New AC technologies to cut power use

The U.S. expends roughly 185 billion kilowatt-hours of energy each year on home cooling, the most by any nation in the world. Air conditioner sales are growing globally by roughly 20 percent per year, with the newly affluent in China and India leading the way. How do we beat the heat without increasing that heat through global warming caused by burning fossil fuels to power the air-conditioner? The U.S. Advanced Research Projects Agency for Energy, ARPA–E, hopes to cut this hot forecast by reducing the energy required for air-conditioning.

Conventional air-conditioners employ refrigerants such as chlorofluorocarbons to absorb heat from the room to be cooled. That heat is then expelled outside, requiring electrically powered pumps and compressors. One idea to conserve energy is to replace coolant fluids and gases—which are often super-powered greenhouse gases capable of trapping more than 1,000 times more heat than CO2—with solid materials, such as bismuth telluride. 

A new device uses electricity to change a thermoelectric solid to absorb heat, and could lead to cheaper air-conditioners or refrigerators. Such refrigerators, which lack moving parts and are therefore less likely to break down, can be lifesavers in remote, rural areas for keeping medicines cool or food fresh.

Another approach is to employ specialty membranes to cool air by condensing water. These technologies are being developed by companies and now have acquired backing from the U.S. Navy, which requires efficient air-conditioners and dehumidifiers for both troops and equipment in hotspots such as Iraq and Afghanistan. "A 30 percent improvement in efficiency means 30 percent less fuel to drag to the front," Martin notes, adding that the Navy program aims for units that use 20 to 50 percent less fuel.

More efficient air-conditioners can provide cooling that could prove vital for people trying to adapt to more extreme heat waves in the future, whether in the U.S. or India. Meanwhile, a simple approach to cut down the HVAC bills would be to keep the knob a level higher than freezing temperatures - a practice in many places!

Storing RE not always sensible

Renewable energy holds the promise of reducing carbon dioxide emissions. But there are times when solar and wind farms generate more electricity than is needed by consumers. Storing that surplus energy in batteries for later use seems like an obvious solution, but a new study from Stanford University suggests that might not always be the case. The costs involved in terms of energy are too high.

Grid-scale batteries make sense for storing surplus solar energy, but not for wind they found. The study, which is supported by GCEP, is published in the online edition of the journal Energy and Environmental Science.

The Stanford team looked at several emerging technologies, including five battery types -- lead-acid, lithium-ion, sodium-sulfur, vanadium-redox and zinc-bromine. Batteries with high energetic cost consume more fossil fuels and therefore release more carbon dioxide over their lifetime. If a battery's energetic cost is too high, its overall contribution to global warming could negate the environmental benefits of the wind or solar farm it was supposed to support.

The researchers compared the energetic cost of curtailing solar and wind power, versus the energetic cost of grid-scale storage. Their calculations were based on a formula known as "energy return on investment" -- the amount of energy produced by a technology, divided by the amount of energy it takes to build and maintain it.

Using that formula, the researchers found that the amount of energy required to create a solar farm is comparable to the energy used to build each of the five battery technologies. The results were quite different for wind farms. The scientists found that curtailing wind power reduces the energy return on investment by 10 percent. But storing surplus wind-generated electricity in batteries results in even greater reductions -- from about 20 percent for lithium-ion batteries to more than 50 percent for lead-acid.

As the team notes, it is important for society to be energy-smart about implementing new technologies.  When plunging into new technologies, policymakers and investors need to consider the energetic cost as well as the financial cost of new technologies.

Productivity to go down as the globe warms

A new NOAA study projects that heat-stress related labor capacity losses will double globally by 2050 with a warming climate. Recent studies project a collapse in labor productivity from business-as-usual carbon emissions and warming — with a cost to society that may well exceed that of all other costs of climate change combined.  A 2 percent drop in productivity per degree rise is how the US study sees it. How about in hotter climes then??

Is it possible to reduce emissions 50 percent globally by 2050s? Only one country, France, has ever reduced greenhouse emissions at the pace we’d have to keep up between now and 2050. Over a remarkable period of 30 years, France went from getting less than 1 percent of its power from nuclear power plants (which emit no carbon dioxide directly) to getting about 80 percent from them. During the period of the fastest nuclear build-out, France managed to reduce emissions at a rate of 2 percent per year, says David Victor, co-director of the Laboratory on International Law and Regulation at the University of California, San Diego. But the transition was tough.

This kind of transition for the rest of the world could be tough to almost improbable. Look at what’s happened in the United States. A major recession slowed energy consumption, and at the same time technological advances unlocked huge amounts of natural gas, leading utilities to shut down coal plants in favor of natural-gas plants that emit half as much carbon dioxide. In just one year, 2009, emissions dropped by an impressive 6.7 percent. But that was only across one year. If you look back to 2000, the average reduction was less than 1 percent a year, less than half of what’s needed to meet emissions goals! Looks like the human race better get set for tough times ahead.

Random wins over order!

The US electrical grid is in danger of breaking down, thanks to orderly networks!

A mathematical study of spatial networks by physicists in Israel and the U.S. says that the research builds on earlier work by incorporating a more explicit analysis of how the spatial nature of physical networks affects their fundamental stability. The upshot, published August 25 in Nature Physics, is that spatial networks are necessarily dependent on any number of critical nodes whose failure can lead to abrupt—and unpredictable—collapse. The electric grid, which operates as a series of networks that are defined by geography, is a prime example. Whenever you have such dependencies in the system, failure in one place leads to failure in another place, which cascades into collapse.

Focussing on idealized scenarios, the team found that randomly structured networks—such as social networks—degrade slowly as nodes are removed, which in the real world might mean there is time to diagnose and address a problem before a system collapses. By contrast, the connections of orderly lattice structures have more critical nodes, which increase the instability. The problem is that such orderly networks are always operating near an indefinable edge. To reduce that risk, they recommends adding a small number of longer transmission lines that provide short cuts to different parts of the grid.

The 2003 blackout stemmed from a combination of bad vegetation management—the first three lines tripped after sagging into trees but were all within their load rating—and a series of monitoring and communications breakdowns. Vegetation requirements have since been standardized, and a new generation of sensors is providing grid operators with more information about what is happening across the grid at any given moment.

Abundant and cheap source

University of Alberta researchers have found that abundant materials in Earth's crust can be used to make inexpensive and easily manufactured nanoparticle-based solar cells. At the university’s National Institute for Nanotechnology, the team has designed nanoparticles that absorb light and conduct electricity from two very common elements: phosphorus and zinc. Both materials are more plentiful than scarce materials such as cadmium and are free from manufacturing restrictions imposed on lead-based nanoparticles.

The research supports a promising approach of making solar cells cheaply using mass manufacturing methods like roll-to-roll printing (as with newspaper presses) or spray-coating (similar to automotive painting). Nanoparticle-based 'inks' could be used to literally paint or print solar cells or precise compositions, the scientist said. The team was able to develop a synthetic method to make zinc phosphide nanoparticles, and demonstrated that the particles can be dissolved to form an ink and processed to make thin films that are responsive to light.

The team is now experimenting with the nanoparticles, spray-coating them onto large solar cells to test their efficiency. The research in this field is tremendous as can be seen with the studies being published. The day is not far off when the planet will be truly living off its star!

The surge gains strength

The Brazilian state of São Paulo — the economic and industrial heart of the country — is currently aiming to possess a total of at least 1 GW of solar energy capacity by the year 2020, a goal which is very achievable, according to a solar atlas of the region that was recently released by the state’s energy secretariat. The state of São Paulo possesses twice the maximum global solar irradiation of the solar powerhouse Germany.

SãoPaulo, which in addition to being the economic heart of the country is also the most populous state in Brazil, has a total solar power generation potential of 12 TWh per year in the areas with the absolute highest annual solar radiation, according to the new solar atlas. The areas in question total 732 square kilometers — 0.3% of the state’s total area of 248,209 square kilometers. It’s estimated that these areas could host at least 9,100 MW (9.1 GW) of installed capacity.

São Paulo is already well on its way to achieving its aforementioned goal of possessing 1 GW of solar energy capacity by 2020 — 207 MW of thermal solar capacity are already installed. The rest of the 1 GW target capacity will be split up thusly: a further 592 MW of thermal solar capacity, 50 MW of photovoltaic solar capacity, 50 MW of concentrated solar power, and 100 MW set aside for passive solar energy exploitation in the form of solar architecture projects.

Indian government announced a $7.9 billion investment to double its transmission capacity – designed to increase access to power from wind and solar projects. India’s installed solar energy has jumped from a mere 17 megawatts in 2010, when India’s National Solar Mission was announced, to over 1200 megawatts today. The second phase of JNNSM programme envisages development of cumulative capacity of 1,000 MW for off-grid solar power and targets 15 million sq mt collector area. The targets include improved energy access in remote areas, heating or cooling applications that would encourage employment generation opportunities, replacement of diesel and kerosene as in Telecom Towers, solar cities and solar cookers and steam generating systems.

Not only do these clean energy projects increase India’s energy supply, they also create much needed jobs. As India’s economy grows and develops, its energy consumption likewise is increasing rapidly: it increased 64 percent from 2001-02 to 2011-12 and is projected to grow an additional 72 percent by 2021-22, according to the Indian Planning Commission. To support India’s burgeoning renewable energy ecosystem, NRDC and the Council on Energy, Environment and Water (CEEW) are striving to bolster the case for clean energy by telling this story of job creation and economic benefits.

The surge should pick up likewise in all places that get good sunlight. 

New kid on the solar block

A new type of solar cell, made from a material that is dramatically cheaper to obtain and use than silicon, could generate as much power as today’s commodity solar cells. Solar cells can be made very cheaply but have the downside of being relatively inefficient. Lately, more researchers have focused on developing very high efficiency cells, even if they require more expensive manufacturing techniques. The new material could deliver solar cells that are highly efficient but also cheap to make.

Perovskites have been known for over a century, but no one thought to try them in solar cells until relatively recently. Very good at absorbing light the new solar cells use less than one micrometer of material to capture the same amount of sunlight. The pigment is a semiconductor that is also good at transporting the electric charge created when light hits it.

One group has produced the most efficient perovskite solar cells so far—they convert 15 percent of the energy in sunlight into electricity, far more than other cheap-to-make solar cells. Based on its performance so far, and on its known light-conversion properties, researchers say its efficiency could easily rise as high as 20 to 25 percent, as good as the record efficiencies (typically achieved in labs) of the most common types of solar cells today. Perovskite in solar cells will likely prove to be a “forgiving” material that retains high efficiencies in mass production, since the manufacturing processes are simple.

Perovskites will have difficulty taking on silicon solar cells. The costs of silicon solar cells are falling, and some analysts think they could eventually fall as low as 25 cents per watt, which would eliminate most of the cost advantage of perovskites and lessen the incentive for investing in the new technology. But it might be possible to paint perovskites onto conventional silicon solar cells to improve their efficiency, and so lower the overall cost per watt for solar cells.