is that the roof is designed to catch water and funnel it through simple gravel filters into large cisterns buried adjacent to the home.
Here you can see a photo of the actual roof, showing how it catches the water and routes it into the cistern.
This is the first-stage filtration system. The water is pumped through a series of cheap and simple permanent mechanical filters. These never have to be replaced, as the sediment simply collects inside the clear part of the filter. Then you can occasionally open the valves at the bottom of each filter to flush the sediment out. I would probably have included drain pipes to carry the sediment to one of the botanical cells.
This system is not very different from a normal house filtration system. They are just using permanent filters instead of replaceable filters.
The first stage above feeds clean water into sinks and showers. Then it is routed into greywater botanical cells as shown below. These are angled rubber-lined containers full of gravel with a few inches of compost/soil on top. This allows fresh fruits and vegetables to grow in that few inches of compost while reaching down with their roots into the gravel and sand to access more water and nutrients. The plants get plenty of water and the water gets filtered before moving on to the next stage of reuse; flushing the toilets.
Here’s where I really disagree with the water reuse strategy they are using. The black water from the flushed toilets goes outside into another botanical cell. This one is also rubber lined, and it contains a lot more gravel and rocks so it can hold much more black water. These outdoor cells can be used to grow some foods, but it’s basically just raw sewage so it can’t be anything that grows on the ground or you will get coliform and e coli on the food. The water basically just evaporates back into the environment. These trees shown below are growing in one of the outdoor blackwater botanical cells.
There are so many better ways to manage black water than this. Arcosanti did something similar; they just route their blackwater into the bottom of a pond where it eventually evaporates.
Blackwater can be processed in a simple bioreactor to decompose any dangerous chemicals and bacteria before being separated into solids and liquids. The liquids can be distilled to reclaim the pure water that’s just being left to evaporate. The solids can be composted to make high quality soil. Dumping it underneath some gravel is just going to great a cesspool that will never really compost and never really evaporate. This design includes big problems for the homeowners once these botanical cells fill up.
Imagine simply putting a greenhouse over this outdoor botanical cell. The humidity could be condensed to form perfectly clean water for reuse.
A far superior better system would be routing the blackwater into an evaporation cistern. Once a year, switch to a different evaporation cistern. This would allow the cisterns to reclaim the water until only solid material is left, then let that material compost for a year in each previous cistern. This would produce lots of heat for the house while also converting black water into valuable compost plus fresh water. Having three cisterns dedicated to this purpose would mean one is always being filled, one is always composting, and one is always being emptied for use as compost.
Food
As we saw above, much of the food grows in botanical cells using either graywater or blackwater. Here’s what that looks like;
There is actually a third type of botanical cell, the aquaponics cell. We didn’t get to see any examples in the tour, but the basic idea is that you have a tank full of fish which forms a closed loop with the botanical cells. This is actually a far superior system to the system they are currently using. Closed loop aquaponics uses no soil and about 99% less water to grow even more food. It is somewhat more complex and potentially not in compliance with building codes which seems to be one of the main barriers here according to the tour guide.
Edible fish like Tilapia live in a tank and their waste products become food for plants. Check out this video of Michael Reynolds fishing for aquaponic Tilapia in one of the Earthships here. Technically fish water is blackwater containing the urine and feces which plants love. The same aquaponics systems can also manage human waste, eliminating the need to dump blackwater outside to evaporate. Here is a video with a longer explanation of this process including examples from actual Earthships.
Check out my post at Resource Sovereignty about the pros and cons of the different closed loop aquaponics methods and how to implement them.
Unfortunately, food production seems to be less of a priority at the Earthships today. I think a vibrant permaculture program could help turn this around, and I’m very tempted to pitch something like this when I return next year to take the academy classes.
The earthships also have facilities built into the greenhouses for food dehydration. I think dehydrated meats and plants would be an excellent community-business to run out of these kinds of structures. Not just because there are natural advantages but also because preserved foods are a natural staple of people pursuing permaculture on their own.
Garbage management
During the tour we learned that most of the materials used in earthship construction are reclaimed garbage. Since New Mexico does no recycle, the people in the community here have built relationships with local hotels and other businesses in order to take their cans and bottles to use in Earthship construction. They have a similar deal with many local tire shops. These tires, cans, and bottles form the aggregate material for the concrete earthship structures.
There is also a lot of composting done on-site. I think this could be improved by adding the cultivation of insects that eat the compost and are then fed to chickens. Mushrooms would also be an excellent crop to feed the compost to.
Here you can see the interior detail of an unfinished wall which shows the way recycled materials are used both as aggregates and as a way of creating thermal mass as insulation in the walls…
Comfortable (passively heated and cooled) shelter
This is my favorite building I saw on site. It has two separate studio apartments which are basically just the minimal survival design. In between them is a large multipurpose room. All three spaces have greenhouses in the front. The two apartments both have bathrooms which use botanical greywater management as well as outdoor blackwater management…
You can also see the unfinished privacy wall in the foreground.
The windows are all south-facing, with a dirt mound covering the other sides of the building for insulation and thermal mass. Here is a view inside the main multipurpose room facing the front wall from above…
And now the view of the back of the multipurpose room from the same spot. As you can see, this whole structure is essentially just a set of three overlapping apses with concrete on lath. It was poured in a single monolithic pour, with wiring simply bolted on afterwards.
The back of the apse has a north-facing door which opens onto a void in the berm, allowing ventilation during hot summer months.
Just like Arcosanti, these structures are designed to take advantage of the changing angle of the sun during summer and winter. The structure blocks the sun out during the summer and lets it in during the winter. The thick walls and berms are constantly forcing the temperature inside the space closer to the average. During the summer, the thermal mass cools the space. During the winter, it warms the space. In this way, no heat or air conditioning is required to maintain a comfortable interior temperature.
Here’s a solar heating retrofit at a “more normal” adobe building nearby. The air is blown through the heating box where it gets heated by the sun before running back into the building…
Another really cool building was the building known as Eve…
This unfinished building is two stories, and intended to eventually serve as a dormitory for academy students.
One of the features I liked most is the way they did the enormous front windows. It’s wood framed, and then heavy plastic is stapled on both the inside and outside. There is no actual glass, but it still has a six inch gap between the two layers of clear plastic, meaning it’s well insulated. Even without any heat, it was 60 degrees inside in February. These windows are much cheaper to produce and after years of testing they are still holding up well to the conditions.
Opportunities For Improvement?
The philosophy of Earthship Biotecture originates in the 1960s with founder Michael Reynolds. I would argue the philosophy is missing several vital things like internet access, radical water reuse, and a focus on producing comprehensive nutrition which does not require any supplementation to meet all the essential nutrients which we must get from our food in order to survive.
According to the tour guide, only about half of the food people in earthships eat actually comes from the earthship. They buy the rest at grocery stores. This seems like a fundamental failure of the philosophy which should be addressed by improved designs. It would be relatively easy to add things like the cultivation of mushrooms and insects which could drastically improve food production while also reducing the enormous waste of dumping black water in the ground to simply evaporate.
Also according to the tour guide, the community has strongly opposed internet access on the grounds that it would make them part of the grid which they are trying to avoid. For that reason, they are using separate satellite dishes on every house to get slow and expensive satellite internet instead of fiber. This seems like the biggest opportunity for development in the community. It just isn’t possible for people to thrive in the modern world without access to the internet. There is just no argument for making everyone buy slow and expensive satellite hardware when the community could be working together to provide much better access to its members. Each man is not an island to himself. The fact that this community is producing just half of its food is proof of that.
I think the younger generation on-site is very aware of this fundamental contradiction in the orthodoxy of the community. It seems likely that the community’s position on these development opportunities will evolve over time towards something more sustainable, affordable, and mutually beneficial.
The other massive problem with the designs I saw is water waste. They are reusing water, but only a few times, and then it is dumped outside to evaporate. There is no attempt to recover the water from the last stage, and no attempt to use black water for its many valuable potential purposes such as mycoculture, composting, etc. This is an enormous missed opportunity.
One technique from the broader field of aquaponics which could solve this problem is what’s called the swirl filter. Removing solid wastes from water is a problem you already have to solve if you want to get serious about doing aquaponics. Earthship Biotecture is already using a form of this filter with their permanent water filters shown above. There is a useful effect from fluid dynamics which causes solids to fall out of solution when a fluid rapidly changes direction. As you can see in the photo below, the water enters the filter tank around the middle of the height of the tank. It is directed down, and then has to change directions to exit at the top. This causes the solids to fall out of the water. There are also many multi-stage versions of this design which do an even better job. The solid waste at the bottom is collected the same way as with the permanent spin-down filters in the water system shown above. The solids can then be composted.
After you separate the solids, you have to deal with any organic molecules left in the liquids. This job falls to what’s called a bioreactor which is just a similar filter tank filled with sand where bacteria and enzymes naturally break down any remaining toxins in the water.
Another comparable technique for purifying reclaimed black water is varying oxygen saturation over time. The liquids can be diverted to holding tanks in stages where one has high oxygenation and then the next has low oxygen saturation. Specific bacteria can either survive in oxygen or they can’t. They are either aerobic or anaerobic. This is the technique Arcosanti uses to process its blackwater before releasing it into evaporation ponds. Implementing this would be very easy. You could just let the reclaimed blackwater fall through a downpipe with an open top into the aerobic holding tank, then let it sit for a while before cutting off its air supply to let it sit for a while longer. Then all the bacteria inside would be dead.
Other techniques include high powered ultraviolet filters which instantly sterilize the reclaimed blackwater. There is a great deal of published research showing that this technique can also be done by simply laying dirty water out in the sun in clear water bottles. After a few hours of direct sunlight, it is completely sterilized of any bacteria or organic toxins.
I think a really robust blackwater reclamation system will probably use all of these methods and maybe more. This system would be able to infinitely reuse water instead of dumping it on the ground. This eliminates the problem of wasting precious water resources by dumping them on the ground.
The reason Arcosanti felt sort of over is that Soleri chased away any smart people who could have taken his place. He demanded strict compliance with his own vision rather than allowing smart creative people to do their own work. Even now, about a decade after he died, the artisans at Arcosanti are still only allowed to produce bells matching his original designs. And they don’t do anything but make those bells, despite all they could be doing with bronze forging. This is not an environment that attracts and empowers the people who could create the future there. I think this is a fundamental difference between Soleri and Reynolds. Reynolds attracts smart creative people and gives them the freedom to build what they want to build (within the context of his philosophy), and then those smart creative people live in their projects here on site. This means there are close to a hundred unique Earthships located close together on the land in Taos. This community is fundamentally different from Arcosanti because it’s full of people who have complete creative freedom plus a huge incentive to stay in the homes they build and continue to iterate on their designs for the rest of their lives. Earthship Biotecture is the true “Urban Laboratory” which Arcosanti merely identifies as being.