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Distributed Wind Energy | Earth Wise

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When we think about wind power, we are usually talking about increasingly giant windfarms – either on land or offshore – that produce power on a utility scale.  But there is also distributed wind energy, which refers to wind technologies in locations that directly support individuals, communities, and businesses.  

Distributed wind can be so-called behind-the-meter applications that directly offset retail electricity usage much as rooftop solar installations do.  It can also be front-of-the-meter applications where the wind turbines are connected to the electricity distribution system and supplies energy on a community scale.  Distributed wind installations can range from a several-hundred-watt little turbine that powers telecommunications equipment to a 10-megawatt community-scale energy facility. As of 2020, there were nearly 90,000 distributed wind turbines in the U.S. with a total capacity of about 1 GW.

A study by the National Renewable Energy Laboratory has estimated the potential for distributed wind energy in the U.S.   According to the new analysis, the country has the ability to profitably provide nearly 1,400 GW of distributed wind energy capacity. 

Entire regions of the country have abundant potential. The regions with the best economic prospects have a combination of high-quality wind, relatively high electricity rates, and good siting availability.  Overall, the Midwest and Heartland regions had the highest potential especially within agricultural land.

Realizing this outcome for distributed wind will require improved financing and performance to lower costs, relaxation of siting requirement to open up more land for wind development, and continued investment tax credits and the use of net metering.

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U.S. has potential for 1,400 GW distributed wind energy, NREL finds

Photo, posted January 3, 2009, courtesy of skyseeker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electricity From Bacteria | Earth Wise

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Microbiologists at Radboud University in the Netherlands have demonstrated in the laboratory that methane-consuming bacteria can generate electrical power.  Their study was recently published in the journal Frontiers in Microbiology.

The bacteria studied is called Candidatus Methanoperedens and in the natural environment it consumes methane in water sources that are contaminated with nitrogen including places like water-filled ditches and some lakes. The bacteria in the study make use of the nitrates in the water to break down and digest the methane. Methanogens, which are bacteria that reduce carbon dioxide to form methane, are the source of the methane in these places. 

The researchers exploited these complex interactions of bacteria to create a source of electrical power that is essentially a kind of battery with two terminals.  One of the terminals is a chemical terminal and one is a biological terminal.  They grew the bacteria on one of the electrodes where the bacteria donate electrons that result from its conversion of methane.  (Other microbiologists at the same institution had previously demonstrated electrical generation from a similar battery containing anammox bacteria that use ammonium rather than methane in their metabolic processing).

In the study, the Radboud scientists managed to convert 31% of the methane in the water into electricity but they are aiming at higher efficiencies. 

This approach represents a potential alternative to conventional biogas electricity generation.  In those installations, methane is produced by microorganisms digesting plant materials and the methane is subsequently burned to drive a turbine to generate power.  Those systems in fact have an efficiency of less than 50%.  The researchers want to determine whether microorganisms can do a better job of generating electricity from biological sources than combustion and turbines can do.

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Bacteria generate electricity from methane

Photo, posted December 3, 2008, courtesy of Martin Sutherland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Giant Wind Turbines | Earth Wise

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Wind turbines keep getting bigger and bigger.  The reason is that the power a wind turbine can theoretically generate is proportional to the disk-shaped area swept out by its blades.  So, the bigger the blades, the more power can be produced by a single turbine.

That being said, real-world turbines don’t achieve their theoretical power output because they have limitations on efficiency.  Things like rotor blade friction and drag, gearbox losses, and generator losses limit the actual power output of a turbine. 

Despite all of these things, the latest and greatest wind turbines are absolutely enormous and produce almost unbelievable amounts of power.  Chinese manufacturer MingYang Smart Energy has recently unveiled an 866-foot tall, 16-megawatt capacity offshore wind turbine.  This narrowly exceeds both the Vestas V236 Turbine announced earlier this year and GE’s Haliade-X Turbine, rated at 15 megawatts and 14 megawatts respectively.

The rotor diameter of the giant Chinese turbine is nearly 800 feet, set by its 387-foot blades that sweep out an area of nearly 50,000 square feet.  A single one of these turbines can generate 80,000 MWh of electricity in a year, enough to power more than 20,000 households.  (It boggles the mind to consider that just one rotation of the blades of such a turbine can power a couple of homes for an entire day).

Offshore wind farms choose the largest wind turbines in part because of the high cost of installing turbines and transporting the electricity.  It is preferable to build fewer turbines because fewer towers, cables, and ground anchoring systems need to be constructed, making the project less complicated.

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This 264-meter tall offshore wind turbine is now the largest of its kind

Photo, posted November 19, 2015, courtesy of Scott Flaherty / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Most Powerful Tidal Turbine Is Generating Power | Earth Wise

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The movement of waves, tides, and currents in the ocean carry enormous amounts of energy that in principle could be harnessed and converted into electricity to help power our homes, buildings, and cities.  Oceans cover nearly three-quarters of our planet, and the most populated areas of the world are located near oceans.

Ocean energy technologies lag far behind solar and wind power and remain mostly undeveloped.  This is a result of the unique challenges standing in the way of widespread deployment.  There are the considerable expenses of early-stage development, the wide variety of technical approaches from which winning strategies have yet to emerge, and the substantial challenges of operating in the ocean environment that include the physical impact of waves and tides, powerful and unpredictable weather, and corrosion and bio-fouling from the ocean and its inhabitants.

Despite these challenges, there is ongoing progress on ocean energy.   The world’s most powerful tidal turbine has come online this past April.  Known as the Orbital O2, the floating turbine is anchored in Scotland’s Fall of Warness, where a subsea cable connects it to the European Marine Energy Center.

The turbine produces enough electricity to meet the demand of about 2,000 homes in the UK.  It is expected to operate for the next 15 years.

Built by the Scottish engineering company Orbital Marine, the O2 was financed by the ethical investment platform Abundance Investment as well as being supported by the Scottish government and the European Union.   Orbital Marine’s goal is to commercialize this technology to play a role in tackling climate change using this new green energy technology.

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The world’s most powerful tidal turbine is now generating power

Photo, posted June 12, 2015, courtesy of David Stanley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Harvesting Blue Energy | Earth Wise

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There are various ways to generate renewable energy from the world’s oceans, most obviously from the power of tides and waves.  But there is also an oceanic energy source called osmotic or “blue” energy.  Osmotic energy uses the differences in pressure and salinity between freshwater and saltwater to generate electricity. 

When freshwater and saltwater are mixed together, large amounts of energy are released. If the freshwater and seawater are then separated via a semi-permeable membrane, the freshwater will pass through the membrane and dilute the saltwater due to the chemical potential difference. This process is called osmosis. If the salt ions are captured completely by the membrane, the passing of water through the membrane will create a pressure known as osmotic pressure. This pressure can be used to generate electricity by using it to drive a turbine.  This has been demonstrated to work as far back as the 1970s, but the materials we have to use are not adequate to withstand ocean conditions over the long term and tend to break down quickly in the water.

New research, published in the journal Joule, looked to living organisms for inspiration to develop an improved osmotic energy system.  Scientists from the U.S. and Australia combined multiple materials to mimic the kind of high-performance membranes that are found in living organisms.  They created a hybrid membrane made from aramid microfibers (like those used in Kevlar) and boron nitride.  The new material provides both the flexibility of cartilage and the strength and stability of bone.

The researchers believe that the low cost and high stability of the new hybrid membrane will allow it to succeed in volatile marine environments.  They also expect the technology will be both efficient and scalable. 

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Inspired by the Tissues of Living Organisms, Researchers Take One Step Closer to Harvesting “Blue Energy”

Photo, posted February 14, 2017, courtesy of Marian May via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Power From The Sun’s Heat

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When we think of solar power, we usually are talking about the panels that generate electricity using the photovoltaic effect.  These panels are on millions of rooftops around the world and in utility-scale solar farms.   There are also solar water heating systems that use the sun’s heat to provide hot water for homes and businesses.

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Storing Energy With Captured CO2

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Capturing carbon dioxide instead of releasing it into the atmosphere is a way we can use fossil fuels without it having harmful effects on the climate.  Energy storage is a way to address the volatility of clean energy sources like wind and solar power.  Excess energy stored during peak production can be used when production ceases, such as when the sun is not shining or the wind is not blowing.

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