Beginner's Biogas Workshops

Dear friends,

As you may know if you've been visiting here for a while, I have in the past taught classes about biogas. Now, however, with the development of a new, low-cost design for a biogas digester, I am teaching "workshops". I call them that because there is a new "hands-on" section added to the previous class, so that anyone who attends-- you?-- will leave able to make their own digesters, in a variety of sizes and for relatively little money.

So, good to see you, so long, and until we meet again. Please visit www.completebiogas.com/workshops.html for complete details.


d.

Mr House,
A quick question & a thought about getting the word out & making biogas more widely used here in the US. Are you currently planning on having a biogas workshop in the Chicago area? The ones listed on your site is just a bit too far away for me at this time due to financial constraints. I haven't yet purchaced you handbook, but plan to in the near future.
Now for my thoughts on making biogas more popular. Have you thought about posting to some of the many auto enthusiast/hot rod forums? I absolutely do not mean to offend anyone here , but if we can convert people that use copious amounts of fossil fuels for recreation purposes they would have a much larger impact per capita than most of the users that are frequent visiters to forums such as this, who are already making an effort to conserve. You may have fundamental disagreements with guys that "have a need for speed" but I think that a fair amount of them would at least consider converting their vehicles to run alternative fuels if they had just a bit of information, such as:

Biogas/biomethane can be made fairly inexpensively
Biomethane has a very high octane rating ,somewhere in the 130 range from what I understand & high powered high compression engines require high octane fuels & unleaded racing gasoline with a 104 octane rating can run as much as $9.00 per gallon plus shipping! leaded fuels with higher octane ratings are even pricier & are not legal for street use. By raising the compression raitio in a spark ignition engine to make use of this high octane fuel power gains of 25% or more would not be unrealistic.
Gas fuels are superior to liquis fuels in many ways.ie liquis fuels are "atomized" by the fuel delivery system and a certain percentage of liquid fuel is not vaporized in the combustion chamber, & thus will not burn. Some will travel past the piston rings & into the crankcase where it will dilute the oil & can eventually cause damage to the engine. Some will pass from the combustion chamber & into the exhaust system where it will either burn or be emitted into the atmosphere where it is of absolutely no benefit. The only real benefit of liquid fuels in my opinion is the storage aspect. Large quantities can be stored without pressurization.
Well scrubbed biogas could be used in a vehicle modified to run on CNG & vice versa making extended road trips more feasible than a vehicle running on not so readily availible race gasoline.
An auto enthuiast driving a car with a nice paint job can easily spend many thousands of dollars on paint & body work & just the thought of spilling gasoline on that finish could cause the old heart to skip a beat or two.This becomes a non issue with bio or CNG.
Lastly SEMA is a force to be reckoned with & if enough auto enthusiasts ask for it , it will get done.
Just my 2 cents worth...look forward to hearing from you soon.
Skip

Dear Skip,

Actually, whether or not it's heresy, my aim is not to convert the US. If that happens, wonderful, but two things tend to remove it from being anywhere near the top of my list.

The first is that in the US we use energy at industrial scales. To provide fuel for an internal combustion engine requires in the neighborhood of 15 cu ft of biogas per HP per hour. Thus a vehicle with 200 HP under the hood would require ~3000 cu ft of biogas per hour to run. Given that, as a rule of thumb, a digester will produce about one vol of biogas for each vol of digester per day, then to produce one hour's worth of fuel for the vehicle would require a digester of that same size (3000 cu ft). But of course, having only an hour's worth of fuel each day is not practical. We should have at least, say, 4 hours worth, so we need a digester of 12,000 cu ft, which is about 90,000 gallons-- four and a half swimming pools worth?

If we have a 30 day HRT (hydraulic residence time) on that digester, then we need to have enough organic matter on hand that we can dump in 3,000 gallons (~400 cu ft) a day.

Then we get to run one muscle car for four hours.


The second reason that I'm not avid to convert the US is that any practical approach to making a significant difference in this country would require enormous amounts of time, millions of dollars, and a fountainhead of sustaining legislation. Sounds like a lot of time in an office cubicle, to me.


My aim is a good deal lower. The WHO says that some 2 million people a year die of smoke inhalation and related causes. Most of these are women and the babies and children on their backs, and the smoke comes from wood fires. Biogas burns with a clean, clear, blue flame, and has no smoke.

Many studies, likewise, show that on average it takes 3-4 hours a day, every day of the week, to gather enough firewood for that dangerous cooking fire. Biogas provides an instant flame.

Much of that wood comes from forests that are not managed, by which I mean they are not replanted-- who has the money, in developing countries?-- and so those millions of wood fires turn out to be a significant contributor to the increase in CO2 in the atmosphere. Biogas uses ag wastes and manures the come from feeds, and it provides a wonderful fertilizer that can increase the fertility of the land.

There are other advantages as well, for the use of biogas in the developing world, but suffice it only to say further that the increased health and dramatically improved time available mostly to women and girls has been repeatedly shown to improve economic well being-- the women start or strengthen businesses, and the girls go to school.


So my aim is simply not domestic. I don't subscribe to any trickle down theories. To my way of thinking, if the poor of the world can improve their circumstances, using planet-friendly technologies like biogas, enough to have disposable income, then everyone will be far, far better off. We need not be worried about whether the rich will create businesses, and therefore should have more tax breaks. No. We need to improve the lot of the common man, who will then spend money. Businesses will flourish when they have customers, and investment will show up. It does not happen the other way 'round.

So if you want to learn how to build a small, modest, cheap digester, I'm your guy. If you want to learn about how to build a large, ostentatious, expensive digester to fuel a boulevard-centered lifestyle... Well, I'm busy elsewhere.



d.

"... to convert the US is that any practical approach to making a significant difference in this country would require enormous amounts of time, millions of dollars, and a fountainhead of sustaining legislation. Sounds like a lot of time in an office cubicle, to me."

This was exactly my point when I mentioned that SEMA (specialty equipment manufacturers association) is a force to be reckoned with. No I am not associated with SEMA in any way shape or form. let's be clear on that . But..you get a bunch of gearheads involved & making noise & things could happen very quickly.Then let SEMAs members & lobbyists invest the time in that little bitty office cubicle & the money required to make it happen. As you're aware imported oil is a HUGE part of the US trade deficit so keeping US dollars IN the US would do nothing but help "the common man", not to mention  that pumping hundreds of billions of dollars into the middle east may not be the best way to end the "War on Terror" .
Part of my thinking here is simply this, if there is one thing that the US currently excels at, it's creating waste. If we start doing what we can to reduce that waste & create useable energy from that waste . we'll be much. much better off.
You also mention the health aspects of smoke inhalation & the like, the same argument could be made for those living here in our cities breathing exhaust fumes from the multitude of cars, buses & trucks on the roads.
I'm sure you're well aware of the biogas plant being built in Flint.Mich. I personally think it's a shame that we are having to rely on foreign investors to make it happen. Are we as Americans so ill informed & short sighted that we couldn't find a way to fund that ourselves?
Also I believe your math may be a bit off as to the amount of fuel a given engine will consume per hour . I personally had a '79 Mustang with a mildly modified 5.0 liter engine producing approx 300 horsepower . That car delivered a consistant 30 mpg highway which would be approx 2 gals per hour of gasoline at highway speeds. Now since the gasoline gallon equivalent of natural gas is 276 cu ft that would translate to about 550 cu ft per hour to run a 300 HP engine.Now I realize that biogas will contain some CO2 but using your calculations that translates to 4500 cu ft. or roughly 8 times what I was using . 16 GGEs per hour REALLY that would be FOUR miles per gallon. Furthermore I could have built a significantly smaller engine with higher compression & still acheived the same performance with a much higher octane fuel which would further reduce  fuel consumption. I think that 15 cu ft per hp per hour  is for a stationary engine running at wide open throttle under a full load for a sustained period of time .You just don't operate a car in that manner.Now I realize that biogas will contain some CO2 so a GGE may be slightly more volume .So for my purposes I believe I can build a car that gets 45 miles per GGE by utilizing a smaller higher compression engine & I would be more than comfortable with enough gas to travel say 100 miles per day which would be a tad over 2 GGEs or about 550 -600 cu ft which translates to what ? about a 3000 or say 4000 gallon digester That's probably doable.

In response to my mention of 15 cu ft per HP per hour, you said:

Also I believe your math may be a bit off as to the amount of fuel a given engine will consume per hour.

From FAO (http://www.fao.org/docrep/t0541e/T0541E0b.htm):

The normal thermal efficiency of [biogas] engines is 25-30%, and they use approximately 0.45 m  [i.e. 15 cu ft] of biogas per horsepower-hour.

With further regard to mobile uses,

I would be more than comfortable with enough gas to travel say 100 miles per day which... translates to what? about a 3000 or say 4000 gallon digester That's probably doable.

The problem with biogas for mobile uses is that methane is largely incompressible. Thus storage would require towing a large pressure vessel behind the car, i.e. storing the fuel as a gas, rather than the much more efficient storage that one gets with, for example, propane or butane, both of which liquefy nicely.

Be well.

d.

Mr House,
Look, I by no means meant for this to turn into a pissing contest. But, let's take a brief look at the numbers of a real world, production, natural gas car, that is available in the US.
  The Honda Civic GX NGV:
113 horsepower 1.8L inline 4 cylinder , epa estimated 36 hwy mpg 24city 28 mpg combined. If we were to calculate total fuel consumption based on your suggested 4 hours of use per day, just for the sake of argument. let's use the 28mpg combined # & an average speed of 40 miles per hour which is actually not realistic where I live where you'd  be lucky to average 30. 40mph x 4 hours would be 160 miles divided by 28 mpg we get a little less than  6 GGEs x 276.67 cu ft per GGE we get 1660 cu ft per day. That isn't even close to the numbers quoted,(using the numbers quoted of 15x113x4 gives us 6780 & again I do understand that biogas, unless it is well-scrubbed will contain a significant amount of CO2, but not 75% ) mainly due to the fact that in a car the engine is not producing maximum horsepower the entire time it's being driven.So using your numbers that would require about a 12,500 gallon digester rquiring about 400 gallons per day with a 30 day HRT. however that 160 miles per day  would actually equate to nearly 60,000 miles of driving per year,  is far beyond what the average person drives. I actually used to average that kind of milage in a previous life and I gotta tell you driving 60,000 miles a year in & around the Chi-town area will burn you out in no time! For someone driving a much closer to "normal" 15,000 miles per year a 3000 gallon digester would be closer to what would be  neccessary.  And that is using a car for our example  that quite frankly, doesn't impress me all that much, I'd think they could acheive better efficiency than that.  Look I know we have our differences, but I think there is enough common ground for us to have a rational discussion. Also in regard to propane, where I live propane isn't anywhere near  as attractive pricewise as cng , sure it burns cleaner than gasoline, but if it's gonna cost me more money then I'm not interested & I haven't even a clue where I could purchase butane in sufficient quantities.
Lastly all the time & money being poured into research & developement of renewable fuels has me baffled. Seems to me you could use natural gas and/or biomethane anywhere you can use biodiesel , ethanol or so called "clean coal". while the reverse is not true. your natural gas furnace , etc, wouldn't operate too well on biodiesel or ethanol, now would it? Yet much of the R&D is in these other fuels. I've seen claims of algal strains that are as much as 50% oil which can be used to produce biodiesel, but even assuming you could extract every drop of that oil efficiently, what do you do with the remaining 50%? Could that not be digested, to produce biogas & the biogas scrubbed of CO2 with a water scrubbing process, the resulting CO2 rich water would then be used to promote further algae cutivation?  I have a lot more questions if you're interested.

Oh by the way, back to my original question, Are you planning any Chicago area workshops??

Dear Skip,

No piss, no vinegar. But I do try to be loyal to facts, where I know any. The stumbling block you will face (as far as the facts I know tend to make one assume) is storage. For mobile uses, it's not just calories, it's energy density, and methane ain't got it. Then there's the issue of where the energy for whatever compression is done comes from. Considering those factors may well impact your plans and it certainly should change your math...

That is not to say that biomethane is a poor source of energy for automobiles. Studies with which I am familiar do, in fact, support the idea of biomethane running automobiles. See http://www.renewableenergyworld.com/rea/news/article/2010/03/why-is-biogas-renewable-energys-cinderella .

As the article briefly demonstrates, biogas has been demonstrated to be superior to biodiesel or ethanol in providing energy from a given unit of land. (And yes, one can put the glycerol fractions from transesterification or the mash from alcohol into a digester and extract yet more energy from it.) But here's the kicker: the most efficient means of making this second-most productive source of bioenergy (pyrolysis delivers more, but with much greater GHG) is through generating electricity and then using that to fuel the transport.

Even so, that's just not where my passion is, and I will be leaving shortly for a workshop in Hawaii, so do forgive me, but I don't plan to further discuss biogas and automobiles. It would be great, however, if you kept looking around, and told the rest of us what you find.

Meanwhile, to answer your appended question, no, I have not scheduled a workshop for Chicago, but I expect there will be one this next year.

Be well....


d.