Source: http://phys.org/news/2013-04-smog-eating-pavement-greenest-street-america.html

Chicago city officials have dubbed Cermak Road in Chicago, Illinois, the greenest street in American on April 1, 2013. This city roadway includes smog-eating pavement, streetlights that run on solar and wind power, sidewalks made with recycled concrete, and shrub-filled “bioswales” to keep storm water out of overtaxed sewers. The Windy City has been experimenting with greener approaches to urban planning for years as part of a broader plan to mitigate the impacts of climate change: more intense storms and more extreme temperatures. The $14 million project to reshape two miles (3.2 kilometers) of the industrial Pilsen neighborhood incorporates pretty much everything city planners could come up with to cut energy use, fight pollution, reduce waste, manage water use and help build a sense of community. The project amazingly costs 21 percent less than a traditional road resurfacing project and should be cheaper to maintain. Chicago is one of a growing number of cities that are no longer waiting for the federal government to deal with climate change and are instead finding local, “no-regret” solutions, said Karen Hobbs, a water analyst with the Natural Resources Defense Council. Chicago is planting more trees, improving public transportation and improving bicycle lanes, and using more efficient street light bulbs. Chicago says it is the first in the nation, however, to lay down smog-eating cement. Because it’s significantly more costly than traditional pavement, Chicago is using this material in thin, permeable pavers for the bicycle and parking lanes along Blue Island Avenue and Cermak Road. Project manager Janet Attarian insists that while the smog-eating pavers are pretty impressive, it’s the combined approach that is going to make a real difference. Officials hope that this project will inspire others to take advantage of the many opportunities there are to improve our roads. Choosing drought-resistant plants for the bioswales means they ought to be able to withstand the hotter summers forecast as a result of climate change without wasting fresh water. The city is currently drafting new guidelines that will incorporate many of these green approaches as requirements for any new road work going forward.

Source: Smog-eating pavement on ‘greenest street in America’ by Mira Oberman, April 7, 2013

Source: Clean Edge Inc., 2013

According to the Clean Energy Trends 2013 Report, although 2012 was a difficult year for clean energy, the fundamental global market drivers for clean technology remained largely intact. This report is issued by clean-tech research and advisory from Clean Edge, Inc. Clean Edge, Inc. is the world’s first research and advisory firm devoted to the clean-tech sector, delivering timely data, expert analysis, and comprehensive insights to key industry stakeholders. The Clean Energy Trends 2013 report found that lower prices for many clean-tech goods and services, combined with a  focus on scalable projects, resulted in record annual solar, wind, and biofuels deployment. Against this continued expansion, however, combined global revenue for solar PV, wind power, and biofuels expanded just one percent, from $246.1 billion in 2011 to $248.7 billion in 2012. This marginal growth was one of the many consequences of rapidly declining solar PV prices.

The report included a few significant findings regarding biofuels, wind power, and Solar PV. Biofuels reached $95 billion in 2012, up from $83 billion the previous year. From 2011 to 2012, global biofuels production expanded from 27.9 billion gallons to 31.4 billion gallons of ethanol and biodiesel. Global wind capacity additions totaled 44.7 GW (gigawatts) in 2012, a record year led by more than 13 GW added in both China and the U.S., and an additional 12.4 GW of new capacity in Europe. While total solar market revenues fell 19 percent – the first PV market contraction in Clean Energy Trends’ 12-year history – global installations expanded to a new record of 30.9 GW. Clean Edge, Inc. projects that these three sectors will nearly double from $248.7 billion in 2012 to $426.1 billion within a decade. Trends that will impact the clean energy market in coming years are outlined in the report including: Smart Devices and Big Data Empower Customers, Distributed Solar Financing Comes of Age, and In the U.S. and Overseas, Geothermal Picks up Steam.

Source: Clean Edge news release- Clean Energy Trends 2013 Released Today, March 12 2013

Source: Wind power plants in Xinjiang, www.treehugger.com

At the end of 2012, wind farms generated 2 percent more energy than nuclear power plants in China, a gap that will most likely continue to widen in the next few years as wind power surges ahead. Following the Fukushima disaster in 2011, the government responded by suspending new reactor approvals and conducting a safety review of plants in operation and under construction. At that time, there were 10,200 megawatts of installed nuclear capacity and 28,000 megawatts under construction. The prediction that China will reach 40,000 megawatts of nuclear capacity by 2015 seems unlikely with the current pace of construction. However the outlook for wind power seems much more promising with 19,000 megawatts of wind power capacity connected to the grid during 2011-2012. Efforts to expand and upgrade the grid in China have been made to fully accommodate fast-multipling wind turbines in remote, wind-rich areas. China has set an official target of 100,000 megawatts of grid-connected wind capacity by 2015, however the Chinese Renewable Energy Industry Association believes that wind installations will reach 200,000 megawatts by 2015. China is taking advantage of this opportunity for a rich renewable energy source with the construction of seven massive “Wind Base” mega-complexes underway in six provinces.

Source: Wind surpasses nuclear in China by J. Matthew Roney

Any rooftop installation requires an engineering review to assure structural suitability. Photo by Anders Sandberg.

The mass media seem to love stories about building-mounted wind turbines, even though bona fide manufacturers, professional installers and knowl­edgeable rebate program managers actively discourage their purchase and installation. While inventors of such “breakthrough technologies” claim that the mainstay small wind industry is just trying to squash potential com­petition, the real reasons are actually quite different.

Rooftop wind turbines will never be a viable technol­ogy for several reasons. First, the small collector size of these devices (a requirement so that the weight of the turbine does not col­lapse the roof) means that only small amounts of fuel — the wind — can be accessed and converted into electricity. Second, wind strength is inadequate at rooftop height to produce significant power. Rooftop wind is also turbulent, and therefore quite destructive of wind turbines. This combination of limita­tions means that rooftop turbines can never be cost-effective. Any number of small wind test sites have confirmed these points.

Now a new problem is emerging: Permitting authorities are receiving applications from homeowners and businesses that want to greenwash their images with building-mounted turbines. Authorities are therefore wrestling with how to write appropriate ordinances.

Zoning and permitting language for standard tower-mounted wind turbines is quite straightforward. The common standard is that the setback for the tower should match the total structure height from property lines unless an adjoining property owner agrees to a shorter distance. What do you do, however, with a wind turbine that is advertised to be mounted on top of a roof in an urban area where property lots are 25 feet to 50 feet (7.6 meters to 15 meters) wide?

There’s a more serious problem: Small wind sys­tems from mainstream manufacturers are engineered structures, designed with a built-in safety factor. The engineering designs cover all components of the wind systems including the turbine, electronics (inverters and controllers), tower and foundation. Tower and foundation are engineered to the specifications of the International Building Code (IBC), which dictates the extreme winds, ice loads, peak gusts and allowable load­ing on the structure.

What does a permitting authority do with a turbine that may (or may not) be engineered, but is mounted on a structure that was clearly not designed to support a wind turbine, nor the loads developed by that turbine when it is spinning and generating electricity? This is a legitimate concern, as there have been reports of building-mounted turbines seriously damaging the roof or wall they were mounted on, in some cases endanger­ing nearby properties.

Residential roofs and commercial building structures were designed for certain loads specific to the building and location, including —

• Dead loads: The weight of the structure plus the addi­tional roof layers and HVAC equipment added over time.

• Live loads: Wind, traffic movement and earth tremors, and occupational loads including workers on the roof.

• Environmental loads: Snow and ice accumulation, temperature changes and rainfall. Since these loads are dif­ficult to model, the IBC usually specifies 50-year extremes.

• Dynamic loads: Severe storms, impacts, wave action near large bodies of water and earthquakes. These are extremely complex loads to model as they are unpredict­able as well as varying in frequency, amplitude, duration — and may or may not have a cyclic nature. The IBC specifies considerations for some of these loads, but usu­ally defers to a specific engineering analysis to account for them. The prudent building owner purchases insurance for such extreme occurrences. A wind turbine on a roof or building would be categorized as a dynamic load not accounted for in the IBC or building structural design.

So how does a permitting authority deal with this?

Unlike engineered tower-mounted wind systems, the structure that a rooftop wind turbine is to be mounted on needs to undergo a complete engineering analysis for the specific wind turbine. This must include the loads placed on the roof, walls, foundation and associated struc­tural support members by the wind turbine; all shear loads and overturn moments; the centrifugal forces and resonant frequency of the spinning rotor and governing mechanisms; the yaw and generator torque developed by the turbine; and the aerodynamic thrust loads generated by the wind system. Only such an analysis will guarantee the same level of safety engineered into tower-mounted wind systems.

This article appeared in the March/April 2012 issue of SOLAR TODAY. Subscribe today!