- wasting less energy as heat. "We think the water layer acts as a pathway that facilitates the transfer of ions through the material.

Stabilizing molecule could pave way for lithium-air fuel cell poor rechargeability, reduced efficiency due to high overpotentials (more charge energy than discharge energy) and low specific energy. the nucleation and growth of dendrites from one electrode to the other, which causes short-circuiting, a source of premature cell failure that invariably ends in fires. the loss of battery power, also known as capacity fade -- that is the focus of the lab's most recent work. Capacity fade occurs when the electrolyte, which transports charged ions from the negative electrode (anode) to the positive (cathode), reacts with the electrodes. "It starts to consume the electrodes," Choudhury said. "It forms many insulating products that impede ion transport. Over time, these build up to produce such prohibitive internal cell resistance that finally the battery fades." Choudhury's solution is called an artificial solid-electrolyte interphase (SEI), a material that protects the electrodes while promoting the flow of electrons from one end of the cell to the other. Choudhury's approach for creating a functional designer interphase is based on bromide-containing ionic polymers (ionomers) that selectively tether to the lithium anode to form a few-nanometers-thick conductive coating that protects the electrode from degradation and fade. All research-grade lithium-oxygen electrochemical cells are evaluated using pure oxygen as the active cathode material. For a commercially viable lithium-oxygen (or lithium-air, as it's also known) cell, it would need to pull oxygen out of the air, and that oxygen also contains other reactive components, such as moisture and carbon dioxide.

Safer alternative to lithium-ion batteries Researchers at the U.S. Naval Research Laboratory's (NRL) Chemistry Division have developed a safer alternative to fire-prone lithium-ion batteries, which were recently banned for some applications on Navy ships and other military platforms. a breakthrough for nickel-zinc (Ni-Zn) batteries in which a three-dimensional (3-D) Zn "sponge" replaces the powdered zinc anode traditionally used. With 3-D Zn, the battery provides an energy content and rechargeability that rival lithium-ion batteries while avoiding the safety issues that continue to plague lithium. Zinc-based batteries are the go-to global battery for single-use applications, but are not considered rechargeable in practice due to their tendency to grow conductive whiskers (dendrites) inside the battery, which can grow long enough to cause short circuits. "The key to realizing rechargeable zinc-based batteries lies in controlling the behavior of the zinc during cycling," said Parker, lead author on the paper. "Electric currents are more uniformly distributed within the sponge, making it physically difficult to form dendrites."

New solar cell design could pave the way for over 50% energy-conversion efficiency A new solar cell design could raise the energy conversion efficiency to over 50% by absorbing the spectral components of longer wavelengths that are usually lost during transmission through the cell. In order to reduce these large energy losses and raise efficiency, Professor Kita’s research team used two small photons from the energy transmitted through a single-junction solar cell containing a hetero-interface formed from semiconductors with different bandgaps. Using the photons, they developed a new solar cell structure for generating photocurrents. As well as demonstrating theoretical results of up to 63% conversion efficiency, it experimentally achieved up-conversion based on two photons, a mechanism unique to this solar cell. The reduction in energy loss demonstrated by this experiment is over 100 times more effective compared to previous methods that used intermediate bands. different bandgaps of Al0.3Ga0.7As and GaAs.

Fast, low energy, and continuous biofuel extraction from microalgae Researchers have used a nanosecond pulsed electric field to extract hydrocarbons from microalgae. By using the shorter duration pulse, they were able to extract a large amount of hydrocarbons from the microalgae in a shorter amount of time, using less energy, and in a more efficient manner than current methods. As an alternative to liquid fossil fuels, biodiesel extracted from microalgae is an increasingly important part of the bioenergy field. While it releases a similar amount of CO2 as petroleum when burned, the CO2 released from biodiesel is that which has recently been removed from the atmosphere via photosynthesis meaning that it does not contribute to an increase of the greenhouse gas. Kumamoto University researchers, on the other hand, used a nanosecond PEF (nsPEF) to focus on the microalgae matrix instead of the cells. A nsPEF generally uses less energy than the ?s/msPEFs even at high voltages, and is not as destructive or costly as the traditional drying method of oil extraction. many extraction processes practiced today use a drying method to extract oil which ends in the destruction of the algae. Our method is relatively non-destructive and the microalgae are able to rebuild their colonies after extraction has finished. One minor drawback is the impurity of the matrix; polysaccharides must be purified from the extracted hydrocarbon solution. Fortunately, these molecules may be used in the creation of bioethanol but their concentration is low.