Repeatability is a lot like sustainability, but it is not the same thing. Repeatability is to sustainability what fairness is to justice. When we ask, “Is this repeatable?” we expect a conditional answer. When we use repeatability as a criterion, we expect to apply it in different ways under different circumstances.
Sustainability is an important ideal. The concept forms the basis for all our efforts to protect our habitat. It is also a perfectly impossible goal.
If nature teaches us anything, it is that nothing is truly sustainable. In the course of time, everything changes.
Repeatability can be visualized when sustainability cannot.
Repeatability is both practical and flexible. There are two kinds of repeatability that represent success. We immediately recognize the value of repeatability across time. Solar power and wind power are superior choices because the sun and the wind will continue producing energy indefinitely. We are not capable of exhausting them. That is their great practical virtue. But they are also valuable for their repeatability across geography. Everywhere in the world, the sun shines and the wind blows. There are places where sunshine is more persistent and where the wind blows harder and more consistently, but they are essentially available to everyone, everywhere. For that reason, they are enormously versatile sources of energy, capable of running mechanical pumps to bring groundwater to livestock in India or generating photovoltaic electricity that fills a Tesla sports car’s batteries and sends it hurtling down the freeway in southern California.
What passes for sustainable, in the current vernacular, is often only repeatable. Repeatability is the discipline through which we pursue the unattainable goal of sustainability.
If sustainability is heaven, then we need to pray for repeatability. If sustainability is nirvana, then our meditations should center on repeatability.
Sustainability by definition implies an absolute value. Repeatability gives us more attainable incremental goals. It provides us with a better tool for implementing change. Some important improvements may not be sustainable, but they are repeatable for a while.
Let’s look at local food production as an example. When you buy food grown by local farmers, you reduce the amount of energy required to transport that food. You have a better opportunity to learn about the farmer’s land-use practices and to make sure she is protecting the long-term productivity of the land. And you create an economic incentive for the preservation of the land’s productivity. If local foods are valuable commodities, then the farmer and the community have economic reasons for preserving farmland. Local agriculture is more repeatable than large-scale agribusinesses because it incorporates diverse crops and can be delivered in a thousand different ways — car, truck, bicycle, oxcart or on foot. It is entrepreneurial: Anyone who can borrow a couple of acres of arable land can get into the business and enhance the local economy. It is not dependent on big, energy-intensive transportation networks. We contribute to the repeatability of local food production by patronizing local farmers, and the preservation of local farms prevents pollution, improving our air, water and soil, thereby sustaining the food source.
The diversity of local agriculture across the continents makes food production more reliable, overall, since the diversity of local products makes food production more resilient. A spring storm might wipe out the apple crop in Washington. A spring storm in the huge apple orchards of the northwestern United States might destroy millions of apple blossoms. But if enough people are growing apples in small orchards across the country in Massachusetts and Minnesota and New Mexico, then there will be some apples to eat.
So local food production is repeatable, thanks to its economic and environmental advantages, plus it contributes to the consistency — the inherent repeatability — of our food system. Local foods provide a superior choice for many reasons, but prominent among them is its repeatability. We can individually contribute to the long-term stability of our food source by buying locally-grown foods.
As we build local food networks, we provide models for farmers around the world. Local agriculture is repeatable across time and across geography.
Is local food production in your community sustainable? Well, if you live in the Phoenix suburbs or Westchester County, New York, maybe not. To sustain local food production we’ll have to stop building on farmland. Once you put a house on 3,000 square feet of farmland, it’s difficult to ever farm there again. Once you pave it, you’ve killed its productivity for a long, long time. To stop building on farmland we may have to curb the growth of our cities. To curb the growth of our cities we may need to stabilize the population.
Big, unanswerable questions lie between us and a vision of sustainability. But we can visualize repeatability right now. If we focus on repeatability, we might be able to lay a foundation for sustainability.
Fairness and repeatability share this essential value: They can be visualized today, even when sustainability cannot. If we make fairness and repeatability part of our criteria for decisions today, they contribute to sustainability in the long-term even if they don’t provide permanent solutions.
Fairness and repeatability also provide us with tools to measure the relative value of more than one option. I wore through the sole on a pair of shoes recently. The local repair shop charges me over $100 to replace the sole and heal. I could probably replace the shoes with new ones for that price. But the shoe industry is infamous for its exploitative labor practices in poor countries. It would be difficult for me to find dress shoes that I could be sure were not assembled by an exploited 11-year-old somewhere. Furthermore, the leather contains valuable natural resources. Grass, grain, water and air are incorporated, literally, in the cow from which it came. The leather upper on my shoes still looks pretty good. So I’ll have the soles fixed by some local Kansas guys I meet at the counter and I can be pretty sure my decision makes a contribution that is both fairer and more sustainable than buying a new pair of shoes.
We are currently considering whether to add a passive-solar sunroom on our house or to put some photovoltaics up to generate electricity. Which would be fairer? Which would be more repeatable across time and space?
Actually, the first question was whether we had thoroughly insulated the house. Anyone, anywhere in the world, can improve their home’s efficiency by making sure its weathertight and well insulated. Insulation is eminently fair – it can be made from old clothes or sawdust and installed by the occupants no matter how old, young, rich or poor they may be. Our attic contains an absurd amount of fiberglass insulation – between three and four feet – and our energy needs are a fraction of the average in our area. The fairest and most repeatable first step toward an energy-efficient home is good insulation. We install efficient fluorescent light bulbs and digital thermostats that turn off our heating and cooling when we’re not around. We close the shades to conserve our heating and cooling resources. We try to use as few lights as possible and we unplug appliances that are not in use. For energy conservation, simple attention to detail provides the fairest and most repeatable measures we can take.
Then there’s the question of where we get the energy to heat and cool the house.
Our heat comes mostly from propane and a little wood we cut from a small patch of forest on our property. Our cooling is provided by an electric air conditioner. The propane is a by-product of oil refining and the production of natural gas. When natural gas is prepared for distribution, liquid propane is removed. It would need to be removed even if it had no market value. Propane condenses from natural gas and damages pipelines. When oil is refined to make gasoline and heating oil, propane is removed as an undesirable ingredient. About 90 percent of U.S. propane comes from domestic refineries. Only about 10 percent is imported, so the environmental footprint of propane is much lighter than other petroleum products. And if it weren’t sold and burned, it would still be a by-product of the gas and oil industries. And the carbon emissions associated with burning propane are low. Compared with our electricity generated by coal-fired power plants, burning propane generates about one-third the carbon emissions per unit of energy.
Our electricity, on the other hand, is mostly generated by a coal-fired power plant on the Kansas River a few miles north of our house. The coal is taken from strip mines in Wyoming and transported about a thousand miles by rail to our local generator.
Our electric usage, measured in calories, runs about 5 times our annual propane use.
And the electric air conditioner runs our summer bills up to twice the winter costs.
Plus, our capacity to generate our own electricity through wind-generators and photovoltaics is orders of magnitude larger in the summer thanks to long, sunny days and a strong, consistent summer breezes.
My original instinct was to make our passive-solar addition my top home-improvement priority. Superficially, passive-solar technology looks obvious and logical. But when I applied these queries to my own problem it changed our plan. If we wanted to improve the repeatability of our lifestyle, we were better off to generate our own electricity before we addressed our heating needs. Our propane – an inevitable by-product of gas and oil production – has the smallest environmental footprint of any fossil-fuel source available to us. And it will be available as long as someone is burning fossil fuels. Burning coal to produce our electricity, on the other hand, is relatively inefficient and places a heavy burden on the environment. Its “repeatability” gets a poor grade. In fact, we should stop generating electricity with coal now, if we can.
So we’ve shifted our priorities. We are pricing a combination of wind turbines and photovoltaics to store electricity in a bank of batteries in the barn until we can convince the local power company to go to a net metering system or, in our favorite visions, a smart grid.
Photo by Bryan Welch
 United States Environmental Protection Agency. Clean Alternative Fuels: Propane. March 2002. EPA420-F-00-039