We get 20 gallons per minute of water from our 228-foot well, powered by electricity from Central Alabama Electric Cooperative. But we’re becoming convinced that the US electrical grid is overtaxed, under-maintained, and increasingly brittle. What happens when we can no longer depend on our grid power to be there?
We have a standby propane generator. Although we slept through it both times, the standby generator has kicked on twice in the past year during brief power outages. It’s ideal for a “quick” interruption, say an hour or two, or overnight. But what happens if the power interruption continues for three weeks? Or more likely, what happens when the hours of good service are outnumbered by the down hours,
as it is now in Iraq? Will we run a propane generator all day and all night? If you’re a typical citizen of the US, that sounds ludicrously far-fetched. OF COURSE we can depend on having electrical service! This is America! What’s this doomer been smoking? But you pay me (in a manner of speaking) to connect the dots, so I do. I look at the proportion of electricity in Alabama that depends on burning coal for its production (about 65%), and I read that we are much closer to peak coal than most of us realize. Even if we had an unlimited supply of coal, dare we burn it when we know the effect that the burning of coal has on catastrophic climate change? (Parenthetically, the answer, distressingly, appears to be yes). And even if we had an unlimited energy source available at every power plant, maintaining the grid takes trucks, and chain saws, and big mean mulchers to chew up trees, and miles and miles of wire, all creatures of cheap oil. And even the most optimistic among us must accept that our days of cheap oil are waning. What becomes of the reliability of the grid when utility companies can no longer justify inspections, or routine maintenance? Each of us is free to prepare in his or her own way for this uncertain future. Even as Amanda and I work to reach out to our community and our neighborhood and build resilient relationships, another part of our preparation is to envision living comfortably without a reliable electrical grid. Every system upgrade needs to start with a thorough understanding of the system already in place. Here’s what comprises our energy/water flow now:
1. Connected via the grid to Central Alabama Electrical Coop. Service is above ground until it gets to our property and underground on our property.
2. Standby propane generator with sufficient power to run all systems when the grid power is not available. Transfer switch activates it automatically when the grid goes down, and turns it back off again when the grid power returns.
3. Pumping water now for household use and for drip irrigation from our 228-foot well using a 2 hp electric pump (pump #1).
4. Pole barn is equipped with robust gutters that flow through downspouts to the beginning of a rainwater collection system. At present, the rainwater collects in a 6-inch PVC pipe and runs freely down the hill below the pole barn. We hope to attach gutters to the similar-sized lodge so that its rainwater joins with that of the pole barn, which would roughly double the rainwater harvested from each rain event.
5. We are fortunate to have a 1-acre pond that has never run dry or even lost water depth, even in the worst drought on record in 2007. We are just now beginning to design our “dream” energy/water system. Here’s my current thinking. Let me acknowledge that right now all of this is just thinking; we haven’t yet ordered any of these components.
- Add a collection tank (the lower tank) down the hill from the pole barn so that it catches the rainwater from the pole barn (and probably later the lodge) after a first flush diversion. The lower tank would be about 10,000 gallons and would be equipped with a “push” pump (pump #2).
- Add a storage tank (the upper tank) on what we call the North Knoll, which is the highest point in our Core Campus. My guess is that the upper tank would also be about 10,000 gallons and would also be equipped with a “push” pump (pump #3).
- Add a pump (pump #4) and filter in the pond to use for drip irrigation of Veg Hill, the blueberries and greenhouse, and the orchard.
- Add photovoltaic panels to the south-facing roof of the pole barn sufficient to drive any two of pumps #2, #3, and #4 and to provide additional power as needed for household use. At 10,000 gallons, the lower tank would accommodate a little more than three inches of rain before it fills up (an inch of rain on our 5,000 sq. ft. pole barn roof produces 3,000 gallons of water), or a little more than 1 1/2 inches if we harvest rainwater from the yet-to-be-constructed lodge. If the lower tank fills and there’s no PV power, we would either turn on the pump in the lower tank with grid power or begin letting the tank overflow. In all likelihood, we would begin pumping with grid power if it’s available, but a hurricane-style thunderstorm would eventually overflow the lower tank, because the pump in the lower tank would use little power and would pump slowly, on the order of 5-6 gallons per minute. The reason we’re content for the pump to work so slowly is that under normal circumstances, rainfall events at Longleaf Breeze are infrequent, and they’re rarely more than two inches of rain in an event. And whenever we get that much rain, there’s generally some daylight intervening during which we could pump some of the water up to the upper tank. And of course once the upper tank is full, there will be no more pumping, and if both the lower tank and the upper tank are full, the water will simply overflow. On days after a heavy rain, we may be pumping from the lower tank to the upper tank from sunrise to sunset. Rarely will we need to hurry. We will draw household water from the upper tank. When power is available, the “push” pump in the upper tank will deliver household water pressure (50 psi+/-). When power is not available, the water will still flow, not by pump pressure but by gravity. The altitude difference between the upper tank and the lodge is 30 feet, and the altitude difference between the upper tank and the pole barn (where Amanda and I live) is 55 feet. I’m no engineer, but I have to think that would give us sufficient pressure even at the lodge, and certainly at the barn, to fill a coffee pot, to take a shower, or to brush our teeth. The flow would be slower than most of us are accustomed to having now, but we would have running water. And yes, it would also provide enough pressure to refill a toilet tank, but by the time the grid is this unreliable I expect to have converted everyone else in our household to the delightful
composting toilet I love so much. I am estimating that each person living in the core campus would use about 40 gal. of water per day. I know this is considerably less than the 80 gal. per day that the average American uses today, but if we have reached a point where the grid is unreliable and we are monitoring our water level daily, I expect we will all be frugal with our water use. Amanda and I have decided to size the core campus to accommodate 10 people including us. So at 10,000 gallons, the upper tank would provide 10,000 / 10 / 40 = a 25 day supply of water. If we have 10,000 gallons in the lower tank, that’s a 50 day water supply. If the supply from both tanks ever dipped below a one-week supply (for 10 people, that would be about 10 x 7 x 40 = 2800 gallons), we would pump from the well (using whatever power we have available – PV if available, then grid power if available, then the standby propane generator if necessary) until the upper tank had at least a seven day supply. We always want to maintain enough water in the upper tank for normal household use! Drip irrigation would come from the pond, also powered whenever possible by PV. If we need to irrigate and the PV is spoken for with pumping household water, we’ll use grid power, or we’ll wait until the load on the PV is lower. Drip irrigation is critical for our growing success, but pushing the watering back by a day or two will rarely cause a problem. I understand that NRCS has funds available to help farmers convert their irrigation from groundwater to surface water. I hope and expect that we would qualify for some financial help with this portion of the project. Once the conversion is complete, I expect we would never again irrigate with groundwater. I haven’t mentioned it yet, but now it’s time to use the “B” word – batteries. Batteries seem to be the weakest link of every off-grid electrical system, so we’re working to minimize their use at Longleaf Breeze. But we don’t stop living at sundown, so I expect we will need a modest battery array to give us enough power when the grid is down to run a couple of ceiling fans, a few lights, and maybe a television and a computer without the need to fire up the propane generator. We will make charging them a priority each day using PV power and if necessary grid power. If their charge level becomes critically low, however, we’ll fire up the generator long enough to recharge them. I would love to have all this governed by a master controller that would monitor tank levels and decide when we need to pump from the lower tank to the upper tank, when we need to recharge the upper tank, etc. Maybe one day. At present I lack both the confidence and the patience to try to connect all the sensors in this way. At first, anyway, we’ll just twiddle the knobs by hand based on human monitoring. One last thought: many of you would quickly realize this system would be inappropriate for you, because you can pump water directly using windmills. And if you can, you would be right. Windmills that pump water (as opposed to windmills that produce electricity) are relatively affordable, simple, and almost maintenance-free. We would have loved to design a system using windmills for pumping. We couldn’t make it work, for two reasons: first, and most important, a windmill needs to be above any obstruction within a 400 foot radius, and it needs to be at least 20 feet taller than any obstruction within a 200 foot radius. We fail on both counts in three of the four places where we would need to position a pump. Second, although a windmill is affordable, four windmills quickly get to be cost-prohibitive. That’s why I’ve taken pains to number the pumps in the system we’re contemplating.