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39% of America's Energy Could One Day Be Generated by Rooftop Solar Panels

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The answer to America’s energy problems could be right under our noses—or, rather, right over our heads. According to a recent study by the Energy Department’s Renewable Energy Laboratory (NREL), America’s rooftops are full of untapped potential. In fact, up to 39 percent of America’s energy could be generated just by installing photovoltaic (PV) solar panels on urban rooftops.

Popular Science reports that NREL analyzed rooftops in 128 cities across the United States, representing about 23 percent of all buildings in the U.S., according to an NREL press statement. The researchers assessed the buildings' suitability for hosting PV solar panels and measured how much power could be generated by each location. They found that 83 percent of small buildings had the technical potential to host PV panels on part of their rooftop areas, while 26 percent could host an entire rooftop’s worth of panels.

Researchers say that their findings far exceeded previous estimates of the amount of power that could be generated by rooftops alone. Their analysis estimates that rooftops have a technical potential of 1118 gigawatts of capacity and 1432 terawatt-hours of annual energy generation, which would equal 39 percent of America’s total electricity sales (based on 2013 numbers).

However, it’s important to note that researchers analyzed technical potential only. That is, they considered resource availability and the availability of space without also analyzing economic or political factors—which means that while America may have the space for rooftop solar panels, it may not currently have the political will or a plan of action.

"An accurate estimate of PV's technical potential is a critical input in the development of regional deployment plans," explains researcher Pieter Gagnon. "Armed with this new data, municipalities, utilities, solar energy researchers, and other stakeholders will have a much-improved starting point for PV research and policymaking, both regionally and nationwide."

[h/t Popular Science]

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Switzerland Flushes $1.8 Million in Gold Down the Sewer Every Year
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Switzerland has some pretty valuable sewer systems. As Bloomberg reports, scientists have discovered around $1.8 million worth of gold in the country's wastewater, along with $1.7 million worth of silver.

Scientists at the Swiss Federal Institute of Aquatic Science and Technology examined sewage sludge and effluents, or discharged liquid waste, from 64 water treatment plants and major Swiss rivers. They did this to assess the concentrations of various trace elements, which are "increasingly widely used in the high-tech and medical sectors," the scientists explained in a press statement. "While the ultimate fate of the various elements has been little studied to date, a large proportion is known to enter wastewater."

The study, which was recently published online in the journal Environmental Science & Technology, revealed that around 94 pounds of gold makes its way through Switzerland's sewage system each year, along with 6600 pounds of silver and high concentrations of rare metals like gadolinium and niobium. For the most part, these metals don't harm the environment, researchers say.

With gold and silver quite literally flowing through their sewers, is there any way that Switzerland could turn their wastewater into wealth? Scientists are skeptical: "The recovery of metals from wastewater or sludge is scarcely worthwhile at present, either financially or in terms of the amounts which could be extracted," the release explains.

However, in the southern canton of Ticino, which is home to several gold refineries, the "concentrations of gold in sewage sludge are sufficiently high for recovery to be potentially worthwhile," they conclude.

Switzerland is famous for its chocolate, watches, and mountains, but it's also home to major gold refineries. On average, around 70 percent of the world's gold passes through Switzerland every year—and judging from the looks of it, much of it goes down the drain. As for the sewer silver, it's a byproduct of the chemical and pharmaceutical industry, which is a cornerstone of Switzerland's economy.

[h/t Bloomberg]

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Grass-Fed Beef Is Actually Worse for the Planet, Report Finds
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There are plenty of reasons to reject factory farming, but in the case of beef, your carbon footprint shouldn’t be one of them. According to EcoWatch, new research shows that grazed cattle provide an outsized contribution to greenhouse gasses, as opposed to cattle kept largely indoors and fed on grain.

The report [PDF], released by Oxford’s Food Climate Research Network, aims to provide definitive answers to what has been a heavily debated topic in environmental circles. Some research has found that grazing cattle actually reduces the carbon footprints of beef operations, because all that pasture stores carbon and prevents it from being released into the atmosphere, and because all that chomping stimulates new vegetation growth. Other research has found that the benefits aren’t as great as the grass-fed boosters estimate—especially since the fields of grain used to grow cattle feed for factory farms sequester carbon, too.

The new Oxford research comes down firmly on the side of the latter camp. It finds that while grass-fed operations can help sequester carbon, it’s “only under very specific conditions,” in part since the definition of what a grassland is can vary wildly. There are natural ranges dominated by wild vegetation, there are pastures that are actively maintained and managed by farmers, and there is land that lies somewhere in between. Overgrazing, trampling, and soil conditions can all negatively impact how much carbon the grasses can sequester. And even under the best conditions, the gains can be short-lived. “This sequestering of carbon is even then small, time-limited, reversible, and substantially outweighed by the greenhouse gas emissions these grazing animals generate,” according to FCRN.

And it seems that even if the vegetation does sequester carbon, grass-fed beef is still an outsized source of greenhouse gasses.

To begin with, all cattle are a huge drain on the environment, no matter how you feed them. The report estimates that the livestock supply chain generates around 14.5 percent of global greenhouse gas emissions, and cattle create 65 percent of those livestock emissions. But even compared to cattle in general, grass-fed animals are heavy polluters. Within the global protein supply, grass-fed beef makes up around 1 gram of protein per person, per day, compared to 13 grams from all ruminants (cattle, sheep, goats, etc.). But these grazed cattle generate up to a third of all global greenhouse emissions from ruminants. In other words, grass-eating cattle create an outsized cost—emissions-wise—compared to the meat they provide.

And the carbon sequestration doesn't help enough to offset that. The report estimates that the carbon sequestration that might occur from grazing practices would only offset emissions by 20 percent.

There are other reasons to buy grass-fed beef, of course, whether it’s about ethical concerns with factory farming or just a taste preference. But if you’re going to choose grass-fed, your reason shouldn’t be concern for the environment.

[h/t EcoWatch]

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