Energy Independence

I have this fantasy of being completely energy independent. I don’t like contributing to air pollution. Or sending my money indirectly to people that kill gays and treat women like animals. And I don’t like the idea of my core sources of comfort and convenience hinging on a distribution system that can be relatively easily disrupted by economics, war, and disaster. I’m by no means a doomer, but if there’s a gas shortage, or a mega quake in New England, I want to be comfortable. Then there’s the more mundane things like an ice storm in 2009 that cut power to some neighborhoods for over three weeks. Plus, this stuff is fun for me. If it wasn’t fun, and was just a way to save money or something, it wouldn’t be worth the trouble.

I’ve got a one acre lot to work with. I can fairly easily take care of household energy needs with thermal solar, photovoltaics, locally-sourced wood heat, and maybe even some home-made methane just for kicks.

But how do I replace transportation fuel? That’s tougher.

First thing’s first. My house is located in such a place that I can do almost everything just by walking where I need to go. If I’m willing to ride a bike about 8 miles roundtrip I can get absolutely everything I might need on a regular basis. So having a motorized vehicle will be 100% a luxury item for me. But I like luxury.

Now, I’ve explored just about every possible home-grown energy option. And here’s how the most viable solutions compare for my particular needs:

Alcohol – Jerusalem Artichokes

I could conceivably grow my own fuel. According to David Blume’s book, Alcohol Can Be A Gas, I could sustainably raise enough Jerusalem Artichokes on my one acre lot to produce about 1,100 gallons of ethanol per year. But in reality I need some land for food production, pretty flowers, and a small lawn. So let’s halve it and say I grew 1/2 acre of artichokes getting me about 550 gallons/year.

I could probably plant them all with one day of hard work. And then harvest them all in the fall with one or two days of hard work. They don’t require much care other than that. To produce the alcohol they would have to be sent through a wood chipper or something to shred them up in order to add them to water to make a mash. The mash would have to be kept warm for about 48 hours while it fermented, and then I would need a fair amount of energy to distill off the alcohol. David Blume seems to think, though, that if I used the spent mash to make methane in an anaerobic digester I would have more than enough methane to power all this alcohol production.

There’s also the initial investment of time and money into all the equipment to consider. If I built everything from scratch I’d probably be looking at over 100 hours of building a still, storage areas for all the harvested biomass, the anaerobic digester, and storage tanks for the finished alcohol.

All told we’re probably talking about an initial investment of somewhere around $3,000 – $7,000 for the still and large storage tanks. Plus lots of labor, but it would admittedly be, for me anyway, fun labor, at least initially. I think the equipment could potentially last me 30 years. Throw in annual costs of renting a chipper and it would all work out to probably around 75 cents/gallon to produce the fuel + hundreds of hours of uncompensated labor.

Alcohol – Automated Hydroponics

Alright, instead of working the land and getting my hands all dirty, what if I instead went a highly-technical route and tried growing a plant hydroponically in a year-round green house, using robotics to take care of most of the labor? Robotics and hydroponics go well together. You can design the system around the automation.

Jerusalem Artichoke really wouldn’t do well in an automated hydroponic setup since they grow to be 6-12 feet tall. But sugar beets might be a good substitute. You can expect about 400 gallons/year per acre from sugar beets.

It would be a fun, non-trivial challenge to build a system that only needed tending on a weekly or monthly basis. I could use aquaponics and a tank of Tilapia sized to provide just the right amount of nutrients to the plants. All with some kind of conveyer belt-type system to automatically move the most mature plants towards a hopper where they could fall into a chipper and be pushed on into a fermenter.

But the costs are even higher than just growing stuff by hand on land. And I think the initial labor input would be just astronomical. I’d have to really love the project for it to be worthwhile.

Vegetable Oil

Vegetable oil, either straight or processed into biodiesel, is another option. Unfortunately the per acre yields of plants that would grow in New England don’t get much higher than 130 gallons/acre.

Waste Vegetable Oil

I could try to source some waste vegetable oil. But that resource is rapidly going away as more and more people take advantage of it. Plus, it has one of the problems I’m trying to solve; my source of it could be easily disrupted.

Algae Oil

It is possible to squeeze vegetable oil out of algae that has been cultivated in a photo bio-reactor (a series of clear tubes filled with water, basically) or just a big pond or pool. And you could also get some alcohol out of the waste after the oil has been extracted. But the technology really isn’t mature enough yet. The yields for a system that wouldn’t take up my entire lot wouldn’t be too impressive. Extracting the oil from the algae is still a bit complicated: You can dry and then pulverize it; Use chemicals to break down the cells, releasing the oils; Use sonic vibrations to break up the cells; Or use osmotic shock, suddenly adding or removing lots of salt to the water.

Initial costs would be high, having to build tanks and oil extraction equipment. It seems like it would be capable of being 100% automated, but current hobbyists run into problems with algae clogging pipes and having to be scraped off of surfaces to stop it from blocking light and inhibiting growth to the rest of the colony. So it might be fun to experiment with, but I’m not sure it’s ready to be relied on.

Diesel Trees

Diesel trees are pretty amazing. The trees store their energy in a liquid form inside their trunks. They can produce close to 15 gallons of fuel per tree per year. The tree is then tapped, similar to tapping a sugar maple, and the fuel just runs right out and can go straight into a diesel engine with no modifications.

Problem is, they only grow in tropical climates and require either lots of rainfall or irrigation. So if I lived in South Florida, an acre or so of these would actually be a pretty perfect solution. But these trees won’t survive in New England.

Wood Gas

If you heat wood up in the absence of oxygen it gives off a gas that can be fed into a car engine built for regular petroleum gasoline. But I’m not gonna drive a wood stove down the highway and I don’t really have a giant wood lot to harvest from anyway.


I could make hydrogen at home from water using electricity. Making and storing hydrogen isn’t too big of a deal technologically. It would take about 55kwh to make an amount of hydrogen equivalent to one gallon of gasoline [or GGE "gallon of gas equivalent"] (assuming a 60% efficient electrolyzer). To have enough fuel for me to feel rich enough to just waste it on a Sunday drive, plus have enough for some long-distance RV trips a couple times a year, I’d need to produce between 2-3 gallons/day 365 days/year. Which means I’d need 110 – 165 spare kwh’s every day. If I bought that power from the grid it would cost me around 10 cents/kwh which works out to $11 – $16/day added onto the electric bill. By itself that’s really not horrible, especially when the cost of a gallon of gas gets up above $6 or $7/gallon. But when you throw in the cost of the storage tanks, compressor pumps, and car conversions, things don’t look so good.

“No problem!” You say, “Just use solar panels!” So living in New England I’m in the solar zone 5, which means I get an average of 4.2 hours of usable sunlight per day. That’s averaged out over all the rainy/snowy days, short winter days, and long sunny summer days. So I would need about a 40kw system (40 * 4.2 = 168 spare kwh). Right now the cheapest wholesale panels can be had for under $2/watt. So that’s about $84k worth of panels (best case). And that’s a LOT of panels. Then there’s installation and mounting costs. Though, consider that if I cut use in half to say, 1 1/2 GGE/day my solar panel costs would only be about $42k.

Finally, while getting an internal combustion engine to run off of hydrogen looks to be a fairly simple task. The problem is finding a way to store a sufficient amount of hydrogen on board the vehicle to have a decent range. Advances in materials science over the past 10 years have allowed for high pressure tanks rated at 10,000 psi, which make for tanks with energy volumes equal to gasoline. Meaning a 1 gallon 10,000 psi tank filled with hydrogen holds about the same amount of energy as 1 gallon of gasoline. But these tanks aren’t exactly sold at the hardware store, and I can’t seem to find what they might cost. The best I could find was a government report from 5 years ago that predicted they would cost about $6,000. Though I read another claim that a 5,000 psi tank sized to hold the equivalent of 18 gallons of gasoline could be had for about $700. So I have no idea.

Now if I had access to a 50kw wind turbine, or hydro turbine, things would change. But right now, with the costs the way they are, plus my aversion to having a 10,000 psi tank anywhere near me, makes hydrogen kind of a tough sell for my needs.

Consider total costs somewhere between $50k – $100k for production equipment, storage, and car conversions, with, say, a 30 year life span on the equipment. That’s 1.5 GGE’s per day for 30 years, or 16,425 GGE’s or about $3 GGE. Cheaper than the price of gas today, which will only go up over the next 30 years. But that’s not counting my hundreds of hours of labor in doing a big custom setup.

If I could get a cheap tank and a good deal on some PV panels and a compressor, and lower my needs to say 1-2 GGE’s (gallons of gas equivalent) per day, it’s not out of the realm of possibility.

Hydrogen can also be produced biologically and by using power to create steam, rather than electricity for electrolysis, but so far, neither of those options are better than electrolysis.


Anhydrous ammonia, or NH3, similar to pure hydrogen, can be produced by electrolyzing water. Ammonia can be burned in a modified gasoline internal combustion engine.  It takes about 33kwh’s to produce 1 gallon of ammonia. So it would have the same high-electric demand problems as producing hydrogen.

The advantage of ammonia over hydrogen though, is that it remains a liquid at ambient temperatures at just 125psi. So there’s no dangerous or expensive high pressure tanks to deal with. It’s very energy dense, you only need about two gallons of ammonia to get the same amount of energy that is in one gallon of gasoline. So that just means doubling the size of the fuel tank in a vehicle to have the same range as a gas powered car, which isn’t really that big of a deal in many cars.

The hardest part is the production of the ammonia. The only inputs you need are air, water and energy. Easy enough. But to make ammonia requires temperatures up to 1,000 degrees Fahrenheit and operating pressures around 500 psi. And you can’t just buy your own small scale ammonia making machine sized for home use (is that opportunity knocking?). So I would have to design and build it from scratch.

Difficult, but given that once it’s setup and operating, all I would have to do is maintain the machine, it is an attractive option. – No farming requirements, no heavy lifting, no repetitive labor input. Though it would require about $50k of solar panels to produce a few gallons per day. With the price of PV’s coming down all the time though, and the price of gas going up all the time, this could turn out to be a pretty good deal not too far down the road. The costs workout similar to hydrogen.

In fact, you can think of the trade off this way; that hydrogen is relatively easy to produce, but difficult to store. Whereas ammonia is somewhat difficult to produce, but easy to store.


Butanol looks really promising. Butanol has almost the same energy density as gasoline (unlike ethanol which only has about 2/3 the energy density). And, best of all, butanol can be made from cellulose, plant matter that we pretty much just consider to be waste, like corn stalks and grass clippings. It can also be run in any typical gasoline-powered car without any modifications.

While butanol used to be a fuel made by farmers in the early 20th century, it is now mostly manufactured by deriving it from oil. Consequently, the art of making it from biomass seems to have fallen by the wayside. Whereas I can find hundreds of examples of people making their own ethanol, biodiesel and electric vehicles, I can’t seem to find people who are making their own butanol at home. Which means, rather than standing on the shoulders of giants and just copying other people’s ideas (easy), I’d be trailblazing my way through figuring out an efficient, small scale production process (not so easy).

It basically involves exposing the biomass to a particular strain of bacteria within a two-stage process within controlled vats, similar to alcohol fermentation, but slightly trickier. Maybe worth experimenting with in the future, but not really a viable solution to my transportation problem right now.

Molasses – Or buying cheap sugars for conversion to alcohol

Molasses is a by-product of sugar production. I couldn’t make enough molasses myself. But it may be worth buying it by the ton in order to turn it into alcohol. One ton of molasses makes about 75 gallons of alcohol. Depending on world markets a ton of molasses would cost me anywhere from $75- $140. Then I would just make it into an alcohol like the jerusalem artichokes. Even at the high end of the price range it’s still less than $2/gallon, and when prices are low, I’m looking at about $1/gallon of ethanol. Plus the by-product could be used to produce methane that I could use at the house. And the final by-product, after methane production, would be a great fertilizer for the gardens.

Buying Ethanol

Another solution, rather than producing my own fuel, might be to buy it from a local producer in bulk, and just keep a large (150-300 gallon) storage tank of it at my house. That way I’m supporting local farmers, and am prepared for a disaster. And in the event of some kind of highly unlikely long-term collapse, I could grow my own crops in order to get a few hundred gallons of it a year.

Doing this with biodiesel or vegetable oil wouldn’t really work because they have a relatively short shelf life.



Building an Electric Vehicle

In order to minimize my need for energy dense transport fuel in the first place I really ought to just build an electric vehicle. Getting between 40 – 90 miles on batteries only is a realistic expectation for a homebuilt with a good budget. That kind of range ought to cover well over 90% of my typical automotive transport needs. A small generator that I can take along on my longer journeys, while I couldn’t carry something large enough to make enough electricity to run the motor in real time, it could be just what I need to extend the range to make 150+ mile day trips possible. A generator that is capable of trickle charging the batteries could be left on for the entire first leg of the trip. Then, at my destination, while I’m sunning myself at the beach, or climbing a mountain, or hanging out with my friends in their apartment, the generator could be left on to keep charging up the batteries while the car is parked, providing enough of a charge to get me back home.

And the generator could be powered by gas, alcohol, methane, or hydrogen (biodiesel and veggie oil would require a diesel generator which would be a bit too heavy for this application).

But with an EV I could go weeks driving around, running errands, visiting friends and not use any fuel (besides sunshine) at all. With the once-in-a-while 100+ mile trips only using a few gallons of fuel to charge the batteries just enough to get me home.

In the very rare event I want to go on a 200+ mile day trip I could either rent or borrow a friend’s car.

Battery replacement costs would be a consideration. Enough batteries for the type of range I would like would cost me somewhere between $1,000 – $2,500. And they would have to be replaced every 6-10 years or so. And the degraded batteries can be refurbished or used for lower-grade applications where energy density isn’t as critical, like home backup power for example.


So, given all these options, what do I think would be my ideal setup?

I think making a home-built electric vehicle is the way to go. It’s the simplest, proven solution that meets my needs, with plenty of people who have already done it to help show me the way.

Aiming for an all electric range near 60-80 miles or so should cover most of my transportation desires. Along with a removable range-extending generator running off of ethanol to trickle charge the vehicle while I’m at my destination (assuming there are no electrical outlets available). -Effectively giving the vehicle a usable round-trip range of about 150-200 miles for day trips.

The generator isn’t an ideal solution. But it’s something that would be seldom used, allowing me to use no ethanol at all for the great majority of my trips, but still saving me from having to keep a second car just for those longer trips every 1-2 weeks or so. If I start off with full batteries, the generator would probably use up somewhere between 3-6 gallons on a 200 mile trip.

So let’s just call that 6 gallons every 2 weeks, which works out to about 150 gallons/year. 1/8th of an acre of Jerusalem Artichoke, according to my numbers above, would produce about 137 gallons of ethanol/year. – Just about there. Making a batch of ethanol from our other miscellaneous yard and kitchen waste could probably make up the extra 13 gallons. 1/8th of an acre isn’t all that much land to work. And if I find I get bored of the farming life, I can just purchase in bulk and store all the ethanol I need, knowing that if I really had to, I could make it myself.

I’d need a still, and some storage tanks, but nothing too large. I kind of want a still anyway for making my own liquor for consumption, as well as for capturing oils from flowers for flavoring and scenting things (hey, a guy needs a hobby!), so it will serve several functions. And I could keep a couple hundred gallons of ethanol in a storage tank, if my home production comes up short I can always just go buy some to top off my stores. And if I come across a source of cheap, waste sugars, I can always take advantage of those to turn them into alcohol. Whether that be cheap molasses or a bunch of expired foods that would otherwise go to waste.

Plus, with a little extra work, the vehicle’s battery bank and generator could serve as a convenient backup in case we lose grid power at the house for an extended period of time.

Fueling an RV

I’d like to be able to do some RV-ing in the future. Perhaps doing a school-bus conversion project or something. At 10mpg, and with thousands of miles of highway to traverse, there is just no way I could produce enough fuel on my one acre to power it. An electric conversion for something that big is out of the question. It seems my best bet would be to get a diesel vehicle, put in an extra large fuel tank, and fill it up with American made biodiesel at filling stations along the way. If a crisis hits and even biodiesel ends up selling at $10+ per gallon, well, it’ll be time to switch to sailboat cruising I suppose.


Down the Road

Down the road, in 5-10 years or so as the price of solar panels drop another 10-30% and the price of gas continues to climb, it looks like anhydrous ammonia, or N3, will be a promising option for my particular situation. Having some solar panels producing an energy-dense near-liquid fuel in a 100% automated process requiring no outside inputs other than water and air is about as close to a perfect fuel as I can imagine.

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  1. KevinW
    Posted April 6, 2012 at 1:16 pm | Permalink

    Nice write-up.

    Are you open to buying an off-the-shelf electric vehicle? I’ve been scheming about building an EV for a long time, but the retail ones are getting more and more compelling. The latest generation perform better than any DIY I’ve seen and cost around $30k (Volt, CODA) or less (Leaf, MiEV).

    If you don’t need an enclosure there are EV motorcycles (ZERO), and if you don’t need highway speeds there are NEVs (e.g. GEM).

    Now that there’s active competition I expect the next round of products to be even more economical.

    Also are road trips a hard requirement? I’ve been trying to sell myself on doing bike tours or sailboat cruises instead of car road trips. A small sailboat can get by on wind and electric power.

  2. Posted April 7, 2012 at 1:00 am | Permalink

    @kevinw Thanks. My uncle just bought a Leaf (and nearly totaled it on the drive home). He seemed to like it for the 60 mins or so he was driving it.

    I’m not totally opposed to buying a factory-made EV. But I just prefer the look and feel of classic cars to the modern sedans that all look alike. And I like the idea of knowing my vehicle inside and out. Plus, I think I could do the whole project, including buying the donor car, for well under $20k, maybe under $10k. And then there’s the gratification of impressing everyone with my technical prowess. Though, in a few years, if there’s a really great EV for sale for under $20k that I don’t mind the look of, I’d be hard pressed not to just buy that rather than spend 3 or 4 months tinkering in the garage.

    A motorbike or NEV wouldn’t really suit my wants. A moped (electric or otherwise) would probably be a good vehicle for me to keep in the garage, but I also want an option for when I want to go on the highway within a climate controlled environment.

    RV road-tripping is definitely something I want to try. I’ve done bicycle camping/touring, which is great, and has its place. And I can’t wait to spend a winter on a sailboat in the Caribbean. But the idea of being able to take my bed, desk and living room along with me for six weeks in Alaska, or a winter in the south, or month of hiking in the great American West just sounds so… comfortable.