Renewable Energy

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infrared image of a cooked turkey

You know that warm, cozy, sleepy feeling you get after an over-sized meal shared with too many friends and family to fit around a single table? It's some gossip to share in the kitchen, but I will never know the truth of it. My compulsion is to doze off on the couch between two over-stuffed uncles watching the game, where I’m lulled into the safety of sleep by vague murmurs and laughter from the kitchen and the drone of the TV. The post-holiday dinner coma is a comforting part of a familiar holiday tradition. What could possibly be wrong?

Indoor Air Quality

When I do home energy inspections, one of the things I investigate is the air quality inside the home. This involves testing for carbon monoxide (CO), relative humidity (RH), and carbon dioxide (CO2). CO is produced when fuels are not completely burned. A concentration of 0.01 percent CO in air is harmful to humans and 0.3 percent is deadly within minutes. RH is a measure of how much moisture is in the air. RH affects our comfort, but too much moisture in the wrong place can lead to mold growth, which also affects our health. CO2 is a normal result of fuel combustion, and is also a byproduct of our own respiration. CO2 concentration in outdoor air is about 0.04 percent, and the air we exhale contains about 4 percent CO2. These are pretty small numbers, but incredibly important ones if we’d like to stay alive and healthy.

Telaire CO2 meter 

Breathing 101

Humans need air that contains at least 20 percent oxygen. Lucky for us, nature has provided us with 21 percent. The main ingredient in air (78 percent) is nitrogen, and the remaining 1 percent is spice in the soup. Mess with the spice, and you ruin the entire meal! The mechanism for removing excess nitrogen from our bodies is through urine, but there is no such efficient biological mechanism for removing most airborne poisons that may be contained in that surprisingly important 1 percent. When CO2 concentration in the air we inhale reaches about 0.12 percent, many of us will start to feel sleepy and maybe head-achy. Not a health risk, but you won’t be functioning at your best. I’ve measured CO2 levels in meeting rooms and school classrooms in excess of .3 percent, eight times higher than normal! Ever wonder why some meetings put you to sleep? Or why your kids are wet noodles when they come home from school? It might not be the presenter’s fault, open a window and let in some fresh air!

The Food Coma

What does all this have to do with your holiday meal? During one family thanksgiving gathering, I got out my CO2 meter to test the air while dinner cooked in the gas oven. The CO2 level in the house quickly shot up to over .15 percent, so we turned on the bathroom exhaust fan. It helped a little, but not much. We needed a large range hood, vented to outside to make a real difference. The CO2 level was closing in on .2 percent and yawns were exchanged by all. Two windows were opened to allow cross ventilation, and within minutes the CO2 levels dropped. But that was just phase one. Cooking complete, windows closed, and fifteen people all exhaling in the dining room meant that CO2 began to rise again. We’ve always blamed the amino acid tryptophan, present in many foods, but I realize now that all those holiday meals at grandma’s house were accompanied by an invisible and unknown poison that put us all to sleep. We were all lethargic from poor indoor air quality, and all we could really manage to do in that environment was watch TV.

A Delicate Mix

The air we breathe is a delicate mix that is easily thrown off balance. Very small changes in its composition can dramatically affect our health, how we think, feel, and behave. Global warming aside, atmospheric CO2 is a pollutant, levels are rising, and our bodies are reacting along with the planet. We are like lobsters that have been thrown into a pot of cold water on the stove top. The heat is on, and we can feel something slowly changing. How long before we start clamoring to get out of the pot?

Get Efficient, Stay Healthy

This year, do your part to keep the flame on the lobster pot low! Check out the Homeowner’s Energy Handbook for ideas. As you tighten up your home for energy efficiency, don’t forget to add a ventilation system for fresh air. Meanwhile, do yourself and your guests a favor by opening a window or two while you’re cooking and entertaining. You’ll be glad you did, and I bet it will lead to more engaging time spent with family and friends.

Paul Scheckel is the author of "The Homeowner's Energy Handbook" and The Home Energy Diet

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.


Save Nature

There were high hopes for green energy when President Obama submitted his 2015 budget to Congress. The highlights of that budget included a $3.9-trillion proposal for investments in renewable energy and a commitment to focusing more on green technology — and less on older energy-intensive industries that produce significant carbon emissions.

Despite that the plan included a phase-out of the 2006 Investment Tax Credit for solar energy, which had helped grow solar energy capacity 20-fold in 7 years, it was still an ambitious prescription for advancing green energy in America. The President and Congress instead settled on a Continuing Resolution to fund the U.S. government through the end of 2014. We’ll have to wait to see what the new Congress and the President will be able to negotiate to facilitate green energy in 2015.

In the meantime, the private sector remains the main driver of current trends in green energy. More plainly, it means that economic decisions that consumers make are going to determine the likely success and failure of various advances in green technology.

Here are three consumer-driven green energy trends which have a direct impact on our pocketbooks.

1. Net-Zero Homes

Homebuyers are now emphasizing a home’s energy efficiency when looking for their next purchase. In a recent National Association of Home Builders survey, 94 percent of respondents said that Energy Star rated appliances were either essential or desirable, and 91 percent of respondents had the same view for the Energy Star rating of the entire home.

In response, home builders are focusing on “net-zero” buildings, which consume only as much energy as can be produced on site. If additional energy can be created and returned to the grid, that’s even better. To help meet this goal, active controls on solar panels and skylights are gaining attention. They “help minimize solar heat gain, control glare and direct light deeper into occupied places,” said Brian Court, principal of The Miller Hull Partnership, LLP.

Coupling active energy efficiency with traditional passive methods — such as superior insulation, keeping a home airtight, and double-paned windows — offers ways to collect and store more energy in addition to using less. These are both important parts of getting to net zero. 

2. Low- or No-Emission Cars

Fuel economy consistently ranks as the most important purchase factor for new car buyers. A Consumer Federation of America survey indicated that 85 percent of respondents support the government requirement to increase the fuel efficiency of new cars to an average 35 miles per gallon by 2017. That impetus has led to more interest in low or no-emission cars.

Even casual drivers are taking note that there are more electric and hybrid cars on the road. These cars are unusual and eye catching, so they’re hard to miss. We see them used increasingly by taxi services, our neighbors (even wealthy neighbors). It would be tempting to think that the green car revolution is already well underway, but it really hasn’t reached critical mass yet.

In 2011, President Obama set forth a goal of having 1 million electric vehicles in service by 2015. Unfortunately, we’re falling short of this objective. As of the third quarter of 2014, when combining plug-in hybrid and all-electric cars, only about 250,000 were sold in the past four years.

The trends do favor low or no-emission cars. Hybrids, such as the Chevy Volt and Toyota Prius, show steady linear growth. Sales for all-electrics, such as the Nissan Leaf and Tesla Model S, are increasing exponentially and almost equal total sales for hybrids. Still, in the USA, green cars account for less than 1 percent of all vehicles on the road, so there’s a lot of room for increased market share.

3. Large-Scale Green Energy Production

Most people think about solar energy when they think “green.” But even with new large-scale solar farms and solar shading for store parking lots, the total contribution from solar power to electrical demand in the USA is projected to remain close to half of one percent. Furthermore, the U.S. Department of Commerce identifies trade barriers with other nations as a limiting factor to the United States exporting solar energy abroad.

Still, the U.S. Energy Information Administration projects that large-scale green energy sources will increase dramatically in 2015. In particular, wind power will increase more than 16 percent and contribute nearly 5 percent of our total electricity generation.

The U.S. also remains the world’s leading geothermal market, and the country exports geothermal energy around the globe — nearly 30 percent of global geothermal. What’s more, with a focus on carbon emissions, the Energy Information Administration estimates an upcoming decrease in U.S. carbon dioxide emissions in 2015, with a marked drop in coal-based emissions.

Home budgeting remain a top concern for most consumers, it’s important to be aware of these green energy trends and understand how they’ll impact us in the future.

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. 


There is no wrong way to build a first biogas digester, so long as it results in the unforgettable experience of seeing the miraculous blue flame of biogas for the first time. Soon afterwards, however, most peoples’ thoughts turn to a continuously operating system for regular daily energy at their home or small farm. If your dream homestead or community happens to lie in a cold region, it used to be believed biogas was not a viable option for you unless it was buried deep underground. Our understanding of the biogas process has improved a lot in recent years together with the introduction of new technology such as evacuated tube solar water heaters, so with a little bit of planning and DIY know-how, it is possible to thumb your nose at Old Man Winter and enjoy biogas in subzero temperatures.

We all know there is no free lunch, heating energy has to come from somewhere. There are a number of different options for heating a biodigester with or without fossil fuels, but before we consider them, it is important to keep in mind two important considerations for wintertime biogas. In the winter and early spring there will naturally be less organic waste available and accessible, requiring lower operating temperatures. Put simply, yes, biodigesters do benefit from heating to operate in wintertime, however, they do not need to be anywhere near peak performance temperatures of 100 degrees Fahrenheit. They need only minimal operating heat between 55 degrees and 75 degrees. Secondly, what heat that is produced needs to be focused in the “active zone” in a biogas digester, which is located on the bottom of the digestion chamber, half-way between the center and the inlet.


Some of the most common methods for heating home biogas digesters are on the chart below. We want to utilize waste heat if it is available and avoid dedicated electric heaters if possible. The following chart is divided by what heating options are appropriate where utility rates are low and where utility rates are high, which includes off-grid applications. The perfect cold climate off-grid combined heat and power system in my opinion would be a home gasifier or boiler burning annually-renewable wood chips or pellets together with a biogas digester. Waste heat from the gasifier heat exchanger or gen-set could be used to heat the biodigester, and in return biogas could provide year-round cooking energy, as wood gas has too much CO to safely burn indoors.

Methods for Heating Biogas Digesters

Where utility prices are low.

Where utility prices are high + off-grid

Home hot water system

Dedicated Electric

(Hot tub heater)

Dedicated Solar

Combined heat & power

Connected to the home hot water system.

Circulates heated water directly back into digester on

Flat panel for warm regions

Waste heat from gen-set, boiler or gasifier.

Evacuated tube for cold regions

If you intend to use your home hot water system to heat your biodigester, you must have your heat exchanger outside the digestion chamber to avoid the possibility contaminating your fresh water supply through a leak or ruptured pipe. For dedicated heater applications, a 50/50 water to planet and pet-friendly glycol is recommended to avoid freezing.

Biogas and solar thermal form a winning team to help reduce fossil fuel use, whether it is with a dedicated solar heater or solar heat supplements your home hot water system. For our two cubic meter home biogas units, I recommend 20-inch x 48-inch evacuated tube heater for Zones 4 & 5, or 10 tubes per cubic meter of digester volume. Provided the heat exchanger is located directly beneath the active zone. In summer months, solar heaters can be covered or disconnected.

In addition to heating, there are some additional steps you can take to maximize your heating energy.

Additional Steps to Improve Wintertime Performance


Thermal blanket

Hoop house


I hope everyone has a happy holidays and has the opportunity to enjoy a fossil fuel-free Christmas dinner prepared with 100 percent natural, clean burning biogas from ordinary household waste.

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.


I will continue the step-by-step introduction to home scale biogas for those interested in learning how to make it with my next post. In the meantime, I thought it might be helpful to mix things up with what I call my Biogas All-Stars series. These are posts where I will highlight one of my colleagues in the international biogas community and let them to answer questions about their projects in their own words.

I believe MOTHER EARTH NEWS readers will find this series useful, as it will offer examples of different types of regionally-appropriate digester designs. These All-stars inspire us all with their resourcefulness and dedication, working with locally available materials in often inhospitable – sometimes even dangerous - conditions to build biogas digesters to transform the lives of people who need it most. The Biogas All-Stars do not appear in any order. I would like to begin with one of the most likeable people I have ever met, Marcello Ambrosio, with the Studio Ambrosio Agricultural Consulting, from Italy.

Marcello (pronounced March-ello) and I met in New York City during a conference for Solar CITIES, an international non-profit biogas education and training organization we both belong to. He is a big fan of Western movies, and once worked as a cowboy in Wyoming during a visit to the U.S. When it comes to building biogas digesters, however, he is definitely the Lone Ranger. Usually working by himself, he has single-handedly built digesters as large as 100 cubic meters (26,000 gallons).  


Marcello specializes in the most common type of biogas digester in the world, the Chinese underground pit-type digester. There are an estimated 50 million of these type digesters in China. They are usually built underground for gas production throughout the cold Chinese winters. The advantage of this type is it allows those willing to get their hands dirty an opportunity to trade labor for material costs. With a readily available supply of bricks and mortar, this type of digester can be built for very little money. Building and operating plans for these types of digesters are available in ‘A Chinese Biogas Manual,’ which can be purchased through online book retailers or a free PDF Copy.


Weisman: When did you discover biogas?

Ambrosio: I first learned about biogas in 2006, as a student at the Polytechnic of Turin. After graduation, I went on to work at large, commercial biogas plants in Germany and Luxemburg. These large plants were using a lot of dedicated crops for feedstocks – mostly corn – and I knew there was no way this was sustainable.

Weisman: Describe the first time you created flammable biogas:

Ambrosio: In 2007 I built a small 100 liter (45 gallon) home plant and produced my first flame. I then built a one cubic meter plant (275 gallons), but it did not work very well, especially in winter. I live in the Alps. I then made my first 12 cubic meter plant, which was big enough to produce sufficient gas throughout the winter.



Weisman: What has been your favorite project so far?

Amrbosio: My favorite size is the 25 to 40 cubic meter plants. They are ideal for small farms with a few cows or horses.



Weisman: What advice would you give young people interested in biogas?

Ambrosio: I would say be careful not to think about biogas by itself, but to consider it as one link in a chain of closed loop sustainability. It is just the first step in the management of the organic wastes and soil ecology. It is important to consider every step of this cycle, for example utilization of the byproducts from the biogas process in agriculture. This multifunctional approach has far more value than the flame itself.

Weisman: Anything else you’d like to add for the American DIY community?

Ambrosio: Just be careful with methane from a climate change perspective. If you generate it, it is okay to burn it, but if you release it into the atmosphere 1 cubic meter (35.3 cubic feet) of methane is equal to 23 cubic meters (811 cubic feet) of CO2. The same impact of driving 60 km (27 miles) in a medium-size car. So, when you build it is important to have proper systems with no leakage and to have the digester sized correctly so when we are not home the gas is not released. Otherwise we are solving the problems of waste disposal and nutrient recycling, while adding to a bigger problem, emitting GHG gases.

Weisman: What is your favorite Western movie and why?

Ambrosio: The Good, the Bad, and the Ugly (1966) directed by Sergio Leone. There is just something magic about Western movies. They commemorate a time when there were still some uncharted lands in the West. Going West was a great adventure for the pioneers in search of prosperity and happiness.

I think people today can learn a lot from that pioneering spirit in our thinking, only instead of heading West we now must look outside the box canyon we have become trapped in to find a better way of doing things.

If you have any home or small farm biogas projects in Europe or non-profit projects anywhere in the world you would like to talk to Marcello about, you can email him at

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.


Canada Off Grid Home 

“Off-the-grid” is a terribly-abused expression. I (Phillip) have heard people say they’re “off-grid” if they switch off their cell phone for a day. Others think that anyone living far from the city is off-the-grid. Some use “off-the-grid” to describe people who wish to run and hide, to go incommunicado. In Canada, off-grid is a technical expression with a precise meaning defined by the government. Engineers and architects, to whom the government’s definition can be attributed, say “off-grid” to refer to those dwellings (individual homes as well as entire communities) that are disconnected from the electricity and natural gas infrastructure servicing a particular region. This definition makes things clear and simple: a home (not an individual) is off the grid in relation to electricity and natural gas.

The reality on the ground, however, is a bit more complex. Off-grid households capable of generating their own heat and electricity are often also intent on harvesting water, growing food, and disposing of their own sewage and waste without the aid of municipal infrastructure. These homes typically also have a cautious attitude towards communication links, and may therefore be cut off from telephone landlines or television cables. At times, they may be in remote places, even off the road. All these are incredibly interesting lifestyle choices that are simply mind-boggling for most people. I’m one of those people.

I moved to a small island off the British Columbia coast in 2010. Though I was no stranger to small town life, moving away from a municipality and off to a rural island meant becoming responsible for my water supply (and don’t get me started on my septic field). It meant, in other words, living with a groundwater well and monitoring it carefully to make sure I wouldn’t consume too much of my own water. My own water. Those three words, spoken in a row, had never even entered my consciousness until then. What could life be like — I started asking myself — if I had not only my own water, but also my own heat and my own electricity? What could life be like, off the grid?

Finding Life Off the Grid

I took a short trip to find out. I reached out to a friend of a friend who lived off-grid on Vancouver Island and asked for a guided tour of his house. Three hours later —three hours full of amperage, wattages, BTUs, inverters, and all kinds of gadgets that looked like something out of a Steampunk catalogue — I was enchanted, mesmerized, in awe. And utterly confused.

I returned home wondering whether I too could live like that. I am no stranger to a slower way of life, to growing veggies and filtering out unwanted television, social media, or cell phone signals, but I questioned whether I could go the extra mile and sever my ties to the power grid too. I puzzled over whether I had what it takes: the ability to do with less, to rely on myself more, to embrace a little inconvenience. I agonized over my lack of handy skills and my tendency to tackle domestic projects with stress and panic, rather than the required “I-can-fix-it” attitude that I admired in so many tool-box-endowed friends. I tossed and turned, debating ad nauseam whether as a good ethnographic researcher I should indeed “go native” and practice firsthand the life I chose to write about.

The prospect of going off-grid, for most people, rightly feels like taking a leap in the dark. Most of us have become accustomed to flicking on a switch and, in virtue of the technological miracle called electric light, stretching daylight deep into nighttime. Those of us living in the Western hemisphere, and fortunate enough to pay the monthly bills, are spoiled with the historically unique privilege of being able to microwave our food in seconds, tumble-dry our machine-washed clothes in minutes, and power up dozens of digital gadgets all day long. Our homes can be warmed at the twisting of a thermostat and kept cooled during the muggiest of summer days. Our store-bought foods can be preserved effortlessly for months in capacious freezers. Our constitutionals can be flushed away in an instant, out of sight and out of mind.

Why Go Off-Grid?

So, how can we, and why would we, cut off these life lines? Some might say because our lives may have gotten just a tad too boring, too disconnected from the natural world, too comfortable, too lazy, too irresponsible, too crowded, too expensive, too confined, too saturated, too superficial, too fast, too incompetent, and too dependent. Though I didn’t know if those arguments would really compel me and my family to make the leap, I felt the urge to understand them better, to experience and practice them vicariously through the everyday lives of full-time off-gridders.  

For the next three years, together with my then-student and now collaborator Jonathan Taggart, I travelled to all of Canada’s provinces and territories to document the ways of life of people off the grid. In June of 2013, Jon and I ended our travels on Canada’s easternmost point, having travelled 65,000 miles coast to coast to coast to find and interview about 200 off-gridders. Our experiences, now told in a book and a film, will be the subject of this blog in the coming weeks and months.

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.


biogas digester

There are two things that are true about biogas. At least two. And I mean things at the core of biogas, down in its chambered, beating heart. The first is that biogas wants to happen. It wants to happen like plants want to grow, like fire wants to burn. And that force, that will to happen, has (at least) those two aspects: life, like the plants; and chemistry, like the fire. But the second thing about biogas is standing on the other side of town, on the other side of the lake, on the other side of the ocean. And that second thing is that as simple as biogas is, it’s just as true that biogas is complex, deep, unfathomable.

It’s not just that there’s a world inside that digester; there’s a universe. It’s symbiotic to the 42nd degree, seething, stochastic, and astonishing. It lives in the dark, underground part of the wheel of life, and to fully understand it (I don’t) requires math, physics, chemistry, engineering, biology, ecology, and agricultural sciences. And I left some out. Now these two poles of biogas bear on my present subject, which is— across this new series of blog posts— to show you the parts and pieces that make up the design of at least one low-cost digester made for US latitudes and realities, and to explain why they exist, what they are intended to do. (And to tell a few jokes too. Jokes are important.)

If you’ve been keeping up with your caffeine intake and you have clever hands, by the end of the series I think you’ll be able to build one, just from what I’m going to show you. For free. Just because I like your sister. (She’s great, after all. No offense, but you need a bit more work. Isn’t honesty really the best policy?) Right then: biogas is simple. Keep it wet, keep it warm, and keep it away from the air, and huzzah! Almost anything that was once alive will yield up the energy in its carbon bonds as lovely burnable methane, mixed into marvelous natural biogas. Like plants want to grow, and fire wants to burn, biogas wants to astonish you.

Of course, we both know that even though plants want to grow, it takes real skill and deep knowledge to grow healthy food, and to do it year after year while keeping the land in good heart, protecting the earth. And even though fire wants to burn, just because you have a book of matches does not mean that you can design a good wood stove, one that will provide warmth without smoke, do it with real efficiency, and throw off lovely warmth without crisping the cat if wanders near. I’m saying, in other words, that to really understand farm-fresh fruit, fireplaces, furniture, fingers or fusion (that little thing the sun does) requires some science. You’ve got to learn stuff. At the same time, drop a seed, strike a match: to grow a garden or build a fire is not all that complex. How hard is it to use satellite TV? How hard is it to design the satellite?

So it is with biogas and biogas digesters. Making biogas couldn’t be much simpler than it is. Making a properly-designed biogas digester is solidly somewhere toward the other end of the spectrum. Make a digester for a science fair? Easy. If you’ve got a something-or-other that keeps the air out and the water in, well sure, that’s a digester. And yes, it may well generate biogas. Some. OK, but there are two critical questions that divide real success from relative failure: 1) Can you demonstrate you’re getting what you should out, given what you’re putting in? And 2) can you keep the thing warm outside on a cold night, with minimal energy input? The problem is the same if you buy a digester. After all, there’s no Institute of Good Gaskeeping, and it may take quite a while before Consumer Reports turns its spotlight in a biogas direction. Is the digester you’re thinking of buying well-designed and worth its cost? Does it look good? Does that mean it works well?

In short, how can you know that what you’ve come up with (or what you’re considering buying) reflects good design? How do you evaluate the quality of a digester, objectively and with some insight? But hey wait a minute. Do you really need to?

Perhaps someday digesters will be a consumer item, and Popular Biogas will publish an article with colorful charts, highlighting the one you’ve had your eye on— the Flatulence 1000 Turbo. That’s a great digester, huh? Their commercials feature Crocodile Dungdeep, a sassy Aussie dung beetle with a great accent. What’s not to like? You won’t have to run the tests that Popular Biogas ran because… well, because they already ran the tests. Your digester got the best score. Nothing else to figure out. Sears carries it, and they have layaway.

Meanwhile, contented sigh, you don’t need to know all that scary and probably complicated stuff some old guy mentioned, in that article you thought about skimming all those years ago. Isn’t the future great? Yeah. Only we’re not there yet. Solar is there, more or less. They have magazines. But small-scale biogas is still … maturing. Meanwhile we — the few, the crazy, the Archeanaunts — we have to design, build or buy something in the hobbyist space, having applied as much knowledge as we can muster.

No doubt it’s a hassle to actually have to learn things, but as my friend T.H. Culhane says (paraphrasing), wait until you get the ‘first flame’, until you set fire to that near-sacred biogas that you produced. Magic. The first hit is free, and then you’ll be hooked. Ergo, this series.

For me, and in this context, I would say that our as-yet mythical good design of a small-scale digester for the US might have certain characteristics, some necessary, some highly desirable. Among them:

• It should be large enough to be practical.
• It should accommodate whatever substrate you intend to use.
• It just absolutely, positively, should be well-insulated. (Did I say, “on all six sides” enough times? No? Yes? Regardless: On all six sides.)
• Whatever is put in should digest. (Now, that may seem blankly obvious— we’re talking about a digester, after all— but what I mean is that each morsel fed in should yield its proper bit of biogas before it comes out. A good digester has got to be designed as if it were, at least functionally, an intestine, whereas not all are. We’ll talk.)
• It should provide some way to get those critical measures (such as, [best case] a numeric measure of daily production), and have some minimum of automatic control. (For example, it must maintain a stable temperature in a selected range against changes in ambient. You can’t do that unless you have a thermostat, at the very least.) All that, except unless you want to wait for Popular Biogas and the Turbo to show up and save your bacon.
• It should be as simple as possible, but no simpler. Einstein’s dictum.
• And finally… it should be as low-cost as is allowed by those other items just above.

Now I have to tell you that for a long time — after all, I’ve been associated with biogas for a long time — I didn’t know whether it was actually possible to satisfy this whole list for a U.S. digester. Yet earlier this year I changed my mind, definitively, because, for the first time really, I started trying to imagine designs for low-cost digesters that would work in the US in a hammer-and-nails practical way. And I actually came up with something, or so it seems to me. (You’ll get to judge if I succeeded or failed, if you keep reading.)

It was the latest stopover on a mostly mental journey I’ve recently been on, after years of working on other things; pretty much the same journey I’m going to take you on. Let me start with the spur, the inciting incident: Some time ago a friend from Sri Lanka came to visit me. I had recently returned to biogas. Visualize. We’ve had tea and talked. He’s sitting in my office at the back of the house where we can look out on the meadow, and he catches sight of The Complete Biogas Handbook down low on the bookshelf. What’s that, he asks; and I explain. His eyes get bigger. “We need this in Sri Lanka!” He’s gotten very excited, and with a dawning illumination, catching sight of the village in which he was born, I had a sort of epiphany. They need this.

When I made the time to look into it, I was stunned by what had been carefully demonstrated, written up in the literature and peer-reviewed, during those years I was not paying attention, about the catalytic power of biogas to provide benefit to the poor. An escape from energy poverty. More time to pursue a better income. Greater health. Lower expenses. Less deforestation. A reduction in GHGs. Greater gender equality. Improved education, particularly for the eldest girl, the first teacher of her children. Better light in the evening for making crafts for sale, for reading books, and for more safely giving birth away from the stifling darkness. What a jaw-dropping list. Seven of the eight UN Millennium Development Goals and a lot more, bubbling out of a literal hole in the ground. Biogas wants to astonish you.

I opened my eyes, and found an enormous great lever of benefit in my hands. What an amazing privilege. You’ve just got to bow down. My father always told me that with every responsibility there is a privilege, and with every privilege there is a responsibility. So: chase that responsibility. Where to find a fulcrum?

My friend and I finally made a strong and direct contact with the founder (father) and the head (son) of a huge NGO in Sri Lanka which provides services to 15,000 villages. Their organization had been a fountain of good works for 50 years. They were also very interested in seeing the potential benefit of biogas unfolding in those villages. They had built a conduit of trust, and we were seeking the opportunity to move this astonishing technology through it. Everybody was agreed. Yes. Yes.

But the organization had no money. If we were going to offer biogas to villagers in Sri Lanka, not to say the rest of the world, then we would have to get the funding for any project ourselves….

And then? And then? Well, this is where (in the interests of having a tight plot line), I leave out a great many things. So will the made-for-TV movie, I’m sure. (I’m thinking Brad Pitt for the lead. We have a similar sort of twinkle, don’t you think? I may be a little taller, though.)

And I will tell you the parts of the story… next time I post. Keep reading.

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Rendering of the net-zero energy school

The following release is reposted with permission from Friends School of Portland.

Here on a wooded 21-acre lot, about a mile from the coast of the Atlantic, Maine’s first “net-zero” energy school is under construction.

Friends School of Portland is building a 15,000-square-foot school that will not rely on fossil fuels, and is expected to be the first school in Maine to produce as much energy as it uses. The new school also will be only the third in the United States to achieve Passive House certification, a high international standard for energy efficiency.

The decision to use Passive House design reflects a commitment to environmental stewardship, which is one of the guiding philosophies at Friends School of Portland, a Quaker day school for preschool through 8th grade.

Students breaking ground

“The best part of this project has been seeing how excited and engaged the students and their families have been,” said Jenny Rowe, Head of School. “They have helped steer the whole process. We’re all committed to being good stewards of the land, and to creating a home in Maine that will meet our needs for years to come.”

Friends School of Portland leaders, along with Kaplan Thompson Architects, Warren Construction, and other partners, hope the new building will serve as a model for others interested in sustainable design. The only schools in the U.S. with Passive House certification are in Hollis, N.H., and Rocky Mount, Virginia.

Foundation work

Passive House standards, overseen by Passive House Institute U.S., use solar gain and air ventilation to warm and cool buildings. The new home of Friends School of Portland will not rely on traditional fuels such as oil, gas, coal or wood. With the addition of solar electric panels and thermal tubes for hot water, Friends School of Portland will be a net-zero energy building, meaning that it will produce as much energy as it uses.

The school is in the midst of a capital campaign to raise funds for the $5.5 million project. They have raised about $2 million toward a $2.5 million goal. A second phase of the project, including a gymnasium, is envisioned for the future.

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