groInnovation Exclamation
Posted By: admin
Date: October 2nd, 2009
Category: Uncategorized
Creating a clean energy future will require a lot of innovation and people taking responsibility. All summer I’ve been working toward three goals: clearing trees to enable a PV system on my roof’; putting in a large garden; and building an experimental hot-water system by collecting heat from composting wood-chips.
The “Brown Mound” is a densely packed mound of wood chips, with 400 feet of water line coiled throughout. As the chips decompose, the anaerobic bacterial process puts out heat. Anyone with a compost pile will tell you that if you stir it up, even in the winter, you’ll see a lot of steam.
So with that in mind, and some research I did on a frenchman named Jean Pain, we created our own version of a compost-powered-water-heater.
And, it’s working! We’re getting 1-gallon per minute of 95-degree water from the system, only 2 weeks after it was built. The temp should increase to 120+ as the composting process kicks into high gear. This should mean we burn very little propane to heat our domestic hot water, and we might even be able to heat the house a little by cycling the water from the mound through a radiant-floor loop.
The video below is a “making of” that shows how we build the mound, with the help of lots of friends and people involved in the Carbon Shredder organization. (Carbon Shredders are also co-sponsoring the KickGas Festival with groSolar in San Diego which includes a solar-power sweepstakes/drawing on Oct 24).
Cheers!
GB, otherwise known as, An Energy Optimist
October 8th, 2009 at 1:24 am
This is not green. The energy in the resources you are using outweigh the energy benifit. This is not sustainable.
If you did not purchase any of the equipment, then you have an arguement.
October 8th, 2009 at 3:46 pm
How long will the wood heap last? What to be done to sustain the process?
October 12th, 2009 at 9:52 am
When Jean Pain did this in the 1970s his mounds lasted 18 to 24 months in terms of maintaining the steady-stream of hot water and methane. The bacterial digestion process (anaerobic) generates the heat. Once the bacteria have processed the biomass, the heat will stop. I will cover the mound with radiant-barrier insulation and haybales to prevent winter-conditions from cooling off the mound.
If you google “Jean Pain Method” you’ll see some good articles about this concept. He developed this over a period of 10 years and according to his measurements, the energy required to harvest/process the wood (fuel for chainsaws, chipper, tractor, truck) was 12% of the energy he captured from each system. When he factored the energy-cost of the actual equipment, plus the fuel, the energy required was 26% of the energy returned from the Mound. That doesn’t factor the HUGE additional value of the compost this creates, to build up soil, a tremendously important asset for food-production and real sustainability.
Since he also captured methane (natural gas), he converted ALL of his motorized equipment to run on NG, meaning ALL of the energy-input requirements were produced from this system with ZERO fossil fuels, and ZERO net greenhouse gas emissions.
Graham, what is your definition of sustainability, if this does not meet the bill? I will bite my tongue in response to your uninformed judgment that this is “not sustainable” and give you a chance to revisit that opine.
My project is an experiment using a WASTE-STREAM of leftover wood-chips (leftover from jobs done by local tree-service work and power-line clearing), capturing the energy from the natural composting process without burning anything, and the end-product will be several tons of soil-building compost for my land. We used a total of 1 (yes, ONE) gallon of diesel-fuel for this project and 40+ hours of manual labor.
So far we have spent a total of $0 on this project and it will offset at least 300 gallons of propane use (that’s what we have been using for hot water over an 18 month period), and it will likely offset 20% of our winter fuel-needs, which would mean we’ll reduce our wood-burning by 2 cords over the next two winters.
IF I can figure out how to capture/store the methane from the inner chamber, that will give me the energy equivalent of another 400 to 600 gallons of propane.
By the way, as of this morning the water from the mound was up to 120 degrees (and it was 28 degrees outside).
Cheers
gb
December 23rd, 2009 at 1:14 am
Can you please send me an update on your system. I have been wanting to build one for some time now here in Albuquerque, NM and want to see how your pile is performing for you. What’s the word on your Jean Pain style brown mound?
Thanks, Dave
December 23rd, 2009 at 5:16 pm
Here is the reply from Gaelan Brown:
From October through the end of November the temperature of the mound, and the water coming from the loop, held steady at 100 degrees. But during the past two weeks of single-digit and sub-zero temperatures, it has cooled off to 80 degrees. Jean Pain claimed it was essential to “shred” the woodchips to create enough surface area for the bacterial digestion process to create enough heat. He was getting 140 degrees with his mounds by doing this. I just used normal wood chips because I couldn’t find a shredder. I’m getting a lower temperature in my mound but perhaps it will last longer than 18-24 months. Ideally you’d shred the material, and fully soak it with a lot of water as you build it, and you’d get water hot enough to use for domestic without needing a water heater. The size of the mound and the amount of water line inside will determine your sustainable “flow rate” and BTU output. I have about 8 tons of woodchips and 400 feet of 1-inch water line in mine. The sustainable flow-rate I can achieve (so that the temp of the water coming out doesn’t cool off) is 1/2 gallon per minute. I am setting this up to circulate into a storage tank at that rate, keeping the tank full of warm water at all times, with an on-demand heater downstream from that to bring the water up to temp. But instead of heating 50 degree water up to 110 degrees with propane (60-degree delta), I’ll only be using enough propane to bring the water up 30 degrees (from 80 to 110), so I’ll cut my hot-water heating fuel use in half with the existing system.
Thanks for your interest and please keep me posted on your progress.
Cheers,
Gaelan Brown