Here’s the prototype front porch in action.
Believe it or not, peak phosphorus is probably our biggest global emergency. I don’t know about you, but I don’t hear anyone talking about it.
Phosphorus is one of the most the important elements of life. It is a major component of RNA, DNA, and ATP (the molecule produced by photosynthesis that carries energy to the other plant cells – which in turn provide us with energy).
Of the nutrients used as building blocks for life, the following elements all have gaseous phases at the temperatures and pressures found on the surface of the Earth and are therefore easily redistributed through the air:
However, the following elements are solids or liquids and don’t move around so easily:
- …64 more
In a natural ecosystem or on a traditional small farm, plants take these molecules out of the soil and air to build themselves. Animals eat the plants and use the same molecules to construct their bodies. When the plants and animals die, microbes return the molecules to the soil. Lather, rinse, repeat.
On the other hand, with our current industrial agriculture system the plants do their part and take in the molecules they’re supposed to, but then we ship them to a feedlot or city where they are consumed and decay far away from where they originated. The molecules of the elements easily transported by air are replaced relatively easily, but the molecules of solid and liquid elements won’t make it back to the field they came from for a long, long time.
Phosphorus is more sensitive to this imbalance than the others because it is 10X more concentrated in the body than it is in the Earth’s crust. None of the others are more concentrated in living beings like that.
To replace the missing phosphorus, we mine phosphate rock and sprinkle that on the soil for the plants to use as RNA, cell walls, etc. This seemed like a great idea when we figured it out 170 years ago. It continued seeming like a good idea all the way up until about 40 years ago when we started noticing the two big problems with this system:
Big Problem #1
Phosphorus that doesn’t get used is washed away by rain into rivers and eventually into the ocean. Phytoplankton (algae) in the ocean are very happy with their newfound abundance. They grow fat and reproduce prolifically. The problem comes when they die. As the algae is decaying, the bacteria breaking it down use too much of the oxygen dissolved in the water, killing everything else in that area.
Big Problem #2
We’ve already used half of the phosphate rock available. According to a study by Patrick Dery peak phosphorus occurred in the US in 1988 and the rest of the world in 1989. Others think we’re still 30 years away from the peak, but it doesn’t matter who’s right. Either way, unless we change what we’re doing now, we will have depleted our supply of the central building block of life within a few hundred years of discovering it, and we do not know how to make more.
Current uses of mined phosphate rock:
5% animal feed supplements.
5% soft drinks, toothpaste, etc.
Fortunately, the solution is easy. We did it for our first 100,000 years, and we’re the only creatures not currently doing it. The answer is eat, poo, and die in one place.
That doesn’t mean we all have to be farmers, but it does mean we need to be localvores and get over being sqweamish about the fact that we’re animals that are part of the web of life.
Plant food in your yard. Buy the food you don’t grow from local farmers. Insist on pasture raised meat. Compost every organic material you can find. Crap in a bucket. When it’s time to die, have yourself planted in the ground without preservatives so that a tree can build itself out of the molecules you’ve been using.
Conventional wisdom says that overgrazing causes desertification of rangelands. Allan Savory says that’s dead wrong.
Plants have external digestive systems. We animals have microorganisms in our guts to break down food and make it useful to our cells, but plants don’t have that luxury. Their digestive bacteria and fungi live in the soil.
Savory divides the world into two areas:
In areas with a year-round high humidity, dead organism decay rapidly, and bare ground is quickly covered with vegetation. These areas cover about 1/3 of the planet’s land area.
The other 2/3 of land area has prolonged dry seasons. During the dry season, plant matter dies, but the microorganisms that the plants need to digest that organic matter also die off. Instead of being digested, dead organic matter is standing. Since it doesn’t mulch the ground, the bare soil doesn’t retain moisture. New plants dry out before they get established.
In brittle environments, the bacteria in animal digestive tracks stays moist and alive during the dry season. Brittle environments require animals to build healthy soil. Before we humans screwed it up, massive buffalo herds in the US midwest would decimate the plant life in an area. However, at the same time they fertilized that area, and they moved on quickly allowing the plant life to recover. This cycle resulted in some of the thickest, richest top soil in the world in a semi-brittle environment.
Savory says overgrazing isn’t what’s turning brittle grass lands into deserts. A lack of animals is. In the US, the natural grazing animals are long gone, and for the most part our domesticated grazers don’t even live on the grasslands anymore. Our corporate industrial farming system has relegated grazing animals to hellish feed lots. Vast tracts of range land are left fallow, which most people would expect to be a good thing, but the plant life isn’t recovering. It’s digestive system is missing.
Smart land management in brittle environments mimics those natural buffalo herds and restores the land by intensely grazing it and moving the animals to new pastures often.
In this 1 hour presentation Savory goes into more detail and shows some convincing photographic evidence. He also argues that humans have been causing climate change because of this misunderstanding for a very long time.
For more information:
And his books:
In their new book, Time to Eat the Dog: The real guide to sustainable living, Robert and Brenda Vale explain that dogs and cats eat a lot of protein, and our agricultural practices have a big impact on the environment. Their research showed that the eco-footprint of a Land Cruiser driven 10,000 miles per year is about half that of a medium-sized dog.
New Scientist has a good summary of the study: Link
Since there are no moving parts, PV doesn’t require any maintenance except cleaning the glass. The photovoltaic collector doesn’t fail. If a panel fails it’s usually because a solder joint connecting the cells fails. Most manufactures warranty their panels for 80% of rated output for 25 years.
Inverters have traditionally been the weak point in the system. Mean failure rate has been 5 years. 2 year warranties were the norm in the late 1990s. 5 year warranties are common now, and some manufacturers offer 10 year.
Central String Inverters
PV panels produce DC power which is either used directly by DC lighting and appliances or wired to a central inverter, typically located indoors. An NREL study (PDF page 41) found that inverters have needed to be replaced every 5-10 years while panels last 25 years or more.
Central inverter PV systems are wired in series like Christmas lights. Central inverters use a Maximum Power Point Tracking (MPPT) algorithm to determine the optimal output of the system. Therefore, the output of the whole system was only as good as the worst performing module. If there is one bad solder connection, one dirty cell, or one partially shaded cell the whole system is affected. Just like Christmas lights it is impossible to find a problem without testing every individual part.
German and Austrian central inverters are the best quality because their government incentive programs require installers to warrant the system for 10 years which put pressure on manufacturers to improve their reliability to stay competitive. North American manufacturers have not kept up.
That’s all changed with micro-inverters. They mount outside attached to each panel. With micro-inverters AC power leaves each panel. There’s less inefficiency due to DC voltage drop. The Christmas light problem is solved. Micro-inverters get as much energy out of each panel as it can produce, so partial shading is no longer a problem. If an inverter fails the rest of the system still functions, and it’s a relatively small replacement cost compared to a central inverter.
Micro-inverters are also designed to be much more reliable. Enphase credits four things:
- Micro-inverters process relatively small amounts of power at low DC voltages which allows them to incorporate more components on the semiconductor chip rather than soldering together a bunch of analog electronics.
- Because of the small amount of power processing, the temperature rise is lower. In fact they use passive cooling rather than fan cooling like traditional inverters.
- NEMA 6 enclosure is air, water, dust, and insect tight. Traditional inverters are like computers with cooling fans actively flowing dust into the enclosure.
- Potted design. The enclosure is filled with “an encapsulating compound” which improves heat dissipation and provides component protection.
Traditional inverters use electrolytic capacitors which are notorious for their short life. Microinverters still use them, but they use a more durable design. From Enphase Reliability Study for Electrolytic Capacitors:
“For traditional power converters, an acceptable useful life of capacitors is as low as 2000h at 85°C. Out of desire to increase the reliability of its inverters, Enphase Micro-inverters use capacitors rated from 4000 to 10000h at 105°C. The capacitor lifetime is very sensitive to temperature as its useful life doubles for every 10°C temperature drop.”
Enphase also parallels their capacitors. When one fails the quality of the current wave degrades because it gets a little more ripple in it, but it’s not catastrophic to the inverter.
Since micro-inverters are a new development there’s no lifespan data. In an Enphase white paper they compare their Mean Time Between Failures (MTBF) determined from accelerated lifecycle testing to other electronics:
“The concept of MTBF is often confused with a component’s expected useful life. In fact, these concepts are not the same. For example, a battery may have a useful life of four hours and have an MTBF of 100,000 hours. These figures indicate that in a population of 100,000 batteries there will be approximately one battery failure every hour during its four hour lifespan.”
Enphase has a 600 year MTBF goal, which would make integrating micro-inverters with solar panels at the factory the default. At that point solar panels will be truly plug and play.
The one downside to micro-inverters seems to be for off-grid systems. Since each panel is putting out AC power, you have to have another central inverter to convert it to DC to store it in the batteries.
There are at least a dozen companies working on micro-inverters, but Enphase is the only company shipping a product that we’re aware of.