Imagine cellular phones that can be charged during conversations and sound-insulating walls near highways that generate electricity from the sound of passing vehicles. A number of approaches for self-powering systems by scavenging energy from environments using photovoltaic, thermoelectric, and piezoelectric phenomena have been intensively explored. Among them, very recent innovative research has been intensively carried out to convert external mechanical stimuli such as body movements, heartbeat, blood flow, and ultrasonic wave into electricity, resulting in piezoelectric power-driven wireless self-powered systems. Such a piezoelectric power generation aims to capture the normally wasted energy surrounding a system and converts it into usable energy for operating electrical devices. New work by a nanotechnology research team in Korea has now demonstrated that it is possible to use sound as a power source to drive nanogenerators based on piezoelectric nanowires.
Most of today's lithium-ion batteries rely on anodes made from graphite, a form of carbon. There are several candidate electrodes to replace graphite as the anode for lithium-ion batteries. Such electrodes like silicon or tin have very high capacities but suffer from poor efficiency and cyclic stability as they experience large volume change and particle pulverization during repeated cycling. Silicon-based anodes, for instance, theoretically offer as much as a ten-fold capacity improvement over graphite, but silicon-based anodes have so far not been stable enough for practical use. Researchers have now used the macromolecular structure of self-assembled Tobacco mosaic virus as templates to fabricate stable three-dimensional current collectors for high power and high energy density Li-ion batteries.
Supercapacitors, also called electric double layer capacitors (EDLC), store energy in two closely spaced layers with opposing charges and offer fast charge/discharge rates and the ability to sustain millions of cycles. It is frequently stated that supercapacitors bridge the gap between batteries and electrolytic ('conventional') capacitors, but contemporary devices have a lower specific energy than Li-ion batteries and are orders of magnitude slower than electrolytic capacitors. A research team has now shown that by moving from porous carbon with a network of pores inside particles as electrode material to exposed surfaces of nanostructured carbon onions of 6-7 nm diameter, it is possible to reach the discharge rate (power) of electrolytic capacitors, but with volumetric capacitance about four orders of magnitude higher. Moreover, observed discharge rates up to 200 V/second are about three orders of magnitude higher than conventional supercapacitors.
The main obstacle to building a hydrogen economy is the lack of efficient hydrogen storage. The research conducted in the hydrogen storage scientific community is aimed towards mobile applications. Hydrogen is a gas at ambient conditions and takes up a lot of space. For stationary storage facilities, for which available space is not an issue, hydrogen gas can be kept in large tanks at moderate pressures using already known technology. However, in order to utilize hydrogen for mobile applications i.e. to produce and be able to sell hydrogen fueled cars on a large scale, it must be stored in a compact, safe, cheap and efficient way. A European research team has now reported on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. They demonstrate that nanoconfined hydride has a significant hydrogen storage potential.
One of the greatest current environmental concerns both for the near term as well as for the future is global warming caused by man-made carbon emissions and its well-recognized impact on climate change. The various strategies which can be adopted to combat global warming are classified under the following three categories: 1) Reducing energy consumption by employing more efficient technologies that minimize use of fossil fuels; 2) Adopting technologies that utilize renewable energy and energy storage technologies; 3) Addressing carbon management issues that involve separation, capture, sequestration and conversion to useful products. The present article will specifically address the first two topics.
An intriguing novel approach to extract the energy from the photosynthetic conversion process has been demonstrated by researchers at Stanford and Yonsei Universities. They have inserted ultrasharp gold nanoelectrodes into living algae cells and extracted electrons, thereby harnessing an - albeit very tiny - electrical current. This is electricity production that doesn't release carbon into the atmosphere. The results demonstrate the feasibility of collecting high-energy electrons in steps of the photosynthetic electron transport chain and prior to the downstream processes associated with energy loss. In addition, the system allows direct monitoring of specific charge transfer reactions in live cells, leading to broad applications for investigating developmental processes and the responses of cells and organelles to light and chemical stimuli.
As it is becoming clearer that one of the critical issues for developing functional nanomachines is the generation of energy required to power them, research into developing nanoscale energy sources has been picking up substantially. The energy to be fed into a nanogenerator is likely to be mechanical energy that is converted into electric energy that then will be used to power nanodevices without using a battery. With the emergence of nanotechnology and the use of nanomaterials, the field of piezoelectrics and nanopiezotronics has experienced a lot of new and interesting research efforts. Researchers in Korea have now demonstrated the first use of chemical vapor deposition-grown large-scale graphene sheets as transparent electrodes for fully transparent and flexible nanogenerators.
Bioethanol, unlike petroleum, is a form of renewable energy that can be produced from common agricultural feedstocks such as sugar cane or corn. Ethanol is already widely used in siome countries, mainly as biofuel additive for gasoline. The tremendous hype about bioethanol in the past few years has now been followed by a debate about how useful bioethanol actually can replace gasoline. Concerns about its production and use relate to the large amount of arable land required for crops, as well as the energy and pollution balance of the whole cycle of ethanol production. Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns. It offers the promise that any plant material, from grass to wood, and not just edible crops, could be used in the production of ethanol fuels. Consequently, cellulosic ethanol could allow ethanol fuels to play a much bigger role in the future than previously thought. With regard to cellulosic production and commercialization, bioethanol production from woody biomass by enzymatic hydrolysis of cellulosic components and fermentation has attracted much attention.