Originally posted at climatecentral.org
By Alyson Kenward
A couple of weeks ago, the social media networks were buzzing over the announcement of new technology that uses sunlight to split water for energy purposes; the so-called “artificial leaf.” It’s a man-made form of photosynthesis, a water-splitting technology that could potentially overcome the big challenges facing solar energy, like its current costliness and inability to provide energy when the sun goes down. MIT chemist Daniel Nocera unveiled the new artificial leaf at a recent American Chemical Society annual meeting, but many of the people commenting on it in the press didn’t have the opportunity to see the technology in action.
As a trained chemist, I wanted to reserve judgment until I could see this invention for myself. Lucky for me, this weekend I had the chance. And I have to say it was pretty impressive.
On Saturday, Nocera gave a lecture in Princeton, N.J. (where Climate Central has one of its offices) as part of a symposium honoring the university’s new chemistry building. The symposium was focused on the big problems the chemistry community should be tackling in the years ahead, and it’s not surprising that three talks, including Nocera’s, were directed at making solar energy more affordable and widely available.
Nocera’s presentation in particular was a show-stopper. He demonstrated via video he can already make a bit of sunlight turn a glass of water (containing a small card made of silicon and a few other materials) into hydrogen and oxygen gas. It might not sound like anything too fancy, and it doesn’t look like any leaf I’ve ever seen, but it’s being described as the first time that a chemist has found what appears to be an inexpensive way to mimic what plants have naturally been doing for millions of years.
Through photosynthesis, plants convert sunlight into energy (albeit inefficiently) by splitting water up into its constituent parts: oxygen and hydrogen, and then storing these alternative forms of energy until they are needed later on. For humans, the goal is to do the same thing because hydrogen and oxygen can be recombined in a fuel cell to produce electricity whenever you might need it. It may also be possible to take the hydrogen and combine it with carbon dioxide (CO2) to make fuels resembling gasoline, similar to the way plants use the hydrogen to make sugars.
I should point out here that water-splitting itself is nothing new. It’s actually been around for decades, but most versions haven’t used sunlight (instead they have required electricity from the wall to achieve water splitting). Researchers from the Department of Energy’s National Renewable Energy Lab found a way to do solar-powered water splitting more than 10 years ago, but the materials in that example were, as Nocera calls them, “space-aged.”
In other words, crazy expensive and not appropriate for widespread use.
Nocera’s set-up, on the other hand, uses much cheaper materials. He hasn’t revealed the exact identity of his new catalysts (which are now being patented), but preliminary versions of his “leaf”, which have been published over the past few years, call on some of the cheapest metals around.
He has said for years that massive expansion of solar power is one of the only ways that the world will be able to meet its growing energy demands in a sustainable way. There are several energy analysts that don’t agree with him, instead saying that other sources of energy, like wind, geothermal and nuclear, must also play a big role.
Nocera’s argument, however, is that most of the new energy demand will be coming from the developing world, where building up solar power for individuals will be a more realistic option than other forms of energy.
“In the U.S., we’re stuck with this ball and chain of legacy energy,” he explained on Saturday. Nocera says that countries like the United States are so heavily invested in existing energy infrastructure that there isn’t much chance the country can easily switch to renewable options like solar. On the other hand, many developing countries completely lack a central electrical grid. People living in many parts of African and India, for example, still rely heavily on the direct combusion of coal, wood, or dung for fuel and don’t have access to electricity.
He says that if solar power technology can be mass-produced on the cheap, there won’t be any reason for developing countries to build massive power plants and thousands of miles of power lines. Instead, each household can have their own energy source. All they will need is a copy of the artificial leaf (albeit one larger than Nocera’s test version) and about 16 ounces of water.
How much water would be needed altogether to power the planet, if an inexpensive version of the technology is manufactured so everyone on Earth can have it? About the same amount as what’s in MIT’s Olympic-sized swimming pool, says Nocera. And this volume could be a one-time demand because, in theory, the water would be remade again in the fuel cell.
Of course, this is all still in ivory tower-territory, and it will be years before a commercial model of Nocera’s setup might be available (and there isn’t any guarantee it ever will be). But the fact that so much energy is stored up in the chemical bonds of water explains why so many chemists think that solar-powered water splitting is such an essential research goal.
At Saturday’s presentation, Nocera didn’t even begin to address exactly how long it will be before his technology, or a similar version of it, could be put to use in the real world. But one day earlier, during an interview with NPR’s Ira Flatow, he said it could be ready in less than a decade:
We’re building prototypes, and there’s a lot to still do because you need to make sure this can go for years, not days. It’s got to go for years. We haven’t had the time to test [it] for years yet.
It’s been going for days now with no drop in activity. So those are all the practical concerns of long-term because if you’re a commercial buyer, you’re a customer, you only use things that are reliable, and that can be the death knell of any technology. But we’re well beyond the science, and now we’re into the engineering and into the reliability game.
To get a sense of what Nocera’s talk was like on Saturday, have a look at this PopTech video from 2009. The video was filmed before he made the entire “artificial leaf” but it describes the motivation for water-splitting and also outlines the calculations on how much water is needed to meet the global energy demand (check out the 15-mark in particular).
Dan Nocera: Personalized Energy from PopTech on Vimeo.
By Doug Garrett
(this article first appeared in the Austin American Statesman in 1996, but it is still relevant today)
We all know that we can pay our auto mechanics a little now for routine service, or pay them a lot later for a major repair. The same idea holds true for your air conditioner or heat pump. If you don’t service your air conditioner or heat pump regularly, you’ll find yourself uncomfortable and broke.
In this article the term air conditioner will apply to a heat pump or a standard air conditioner. Both benefit equally from annual service tune-ups.
An air conditioner is a very tough piece of equipment. It is engineered to withstand all sorts of abuse and keep on running. This is great in most respects, but it can lead to complacency about maintenance. Like a car, air conditioners need regular tune-ups to run properly.
Without regular maintenance an air conditioner loses about 5% of it’s original efficiency for each year of operation. This means that the 12 SEER unit that you bought just a few years ago may be functioning like a 9 SEER unit today! The good news is that you can recover most of that lost efficiency through regular maintenance. Studies show that with regular tune-ups a unit will maintain up to 95% of it’s original efficiency. This means that the cost of an annual tune-up is recovered very quickly in savings on your monthly electric bill and reduced repair costs. A properly serviced air conditioner will also do a better job of dehumidifying your home.
Many local air conditioning firms offer special prices at this time of the year (spring and fall, when weather’s not as extreme –Ed.). Some even offer annual service programs that insure that you will be reminded of the need to service the unit at the beginning of the cooling and heating seasons.
The service check should include cleaning the condensing unit coils, checking the amp draw of the compressor, oiling the fan motors, checking that belts are well adjusted, and checking the system operating pressures and temperatures against the manufacturers specifications. One of the most important items to check is the coolant level (previously known as Freon) in the air conditioner. A system that is only 10% low on coolant will cost about 20% more to operate! The Air Conditioning Contractors of America (ACCA) recommends that coolant levels be checked every year.
If your unit is low on coolant, and more must be added, there are new laws governing its use. Freon is a chlorofluorocarbon (CFC) that will damage the Earths protective ozone layer if released into the atmosphere. The laws governing CFC’s now do not allow your air conditioner contractor to add Freon to a leaky system. [Ed note: CFCs are no longer allowed and various alternative refrigerants are now common.] They are first required to find and fix the leak in the system. Don’t ask them to violate this law as they may lose their license if they are caught doing this.
There are some things in addition to yearly tune-ups that you can do to help ensure a high level of comfort and proper system operation. First, buy good filters and change them regularly. Next, keep bushes and other materials away from the outside unit of your air conditioner. Another good idea is to avoid closing supply air outlets in your house. In almost all cases, closing supply outlets is harmful to the operation of the overall system.
All equipment, even the most reliable, needs routine maintenance. Complicated equipment like today’s air conditioners benefit in many ways from annual service. They recover much of their lost efficiency, they are less likely to suffer a major break down, they have a longer life span, they increase your comfort, and they operate for less money.
Word on the street is it’s pretty well done: http://www.leedforhomes.org/OST/homepage.aspx
Did it work well for you?
Update: I got a chance to give this a spin. The “quick score” is straightforward and works well (the dream building I entered came in about half way between Gold and Platinum). The more detailed scoring gets into a few areas where making one choice takes several others off the table, but other than that and the time it takes to go through all the myriad details, it also works well. Give it a try.
By Dick Peterson
Winter is one of the best times to plant a tree. Many excellent varieties are available at your local nursery, with some of the best trees available in the winter. Your new tree will use the winter dormant season to establish new roots. When spring arrives, your tree will be on its way to providing shade for generations to come. While it may seen obvious that planting a tree is a good thing, here are some reasons which may not have not occurred to you. Well-placed trees can save you money on your utility bills. In the summer trees shade your roof and windows and also cool the air around your house as they breathe. In the winter, evergreens can block cold north winds. By using less electricity you help cut down on emissions from power plants that contribute to the “green house effect.” Trees of course clean the air by creating oxygen, and they also keep our cities cooler by reducing the “heat island” effect. This is caused by concrete and asphalt storing and reflecting heat, making urban areas hotter.
Choosing a Tree
Ask your nursery professional to recommend a tree that is native or adapted to this area. Don’t ask for the fastest growing tree such as an Arizona ash, cottonwood, Chinese tallow or poplar. Their fast growth results in weak, brittle wood. They are also prone to freeze and insect damage, leaving you with the expense of tree removal just when you expect to be receiving shade. Excellent deciduous trees for this area include Chinese pistache, cedar elm, Drake elm, pecan, Texas ash, and bald cypress. These trees will lose their leaves in the winter and provide access to the winter sun to warm your home. Two of the best choices in this category are the burr and chinquapin oaks. Recommended evergreen selections include live oak, Afghan pine, deodar cedar, and cherry laurel.
Choosing a site
Survey your site and decide the best location for your tree. Choose the variety based on mature size compared to the space you have available. Most planting mistakes are made by placing a tree that will become very large in the wrong place; under a power line or too close to the house, driveway, or walkway. Don’t place the tree near water, gas, cable TV, telephone or sewer lines. In Austin, phone One Call (they’re listed in the Phone book); they will locate and mark all underground utility lines in the digging area. In other locations, call your utility or service supplier. Now dig a test hole. Be sure your location is not one large limestone boulder with a thin layer of soil over it. If you hit a large rock, move over a bit and try again. When you are sure you can dig an adequate hole, then purchase the tree. When you know the size of the hole you can dig, your original plan for a large balled and burlaped tree may change to a five gallon size. The smaller size is easier to plant, less expensive, and may grow more rapidly than the larger tree.
Planting the Tree
Dig your hole three to five times as wide as the container or root ball. The hole should be no deeper than the container. If you disturb the native soil below the root ball, the tree may settle and sink too low. The sides of the hole should not be smooth. Dig an ugly, ragged hole or even a square hole. Use a pick or shovel to break up the vertical soil surface. This gives the roots a chance to grow into the native soil. Carefully remove the tree from its container and place it in the hole. Large trees may require the aid of several helpers to avoid damaging the roots. If the roots have begun to circle inside the container, straighten them out from the root ball as you refill the hole. Most times a newly planted tree will stand on its own. If necessary, drive a sturdy stake at the edge of the root ball. Use an old nylon stocking to loop a loose figure eight around the tree and the stake. Fill the hole with the removed soil, not peat moss, compost, or bagged soil. It’s best to get the tree immediately accustomed to the soil in which it will be growing. Otherwise the roots tend to stay in the amended soil and never grow into the surrounding native soil. As you fill, compress the soil with your foot several times to prevent air pockets. Use the extra soil to build a dam around the edge of the hole. Water thoroughly and deeply. A liquid root stimulator may be used, but is usually not necessary. Cover the area inside the dam with 3-4 inches of organic mulch. In the absence of rain, a good soaking every two weeks is sufficient during the winter.
This article first appeared in the Austin American Statesman. At the time of publication, Dick Peterson was City of Austin Xeriscape Coordinator.
May 27, 2010
The U.S. Department of Energy today announced the launch of the Highly-Insulating R-5 Windows and Low-e Storm Windows Volume Purchase Program, part of a multi-year integrated strategy to transform the market for high efficiency windows. The initiative will facilitate the broader deployment of these windows by pairing manufacturers with buyers looking to purchase large volumes of windows and by setting performance expectations for two new types of energy efficient windows. This will provide support for window manufacturers to help overcome the initial costs associated with producing windows at an even higher efficiency level while connecting volume buyers with pre-cleared suppliers.
“The Department of Energy has played a key role in rapidly advancing window technology in the past few years. This program will help move these technologies into the marketplace, providing significant energy savings to homes and businesses across the country,” said Roland Risser, DOE’s Building Technologies Program Manager. “This initiative will help drive demand and increase the number of offerings available to builders and project developers.”
The program includes both Highly-Insulating R-5 (U value 0.2) Windows and Low-e Storm Windows. When replacing windows or building a new building, R-5 Windows can reduce heat loss through the window by 30 to 40% compared to a typical R-3 window available today. In situations where full replacement is not an option, Low-e Storm Windows, which fit over existing windows, can be used to reduce heat loads by up to 20%. The savings for both R-5 windows and Low-e Storm Windows are a significant improvement over products available today—and many meet DOE’s price premium target of less than $4 per square foot. With higher energy performance and lower purchase prices, windows can become an even more cost effective measure for building retrofits.
Volume purchasers of windows, including government agencies, builders, energy retrofitters, renovators, and weatherization providers, will gain online access to window sellers whose products are certified to meet the High-Insulation R-5 and Low-e Storm Windows specification. Buyers can review size and price ranges and then connect directly to the vendors’ Web sites to purchase. The program includes more than 30 suppliers. For more information, visit the Highly-Insulating Windows and Low-e Storm Windows Volume Purchase Program Web site.
The Volume Purchase Program received significant interest from manufacturers, the building industry, and other key industry stakeholders. More than 50 eligible proposals were submitted from suppliers; over 30 suppliers meeting all program requirements are currently listed on the Web site ready to sell windows products. Today’s launch event co-hosted by the National Association of Home Builders (NAHB) will include participation from a broad spectrum of building industry stakeholders, including NAHB, American Architectural Manufacturers Association, the Alliance to Save Energy, Community and Economic Development Association of Cook County, Illinois (CEDA), and Habitat for Humanity.
Windows that are part of the program must have National Fenestration Rating Council (NFRC) thermal performance certification and minimum structural certification in accordance with the North American Fenestration Standard (NAFS). Additionally, all storm windows must have their glass type registered in the International Glazing Database created by Lawrence Berkeley National Laboratory (LBNL).
To participate, interested suppliers and potential buyers can visit the Highly-Insulating Windows and Low-e Storm Windows Volume Purchase Program Web site.
Tips to keep your attic cool
By Marc Richmond*
Picture this: It’s a hot and humid summer day. You head for the indoors and some relief from your trusty air conditioning (A/C) system. Three hours later, you’re slightly cooler, but you’re wondering why your A/C unit hasn’t shut off yet. Here’s why: all day long, solar radiation has been heating up your home through the windows, walls, doors and especially the roof. Your attic temperature can easily reach over 140 degrees. That heat up there is working its way through your meager attic insulation into your home and through the A/C ductwork, located in your attic, into your cooling system. Your A/C system has to fight that added heat to change all that hot air in your home into cool air. You can install solar screens for the windows, porches around the house for shade, and plant trees around the home, but what do you do about the roof which accounts for a third of all the heat build-up of your house?
Here are a few options:
Ventilate your attic with ridge and soffit vents. Vents are louvers, grills, or screen materials which allow passage or air through them. They are typically installed along the top peak (ridge) of your roof, at the top of the side wall (gable), and on the underside of your roof overhang (soffit). Ventilation moves air through your attic by force of wind or by heat rising through natural convection. This leaves cooler air sitting on top of the insulation on the attic floor. Ventilation also has the ability to remove humidity which has built up in your attic and which reduces the effectiveness of your insulation. It is often best to hire a contractor to install these.
Insulate your attic to R-30. R-30 is roughly a 10 inch thick layer of insulation material above your ceiling. This is a job for any handy homeowner or it could be handed over to a contractor. When installing the insulation, be careful not to block your vents.
Install a radiant barrier between your roof and your attic insulation. A radiant barrier is an aluminum foil material which prevents 95 percent of the heat that radiates from your roof from reaching the insulation on your attic floor. It comes in a roll and is stapled to the underside of your roof rafters, or as a metallic paint. Radiant barriers are sold in most building material supply centers and can be easily installed by a homeowner. This system can save you up to eight percent on your summer cooling bills.
When it comes time to replace the roof, use roofing material which resists or reflects heat – typically lighter colors are best, though there are some new materials which are effective at reflecting infrared radiation (heat) with a more ‘traditional’ color.
This article first appeared in the Austin American Statesman and was republished by us in 1997. *We have since edited the article. At the time of publication, Mr Richmond was with the City of Austin’s Green Building Program; he now is president of Practica Consulting.
ScienceDaily (Sep. 17, 2008) ˜ Houses made of hemp, timber or straw could help combat climate change by reducing the carbon footprint of building construction, according to researchers at the University of Bath.
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