Engineers Forum

Nanomaterials are poised for widespread use in the construction industry, where they can offer significant advantages for a variety of applications ranging from making more durable concrete to self-cleaning windows. But widespread use in building materials comes with potential environmental and health risks when those materials are thrown away.
Those are the conclusions of a new study published by Rice University engineering researchers this month in ACS Nano, published by the American Chemical Society.

“The advantages of using nanomaterials in construction are enormous,” said study co-author Pedro Alvarez, Rice’s George R. Brown Professor and chair of the Department of Civil and Environmental Engineering. “When you consider that 41 percent of all energy use in the U.S. is consumed by commercial and residential buildings, the potential benefits of energy-saving materials alone are vast.

“But there are reasonable concerns about unintended consequences as well,” Alvarez said. “The time for responsible lifecycle engineering of man-made nanomaterials in the construction industry is now, before they are introduced in environmentally relevant concentrations.”

Alvarez and co-authors Jaesang Lee, a postdoctoral researcher at Rice, and Shaily Mahendra, now an assistant professor at the University of California, Los Angeles, note that nanomaterials will likely have a greater impact on the construction industry than any other sector of the economy, after biomedical and electronics applications. They cite dozens of potential applications. For example, nanomaterials can strengthen both steel and concrete, keep dirt from sticking to windows, kill bacteria on hospital walls, make materials fire-resistant, drastically improve the efficiency of solar panels, boost the efficiency of indoor lighting and even allow bridges and buildings to “feel” the cracks, corrosion and stress that will eventually cause structural failures.

In compiling the report, Lee, Mahendra and Alvarez analyzed more than 140 scientific papers on the benefits and risks of nanomaterials. In addition to the myriad benefits for the construction industry, they also identified potential adverse health and environmental effects. In some cases, the very properties that make the nanomaterials useful can cause potential problems if the material is not disposed of properly. For example, titanium dioxide particles exposed to ultraviolet light can generate molecules called “reactive oxygen species” that prevent bacterial films from forming on windows or solar panels. This same property could endanger beneficial bacteria in the environment.

“There are ways to engineer materials in advance to make them environmentally benign,” Alvarez said. “There are also methods that allow us to consider the entire lifecycle of a product and to ensure that it can be recycled or reused rather than thrown away. The key is to understand the specific risks and implications of the product before it it is widely used.”

The study was funded by the National Science Foundation via Rice’s Center for Biological and Environmental Nanotechnology.

Yesterday, the world’s tallest building (for now) opened in Dubai. The Burj Khalifa has moved ahead of other tall buildings that have recently debuted and in the next decade or so, it will no doubt be eclipsed by even taller buildings, mega-skyscrapers.

I got to wondering about these kinds of buildings, why people build them, how they build them and the engineering challenges they face. So I called up Ron Klemencic, president of Magnusson Klemencic Associates, Inc., a structural and civil engineering firm headquartered in Seattle, Wash., and asked him. Here are some of the things we talked about.

Tall Buildings Sway…More Than You Think
I shouldn’t be surprised, I guess, that a tall, relatively slender object would sway in the wind. If it were a tree, yes. But a building? According to Klemencic, engineers use a pretty basic formula to get a good idea of how much a building will move back and forth. Take the height of the building and divide by 500. So a 1,000-foot building would sway two feet to the left or right. At 2,716 feet, the Burj Khalifa would sway back and forth about 5.5 feet. Some people feel the motion when the building changes direction and accelerates and it’s one of many factors that architects and engineers take into consideration when designing the building.

“Structural engineers spend a lot of time trying to figure out how to distribute the material in the building,” said Klemencic. “They work closely with the architect to shape the building to minimize the sway effect.”

Skyscrapers Are Like Rocks in a Stream
Wind flows around buildings similar to the way water flows around rocks in a stream. As the water flows over the rock, small vortices or eddies swirl near the rock. Wind does the same thing. If those wind vortices break off the building in an organized, rhythmic fashion, the building will rock.

“If you can have the vortices break off at random or unorganized points in time, you can reduce the resonance,” said Klemencic. The Burj Khalifa achieves this with a design that’s terraced at different levels, which disrupts the wind vortices.

Are Skyscrapers Terrorist-Proof?
“I don’t know of any buildings that can withstand the impact of an aircraft,” said Klemencic. “In the building industry, the view is that [9/11] wasn’t a building problem, but an airport security problem. While we are taking measures to enhance safety and security at the ground, there’s not a lot of emphasis placed on missiles, if you will.”

Why Do People Build Mega-Skyscrapers in the First Place?
Tall buildings such as the Petronas Towers or the Taipei 101 generally are not built to make money, said Klemencic. If they’re lucky, the developers will break even and may even lose money.

“The purpose of building these things in the last 10 or 15 years is a symbolic gesture,” said Klemencic. “Planting your flag in the ground, as a developing nation, [saying] ‘we as a nation have arrived and here’s our big building to prove it.’”

The real money, he said, is made off of the surrounding developments, the retail, hotel, commercial and residential buildings that go up in the building’s shadow.

AP Photo/Kamran Jebreili

Source: http://news.discovery.com/tech/tall-buildings-sway-more-than-you-think.html

A giant Green Noise Wall is coming to I-70, east of Columbus, Ohio. The concrete barrier alternative will be constructed from bags of dirt and seeds, making it a second major vegetation highway wall attempt in the U.S. Officials are hoping this one fares infinitely better than an earlier one in Wisconsin, which ended badly.

Concrete sound barriers have been around for a while, usually erected to protect residents nearby from the roar of vehicles passing on the highway. The problem is twofold: concrete is an enormous source of greenhouse gas emissions worldwide, and existing barriers have varying levels of sound-blocking effectiveness. Sure, some are made from bricks and even wood, but those are often not substantial enough. And, I’ll just say it, these walls are ugly. So when the Ohio Department of Transportation began cutting down trees along I-70 for a new concrete sound barrier, locals pushed for something more aesthetically and environmentally pleasing.

Back in 1994, the Wisconsin Department of Transportation put up a 520-foot wall consisting of a plastic frame packed with soil and plants, according to Karen Farkas at the Plain Dealer. It was a disaster. She cites a report that says nearly 5,000 of the plants died and about half actually fell out of the structure, along with dried soil. Weeds took over and then part of the frame came down. The $396,000 structure was a complete bust.

In Ohio, the plans are radically different. The Canada-based civil engineering products company Deltalok came up with an original design for a wall that the Ohio DOT will be testing over the course of two years. Deltalok specializes in patented anti-erosion bags made from permeable fabric. The DOT has opened up the design to outside researchers and is currently seeking proposals (Download PDF) for a test wall that incorporates Deltalok’s bags.

The experimental phase will allow the DOT to look at a variety of factors, including how much water and maintenance a growing wall of vegetation might need. A research team will try out bags containing several different grass varieties that are stapled, tied, and sewn together. A rep from the Ohio Department of Transportation told Farkas that the bags will work like a Chia Pet: just add water and watch it grow.

The initial test wall will be 12 feet high while the ultimate plan is to put a 500-foot vegetation wall on a westbound section of I-70 east of Columbus. Evaluations will determine whether the test wall can actually compete with concrete.

I’m all for less concrete use, as long as the alternative is safe and sustainable. Come to think of it, maybe in another 10 years we won’t even need hardcore sound barriers along the highway. Electric vehicles are awfully quiet.

Source: http://news.discovery.com/tech/chia-wall-to-muffle-highway-sound.html

Howard Chapman, editor, writes…
ISG is to help build a Victorian ‘energy house’ for Salford University, which is working with BRE to research how to improve terraced housing built in the UK during the pre-First World War housing boom. These homes account for 23 per cent of domestic carbon emissions in the UK. The replica house will be built inside a three-storey sealed testing unit. This will be used to examine the real impact on environmental performance of potential changes to the structure under various climactic conditions.

ISG believes the experiment could prove hugely influential for homeowners, landlords and maintenance and refurbishment companies. The university hopes to have the initial results announced at the UK’s first conference on ‘sustainability and retro-fitting’, which it is hosting in January. I would be interested in attending this to get some feedback for Buildingtalk readers.

Sustainability is also having an impact on building materials through the Global Reporting Initiative (GRI), which encourages companies to measure the amount of CO2 produced per tonne of manufactured product. GRI seeks to make sustainability reporting by all organisations as routine as, and comparable to, financial reporting. Cemex UK, for example, announced last week that it has made a 10 per cent reduction in CO2 in 2009 based on this measure, which is quite an achievement

This week we feature a raft of heating, air-conditioning and ventilating products that boast sustainability gains. These include the Unico System Green Series air-handler unit, which saves more than 10 per cent of input energy; the Johnson and Starley whole house mechanical ventilation system with heat recovery; and the Ambiflo air source heat pump, which offers a solution for pre-heating mains cold water that can significantly reduce carbon emissions and running costs within commercial and industrial buildings. All these and more are summarised below. You can follow the links to read more or, where available, to download the relevant literature.

Finally, I have included a project story from Waterloo Air Products, which designs and manufactures a wide range of air-conditioning systems. It features its diffusers that have been installed inside the Hotel Verta, Europe’s first integrated hotel heliport solution. I pass this new building at Bridges Wharf in Battersea when I’m cycling along the river Thames in London. It is an impressive site. I mean the hotel heliport, not the ageing overweight editor cycling to work as part of his contribution to reducing CO2 emissions in the city.

Texas, United States Demand for wind energy is down. Valuations of wind farms are decreasing. And competition is getting more fierce. It’s a tough market out there – so what is a wind company to do? Innovate.
Innovation isn’t always the easiest thing to pursue in a bad economy. It can be next to impossible to bring new technologies to market when investors are skittish about financing even the most well-established ones. But many of the major wind players agree that now is the best time to focus on improving technologies and differentiating products.

The companies that choose to innovate will come out of the economic malaise in a strong position. Those that don’t will likely fall behind in the race to compete with fossil energies.

“We’ve been working on a lot of things. We’re taking a multi-pronged approach,” says Wally Lafferty, head of the Vestas Americas R&D program. “We’re expanding operations and hiring all kinds of people.”

Two years ago, Vestas opened an R&D facility in Houston, a city rich with aeronautical engineers. The facility is focused on aerodynamics, electro-magnetic machines, new blade designs and grid integration issues. Lafferty says that all the R&D efforts at Vestas revolve around one thing: Bankability.

“Ultimately, we need to drive down the cost of wind electricity so that it’s competitive,” he says.

Other companies like Siemens, GE and Statoil are undertaking similar internal pushes to expand R&D and push the limits of wind turbine size, location, weight and portability. This spring, Siemens released its new 3-MW direct-drive turbine. Vestas is also coming out with a new V112 3-MW machine and a 6-MW offshore machine. And the Norwegian oil and gas giant Statoil is continuing its $65 million program to develop a floating offshore unit for deep waters.

Developing new technologies in-house is one thing, but actually deploying them in the field is another. Some companies with new technologies ready for market are finding it difficult to move on projects.

“It doesn’t matter how good your innovation is, no one will put any money in a wind plant that uses new technology because of the perception that it increases financial risk,” says Fort Felker, director of the National Wind Technology Center at the National Renewable Energy Laboratory.

Take American Superconductor (AMSC). The company has been working on high-temperature superconductors (HTS) — wires that can carry 150 times more electricity than copper — since the late 80′s. The superconductor power cables constructed with AMSC’s HTS wire can be deployed underground at roughly the same cost as conventional above-ground lines. The cables include distribution and transmission voltages and can be either AC and DC systems.

In the last 12 months, a couple of utilities in the U.S. pulled back on projects to develop cables with these wires.

“If it weren’t for the economic downturn, I’m pretty sure we would have had by now our first commercial contract for superconductor cables for urban applications here in the United States,” says Greg Yurek, Founder and CEO of AMSC.

AMSC recently signed a deal with LS Cable in Korea to deploy 30 miles of superconductors in the country. A number of Chinese companies have also expressed interest in the cables, says Yurek. But business in the U.S. has come to a halt.

AMSC continues to sell mechanical and electronic equipment for wind turbines, waiting for the U.S. market for superconductors to open back up. When it does, Yurek believes that his company will do a lot of business. AMSC was already picked by Tres Amigas LLC to provide $1 billion worth of the company’s DC voltage Superconductor Electricity Pipelines for a project that will unite America’s three power grids. (AMSC has a minority stake in the company). And when utilities start building out new transmission to accommodate wind farms, he says that business will increase further.

“We are confident that this will take off in the U.S.,” says Yurek. “It might happen in other countries first, but the U.S. will be an important market.”

AMSC is also working on a 10-MW direct-drive offshore wind turbine that features a generator with superconductor rotors, potentially making the machine lighter and more efficient. That turbine is still in the early R&D phase, however.

Despite the slowdown in business, AMSC — like most of the other leading wind companies — is trying to stay on top by thinking about innovation. It might be difficult to get projects in the ground today, but it will inevitably get easier as the economy improves. Companies must be prepared to deploy their technologies when the time is right.

For more on wind technology innovation from AMSC, NREL, Statoil and Vestas, listen to this week’s podcast linked above.

Source: http://www.renewableenergyworld.com/rea/news/podcast/2010/06/wind-r-d-why-its-more-important-than-ever
Written by Stephen Lacey, Podcast Producer
Published: 18 June 2010