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Offshore wind turbines. Photo by Fotolia/MichaelRosskothen

Reposted with permission by the U.S. Department of Energy.

The Energy Department today recognized the nation’s first grid-connected offshore floating wind turbine prototype off the coast of Castine, Maine. Led by the University of Maine, this project represents the first concrete-composite floating platform wind turbine to be deployed in the world – strengthening American leadership in innovative clean energy technologies that diversify the nation’s energy mix with more clean, domestic energy sources.

“Developing America’s vast renewable energy resources is an important part of the Energy Department’s all-of-the-above strategy to pave the way to a cleaner and more diverse domestic energy portfolio,” said Jose Zayas, director of the Energy Department’s Wind and Water Power Technologies Office. “The Castine offshore wind project represents a critical investment to ensure America leads in this fast-growing global industry, helping to bring tremendous untapped energy resources to market and create new jobs across the country.”

Offshore wind represents a large, untapped energy resource for the United States, offering over 4,000 gigawatts of clean, domestic energy potential – four times the nation’s current total generation capacity. According to a recent report commissioned by the Energy Department, a U.S. offshore wind industry that takes advantage of this abundant domestic resource could support up to 200,000 manufacturing, construction, operation and supply chain jobs across the country and drive over $70 billion in annual investments by 2030. In Maine, as with many other areas off U.S. coasts, the bulk of this clean, renewable energy resource lies in deeper waters where conventional turbine technology is not practical. Innovative floating offshore wind turbines, like the one launched today, will open up new economic and energy opportunities for the country.

With the support of a $12 million Energy Department investment over five years, University of Maine and its project partners conducted extensive design, engineering and testing of floating offshore wind turbines, followed by the construction and deployment of its 65-foot-tall VolturnUS prototype. At 1:8th the scale of a commercial installation, this project will collect data to validate and improve floating wind turbine designs, while helping to address technical barriers to greater offshore wind cost reductions.

The University of Maine design uses advanced materials that help reduce the overall cost of the system while ensuring high performance and efficiency. For example, the floating wind turbine features a unique semi-submersible platform that uses a lower cost concrete foundation in addition to a lighter weight composite tower. As part of the five-year project, the Maine Maritime Academy helped test and conduct analysis on these pioneering designs, while Pittsfield, Maine-based Cianbro Corporation leveraged its experience in maritime energy infrastructure and ship building to construct this first-of-its-kind wind energy system.

As part of a separate project, the University of Maine is planning a larger offshore wind demonstration called Aqua Ventus I – one of seven offshore wind design and engineering projects announced last year by the Energy Department. Upon completion of the engineering and design phase, the Department intends to select up to three projects for additional funding in 2014 to support construction and installation.

Find more information on the Energy Department’s broader efforts to grow America’s wind energy industry at

Photo by Fotolia/Michael Rosskothen


This article is published with permission from the University of Washington's Conservation Magazine.

People living near wind farms have complained of headaches, dizziness, and other health problems. Now researchers have found that simply watching videos about these complaints is enough to make others report the same symptoms. (Hat tip: Slate.)

Many residents have fought wind farm development because they worry that sound from the turbines will make them sick. Turbines produce low-frequency sound that isn’t audible to humans, called infrasound. But scientists haven’t found a plausible way that infrasound could cause the symptoms people describe.wind farm

The authors tested whether people might be influenced by the widespread reports of wind farm-related health complaints on the Internet. The team told 54 college students that they were being exposed to infrasound for two 10-minute sessions. During one session, the researchers were indeed transmitting infrasound. But the other session was a sham treatment; no sound was actually transmitted.

One group of students watched a video of people describing symptoms that were blamed on wind farms. The other group watched a video of scientists saying that wind turbine infrasound didn’t cause illness. During the infrasound and sham infrasound sessions, the students reported whether they experienced symptoms such as headaches, itchiness, and nausea.

Students who watched the video of health complaints reported more symptoms and more intense symptoms during the exposure sessions than the other group did, the team found. Their symptom scores increased regardless of whether they were being exposed to infrasound or the sham treatment, “confirming that infrasound exposure itself did not contribute to the symptomatic experience,” the authors note in Health Psychology.

The results suggest that Internet reports of wind farm-related health problems could make other people more likely to report the same symptoms. Some people have suggested keeping wind turbines farther away from residents, the team writes, but such efforts “may do little to alleviate health complaints and related opposition to wind farm development.”

Photo by fotolia/Edelweiss


This post is a follow-up to five others I have done on Cuba and Vermont, Perspectives on Energy and Culture: Part 1Part 2Part 3, Part 4, and Part 5 - about my visit to Cuba with a delegation of energy industry professionals, and a Cuban colleague’s visit to Vermont where I developed a similar tour. Learn more in The Homeowner's Energy Handbook!

Jasper Hill

Jasper Hill Farm is a clandestine world treasure that you could drive right by even if you had a map and GPS (forget about cell service here). This is a success story of two brothers who started with 40 dairy cows and went on to win the title of “World's Best Unpasteurized Cheese" for their Bayley Hazen Blue at the 2014 World Cheese Awards in London. Here you can see the entire process of making cheese from grass to cow to milk to cheese. The crew constructed underground cheese aging caves where each cave is specifically controlled for environment and inoculated with the right culture.

They didn’t stop at great cheese though; Andy and Mateo are working to close the loop from food to energy by converting the farm’s waste products to energy in their Green Machine. Cow manure is separated into liquids and solids. The solids are composted, the heat generated from decomposition is used to heat the green house, and composted manure fertilizes the soil. The liquids are combined with waste whey from the cheese making process and put into an anaerobic digester to produce methane gas that is burned to heat water. On this record breaking day of cold, we also enjoyed fresh greens from the greenhouse which gains heat from both the sun and from the manure composting on the other side of a mass wall that stores and re-distributes the absorbed heat.

That night at dinner Mario said “I’m worried that I’m not sweating. It’s bad for the skin.” Another hidden-in-plain-sight difference in what’s engrained in us as ‘normal’. When I was in Cuba, I didn’t stop sweating and I found it annoying and uncomfortable.

“You are sweating” we told him. “You just don’t feel it because the air is so dry in the winter that sweat evaporates before it has a chance to bead up.” I was reminded of my southern California cousins who came to live in New York City for a summer. They never sweat in their home climate and were uncomfortable and embarrassed at how they were constantly sweating in the unfamiliar east coast humidity. 

Unnatural Timekeeper

Friday, our last day together, would be a long one. After an extended breakfast conversation came the ‘ridiculous’ process of dressing for winter. We were late before we left and this day was already over-planned. I wanted to do it all! I don’t know how I ended up as a tour guide and event planner, I’m usually the one who’s late for everything and now I find myself in the unnatural role of timekeeper and whip cracker. I was very aware of taking up people’s time during their workday, and was continuously surprised at their understanding welcome despite our consistent lateness. I wondered why we do it. Our lives are so busy, bills keep coming in, clients are waiting, and nobody stood to earn anything from our visits. As an introvert, I know I have shortcomings around social graces, but I was getting an education in building a social economy of my own, learning from the grace of both my guest and our hosts.

Better World Workshop

On the way to The Better World Workshop in Bradford VT I took a wrong turn on a dirt road. Ahead was a hitchhiker and Mario asked if lots of people hitch rides here. “Maybe not as much as they once did.” I replied. “In Cuba, everybody hitches a ride and everybody picks up riders, all the time, every day.” I recalled that our tour busses and taxis in Cuba were always stopping to pick people up. We picked up the rider who set us down the right road to Bradford.

Engineer Carl Bielenberg has been developing biomass based renewable energy systems for nearly thirty years. At the Better World Workshop, he is currently developing a small biomass gasification system for rural villages in developing countries called the Village Industrial Power (VIP) generator. Gasification is the process of heating biomass to combustible temperatures and controlling the air to the combustion chamber so that the material doesn’t burst into flames. Controlling combustion in this way allows for an extremely clean, efficient, smoke-free source of heat. The VIP burns a variety of biomass types ranging from wood to corn, or even nut hulls, making it a versatile power producer in almost any region of the world. The heat produced is used to operate a simple steam engine that powers a 10,000 watt electrical generator, while waste heat is used to heat water.

South of Bradford, and on the way to our next stop, is the King Arthur Flour baking center in Norwich Vermont where we enjoyed a delicious lunch from their café. As we pulled into the parking space he asked "What is that noise? It sounds like it's coming from the car." I sighed inside, because I hadn't told him that the car had suddenly lost power and the engine light was on. Not hearing anything unusual, I asked him what it sounded like. "A squeaking sound." All I had to offer was an unknowing shrug and sighed to myself. Walking across the parking lot after lunch we stopped to wait as a car backed out of its spot. "That's the sound I heard!" he exclaimed, pointing at the front tire. It was the sound a tire makes as it slowly rolls over fresh snow. We both laughed, but I still didn't know why the engine light was on. While he was busy talking to Carl about the VIP I slipped out to get the error code off my OBDC scanner. Vague as usual. Was it the $25 fix or the $900 fix? In the end, it was right in the middle. With 230k miles on my VW Jetta TDI, repairs are inevitable, but the maintenance cost is still less than new car payments.

Next week, final installment: The Energy Innovation Center and Mario’s message.

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.


When last we left you, I was talking about my friend from Sri Lanka, and the prospect of helping the poor in that country— and worldwide— through low-cost biogas. (And my apologies for the radio silence: I’ve been busy…)

Ideals are important, to be sure. And some say that we are either idealistic or realistic, as if becoming aware of injustice somehow necessarily prevents us from addressing it. But at least in my experience, that’s just not the way the world works. Just look around: there are a fair number of people who are both idealistic and realistic: but we could always use many more.

No doubt talk is cheap, and many things are difficult. That means that whether our goals are noble or selfish, failure to achieve those goals is not uncommon. But hey: Surely it’s better to fail when trying to help people escape poverty than it is to fail to add another zero to our personal wealth, no? (The zero is supposed to go on the right-hand end of the number, for any who were unsure…)

My father taught me a lot about how to find ways to have high ideals and achieve goals. (He invented the cochlear implant, if anyone can be said to have done so. Dr. William House: you could look it up.) And after all, I reasoned (underneath my gray hair), I’ve done my service to capitalism, established a strong marriage, raised a family and launched them into their amazing success stories (and they are amazing; just ask me)… So what was preventing me from trying for this brass ring— helping the poor worldwide— except a desire to sleep late on Sunday?

Well naturally then when my friend from Sri Lanka woke me up to the potentials of biogas for global benefit, I began to pursue this dream of helping many, many others, with limited resources and all by myself. How does one do that in a practical, step-by-step, realistic manner?

Well, you won’t be surprised if I tell you that thus far, it’s fair to say that what I’ve tried has met with limited apparent success. I won’t bore you with all the messy details, but let me give you a sketch.

I first tried a very conventional approach, developing a darn spiffy, multi-page, gee-whiz spreadsheet, a timeline and other accoutrements, and using these to pursue grants. But after shopping it around and doing the standard hey-there-fund-this-grant two-step, I was left with the feeling that I was standing on a field— along with 10,000 other folks— where all of us were waving our particular fistful of paper about our particular Good Idea, trying to gain some funding, then maybe some attention. Up close maybe you could hear one of us. From a few yards further away, where I imagined the closest grantors were standing, it would have been just sort of a lot of noise.

The experiences left me with the thought that, well, this would be a lot easier if I was able to get the attention first; the funding will follow. So I began to plan and build a solar-heated greenhouse with some fairly revolutionary features, intended to house a 10-cubic-meter digester fed entirely with food waste from a local restaurant. I got some modest funding from a few good friends, developed the design, spent months going up and down a ladder, and gradually the thing began to take shape. Here was to be something that people could point cameras at, to come and watch biogas in action.

Then, months into the build, a huge winter storm came through and brought it all down. Wham. Flat. Kindling. I had neither the heart nor the funds to start such a large project again…

Meanwhile, I had developed a small, very cheap digester suited to the tropics and intended to be manufactured in quantity. Materials cost? $10.

Now, I happen to know something about design and manufacturing because of my past work experience, and I knew that for something like a digester-for-the-poor— which is supposed to work well where every floor is a dirt floor— one crucial design process is to have people bang on the thing and try to break it. It should be reasonably sturdy, right?

So to provide funding for efforts to improve the design, to get the designs out and about and under stress, and to begin the process of gaining attention, I decided to start teaching workshops about biogas, capped with a half-day segment where we would all manufacture these low-cost digesters from kits and parts.

That went very well. I love to gab and I had something useful to say. My dear friends Tim and Suzanne of Friendly Aquaponics invited me to come to Hawaii and teach, I got invited to Australia, and the National Center for Appropriate Technology organized a workshop in Iowa, just to mention a few. From California to upstate New York, groups of charged-up folks had a good time and learned all about biogas. And they loved it, at least according to the evaluation forms I gathered from each class.

The favorite part of these workshops for most of the participants, it seemed, was building those low-cost tropical digesters. But at the same time, that was also the key problem, that little word there: “tropical”. The information was good, the folks were enthusiastic, the workshop was humming and the digesters were… tropical. In Iowa there was snow on the ground. In New York, it was early spring. Too cold. Even in Hawaii, perhaps surprisingly: it was too cold almost everywhere.

Then this last spring I was invited to do a workshop in Brooklyn, and as I was doing the work to prepare for it, I gradually came to realize two things. The first was that these workshops, as popular and fun as they were, were not going to get me close enough to the brass ring. It was a great job description to add to a number of others, like “scriptwriter” that I had accumulated— “Biogas workshop leader”— but all by themselves, these get-togethers probably weren’t going to get me to Sri Lanka, organizing the manufacture and distribution of many thousands of digesters.

It hit me: I had given a lot of thought to low-cost, practical, tropical digesters, but I hadn’t thought at all about digesters that would work in Burbank, upstate New York, or Iowa in the winter during a hard freeze: That is, almost anywhere on this continental land mass here that I’m sitting on just now.

The good news, as I came gradually to realize, was that all the design ideas and testing, all the invention of manufacturing equipment that I had undertaken in my quest for tropical, could help me— it could help you, come to think of it— to produce that utterly rare creature: A low-cost, well-designed, small biogas digester that will work profitably here, where tropical is a travel brochure, not a weather pattern.

The key ideas, as it turned out, were pretty simple. What I knew was that if I took two sheets of plastic and carefully pressed them— compressed them— together along a line, say with a couple of 2-by-4s and a bit of weather-stripping, nothing would leak through that line: not liquid, and not gas (at least not at low pressures). So in fact, with a bit of ingenuity and modest folding, I could create a water- and gas-tight container out of plastic sheets pressed into place by rigid pink polystyrene foam insulating boards, held in place by plywood. The polysty would provide good insulation. I knew from my experiments how to create a very cheap, very strong bung— a pipe-hole through the wall— and that’s all anyone really needs: A tight box with some pipes, minimum three: a slurry inlet, an effluent outlet, and a gas collection pipe.

And that’s it right there, really. That’s an entirely new design for a biogas digester which is cheap and well-insulated: the grail. And for the next many posts in this blog, that’s what I’m going to tell you, in some detail, how to make.

It will take more than a few posts and therefore some time, because there’s only so much you can say in a 1,000 words or so, even with pictures to multiply the syllable count. If you want to learn much more, a lot more quickly, then you are welcome to attend the next Beginner’s Biogas Workshop, which will be held in Washington DC in mid-April. (Read the details.) There and then, we will be revealing all. (Well, almost all. But in any case, enough.)

And if you can’t make it there, then no worries. There will be more workshops (sign up to be notified on the TCBH site), and whether or not it's practical for you to attend a workshop, keep reading the blog and I’ll tell you everything I can.

Here’s my hope, finally. This isn’t just about providing practical, cheap, small biogas to a small set of dedicated crazies in the US. I firmly believe that this effort can help catalyze greater use of wasted food in this lovely, forgetful-of-its-high-ideals nation, and that in turn, it is my fond hope, can have a measurable impact on the release of climate changing ‘wild’ methane from out of landfills. (Food wasted around the world produces as much greenhouse gas as all the annual emissions of the entire country of India, the third largest GHG emittter! And if we can reduce methane emissions, according to the New Scientist magazine, we can delay the impacts of climate change by 15 years... Hey: that's worth doing, right?)

Then finally, if I can create enough excitement and pay down my mortgage from these efforts, I’ll bet I can take it all the way to Sri Lanka. What do you think? What are my chances?

Keep reading, and we’ll both find out.

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.


solar powerEnergy is expensive. Thanks to the laws of thermodynamics, it’s just not possible to get more energy out of a system than you put in. Thus, when it comes to generating power, you’ll always be stuck with a bad investment. However, there is a bit of a work around to this problem. See, if you can get someone or something else to supply the initial energy for you, then you can reap the rewards without having to worry about the cost. And while that may not sound very honest, it is in fact the basic idea behind solar power.

See, the sun does all the work, crushing hydrogen atoms together and flinging the resultant energy out into space. All we have to do is figure out a way to harness it when it reaches earth.

Of course, that’s not to say that harnessing solar energy is easy. In order for us to be able to convert it into useable electricity, humanity first had to discover the photoelectric effect. See, when sunlight hits an object, the energy that it carries has to go somewhere. Some of it is reflected, but the majority of the energy is bled off as heat. However, certain materials allow for a third option. Silicon, for example, is a semiconductor, which means that the electrons contained inside it tend to get excited and move around when exposed to direct sunlight. This is known as the photoelectric effect. These electrons generate an electrical current, which can be captured and utilized.

This was first discovered in 1876 by William Grylls Adams and Richard Day, but it wasn’t until 1953 that Calvin Fuller, Gerald Pearson, and Daryl Chapin developed an efficient enough solar cell to actually be able to run small electrical devices from the power it produced. Within a few years, solar power began to be heavily used by both American and Soviet space programs.

Today, solar power is viewed as one of the most promising alternate energy sources available. After all, sunlight is free and abundant all over the world, and will continue to be so until the sun burns itself out in a few billion years from now.

As such, the solar industry is booming. In 2012, the solar industry grew a whopping 76%, and now supplies the United States with 3,133 megawatts of clean energy. This is, in part, thanks to growing concern over the environmental damage caused by the processes used to generate conventional power, as well as issues regarding the lack of coal and fossil fuel renewability.

The people are becoming interested in solar power, and the industry is answering them with exciting advances. The production of new, less expensive crystalline silicon panels, as well as advances in paper-thin solar cells, is making the once expensive panel production process more and more affordable. At the same time, home automation companies, such as Vivint are offering rentable solar power systems, which allow consumers to save on energy costs without having to worry about installation or maintenance.

As for what we can expect in the future, well, there has been a great deal of talk surrounding the possibility of double-sided solar panels. When strategically placed (as in such a way that allows it to capture sunlight both in the morning as well as in the afternoon, or on reflective surfaces that can pick up extra light that is being bounced back), these panels could possibly double the energy output of traditional single-sided panels. And if the United States wants to meet all of its energy requirements, it’s going to need much more solar paneling to do so. Some have discussed the possibility of replacing asphalt with durable solar panels across the country, and there is even some interest in placing a solar ring around the moon’s equator to “beam” energy back to earth.

Solar power is probably the best chance we have at creating a sustainable, efficient, and clean energy source. However, we still have a long way to go before we can all get our electricity from the sun. Still, with current advances pointing us in ever more promising directions, we may someday be able to run all of our machinery and electronics with nothing more than a stray sunbeam.

Feeding an ARTI-style digester with a floating gas holder

Cliff hanger, right? We told you there was a gold mine in back of your local restaurant in part one of this subject series (here), and we waved somewhere toward the direction of using the “found energy” tied up in the carbon bonds of that wasted food for this and that. (We mentioned cooking with that energy, for example.)

So the question is: How? How can we make the energy which is potentially available in food waste into usable energy? Let’s see….

In the developing world, many things happen at the village or household scale. If we cook our own meals using wood that we’ve gone into the forest and gathered, that is a system that has a household scale. (And it would please Thoreau, eh? Wood fire warms you twice, he said.)

But virtually all our systems in the US are industrial scale (that is, Big), including our energy systems (consider those long electric lines on towers marching along the freeway) and this includes the scale at which we waste food. Studies (such as this NRDC study) show that not quite half the food we produce in the US is thrown away.

From the NRDC study:

“Getting food from the farm to our fork eats up 10 percent of the total U.S. energy budget, uses 50 percent of U.S. land, and swallows 80 percent of all freshwater consumed in the United States. Yet 40 percent of food in the United States today goes uneaten. This not only means that Americans are throwing out the equivalent of $165 billion each year, but also that the uneaten food ends up rotting in landfills as the single largest component of U.S. municipal solid waste where it accounts for a large portion of U.S. methane emissions. Reducing food losses by just 15 percent would be enough food to feed more than 25 million Americans every year at a time when one in six Americans lack a secure supply of food….”

[Given the population of the US, ‘one in six Americans’ is about 50 million people.]

Now even given that almost all of our energy systems exist at an industrial scale, there are some circumstances where smaller scale energy production makes sense: a farm, a homestead; the kind of place you have now, or (since you are reading this) the kind of place you may want to have, someday soon. For those situations, a local energy system providing all or some of your energy may make sense.

And in planning for that local situation, your situation, one of the first things you need to consider is matching needs to energy sources. Wind can be a great source of (intermittent) electricity. Direct solar is also good for electricity (PV), for space heating and hot water. But cooking presents a modest challenge for those two common local energy sources. You can make a solar oven— it’s pretty easy, really— but (begging the forgiveness of the solar gods) most solar ovens are kind of bulky and clumsy, don’t you think?

So here’s a twist: how about using wasted food to supply all of your cooking needs, and to supplement your space heating, or even hot water supply?

And how can you do that? (Gee. Somehow biogas comes to mind….)

Homemade Biogas

The short story is:

Start with a container. It doesn’t have to be strong, but it has to hold liquid, and gas at very modest pressures. The container can be steel, concrete, plastic or made of any other suitable material, with few exceptions. (Toxic stuff is not good; the biogas biology is sensitive.)

Get some organic material, of the kind we might use in making a compost pile. (Not woody stuff, but almost anything else. Food waste makes great biogas.)

Keep it wet, keep it warm, keep it pH-balanced, and very shortly, by a process that is natural, very ancient, and which may seem a bit magical (hey presto!) a burnable gas— biogas, made almost entirely from methane and carbon dioxide— will bubble out. (And just to clarify: methane is the main molecule in natural gas, the fossil fuel that is getting so much press nowadays because of fracking. Biogas gives you methane without the fracking. And it can even shrink your carbon footprint.)

There’s nothing else that’s essential, although lot’s more can be said about it. It really does not get any simpler for any kind of renewable energy use, except maybe standing in the sun to get warm, or burning wood. (Or eating. Definitely eating.)

It really is simple. Honestly. In fact, would you like some free plans for building any of four of the most common kinds of digesters? Then visit the free plans for biogas digesters page on the Complete Biogas website….

Of course, what you get out of your digester will be determined by what you put in. It has to be sized properly— and again, again, again, kept warm— but all else being equal, the more you feed it, the more gas will be produced.

Realizing this, you may well want to ask: How much food waste should I put in the digester? And what size should that digester be so that I can cook my meals, and get light in the evening?

And booyah, while we’re at it: How about the holy grail of biogas? Can I run my car on biogas?

Well, friends…. That’s all going to be discussed in the next blog… Keep reading.

A biogas plant installed at a house in Coimbatore, Tamil Nadu. Photo: S. Siva Saravanan” Or one might say: Feeding an ARTI-style digester with a floating gas holder.

Source: The Hindu (newspaper), “Cost effective green fuel for the kitchen


In the previous two blogs of this series of three (Part 1, Part 2), I discussed the concept of passive solar architectural design, the potential for system autonomy, solar electric on-grid power and the way a heat pump works. This blog is about putting these together with a way of controlling their interface to achieve stand-alone heating and cooling systems that are powered by the sun and take energy from the earth or atmosphere, and that working with the patterns of nature approximate perpetual motion. As long as the earth circles the sun this type of system will continuously function within the lifetime of the equipment.

A system that is properly designed will heat and cool a house year around without requiring additional auxiliary heating or cooling. When a ground source heat pump system is coupled with a solar electric photovoltaic system for powering the unit, we create a closed loop operating system that does not need imported, or off site energy to operate. A heat pump can deliver hot or cold water or air to the house by using heat exchange devices; which means it can be used to: provide hot water for radiantly heated floors and domestic hot water, (one of my clients is using a system like this to melt ice off the driveway in winter), cool water or air, or heat a spa or swimming pool. It is best to use a system year around for both heating and cooling to optimize return on the investment. Heat pumps are not the cheapest first cost type of space conditioning systems, but in the long run they are the most cost effective when compared to standard fossil fuel heating or cooling methods.

When a combined photovoltaic powered ground source heat pump installation is activated by a control system that senses the passive solar heat gain to the house, total automated comfort can be achieved. Sophisticated controls can use mean-radiant temperature sensors, differential temperature reading thermostats, and even microprocessors to manage the delivery of heat and cold to different parts of the house. For example in a space heated by a radiant floor if the sun starts shining into the room adding passive solar gain, a mean radiant temperature sensing thermostat will quickly shut off the hydronic delivery to the space to keep it from overheating, automated ceiling or duct fans can be used to further move heated air to remote parts of the house effectively balancing the heat comfort of the entire house.

differential controller

To see a larger version of this image, click here.

Smart microprocessors with memory capability can anticipate outside sun/temperature affecting the weather skin of the house to allow delivery routines to respond to near future space conditioning needs. These same devices can be set to vary the temperature of various spaces, or zone control, giving custom heating/cooling options to provide better comfort and energy management. For instance the temperature in a bathroom can be reduced at night to save energy when unoccupied, but be programmed to either sense occupancy, or go on at predetermined times such as warming the space in the morning before you rise, or even heating the shower floor and towel bar before you take your normal shower. The limitations are our imaginations.

These developments in technology are available now and will become commonly used in the future as our conventional energy resources become more expensive. Tapping directly into the sun and the earth’s crust, to power and regulate the comfort of buildings, is making good advantage of Mother Earth’s potential. Designing towards a perpetual motion machine is what I consider to be the natural pathway to true sustainability.

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