Geo thermal Cooling

Its been extremely hot outside this week, and were suffering a significant drought in much of the country. The chart above shows the levels of streams compared to their historical levels for this time of month. Though some regions are getting a lot of rain (the deep blue dots), much of the center of the country is experiencing drought conditions reminiscent of those over sixty years ago. The Dustbowl, as the period from 1934-1936 became known, was a drought characterized by Roland Dewing as the "most extreme natural event in 350 years."

Back to the heat, I got thinking about the Underground Heating Exchange Systems (UHES) the Chinese developed a while ago. The idea to pump air underground was first patented in the United States in the wake of the oil crisis in the 1970s. But the Chinese picked up on this technology and highlighted it as part of an integrated agricultural approach to feeding the Cold North East.

When I saw the Chinese paper (republished on the UN FOA website), I thought it was amusing that theyd used clay pipes for their experiment. After all, folks in the US typically use plastic drainage tubing for this sort of heat exchange system.

Then I got thinking last night - a problem with the plastic is getting it to simultaneously drain the water that condenses and keep out roots and pests. Clay pipe didnt sound bad, after all. Then the light bulb went off.

What if I used cinder blocks underground for the heat exchange "tubing?" At $1.65 per linear foot, it is more expensive than the HDPE drainage pipe. But I wouldnt have to worry about water draining through the blocks (it would) and I wouldnt be worried about the "tube" getting crushed.

That took me on another little adventure of the mind, as I tried to figure out how deep to run the "pipes" underground. The Chinese used half a meter, but what if one went deeper?

The ground temperature at 30 feet below the surface is constant - which is why caves are cooler than outside in the summer and warmer than outside in the winter. How far below the surface do I need to go to get to that constant heat, I wondered?

Then I found out something really fun at the Build it Solar website. It turns out the temperature profile of the ground lags the air temperature profile. Air temperatures peak in July (in my area), but the soil temperature peaks in August.

Then comes the cool part. That peak heat migrates slowly down towards the earths heat skin, so that the date of peak heat level at deep depths lags the temperature of the surface soil by weeks and months.

So not only will deep Underground Heat Exchange Systems access a larger thermal mass, the ground around that thermal mass will actually be heating up when the rest of the world is cooling down.

Im not sure how practical it is for a home owner to dig down 6 feet or more, but this kind of effort would be within the reach of a minor business. I would love to experiment with this next summer, if I can find a lot where I could dig deep...

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How it all started in Australia

Im writing about Australian Fish, and wanted to hark back to the 2006 segment on Gardening Australia that kick-started aquaponics in Australia. It was a five minute tour of Joel Malcolms backyard paradise, lush plants powered by silver perch and yabbies, all free of chemicals and enjoyed to the sound of constantly flowing water, yet far more water-efficient than any other form of gardening.

I searched my blogs high and low and couldnt find this video. Crazy! So here it is. If youve seen it, you know how delightful and relaxing Joels 2006 garden paradise appeared to a parched nation worried about chemical additives.

Enjoy!

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The Titan Arum or Corpse Flower

The US Botanical Gardens Titan Arum on July 21, 2013

The Titan Arum is called the Corpse Flower because of its intensely pungent scent when it blooms, which it does for a single day once after several years. For over a week weve been watching for the Titan Arum at the US Botanical Garden to bloom. Then Sunday happened and in the press of family stuff we forgot to check.

Apparently the Titan Arum did its stinky Corpse Flower thing Sunday night. By Monday morning the stench was gone, leaving only a humongous flower (still pretty danged impressive). Folks at my household hope to view the amazing bloom Tuesday morning, assuming it survives the night.

From the description currently up at the US Botanical Garden website:

The titan arum (Amorphophallus titanum), also known as the corpse flower or stinky plant, is blooming at the United States Botanic Garden Conservatory! Once fully open, it may remain in bloom for 24 to 48 hours, and then it will collapse quickly.

The magic of the titan arum comes from its great size - it is reputed to have the largest known unbranched inflorescence in the plant kingdom. Referred to as the corpse flower or stinky plant, its putrid smell is most potent during peak bloom at night into the early morning. The odor is often compared to the stench of rotting flesh. The inflorescence also generates heat, which allows the stench to travel further. This combination of heat and smell efficiently attracts pollinators, such as dung and carrion beetles, from across long distances.

The titan arum does not have an annual blooming cycle. The time between flowering is unpredictable, which can span from a few years to a few decades. The plant requires very special conditions, including warm day and night temperatures and high humidity, making Botanic Gardens well suited to support this strange plant outside of its natural range.

This plant is native to the tropical rainforests of Sumatra, Indonesia, and was first discovered in 1878. Public viewing of this unique plant has occurred a limited number of times in the United States. The U.S. Botanic Garden last displayed a blooming titan arum in 2007.

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Aquaponics on 60 Minutes in Australia

I was pleased to see that 60 Minutes in Australia did a piece on Aquaponics this Sunday. I always love seeing footage of Murrays farm, and it was cool to see the segment about the roof-top farm in Brooklyn.

On the other hand, I was a bit less enthused about the idea of growing plants in high rises using high-tech LEDs. If the business case supports it, thats great. But I dont think were there yet.

I was pleased the other day to re-read a 2005 article by Dr. Wilson Lennard, where he discussed his findings that aquaponics is almost always more productive than chemical-based hydroponics. Beyond that, deep water culture and media-based growing systems are 20% more productive than the nutrient film technique so often used in hydroponics. This is important because so many of the farm-in-a-highrise schemes are based on hydroponics, and presume ample use of electricity to achieve adequate growing conditions.

I think the secret is to start small - at the level of individual families and communities. Grand schemes that require hundreds of thousands of dollars (or even millions) in up-front investment must first be found attractive by venture capitalists. Even then, the big money involved in such endeavors can tempt the weak and immoral among us, as sad experience has demonstrated.

Still, its fun to see these topics being aired on major TV shows, rather than simply on gardening channels.

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