Fish Pee and Sunshine

This is not an article on how to relocate your CELSS, but rather about how matter and energy get moved around in the habitat.

Ecosystems are fundamentally reliant on the cyclic flow of matter driven by the flux of energy through the system. Most of us past elementary education are familiar with the most basic of these processes, the hydrologic cycle.

Most aquaponists are also pretty familiar with the nitrogen cycle.

There are also many other cycles for the various macronutrients and micronutrients critical to the function of an ecosystem and its constituent organisms. And of course they are all interrelated- the nitrogen cycle depends on the transport of water, and vice versa (to a lesser degree). These also effect the flow of dissolved nutrient minerals, erosion and sedimentation.

For example, in a CELSS you have to account for the salinization of the water table, and have some mechanism for desalinizing it. Sometimes that mechanism will be human elbow grease, but the more you rely on that, the less stable your system will be. 

Transfer Mechanisms

Back in the dark ages when I was in college, the chemical engineers had a class they called Meatballs, which I believe was shorthand for Mass and Energy Transfer and Balance. Almost wish I'd taken it, but I was a mechanical engineer dual majoring in physics and probably had enough on my plate.  The term mass transfer is commonly used in chemical engineering for physical processes that involve diffusive and convective transport of different chemical species within a system. For a ChemE, that would typically be a pharmaceutical factory or petroleum refinery. As regards CELSS, it occurs to add a few other processes: 

• Diffusion


• Absorption / Adsorption


• Evaporation


• Drying 


• Precipitation


• Membrane filtration


• Distillation

At any rate, I've been talking with Paul lately about how he moves things around in his biospheres. I've recently added a page on pumps. And of course I've assigned myself some additional reading:

It is not unusual (away from this website, anyway) to see CELSS defined as a controlled environmental life support system. I personally prefer closed, because 1) I think that is the more critical characteristic to strive towards, and 2) controlled gives the impression of sitting in front of a console and "driving" the system. Incidentally, I also prefer ecological to environmental, as it implies a biological basis to the system, rather than just a fancy HVAC system, which won't produce food.

Definitions

Control systems and (thermodynamically) closed systems are both engineering terms, and in the engineering sense, neither term is wrong as applied to the kind of habitats that are the goal of this community. A controlled system is, nominally, a stable system. A thermodynamic closed system must be stable, and must therefore be controlled. A control system can be open or closed, not necessarily in the thermodynamic sense. Below shows an open control system driven by an external input, r, outputting from the system, y. A closed control system would take no external input, and all the output would be internal.


In thermodynamic systems, closed means that matter cannot be exchanged from without the system, but forms of energy (heat, light, electricity, etc.) can. By contrast, an isolated system cannot even exchange energy; and a thermodynamically open system can exchange both matter and energy (think of a jet engine, with air and fuel going in and faster air, thrust, and heat coming out).

A CELSS habitat is a closed thermodynamic system made of up of many controlled subsystems.

In the control system diagram, you'll notice the little circle where the external input is modified by the feedback. There is a minus sign there denoting a negative feedback. Negative is good. Positive feedback loops quickly spin out of control, and are inherently unstable. This may be useful when the goal is a chain reaction, but negative feedback control systems are what engineers usually are referencing when discussing the subject of control.

In lay terms, control (as in "remote control"), often implies manual operation, or active control. In control systems engineering however, the goal is typically automation, i.e., passive control (think robotics). The other thing that folks often assume with a controlled system is that it is inherently technological, either mechanically or electrically controlled. This seems to be the direction NASA has taken, but Nature has been doing control systems chemically, geologically, biologically, and ecologically for over 4 billion years on Earth, with global stability generally measured on the scale of millions of years, and local ecosystem stability on the order of hundreds or thousands of years. The question here is how far can this snapshot of Earth's evolved system (so crucial to human existence) be scaled down in packaged form, and still retain stability over the timescale of multiple human generations? Clearly, system size plays a role in stability: more mass means greater reserves of chemical resources and also dampens external thermal fluctuations; more diversity of biomes leads to greater biodiversity which makes a system more robust and stable. It can therefore be assumed that a scaled down version will be inherently less stable than the Earth's ecosystem. On the other hand, an off-Earth system might benefit from a lack of geological perturbations such as volcanism and extreme weather.

This is not to say that the ideal CELSS is completely controlled passively. As the apex consumer in an EcoArk, the humans will be uniquely in control of the system, if nothing else, by when, what, and how much they choose to consume. I would likewise argue that CELSS should ultimately be designed not only for humans, but to require humans, at least for long term stability and reproduction.

The measure of control system effectiveness is how quickly it reaches the desired value. The selection of gain terms for each type of control is known as tuning. For complex systems, tuning is not a trivial endeavor and must often be done iteratively.

Biological Systems

In many ways the operation of a CELSS is analogous to the physiology of an organism, so we can borrow some terminology.

• Homeostasis is defined as the maintenance of a constant or unchanging “normal” internal environment during unstressed conditions.

• Steady state is also defined as a constant internal environment, but this does not necessarily mean that the internal environment is at rest and normal. When the system is in a steady state, a balance has been achieved between the demands placed on the system and the system’s response to those demands.

It should be noted, that many biological and ecological response mechanisms do not fit neatly into the PID categories the way, say a spring represents a proportional response in a mechanical system, or an inductor a derivative response in electronics

Biosystems are inherently complex, but are generally well tuned by nature through the iterative process known as evolution. The complexity of biosystems is due to the chemical control systems used which are temperature and pressure dependent and usually nonlinear. The field of ecology is ripe for quantifying and characterizing control responses mechanisms experimentally using CELSS.

I think I can safely characterize this year's warmest months as "The Summer of Compost." We got the quail and rabbits in late spring and leveraged their copious waste product to introduce BSF to the area.

The BSF were mail ordered and arrived pretty mature. They went in under the rabbit hutch and started pupating in a week or so, which slowed down the composting. I thought they were done, but then started seeing the flies around. Soon they had taken over my worm bins and quail composter as well. While my fish and quail both love to eat worms, the worms just do not reproduce quickly enough to make it part of the daily diet. The BSF can easily keep everybody fed, enough to get off commercial feed. At least during the summer.





As noted in the second video, I am planning to replace the BSF under my rabbits with red worms, which have currently died out.

Stable systems must be robust. System stability requires negative feedback loops. Nature is generally very good at this, because... well, evolution. Anytime an organism is too successful, it becomes an opportunity for something else to exploit (note to humans: beware). What causes instability is generally a rapid perturbation to the system: invasion of a foreign species (not co-evolved to the local ecosystem), or a change to the environmental inputs.

For a planet sized system, such as the Earth, it takes a pretty big perturbation like an asteroid impact to throw off the stability, and even that was recoverable when it happened to the dinosaurs, albeit not for the megafauna of course.

For a much smaller system, such as my quail hab or aquaponics system, a smaller perturbation can be potentially catastrophic. The inputs to a CELSS are mainly electromagnetic and thermal. Earth life has evolved robustness to the degrees of Earth's daily and seasonal variations of light and resulting heat, but my systems while not exactly closed yet are also very susceptible to mechanical failure of pumps. This happened to my quail earlier this week, and they went a day or two without water. The quail survived, but egg production is still recovering. We had gotten up to 3-4 eggs per day (from 4 hens), and have been getting about 1 a day since the drought.

I try to personally monitor all my systems on a daily basis, and I think interaction is important, but I also value a certain degree of automation. To say it another way, I think it is important to check the animals have food and water daily, but it's nice not to actually to have to give them food and water every day. Also, in the real world, my wife makes me take vacations.

Subsequently I've been looking into electronic monitoring systems. I really like the Grove system for this, and there are some nice Instructables showing how to put it together.

This will likely be one of my winter projects.

While we've been enjoying home grown lettuce, kale, and mint for several weeks now, we finally had our first quail meat, eggs and catfish this week, not quite all to plan, however. This is why food storage capability is important.

Floods and Drains

With all the work to be done outside, my basement AP system has been a little neglected, so the other night I decided to add a few gallons of water to bring up the level of the 80gal sump. My wife had been using all my 5gal buckets, so I improvised and used the hose.

Big no-no. After a 7 yr old tantrum, supper, guitar practice, a trip to the store, and sealing my wife's cichlid tank, the oh-shit moment hit me, just as I was about to head upstairs to bed.

When I got back down there, the water in the fish tank was a color I haven't seen in a long time (more bluish than brownish), and very clear. There was also water all over the unfinished part of the basement. I vacuumed up at least 30 gallons. I am fortunate that there is a drain in my workshop next to the water heater (the workshop is next to the Hab Lab), or it could well have been much worse.

One of my footlong channel cats was also swimming sideways, apropos the heavy dosing of chlorine, no doubt. By the time I ended up shop-vaccing the bulk of the water up aound midnight, he was dead. Fortunately, all the other fish (17 tilapia, 1 goldfish, 3 other cats, and two plecos) withstood the trauma, and are doing fine 2 days later. The dead cat I cleaned, and pan fried for supper last night. I had forgotten how sweet the flavor of catfish was.

During cleanup, I discovered that my growbed pump had stopped working. This was actually good news, as it meant that I didn't have chlorinated water running through the media. I temporarily diverted the fish tank drain hose to run directly into the grow bed. Put in a replacement pump from the local hydroponics store yesterday. In the process of doing that, I apparently bumped the drain elbow on one GB tank and after I went upstairs it started splashing out of the sump on the drain cycles. I came back to another flood to clean up.

I am considering putting the GB pump on a timer to slow the cycles down a bit, but one thing I am most definitely going to do is install a flood alarm with an SMS push.

Farming in Suburbia

We had started out with 11 quail, 2 or 3 weeks old, and kept them in the basement, since they still required a heat lamp. Before going on vacation I made a recirculating watering system for them. After returning from our summer vacation, I built a rack for their cage and moved them out to our back patio. Unfortunately, about this time, the 7 males were starting to crow, which for coturnix quail is little more than a squawk, but at 0500 can be somewhat annoying. Neighbors complained. Next morning we were processing 7 six week old quail before work, and we had them for supper two nights ago.



The hens started laying this week as well. Not sure how many of the 4 hens are actually laying yet, but we've been averaging 2 eggs a day since they started.

I wouldn't mind having one or two males for breeding purposes, but it's really not feasible living where we do, at least not with the current set up.

I've been thinking lately about the art and science of making soil. The large variety of products available at the local gardening supply, and the fact that I have an uncle who made a career in soil geology implies that this post will probably just scratch the surface of such a rich and complex topic.

Soil Defined

Soil is the mixture of fine and coarse solid aggregates (i.e. regolith), gases, liquids, and organisms that together support plant life. It is a substrate that

1. Physically supports plants by their root systems
2. Provides surface area for the microorganisms that convert organic wastes into nutrients to plants (vis-a-vis the Nitrogen Cycle).
3. Retains moisture to buffer water delivery.

Soil is also a sub habitat for organisms, such as worms, that form a part of the human food chain.

Making Soil on Mars

In the MIT analysis I read a couple months ago, there was an ISRU "soil" module for extracting water from Martian regolith, not explicitly for creating soil per se, but it did remind me of a story I read a few years ago when Andy Weir was posting it chapter by chapter on his website. "The Martian" is now a best selling novel and about to be released as a major motion picture. Hopefully it won't spoil the story for anyone by discussing how the protagonist, stranded on Mars, grows potatoes in soil made from his own feces and Martian regolith. This is a kind of attention to detail that most writers don't consider. That said, I doubt it is quite so simple to grow a food supply on Mars (see previous post). For one thing, the light requirements are not trivial, as my basement AP system has shown.

Using Soil on Earth

Earth has the advantage of having had millions of years to work organic matter into the soil. I'm still figuring out how to take advantage of that.

Over the last couple of years, I've experimented a fair deal with growing tomatoes and to lesser degree with potatoes. I can say with certainty, I've grown more tomato plants than tomatoes. The same is probably true of potatoes. This year I have tomatoes growing in:

• AP-phenomenal growth, but no blossoms or tomatoes (my guess is not warm enough conditions in my basement. Pollination might be a problem if I got blossoms, not sure)
• Pots- slow growth largely due to intermittent drought (outdoor pots require daily watering, and I am sometimes negligent), no blossoms or fruit yet. Potted with garden soil.
• Garden- per typical, planted 3 in the garden, amended clay with garden soil and compost.
• Inverted bag planters- did three last year, all pretty scraggly, few tomatoes. This year only planted two of these, one has died. No fruit yet on the other. Potted with garden soil.
• Earth box style planter- so far the most prolific producer of fruit. This is basically a wicking bed system, but is filled with mix of garden soil, coconut coir, and pearlite.

My potatoes are mainly growing in a stackable grow bed filled with straw and dead leaves, with a little manure thrown in.
Last year's crop was unremarkable, possibly due to the cool summer. I got a handful of small potatoes at the end of the year, but had planted a mixture of white potatoes and sweet potatoes. Got no sweet potatoes. This year it's all blue potatoes.The plants at least seem to be doing well so far.

So, comparing soils, it seems that tomatoes really prefer light, good draining soil. I also have a pepper plant and broccoli in the Earth box that are doing better than my garden controls, so I don't think it's just tomatoes. I think the pearlite provides magnesium that maybe helps also. Certainly the wicking bed provides good buffering for water, not quite as maintenance free as my AP system, but close. I think that is the main purpose of the coir, which has a high surface area. Surface area is one of the advantages of expanded clay balls, and I suspect one of the reasons for terra preta and biochar effectiveness.

Back to Mars

I'm thinking coconut coir may not be readily available on Mars, or in the typical CELSS for that matter. Mars soil will likely need nitrogen and phosphorous, so pack lots of asparagus for your trip.

To the Moon

I play soccer with a guy who did some of the original research in making fake poop for NASA to mix with lunar regolith. While artificial poop is probably a more controlled experiment, it lacks the microbial biodiversity of the real stuff. I understand that lunar regolith is fine and sharp. Sounds like diatomaceous earth, which kills insects. Might need to mechanically process it before putting it in your worm bin. Bring biochar to the moon, it's deficient in carbon. Or just make a practice of cremating colonists when they die.

Biological Advantages

One of the things that has me thinking about soil has been watching our new quail poop in their sandbox (and everywhere else, their food, their water, each other). When I change their sand out, the worms will get the poopy stuff, since I understand the worms also like sand for digestion. One advantage of worm composting is that they aerate and stir the decomposing material. BSF larvae supposedly do this to an even greater degree, although I've not yet observed this. The nitrobacter also require a certain amount of oxygen, which is why my aquaponics uses a flood and drain system. Now compost is not the same as soil, it's more like a soil ammendment, the organic component of the soil. Without some structure, it doesn't drain well. Sand and coarser media provide that structure in soil, like the expanded clay balls in my AP grow beds. The biochar provides surface area and probably traps certain nutrients.

Anaerobic fermentation can also break down the wastes, but you end up with more methane, which while useful in other ways, doesn't help plants grow and won't produce breathable air (just ask my wife).

Found out that my neighbor, directly adjacent to where my bees resided last summer along my back fence, just hired a company to spray pesticide with a firehose over their entire yard. Apparently it's an anual event for them to sterilize their habitat, with what turns out to be neonicotinoids. I found out because my other neighbor adjacent to the first, also gardens and has kids. Kids who were outside playing under the trees being sprayed.

I believe it was Shakespeare who said, "Hell hath no fury like a woman scorned." In my experience, a mother bear is a lot worse, and in this case as you might imagine, the mother was livid. My wife also, even though she and the kids were not home at the time.

Last weekend, I sent my wife out to pick up chicks for me and she came back with 11 unsexed quail, 3 weeks old.


The week before, we got a couple of rabbits, but I've been advised by the rest of my family that they are too cute to eat.



That's ok, I mainly wanted them for their poop. The BSF larvae are due to arrive in a couple days. Their compost bin will be right under the rabbits, and the pupae will be fed to the quail and tilapia. The quail are currently in the compost bin, prepping it with their poop.

Crummily, that is. The adjective form of crummy. As in weather. It snowed on Mother's Day again this year, taking out a few tree branches, but hopefully not affecting much else. Still waiting to see if my sweet cherry tree and Chinese pioneer apricot made it- they are still bare. The harsh winter (a week of -20F around the new year) already took out my bees and some trees, including the paw paw I'd replanted. I put in a replacement for it last week, along with some elderberry, and a Cornelian cherry dogwood. The bigger problem this spring has been the atypical monsoons drenching everything and hiding the otherwise prolific sunny skies for which Colorado is supposedly famous. Other than the grass, dandelions, and lettuce/kale, not much is taking off. I ended up mixing dandelions into my first batch of honey wine, since the rhubarb was still not ready.

A good CELSS should be relatively immune from weather (although seasonal insolation changes will certainly have an impact), and with the introduction of the LED grow light, the stuff in my basement aquaponics has been thriving quite well, including the tomatoes, cukes, peppers and eggplants my wife had picked up for me to plant. I haven't bothered to put them outside yet due the lack of decent conditions. On the plus side, the lousy weather has convinced my wife of the utility of a greenhouse.

I planted the chinquapin seedlings indoors, five of them. So far one has sprouted.

It is hailing outside now. The biggest problem with a lack of sunshine is that it is depressing. Grow lights don't quite make up for it.

Bees are gone. Not sure if was CCD or something else. They did leave me a bunch of honey at least, so when the rhubarb comes in I'll be making some rhubarb honeywine. I fed the dead bees to the fish. The tilapia were not super excited, but I caught the cats actually top feeding to get at the floating bees. With a second topbar hive standing ready, I am prepared to kidnap another swarm when the season starts in another month. I'll get the other defunct hive cleaned up and ready too, in case I have opportunity for two swarms.

I hooked up the LED grow light, and could virtually see the plants respond within minutes. It was especially gratifying to see my moringa come back from being a stick. I had to move it in to avoid the cold.

Got most of the garden in, including some companion plants for my fruit trees:
Sweet cherry - Mint, yarrow, pole beans
Tart cherry - Yarrow, nasturtium
Juneberry - Chives, oregano
Peach - Yarrow
Asian pear - mint, pole beans
Crabapples - pole beans
Apricot - Yarrow

Aside from providing ground cover around the bases of the fruit trees, the beans help to fix nitrogen, the yarrow attracts pollinators, is edible, and medicinal. The mint and oregano I transplanted. Everything else, planted from seed.

I was intent on getting some perennials going this year, so planted two varieties of asparagus and some horseradish. The yarrow, mint, and chives should also be perennials. It seems the neighbor's raspberries have run under the fence and are volunteering next to where I planted a different variety of raspberries last year. The strawberries are already blossoming, and the lovage is thriving.

My hugel bed is a big U, planted like this with mostly annuals:

Garlic		Garlic
Dill		Carrots
Cucumbers		Peas/ Radish
Beans		Kale
Onion	Broccoli	Onion
	Onion

Debating about whether to bother with tomatoes this year, previous attempts have not been very successful. I planted an extra two containers with lettuce this year to keep up with my 7 year old, who loves salad. I prefer to keep it in large planters on the patio, for convenience and to keep the rabbits out of it.

Tried grafting apple scions onto my crabapples again this year, so far without success. Looks to be a good year for crabapples though, judging by the blossoms, which made it through the one mild freeze we had in early April.