What is Green Technology? The term "Green Technology" has been adopted over the last 5 years to identify a group of industries and industrial applications which exploit the commercial value of technologies that benefit the environment; particularly as it impacts the human condition. This basket of effected industries is quite diverse and includes businesses as far a field as energy and agriculture. Some predict every consumer product will someday be affected. Unlike the technological waves in recent decades, Green Technology is almost entirely materials science based. Ventures such as Google and Facebook do not primarily rely on advances in material science for their success. But solar energy panels and pollution-free recyclable automobiles do.
Much of the coming green revolution also relies on the availability of "Alternative Energy" sources to both eliminate the emission of green house gases that cause global warming and to make the limited resources we have on the planet perpetually "sustainable". Alternative Energy is defined as both energy sources other than mined hydrocarbons (e.g. solar energy in replacement of oil and natural gas) as well as alternative methods to process mined hydrocarbons that are more efficient than current means (e.g. use of fuel cells in replacement of combustion engines).
What are the raw materials of Green Technology?
As stated, nearly all Green Technologies rely on the use of new advanced materials. These new materials vary from metals commonly used today in many ways. First, elements on the periodic table such as copper, tin, iron and carbon are stepping aside in favor of less common metals, such as zirconium, yttrium, tellurium and the 14 elements that make of the group of metals known as the "rare earths". For example, batteries that were once made of lead are now made of lithium.
Second, the purity of advanced materials can often be measured in atoms with ultra high purities up to 99.9999%.
Next, the scale and size of the raw chemical and metallic powders may be as small as the nanoscale. "Nano" equals a billionth and therefore a nanometer is one-billionth of a meter. To appreciate the size, a human red blood cell is over 2,000 nanometers long, virtually outside the nanoscale range. For a given amount of material, as particle size decreases, surface area increases. Since the surface of any material tends to be where it reacts with other materials, the more surface area, the greater effect using less material. It is not uncommon for one gram of a nanoscale material to have the surface area of a 60' x 30' floor!
In addition to the use of new metallic elements is the use of these less common metals with common metals to form new super alloys with unique properties, such as scandium-aluminum alloy which can combine lightness, extreme strength and high temperature and corrosion tolerance in a single material. Another example would be newly developed carbides of various metals to create super hard and corrosive resistant materials with interesting properties. Similarly, the use of glass and ceramics in functional components of electronics and energy efficient systems is giving way to the use of crystal structures, semiconductors and super conducting materials.
How are Green Technologies used today?The vast number of "Green Technologies" fall into one of two broad categories. These are:
those intended to deal with global warming by either reducing greenhouse gas emissions or in the alternative its potential harmful effects on the planet, and
those technologies associated with establishing economic "sustainable growth" which includes recycling, resource reduction and many aspects of the biosciences.
Each of these two categories has several major associated industries addressing some aspect of achieving their goals. And of course many of the important industrial and technological revolutions taking place today touch on both. For example, fuel cells both decrease the green house gases that cause global warming by potentially eliminating air pollution from automobiles and they also make our energy sources more "sustainable" by reducing the amount of hydrocarbon-based fuel needed to generate the same amount of energy as compared to current combustion engines, i.e. far greater miles per gallon.
GLOBAL WARMING
There seems to be little debate that human activity has increased the level of air pollution and CO2 in the earth's atmosphere and that this will increase global temperatures. The ultimate effect to humanity of this rise in the planet's temperature is a matter of great debate but the fact that this will result in significant changes to how we live and work is not. Today there are essentially two approaches to global warming. The first is best known from the work of former Vice President and Nobel Peace Prize Winner Al Gore as presented in his film "An Inconvenient Truth" holds that global warming should be addressed at its root cause by all of humanity working in consort through technological/industrial innovation and international governmental policy to reduce the quantity of air pollution and CO2 emissions being generated. The second approach is best expressed in the work of the environmentalist Bjorn Lomborg as presented in his writings and books, such as "Cool It" which holds that a "rational as opposed to fashionable" approach to global warming is to recognize that the least expensive method of dealing with its effects is to treat them as they occur sometimes at the very local level. This is based on the premise that when the actual effects are examined in a sober and scientific way, policymakers will discover addressing them piecemeal is significantly less costly in capital than the effort that would be necessary to reduce green house gas emissions to a point where the Earth's temperature actually began to fall again.
Those technologies that are intended to deal with the root causes of global warming as proposed by Al Gore and the larger environmental movement work by reducing the emission of the green house gases that are changing the earth's atmospheric temperature. Green house gases are either of the type we commonly think of as "Air Pollution", such NOX (Nitrous Oxide) and SOX (sulfur dioxide) and the non-pollutant CO2 (carbon dioxide) which we exhale.
Fuel Cells
An example of materials science playing a part in eliminating production of green house gas causing air pollutants is in the use of solid oxide fuel cells (SOFCs). SOFCs are electrochemical power plants that some believe will power automobiles in the future because they produce no air pollutants in the process. However, because they still rely on hydrocarbons as their energy source, they do not eliminate generation of CO2 emissions. This would require the creation of a hydrogen infrastructure which is often discussed but is not being seriously proposed at this time due to both safety concerns and the cost to produce, store and transfer hydrogen.
Technologically, SOFCs are all materials science. There are no moving parts in the conversion of hydrogen to electricity. They are comprised of three layers. An electrically conductive cathode made of one of several perofskite materials such as Lanthanum Strontium Manganite (LSM), Lanthanum Strontium Ferrite (LSF), Lanthanum Strontium Cobaltite Ferrite (LSCF), Lanthanum Strontium Chromite (LSC), and Lanthanum Strontium Gallate Magnesite (LSGM), an ionically conductive electrolyte, such as Yttria Stabilized Zirconia or YSZ (Zirconium Oxide stabilized with Yttrium Oxide), Gadolinia doped Ceria or GDC (Cerium Oxide stabilized with Gadolinium Oxide, Yttria doped Ceria or YDC (Cerium Oxide stabilized with Yttrium Oxide), and Scandia Stabilized Zirconia or SCZ (Scandium Oxide stabilized with Zirconium Oxide and an electrically conductive anode which usually is Nickel Cermet compositions of nickel oxide and yttria stabilized zirconia. As hydrogen is pumped under pressure through the electrically conductive anode layer and oxygen is made available through the electrically conductive cathode layer, a circuit is completed through the ionically conductive electrolyte completing the circuit. As long as hydrogen is pumped into the system, electricity will be generated.
Solar Energy
An example of a technology intended to reduce both air pollution and CO2 emissions is the use of photovoltaic cells to generate electricity (actually electrons) from photons emitted by the sun. Given the enormous amount of capital today being invested in solar energy technologies globally from Silicon Valley to the Nation of Singapore, solar energy will unquestionably play a major role in reducing green house gas emissions by supplanting hydrocarbons such as oil, coal and gas as our energy source for many applications. From its start solar energy has been essentially a field of materials science. In the 1970s the first silicon-based photovoltaic (PV) cells were produced. These basic cells were created by doping silicon to form two oppositely charged layers.
All silicon-based photovoltaic solar energy collectors however suffer from their ability to absorb energy from a relatively narrow range of the sun's light wave emission. More recently advanced materials have been developed that can either expand this band gap or create multiple band gaps in order to absorb a greater portion of the solar energy spectrum. This has lead to the development of PV cells based on Copper Indium Selenide (CuInSe2) or "CIS" Absorption Layers which can capture energy from portions of the light's spectrum not collected by silicon-based PV cells. Doping CIS with Gallium increases the band gap even further and as such most PV cells are now based on Copper Indium Gallium Selenide (CuInGaSe2) and are referred to as "CIGS".
Other promising designs include cells based on III-IV Nitride materials and research on Zinc Manganese Telluride, Cadmium Telluride (CdTe) and Gallium Selenide P-Type layers. The band gap for III-IV Nitride materials, such as Gallium Indium Nitride, covers nearly the entire energy spectrum of the sun because of multiple band gaps in the semiconductor materials. Similarly, Zinc Manganese Telluride crystals have three band gaps which can absorb greater than 50% of the solar energy spectrum. Further important research involves nanotechnology approaches using nanoparticles of the above materials.
Wind Energy
Converting wind energy into electricity using various blade and turbine systems has been utilized since the mid-1970s when tax incentives were written in many states to encourage public utilities to purchase the power generated. Many of these earlier systems failed to deliver efficient energy and were only financially viable as tax shelters. More recently advanced materials particularly advanced ceramic, such as yttria stabilized zirconia (YSZ) and composites, have played a part in the development of light, less costly and more efficient wind turbines. Additionally, the decades of experience with wind as an energy source has allowed for the design of better overall wind generator "farms" placed in strategically determined locations, such as the 4,000 megawatt farm proposed by T. Boone Pickens in Texas.
The Nuclear Power Dilemma
One source of energy that is entirely free of green house gas emissions and that could have today already reached wide use is nuclear fission of enriched radioactive isotopic materials to produce electricity. Nuclear generators are the single greatest source of energy that in no way impacts global warming. They fully achieve the goal of environmentalists as a massive source of energy capable of sustaining our present standard of living and reducing planetary temperatures. However, the second goal of the "Green Revolution" is sustainable growth (discussed below) which requires that human activity not produce waste products that cannot be perpetually reused or recycled to something useful. All nuclear fission systems generate some form of radioactive waste which must be disposed of. Given the lengthy half life of the waste materials, "disposal" actually means perpetual storage. However, public policy may come to view storage of nuclear waste a better alternative than allowing for the continual rise in global temperatures.
SUSTAINABLE GROWTH
In the 1960s American's first became aware that their massive increase in consumption after World War II was causing an equally massive generation of waste products for which there was little technology or public policy to address. This spawned the original environmental movement with it's emphasize on reducing ground, air and water pollution. As policies and technologies were created to address pollution, it became clear that the real long term goal must be to ultimately establish a fully sustainable planet; one that could perpetually sustain itself in its present form through better management of its resources. This would require efforts on several technological fronts. First, products needed to be designed and built with an eye towards (1) eliminating wasteful materials use and (2) the reuse and recycling of the materials that are used once the product has exhausted its useful life. Second, reliance on difficult to replenish resources from timber to oil needed to be drastically reduced through the development of new recyclable advanced materials.
Thin Film, Nanomaterials and Organo-Metallics
When Thomas Edison first did his experiments with electricity and the electronic equipment it could power, he wasn't concerned with how much copper was required to carry a circuit or the amount of power being used. As electronics became smaller and more complicated the company he built, General Electric, became very concerned with reducing the scale and volume of metals. Thinner conductive and semi-conductive layers and wires were necessary. Until the 1970s this was accomplished using electroplating of metallic solutions, such as metal chlorides combined with etching technologies.
But the movement towards "Smaller, Cheaper and Faster" products and equipment didn't end there. Advanced technology has introduced three new areas of materials science that will have a major impact on the further reduction of resources necessary to maintain our standard of living. These are nanomaterials, organo-metallics and the application of thin film coatings in replacement of electroplating using sputtering targets and high purity foils.
Thin Film
The fabrication of functional layers of materials at the naoscale can now be accomplished by converting the material into a plasma-like chemical vapor which deposits the material on a substrate. Modern hand-held electronics rely on thin film deposition to achieve their small size.
Nanotechnology
Nanotechnology is playing an increasing role in solving the world energy crisis. Platinum nanoparticles are ideal candidates as a novel technology for low platinum automotive catalysts and for single-nanotechnology research. Lanthanum Nanoparticles, Cerium nanoparticles, Strontium Carbonate Nanoparticles, Manganese Nanoparticles, Manganese Oxide Nanopowder, Nickel Oxide Nanopowder and several other nanoparticles are finding application in the development of small cost-effective Solid Oxide Fuel Cells (SOFC). And Platinum Nanoparticles are being used to develop small.
Proton Exchange Membrane Fuel Cells (PEM)
Lithium Nanoparticles, Lithium Titanate Nanoparticles and tantalum nanoparticles will be found in next generation lithium ion batteries. Ultra high purity Silicon Nanoparticles are being used in new forms of solar energy cells. Thin film deposition of Silicon Nanoparticle quantum dots on the polycrystalline silicon substrate of a photovoltaic (solar) cell increases voltage output as much as 60% by fluorescing the incoming light prior to capture.
Organo-Metallics
A third technological area of materials science that will advance the goals of smaller equipment and reduced reliance on resources is the development of functionalized metallic particles and nanoparticles to introduce the capabilities of a metal to a polymer or bioscience application. Organo-metallics are metal compounds with an organic anion or ligand that allows the metal to dissolve in organic environments such as polymers or attach themselves to living systems such as cellular structures. This makes them also valuable in new medical treatments and water treatment applications.
Alternative Energy Sources
As described above with respect to global warming, even if all material resources on the planet were used in a fully recyclable manner, alternative sources of energy are also necessary since those currently powering civilization are being exhausted. Thus, the most pressing concern of the green revolution is establishing a global energy infrastructure to replace hydrocarbon fuels before the best of those sources are exhausted. Note the less valuable sources such as coal may be plentiful but in their case the challenge is the development of advanced technologies to address elimination or sequestration of the massive volume of CO2 coal generates in its production and use.
Solid State Lighting
By narrowly controlling the particles distribution (PSD) of quantum dot nanocrystals to within 10 nanometers, discreet colors with long term photostability can be emitted with wave lengths representing the entire visible spectra. Prior to quantum dots, light emitting semiconductors, such as light emitting diodes (LED), could not emit white light and therefore could not light a room. With the development of quantum dots with particle size distributions less than 500 nanometers (nm), LED emissions in the blue range can be achieved which may allow for the commercial use of solid state semiconductors to generate luminescent light. This ability has also found application in fluorescent biomarkers and dyes for live cell imaging and antibody conjugates.
What are the safety and public policy issues associated with Green Technology?
Government policymakers have begun to take several initiatives towards advancing the goals of the green revolution. As to Global Warming, the Kyoto Protocol first made a significant effort to establish a global framework for reducing green house emissions. As to a sustainable planet, most nations now have established reuse and recycle programs. Europe is in the process of possibly the most far reaching effort to manage the materials that go into our daily lives through the REACH program of chemical registration. Once enacted, REACH will allow government to better track whether products are being manufactured from materials that can be recycled or reused. As Green Technology becomes increasingly integral to the economy, American Elements contributes throughout to our customers' efforts providing research support, toll production of new materials with predetermined specifications to allow for optimization studies as well as of course timely and certified bulk volume deliveries globally of advanced materials in support of these programs.
[source : www.scientificamerican.com]
