Renewable Energy

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7/2/2015

Hydropower is often considered a clean energy source, free of climate-warming carbon dioxide emissions. But although dams have been demonized for disrupting fish migrations and flooding valleys inhabited by families for generations, this so-called renewable form of energy has largely escaped scrutiny for its climate impacts. After all, how could the atmosphere be harmed by letting a river flow through a few energy-generating turbines encased within a 50-foot wall of concrete and steel?

Hydropower is the world’s leading form of renewable energy, accounting for more than 16 percent of global electricity generation. But dam enthusiasts who tout hydro’s climate credentials may not like the news about its emissions numbers.

Studies conducted over the past decade have shown that greenhouse gases, such as carbon dioxide and methane, are produced by hydroelectric systems in potentially huge amounts.

In some cases, emissions from hydropower can even exceed those that would have been produced from burning conventional fossil fuels instead. For example, a 2014 study finds that the Curuá-Una Reservoir in Brazil emitted 3.6 times more greenhouse gases than would have been emitted had the electricity come from oil.

How Hydroelectric Dams Produce Greenhouse Gases

When a dam is built for energy generation, the land upstream of the impoundment is flooded. The more than 45,000 large dams built around the world cover a combined area the size of Montana (Barros et al., 2011). For many, within their depths lies former forest land.

As the submerged trees, grasses, shrubs and soil decompose, microbes convert the carbon stored in the vegetation into gas that can bubble up to the surface and escape to the atmosphere. Carbon trapped within the soil percolates out in the form of carbon dioxide.

Age matters. Studies show that younger reservoirs may be bigger emitters than older one, because most carbon is released from drowned vegetation within the first several years of flooding.

Location matters, too. Emissions seem to be highest from dams built in the tropics, presumably because higher temperatures give decomposer microbes the metabolic boost to do their work.

Methane Matters

Methane is of particular concern. The gas is made anywhere methanogenic (methane-producing) bacteria can thrive without oxygen—so, in the guts of pigs and people, peat bogs and permafrost. Unfortunately, methane is also 25 times more potent a planet warmer than carbon dioxide over 100 years. And warm, tropical places can produce more of it.

Methane has plenty of opportunities to escape during the hydropower process: It bubbles up from the oxygen-free muck that accumulates at the bottom of reservoirs. It is churned out in the spray coming off spinning turbines. For miles, it wafts off the newly agitated surface of the river downstream from a dam.

So much methane is produced that studies suggest more than 20 percent of what humans are responsible for may come from dams, which may be releasing up to 104 teragrams of the gas annually. (This may be more than all the methane produced per year from burning fossil fuels, according to NASA.)

A Lack of Information or Regulatory Failure?

Of course, impacts from big hydro projects go beyond greenhouse gas emissions to include altered land use, the collapse of migratory fish populations and the displacement of people. Coastal erosion can occur downstream from reservoirs when sediment becomes trapped behind dam impoundments, preventing the silty particles from reaching   the sea where they build and stabilize coastlines.

Despite large hydro’s detrimental impacts on life, land and atmosphere, many nations fail to include emissions associated with dams in their total greenhouse gas reporting. This gap in information makes hydro emissions difficult to track—and to regulate.

Most hydropower is concentrated in Asia, but more than 150 countries employ the technology for at least some of their energy. The Worldwatch Institute reports that “in 2008, four countries—Albania, Bhutan, Lesotho, and Paraguay—generated all their electricity from hydropower,” and “15 countries generated at least 90 percent of their electricity from hydro.”

Moreover, when nations have made steps to report hydro emissions, the international hydroelectricity industry has attempted to muddy the waters by downplaying the amount of carbon degassing from their projects.

Take Down the Dams?

Before you think tearing down all dams is the answer, consider this: Taking down a large dam may actually release more greenhouse gases from the newly exposed, carbon-rich soil than were produced throughout the entire life of the dam.

For example, decommissioning Arizona’s Glen Canyon Dam in the United States, which provides power from Lake Powell, would theoretically produce nine times more methane following takedown than all the methane produced during Glen Canyon’s 100-year operation.

What is the Solution?

What many believe would be a good first step is for the Intergovernmental Panel on Climate Change, the world’s foremost scientific authority on the subject, to ask all participating nations to report greenhouse gas emissions from hydroelectric reservoirs. Can that happen with so many questions left unanswered?

More research on the climate impacts of hydropower is needed, in more places and at all stages of big dams’ lifecycles. Until then, policymakers may be overlooking a potentially significant contributor to climate change, perhaps difficult to calculate but ever present, hidden at the bottom of a placid reservoir.

References

Barros et al. (2011). Carbon emission from hydroelectric reservoirs linked to reservoir age and latitude. Nature Geoscience, 4, 593-596.

Demarty, M. & Bastien, J. (2011). GHG emissions from hydroelectric reservoirs in tropical and equatorial regions: Review of 20 years of CH4 emission measurements. Energy Policy, 39, 4197-4206.

International Energy Agency [IEA]. (2010). Renewable Eenergy essentials: Hydropower. Free publication. Accessed May 11, 2015, from http://www.iea.org/publications/freepublications/publication/hydropower_essentials.pdf.

IPCC. (2006). Appendix 3: CH4 emissions from flooded land: Basis for future methodological development. 2006 IPCC Guidelines for National Greenhouse Gas Inventories.

Magill, B. & Climate Central. (29 October 2014). Methane emissions may swell from behind dams. Scientific American. In Energy & Sustainability. Accessed May 09, 2015, from http://www.scientificamerican.com/article/methane-emissions-may-swell-from-behind-dams/.

NASA. (2010). Education: Global methane inventory. GISS Institute on Climate and Planets. Accessed May 11, 2015, from http://icp.giss.nasa.gov/education/methane/intro/cycle.html.

Pacca, S. (2007). Impacts from decommissioning of hydroelectric dams: a life cycle perspective. Climate Change, 84, 281-294.

Worldwatch Institute. (2013). Use and capacity of gobal hydropower increases. In Vital Signs. Accessed May 09, 2015, from http://www.worldwatch.org/use-and-capacity-global-hydropower-increases-0.

Yang, L., Lu, F., Zhou, X., Wang, X., Duan, X., & Sun, B. (2014). Progress in the studies on the greenhouse gas emissions from reservoirs. Acta Ecologica Sinica, 34, 204-212.

Photo by Robert Campbell, Wikimedia Commons


Kale Roberts is the Blogging Coordinator for MOTHER EARTH NEWS and a Rachel Carson Scholar at the Bard Center for Environmental Policy. His interests include renewable energy, real food and sustainable rural development. You can find him on Google+.



6/17/2015

Woodgas Generator

This is a guest post by Ben Peterson, author of the Wood Gasifier Builder's Bible.

A wood gasifier is a marvel of technology. Imagine being able to turn dead tree branches from your own property into motor fuel. Make power just about anywhere, at any time...for free. Sounds futuristic, right? Well, it's actually an age-old technology from the industrial revolution that is still used to this very day by homesteaders and folks in developing countries where power is expensive or non-existent.

Wood gasification is again growing in popularity as people return to the land in search of clean, sustainable living. Its utility is becoming recognized as more off-grid solar systems are installed and the reality of cloudy days and dark winter nights are experienced firsthand. "What can I use to fuel my backup generator that isn't petroleum based?"

My Experience Going Back to the Land

When my kids were old enough to swim in a pond and chase off coyotes, we bought an old homestead and moved onto 20 acres in the sticks. I wanted them to experience nature firsthand and not just read about it in a book. I get irked by concrete-dwelling city environmentalists, but I digress.

Our dilapidated old farm had two main problems: Weak power and mountains of wood waste. So I started looking for a solution to both problems and stumbled across wood gasification. It turns out people had used wood gasifiers to power 1 million cars, factories, boats and homes during WWII— a forgotten technology with real potential. Living in Western Washington, we have tons of wood. I like to joke that we are the Saudi Arabia of wood.

On July 4th weekend 2007, I was able to cobble some scrap metal together into one of these gasifier contraptions using a set of FEMA plans. A quick proof of concept. It only made a belch of gas, but it was magic! I felt like a wizard. Hillbilly witchcraft in action.

Then, I discovered the MOTHER EARTH NEWS wood gasifier plans from the 1970s used during the gas crisis. I grabbed my torch and a water heater and went to work! A major improvement, indeed. I was making steady gas now and my mind raced with the possibilities.

For a time, I built a new machine every week just to test new ideas and check the assumptions of others. There was a lot of good information online blended in with a lot of armchair theory. I'm not going to lie, it was frustrating at times.

But the frustration paid off during the catastrophic winter of 2008. The freeway flooded, then froze, water pipes too. Power was down for a long time. There was no gas in my town of 900 people. Luckily my kids had gone south with their mom. It was just me and my dog and our frozen farm as a laboratory to test wood gas in action. I needed power and all I had for fuel was wood. It was a perfect match.

I used a wood gasifier made from propane tanks to fuel an old Lincoln welder generator. This gave me both electricity and welding ability to keep working. The old welder generator was very forgiving and worked beautifully. I was able to get the lights back on and defrost pipes so I could flush the toilet and take a shower. It wasn't the fanciest setup, but it worked. It made me a believer.

Woodgas Generator Flames 

Building a Wood Gasifier

Wood gasifiers can be built from mostly local parts like propane tanks and scrap steel. Expect to spend $1,500 and up for a low-budget DIY build. If you can afford stainless, then please use it in the high temperature areas to extend their life. A 180-amp mig welder or larger is desirable for the welding, but a stick welder can work if you use propane tanks.

Many people use oil drums, but I avoid them because they are very thin and prone to rust through or burn through. Why do the same job twice? I outline a complete step-by-step build in my book so you can see the entire process from start to finish.

1. Instead of having a weld shop build your gasifier, look for a blacksmith or metal artist. They have more passion and cost half as much.

2. If you use a fab shop, tell them you are an OEM (original equipment manufacturer) to get their best rates. Let them know this is a prototype.

You do need to modify the intake of your engine to accept wood gas and still run on its standard fuel, too. Here is a video I put together that explains the process better:

Challenges and Dangers

No fuel source is perfect and wood gas is no different. Here are the nitty gritty facts:

• Wood gas is best for spark-ignited engines; diesel engines need 20 percent diesel fuel to auto ignite.
• Wood gas has about half the power of gasoline, but this is overcome by using larger engines, which don't cost much more.
• It does take a little effort to gather and chunk wood. Small chips don't work well. Forget about using grass. Pellets can be problematic.
• There are hot surfaces on a wood gasifier. You wouldn't grab a wood stove would you?
• There is carbon monoxide in the gas, so use it in a well ventilated area. Don't use indoors. • Expect to run for several hours, but not 24/7.
• If you don't get your setup correct, you can make tar and stick an engine valve. (This usually only happens to newbies.)
• There is a small amount of soot in the gas even after filtering. Keep the gas above the dew point and it will flow into your combustion chamber nice and dry and get burned up with the rest. You may notice a darkening of your oil, but it's not a problem. Feel the oil between your fingers to validate it still has lubricity.

The Benefits of Wood Gasification

A wood gasifier is a marvel, because it puts refining capability on your own property and the cost of the fuel once you are set up is just the time it takes to pick up sticks and chunk them down. It has these benefits and more:

• Make your own fuel day or night.
• Keep your energy supply chain on your own property.
• Proven at scale during war time.
• High power capability compared to other renewables. 5-20 kilowatts stationary power is easily achieved.
• Portable, so you can take it with you in case of an emergency.
• Utilize cheap land with wood and avoid expensive power lines.
• Use the activated carbon (charcoal) for water filtration.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Best Practices, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on the byline link at the top of the page.



6/12/2015

 

Solar energy has been an attractive alternative energy source for decades, but it wasn’t until recently that widespread adoption has increased. The cost of panels, installation and system maintenance have fallen, making the prospect of solar affordable and appealing to both homeowners and businesses.

To encourage solar power consumption, the federal government has implemented tax incentives. The ITC (Solar Investment Tax Credit) provides a 30-percent tax credit for solar systems on residential and commercial properties. Competition among solar companies has also helped to lower costs and simplify the solar installation and rebate process.

Part of the government’s interest in solar isn’t just about helping the environment; it’s about helping the economy. The solar industry has contributed a substantial number of new jobs. In the last four years, job creation has grown by 86 percent, a period during which many industries were stagnant or shrinking.

Unfortunately, not everyone has been so welcoming to the new kid on the block. As residential and commercial solar installation surges, utility companies who have grown accustomed to large market share are pushing back.

Utility Push-Back

As more consumers make the switch to solar, utility companies around the country are looking for ways to curb the trend. Though solar power still makes up less than 1 percent of the energy produced in the United States, many utility companies can sense a shift in the energy market and are fighting to maintain market share.

The demographics of solar consumers have changed dramatically in the last few decades, due to both affordability and public awareness. Over 40 years ago, most solar panels were being installed on structures that were off the electrical grid. In contrast, today over 95 percent of installations are “grid-tied.” With these changes, utility companies set on sticking to the status quo may have reason to be concerned.

To stop solar expansion, utility companies are spending a lot of money to sway public opinion and push legislation to increase fees for solar users.

Net Metering

The Energy Policy Act of 2005 provided tax breaks for consumers making energy conservation improvements on their home and mandated all public utility companies to provide net metering options when customers request it. Since then, 43 states have adopted net metering policies and solar power consumer adoption has grown by over 1,600 percent.

The debate surrounding solar energy production primarily deals with the issue of net metering, which is the practice of solar customers selling excess power generated from the panels to power companies. Many utility companies feel that net metering isn’t fair because it forces them to buy solar-produced power. They argue that the cost of maintaining the grid should be shared by everyone that benefits from it.

The problem, utility companies say, is that the solar consumers who produce excess power are not paying anything to maintain the use of the grid. Because utility companies are required to buy and sell the power produced at retail cost, they don’t recoup the cost of maintaining the grid system.

Meanwhile, solar companies contend that the excess power produced by residential solar panels helps generate power for their neighbors on the grid, which decreases the load for central plants. The fees that utility companies are pushing for are intended to force solar companies and consumers to pay additional costs and deter “freeloaders” on the grid from using solar.

Whether your residential solar panels are self-installed or installed by solar providers, these proposals for legislation and utility fees have the potential to impact you as a solar user. In many states, utility companies have proposed a fee for customers to sell their excess power. Additionally, states like Arizona, Utah and California are seeing an increased lobbying effort to gain support for discontinuing net metering policies.

Solar Battle in the “Valley of the Sun”

Phoenix and surrounding areas see almost 300 days of sun a year, making Arizona a “hotbed” for solar expansion and energy competition. Arizona’s largest electric utility company, Arizona Public Services (APS), began pushing for monthly $50 solar fees in 2013, but was only able to get a $5 fee approved.

As solar continued its growth, APS hired nonprofit lobby firm Prosper to release several ads describing the perceived burden of solar customers on the whole grid. Just before a proposal for rate hikes to the Arizona Corporation Commission, one ad claimed that every solar system "adds $20,000 in costs to customers." In addition to the APS ad spending, Arizona utility company Salt River Project (SRP) spent roughly $1.7 million on advertising in an effort to increase support for solar rate hikes and solar fees.

No matter how large or small these policies and fees are, they are intended to discourage widespread solar energy and reduce the competition traditional utility companies are facing. Although solar power is the most popular alternative energy source, with public support near 80 percent, utility companies are still succeeding in their efforts to raise fees and dissuade the public.

In February 2015, the SRP board of directors approved a basic service fee increase for solar consumers, as well as an additional fee of $50 a month. With every increase in fees, solar systems become less profitable, making the prospect of clean and renewable solar power less appealing. Solar customers are facing similar situations all over the country.

The Future of Solar

Despite legal and policy battles, many industry analysts say that the future of solar looks bright. A recent report from Deutsche Bank projected that rooftop solar will become as affordable, if not more affordable, than grid power by 2016 in all but 3 states. That affordability will continue to drive massive solar adoption.

The Solar Energy Industries Association reports that US solar capacity increased to 20 gigawatts in 2014, an increase of 30 percent. They predict solar capacity will double to 40 gigawatts by the end of 2016, producing enough power for 7.6 million homes.

To stay competitive, solar companies are determined to find solutions that will require less support from the grid. One option gaining in popularity is the use of batteries that can store the power generated during peak daylight hours for use in the evening. Energy consumers have shown they’re ready and willing to use alternative energy sources, which will continue to drive innovative solar technology advancements.

Solar energy is a renewable energy source that benefits the world. Some utility companies have seen the opportunity to increase their market share by entering the solar space as well. Ideally, utility companies will adapt to changing markets and work together with solar providers to create new renewable solutions for everyone.

Photo by morgueFile/Jusben

This is a guest post by Bryan Phelps at Vivint Solar.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Best Practices, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on the byline link at the top of the page.



5/27/2015

Smart Meter

When we look at important issues facing our nation today, we inevitably find commercial interests influencing policy. Industries, understandably, are eager to advance their own agendas. Briefings and impact analyses presented to policymakers can be incomplete for this reason. They can tell a narrow, limited story to attract government support—whether for a contract, funding, or legislation. Unfortunately, important sides to the story that are highly relevant to quality of life in America are often left out.

This scenario is playing out today in the U.S. electricity sector, where federal spending to help the utility industry is having unintended negative consequences for our economy, privacy, the environment, safety, security and health, while stalling our transition to a renewable energy economy, with consequences of its own.

As was explained in the National Institute for Science, Law & Public Policy’s Getting Smarter About the Smart Grid report by Timothy Schoechle, PhD, the new meters help the utility industry’s bottom line, as by a law the utilities can charge ratepayers enough to recoup their investment, plus an additional a 10-13 percent return, depending on the state. But the billions spent on meters is wasting federal tax dollars, increasing ratepayer utility bills and, importantly, not delivering on the benefits claimed.

The ‘story’ about the value of the “smart” meters is that the meters are necessary to upgrade the electricity grid, that they have energy efficiency benefits, and that installing them will facilitate integration of renewable energy technologies. This is what communities across the country are being told. None of these claims are true.

Wasting billions of taxpayer money on unneeded new meters would have been bad enough if the meters had been safely hard-wired. But the meters are wireless, which means they come with additional risks, such as privacy, security, health, fire and safety risks. The former head of the CIA James Woolsey called the vulnerability of the new grid using wireless technology a “really, really stupid grid”. It is no wonder there are protests about the “smart” meters in dozens of states today. The award-winning film on this topic, Take Back Your Power, of which I was an Executive Producer, is a must-watch film to get up to speed on this whole topic.

There will be national economic consequences from propping up utilities set on resisting transformation to a renewable energy economy. As other countries race ahead to tap into the potential for clean energy abundance, our industries in the end will suffer in the global marketplace if the U.S. does not reconfigure its electricity system to embrace distributed, renewable energy and the rooftop revolution. 

More than likely, fortunately, as Tim Schoechle, PhD discusses in Getting Smarter About the Smart Grid, the revolution will happen from the bottom up through innovative communities moving to secure their renewable energy future, like Boulder, CO is doing. And, through innovative technologies, such as advances in storage.

Very recently, Tesla announced a battery for the home, the Powerwall, a leapfrog forward offering consumers the ability to store backup power, minimize peak time use of utilities’ electricity at high prices and even get off the power grid entirely.

Transformation of the electricity sector may be able to be delayed by wasting billions of federal tax dollars on unnecessary meters, and large long-distance transmission lines, but it cannot be stopped. It may be a politically rocky transition for the foreseeable future, but I am confident America will certainly achieve energy independence and clean energy abundance.

9 Problems with the Smart Meters and Present Electricity Approach

1. Data to be collected by the smart meters, including intimate personal details of citizens’ lives, is not necessary to the basic purpose of the smart grid, such as supply/demand balancing, demand response (DR), dynamic pricing, renewable integration, or local generation and storage, as promoters of the meters, and uninformed parties, routinely claim.

2. Federal, state and local governments have mistakenly believed that the installation of smart meters will somehow lead to reduction in use of fossil fuels, greater electricity efficiency and long-term energy economy benefits for the U.S. In fact, efforts to further develop and standardize those technologies that could achieve those goals have languished, while investments with stimulus funding have instead been made in technologies that merely serve the short-term economic interests of the utility industry and its suppliers instead of the interests of a true smart grid which could economically integrate renewable technologies and distributed, or decentralized, power generation.

3. Much of the multi-billion dollar federal subsidy for smart meters does not benefit ratepayers, nor support economic growth, but primarily benefits meter and meter networking manufacturers, while financially propping up unsustainable Investor-Owned Utilities (IOUs). Regulated utilities can charge back their capital investments to ratepayers, with a guaranteed 10-13 percent rate of return (ROR) on assets, by law. Thus, investors in utilities gain from the smart meter deployment, as they would from any other capital expenditure, while there is no clear gain and significant new risks (privacy, security, health & safety, costs) for the ratepayer. The allocation of stimulus dollars to subsidize smart meters has also been a net job destroyer, eliminating meter readers and creating manufacturing jobs overseas, while being an egregious waste of federal resources that only supports corporate interests and delays the needed transformation of the electricity grid.

4. Because Investor-Owned Utilities (IOUs) are paid on a per-kilowatt-of-energy-sold basis, and also receive a guaranteed rate of return on assets, they do not have a financial incentive to encourage less energy usage, or to invest in technologies that would help citizens reduce energy consumption.

5. Because coal plants must run at near capacity to achieve necessary economies of scale, adding renewable energy to the power mix may be in fact cost-additive for utilities, not cost-reducing, and ultimately cost-additive for ratepayers. Thus, there is an inherent conflict between coal-based power generation, the dominant means of electricity generation in the U.S., and a transition to renewable energy technologies that could lead to sustainability. The report recommends the U.S. “move away from dependency on baseload generation, particularly coal, as quickly as possible” to facilitate renewable integration and reach our potential for energy independence.

6. Despite paying lip service to the public’s interest in incorporating renewable energy, as evidence in their marketing materials, utilities actually ‘curtail’, or waste, much of the renewable energy now generated in order to protect the economics of investor-owned coal plants. This explains why state initiatives wanting to fulfill the promise of a 30 percent or higher renewable portfolio standard (RPS) is practically impossible in a coal baseload system. The paper suggests that decommissioning coal plants, possibly through a public bailout, may be required to move the United States to a renewable energy future.

7.  U.S. policy statements “reflect the mistaken belief that the basic solutions involve fixing or modernizing the existing electricity grid, rather than complete structural transformation of electrical service, which goes beyond particular ‘smart’ technologies.” In reality, shaving peak energy usage by shifting loads may actually increase energy bills as well as CO2 emissions by increasing dependency on coal baseload generation—the most expensive generation there is when considering the totality of subsidies and externalized costs. Increasing baseload dependency will not lower energy costs, as it appears our Administration believes, and it will further obstruct integration of renewable sources.

8.  Expected growth in electric vehicles within a coal-based system will only worsen the nation’s baseload dependency, thus making the needed shift away from coal to a renewable energy future that much more pressing.

9.  Leadership in the energy sector is unlikely to come from the top, due to conflicts of interest and ‘regulatory capture’ unless forced by a catastrophic event or consequence. At present, there appears to be little evidence utilities and their regulators want to or know how to make the needed changes to the utility business model, leaving it to the American public, through community-based initiatives and municipalization efforts, to drive the needed change toward renewable technologies and distributed, non-centralized power generation—as is now happening in such places as Boulder, Colorado.

When I learned billions of dollars were wasted on meters purporting to be “smart,” I realized how desperately we need accountability in Washington. The magnitude of the misspending is mind-boggling. I wonder how policymakers could not have understood the technology’s limitations. Did they just not do their homework, swayed by utility industry lobbyists? Did they not realize stimulus funding could have been better spent on other investments to move us forward faster toward a clean energy economy? Is there any mechanism at all in Washington to independently evaluate the impact of potential spending, and to make decisions strategically with long-term impacts in mind?

In the next blog post in The Wise Grid series, my colleague, Tim Schoechle, PhD will summarize his critique of the recent “Future of the Grid” report by the Department of Energy (DOE) and the Gridwise Alliance. Stay tuned!

All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Best Practices, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on the byline link at the top of the page.



5/26/2015

Turbulence is the enemy of small wind turbine productivity. By turbulence, we mean interruptions in the steady flow of wind to the turbine. What causes turbulence? Trees and buildings, mostly, but also anything else that stands close to the turbine and has the potential to block or redirect wind traveling toward the turbine.

The tower plays a big role in avoiding turbulence, primarily by getting the turbine well clear of all turbulence-causing elements. As a general rule, it’s best for a small turbine to be about 10 meters (~30 feet) above all trees, buildings and other structures. That’s where the “good wind” is going to be, and your wind turbine’s power production will be much higher as a result of getting into this altitude.

For small turbines, wind speed is generally best at 30 meters (about 100 feet). One reason this matters so much is that the power a small turbine generates is a cubed function of wind speed. In other words, an increase of wind speed from 10 to 20 mph results in 8 times the power production (2^3 = 8). That’s why it’s so beneficial to get to the good wind!

Therefore, it’s usually best for a small turbine to be mounted on a tower that’s anywhere from 40 feet to 100 feet tall. There are of course outlying situations: In some cases, a turbine could be at 150 feet atop a lattice tower, if the owner has access to such a tower.

Steel turbine towers are usually found in two main varieties: Guyed and monopole. Guyed towers are held in place by four sets of guy wires extending from the tower’s sections to anchors set in the ground away from the base of the tower. The math for where to anchor the guy wires is simple. The formula, where n is the distance from the base to the anchor, is:

n = h/2

...where “h” is the height of the tower. So, for a 100 foot tower, the distance from the base to the anchors should be 50 feet.

Wind turbine owners who don’t want guy wires can opt for a more expensive monopole solution. This tower stands independent of any wires for a cleaner look and more access to the ground surrounding it.

To make installation and servicing easier, many small wind turbines are installed on tilt-up towers. Both guyed and monopole towers can be set up as tilt-up towers. This means that the tower is affixed to a hingeplate at its base, which has a length of pipe called a gin pole protruding at a 90 degree angle from the tower. Installers attach a winch to the gin pole and crank the tower up and down when needed.

Simple? Yes, but it’s still a careful process requiring knowledgeable installers who understand tower physics. Counter-tension, a solid, level base and proper anchoring are all critical factors in a plumbed, happy tower.

When you’re planning for your small wind turbine, consider your tower options. Again, you’ll want to be 30 feet clear of obstacles, so height is a prime factor. If you’re opting for a guyed tower, make sure you have enough cleared land to allow for the radius of the tower anchors.

The next and final part of this series will relate what we’ve learned about small wind turbines to the concept of the smart home microgrid.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Best Practices, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on the byline link at the top of the page.



5/21/2015

small wind turbine diagram

HAWT and VAWT 

Small wind turbines occupy two main families: Horizontal-axis wind turbines (HAWTs), which comprise the vast majority of all small wind turbines, and vertical-axis wind turbines (VAWTs), which comprise a far smaller group. For the most part, people looking for a small wind turbine for their property will be reviewing their options in the HAWT family.

Upwind and Downwind

HAWT turbines have two primary subclasses: Upwind and downwind turbines. A downwind turbine has no tail and the wind blows into it from behind. Upwind turbines have tails, and they face into the wind.

Upwind turbines have the benefit of increased wind responsiveness. That is, they respond to wind direction and maximize the potential of the wind’s speed and power. Additionally, they tend to be quieter than downwind turbines; as the wind is hitting the blades first, the resonant sound is typically a white noise, rather than a strobing or chopping sound that can result from a downwind turbine, in which the wind hits the tower before hitting the blades.

Blades and rotor hub

Most small HAWT turbines use a three-blade design. The blades are affixed to a central assembly called the rotor hub. The rotor hub serves two functions: It holds the blades together, and it attaches to the spindle that drives the alternator.

Alternator

The alternator is the key mechanical element of the turbine, and it’s what generates electricity as the blades spin. It is housed inside the nacelle of the turbine.

Nacelle

The turbine’s nacelle is the body of the turbine that is connected at its front to the blades and rotor hub, at is base to the yaw assembly, and at its rear to the tail assembly (for an upwind turbine). The nacelle for large industrial wind turbines is the housing for the gear box and all other major power components of the machine. For a small wind turbine, the nacelle can house very few electronics in some cases, or much more circuitry in others.

Yaw assembly

If you’ve ever learned about aviation, you’ll recall that yaw is the pivoting action of the aircraft on a horizontal plane, left to right. Similarly, a wind turbine’s yaw is its horizontal planing motion. The yaw assembly attaches the nacelle to the tower while allowing the turbine to spin freely about the horizontal plane.

Tail assembly and vanes

Upwind turbines feature a tail assembly that includes tail vanes, which keep the turbine’s blades faced into headwinds.

Inverters and charge controllers

A home wind turbine won’t do much for you if you don’t connect it to anything. Like solar arrays, small wind turbines connect to inverters, and in the case of off-grid or battery-backup homes, battery charge controllers. These typically house the system electronics that let you retrieve, store, and output energy as needed, whether to your appliances, your battery bank or out to the grid.

In our next episode, we’ll get into the nitty-gritty on a major home wind turbine system component: The tower.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Best Practices, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on the byline link at the top of the page.



5/11/2015

In our first installment, we covered the basics of electricity generation and the process by which a wind turbine creates power. This time, we’ll look at the benefits of adding a wind turbine as a source of clean power for your home.

If there’s one core aspect of wind turbines that makes them a smart option for clean power, it’s that the wind is always doing its thing. It doesn’t “set” at night, and it doesn’t follow strict seasonality. And just like solar power, it doesn’t require any industrial activity to be brought to a level at which homes can use it. The wind is there, and a wind turbine can tap it in the same way a solar panel taps the sun for power. But wind’s real advantage is in those off-hours, when the panels go dark, but the turbine keeps spinning.

For this reason primarily, a wind turbine makes an outstanding complementary energy source when it’s working in concert with solar panels. Owners of these “hybrid” systems know the beauty of looking outside on a sunny, windy day.

This benefit is even more underscored for homes that aren’t connected to any utility. Off-grid homes use battery banks to store energy that they’ll need at night or during dark, rainy days when solar isn’t getting the job done. Off-gridders with wind turbines get the bonus feature of having a constant battery charging source. It’s a better night’s sleep when you know your batteries are staying full while the wind blows your turbine.

Beyond off-hour power and constant battery charging, small wind turbines provide a big benefit to homes that rely on backup generators as a source of energy. You don’t have to be living off-grid to have a very real need for a backup gas generator. Despite our advancements here in the technology age, there remain parts of the United States in which the grid is unreliable, prohibitively expensive, prone to extended outages, or all of the above. The home wind turbine provides energy security and reliability for people living in these regions. If a powerful storm blankets your solar panels in snow and knocks out your power lines, wouldn’t it be nice to use those wind gusts to a productive end? It’s certainly nicer than paying $1 per kilowatt-hour for a gas generator to run.

In review, the primary, basic benefits of home wind turbines are:

• Maximizing home energy production in areas that have windy climates
• Supplementing solar by generating more power at night, during storms, and winter months
• Enhanced battery charging efficiency for off-grid and battery-backup homes
• Cost control and protection from variable utility rates
• Energy security and reliability in areas with poor grid performance
• A clean, affordable alternative to running a backup gas generator

In our next episode, we’ll run through turbine terminology to make sure that when you’re talking about small wind, you’re talking like a pro.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Best Practices, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on the byline link at the top of the page.









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