Monday, November 24, 2008
A backyard garden in Oregon
Over the past two weeks, I have examined the challenges facing suburbia in a post-peak world. I’ve argued (in Part 1) that financial reality will prevent us from building an alternative to suburbia, and (in Part 2) that the superficial transportation issues facing suburbia are better viewed as a much broader economic threat posed by peak oil that equally threatens urban and suburban living. In this post, I’ll look at some of the unique advantages of our present suburban arrangement—is it possible that suburbia not only won’t be abandoned post-peak, but that peak oil will act as a catalyst for the adaptation of suburbia into a flourishing, vibrant built environment? I think it’s possible, but that it will be challenging. In this post I’ll explore this possibility—both the potential, and the challenges—of creating A Resilient Suburbia.
Specifically, this post will look at the potential of suburbia to produce some degree of self-sufficiency in food, water, and energy. At one extreme, if suburbia can sustainably produce 100% of the food, water, and energy, then the prospects are excellent for a resilient suburbia.
While true self-sufficiency may be theoretically possible, I don’t think this goal is realistic. Some degree of self-sufficiency, however, is possible. While the majority of this post will address the potential, and challenges, of attaining different degrees of self-sufficiency, there are two additional issues that must be addressed.
First is the degree of self-sufficiency relative to urban settlement. Suburbia is (in virtually all instances) a more energy intensive form of civilization than urban settlement. If, however, after adding the potential resource production of suburbia into the equation, suburbia has the potential to be less net-energy intensive than urban settlement (which, in almost all circumstances, has a lower potential for resource production), then suburbia would be, on balance, more sustainable than urban settlement.
Second, a point which I will raise now but leave unaddressed until next week’s post, is the function of economic coordination. Urban settlement, by its very nature, sits atop a large pyramid of control and dependency--in isolation it is less energy intensive, but it depends on a vast hinterland, the energy requirements of which are often ignored in calculating the sustainability of urban living. Suburbia, in contrast, has the potential to evolve into a flatter, more inclusive mode of civilizaiton (it certainly isn't there now!). Traditionally, urban areas, by virtue of their geographic density, best serve the critical function of coordinating economic activity in a hierarchal fashion. While this function—its costs, benefits, and alternatives—must be considered in weighing the sustainability of different modes of the built environment, I’ll ask that we focus discussion on the first topic for this week’s post.
How much of its own food can suburbia produce? In America, the average suburban lot size is approximately 12,000 square feet. That’s about a quarter-acre. At an average of 2.56 people per household, and a rough average of 10,000 feet per lot not covered by structures, that’s just under 4,000 square feet of yard per person. Of course, this ignores the potential for parks and other open spaces in suburbia to be converted to food-production. It is also an average figure—some neighborhoods will have far less space, others far more. Despite these sources of variability, it is a good jumping-off point. Is 4,000 square feet enough to provide for a person? There are three requirements: calories, nutrition, and the variety and selection necessary to support culture and quality of life. In addition, there are four limiting factors to food production in a given area: sunlight, water, labor, and soil/nutrients. In the interest of space, I’ll only address three of these: calories, nutrition, and soil/nutrients—please feel free to discuss the other requirements and constraints in comments.
Can 4,000 square feet produce enough calories to feed one person? At 26 calories per ounce and roughly 8,000 pounds of potatoes harvested from 4,000 square feet (based on intermediate yields from John Jeavons “How to Grow More Vegetables,” p. 92), that’s 3.3 million calories, or 9,000 calories per day. This is, of course, completely unsustainable, insufficiently nutritious, etc. But it does answer the question—it is possible to grow enough calories on 4,000 square feet per person. The real limiting factors are nutrition and soil, discussed below:
Can 4,000 square feet produce enough nutrients to feed one person while simultaneously sustaining and improving the soil? One issue is that topsoil has been scraped away from more recent suburban developments. How effectively can we re-build soil, and how long does it take? John Jeavons has addressed this question in depth (summarized at p. 28-29 of “Grow More Vegetables”). He concludes that 4,000 square feet is roughly enough to feed one person a complete, nutritious diet, while simultaneously improving soil quality. His method involves 60% (by area) focus on growing soil-improving crops (high carbon content food crops for eventual compost), 30% mixed high-calorie root crops, and 10% mixed vegetables.
I’m sure Jeavons’ is one of many possible ways to approach the problem. One alternative is forest-gardening, depending largely on fruit and nut production from long-lived trees coupled with understory vegetable and root crops. Another, more high-tech route is hydroponics. While I anticipate a lively discussion on these points, I’ll cut my presentation short, closing this point on a simple thought: Jeavons (a practicing expert in the area) argues that 4,000 square feet is realistic. My mother (admittedly, a Master Gardener) is doing exactly this in her roughly 5,000 square foot home garden. I don’t claim it will be easy. I don’t even argue that suburbia can consistently provide 100% of its food production. But I do argue that suburbia can realistically provide around 50% of its food, can act as a localized buffer against disruptions, and can provide a high percentage of vitamins, minerals, flavor, and culturally-important foods.
Critically, while attaining self-sufficiency on suburban lots may not be easy, it is certainly more practical to obtain a significant degree of food self-sufficiency in suburbia than it is in urban settings. This isn’t to say that urban areas shouldn’t explore gardening possibilities—it is simply to point out that suburbia’s food-production potential is an asset when compared to urban settlement. Whether or not its food-production advantage outweighs its transportation disadvantage is not clear—but more on this later.
In the next century, water will be one of the most critical, and scarce, resources for many parts of the world. Even in those areas where there water supplies are plentiful, there is a significant energy requirement to build, maintain, and operate the infrastructure required to gather, store, transport, and purify water. How realistic is it for suburbia to provide its own water, both for domestic use and for suburban gardening?
Many people will initially object to the potential for suburban water self-sufficiency on the grounds that rainfall is erratic, and that some areas of the country are quite arid. While it isn’t the Atacama Desert, skeptics should read Brad Lancaster’s excellent guest-post on rainwater harvesting in Tucson, Arizona (average 12” of rainfall per year). For several years now, Lancaster has been using simple rainwater harvesting techniques at his modest suburban Tucson residence to harvest sufficient rainwater for both domestic needs and to sustain an impressively productive garden. The average suburban home has a roof area of roughly 2000 square feet (garage roofs and overhangs count here, but not on home square footage). In Tucson, with 12” of rain per year, that catches as much as 14,000 gallons per year (or 40 gallons per day)—more than enough for frugal domestic usage by one family, though certainly not enough for several hot baths, a backyard pool, and multiple loads of laundry daily. In wetter climes—say, Ohio with 37.77 inches per year on average--the potential is even more clear.
Two concerns for rainwater harvesting are droughts and purification. Lancaster’s article, and his several books on the topic, address both in depth. Bottom line: storage and purification are relatively simple, cheap, and require little energy, though the solutions are by no means fool-proof. In perhaps one of the greatest differences between suburbia and urban areas, suburbia has the clear potential to be water self-sufficient, whereas dense urban areas do not.
What about the potential for suburbia to produce its own energy—for heating, cooling, cooking, lighting, and transportation? While suburban homes tend to use more energy than urban homes—for all of these requirements, with the possible exception of cooking—does their potential to produce energy compensate for this?
Let’s start again with the average roof area of a suburban home: about 2,000 square feet, or roughly 780 square feet per person. Solar photovoltaics have the potential to produce roughly 180 Watts per 15 square feet, or 12 Watts per square foot (one sample spec sheet - .pdf). That works out to about 24 KW per house, or about 9 KW per person. Cut that by two-thirds to confine placement to properly oriented sections of the roof, and the average suburban home can install roughly 8 KW of photovoltaic panels (or 3 KW per person). What percentage of a home’s energy needs would that provide? First, it’s important to note that 1 KW of installed capacity doesn’t equal 1KW-Hour of production for every hour of sunlight—it provides significantly less, depending on location and weather. Based on a very informal survey of conservation-aware households, a WAG is that 20 KW-Hours per day, per household is realistic (probably conservative) for suburban electricity usage with some focus on conservation. Using the rough metric of 1300 KWh per year from 1 KW installed capacity, our hypothetical suburban household would require 5.6 KW of solar capacity. In other words, there’s plenty of roof space in suburbia to meet suburbia’s electricity demand. Two important caveats: 1) such a system won’t provide power when suburbanites currently use it (a net-metering system paired with other forms of generation would be necessary), and 2) while some households use electricity for home heating, water heating, and cooking, in many areas and homes it simply isn’t realistic to heat a home with 5.6 KW of installed solar power only.
While I’ve been focusing on photovoltaics (actually one of my less-favored forms of renewable energy) because they’re readily available and easily understood, I think that solar hot water, passive solar heating, and increasing insulation and on-demand ventilation are actually more promising means for suburbia to generate its own power. By combining passive solar hot-water and air heating with sufficient thermal mass and improved insulation and sealing, it is possible to provide nearly all energy requirements for the vast majority of suburban homes using only that home’s roof space. Urban homes often lack one of the key features of suburbia: plentify solar access. The vast majority of suburban roofs have excellent solar access--though some tree-pruning may be required. Even moderately dense apartment blocks (not to mention high-rise residential) does not have the necessary insolation to power itself through in a distributed fashion. In the interest of space, I’ll leave discussions of home geothermal and heat pumps (promising), home wind-power (less promising), and home wood-lots (less promising) for another day.
While these kinds of retrofits cost money, by improving the viability of suburban homes they don’t face the same kind of financial Catch-22 addressed in the first post in this series (whereby it isn’t possibly to finance alternatives to suburbia because credit markets are tied to the value of suburbia that is destroyed by the creation an alternative).
Additionally, it isn't realistic at present to think that we'll be able to put enough solar panels on our roofs to charge the batteries on the twin electric-Escalades sitting in our garage for the daily commute to work. I increasingly believe that suburbia can be resilient and sustainable, but not as a mere "Star-Trek" version of the present. Rather, by minimizing our travel requirements at the outset, and then transitioning to high-efficiency vehicles, ridesharing, bicycles, and especially electrified rail for remaining journeys, suburbia can adjust to a radically lower transportation energy-budget.
Suburbia has a significant potential to provide its own food, water, and energy. It won’t be as simple as snapping our fingers. And it likely won’t be possible for suburbia to consistently produce 100% of its needs. But I think one thing is quite clear: the potential increase in suburbia’s self-sufficiency is significantly greater than the potential for urban areas to increase their self-sufficiency in food, water, and energy. We can argue the degree to which this is the case, but I’ll be interested to see if anyone seriously disputes the issue generally. If we accept that suburbia has greater potential for self-sufficiency, and if we accept that suburbia requires more energy for transportation and transportation infrastructure in its current manifestation, then the big question is this: does suburbia’s advantage in potential self-sufficiency outweigh its disadvantage in transportation? It's quite easy to toss out an unsupported opinion on the answer--I won't attempt to do so, and I'll caution that anyone who does, without empirically and irrefutably answering the potential for suburban self-sufficiency, is just guessing. The answer partially turns on the degree to which suburbia can convert itself away from a commuter model and toward a knowledge-based, distributed production model. It also, as I’ll discuss next week, turns on the value of distributed ownership and self-sufficiency as a force in determining the political structure and evolution of civilizations.
Monday, November 17, 2008
In the second post in this series on suburbia and peak oil, I’ll consider one of the threats that peak oil poses to suburbia: the increasing cost of commuting to and from work for suburban residents. My conclusions may surprise readers: suburbanites aren't particularly vulnerable to the rising cost of gasoline. Instead, like all of us, they are vulnerable to general economic shocks that may be caused by peak oil, but the elasticity of their commuting budgets may better position them to deal with these shocks than urban residents.
The first thing that comes to mind when people discuss peak oil and suburbia is the massive amount of gasoline used to commute to and from work. I think this is also the least problematic. However, to the extent that it is a problem it won’t result in the abandonment of suburbia—rather, it will act as a catalyst to reshape the economic structure of suburbia.
For the purposes of this article, I’ll discuss the hypothetical suburban commuter who drives 10 miles to and from work 22 days each month. I realize that many suburbanites drive farther than this, and that some drive shorter distances, but it’s an easy number to work with. Here’s a graph of what that commute costs each month at varying prices of gasoline and vehicle MPG figures:
Not very scary, is it? It’s important to remember that most suburbanites drive more than just to and from work, that most suburban families are two-income/two-commute families, and that there are more costs of commuting than just the gasoline (auto depreciation, parking, etc., though these don’t generally increase with increasing gasoline costs). So let’s make a more extreme, scary, and arguably realistic graph. Here’s the cost to a family that drives two cars 40 miles each per day, plus 48.5 cents per mile (the IRS business deduction) as an approximation of cost of car-ownership, plus $10 per day for parking for each commuter, plus $100 for insurance for both cars (that’s $1394/mo baseline plus the cost of gasoline):
There’s a number of take-aways from these graphs: 1) these numbers are higher than average cost of commuting, 2) to the extent that they’re accurate, commuting is VERY expensive, 3) the majority of the cost of commuting is the base cost, not the gasoline, 4) for most suburbanites, the ability to afford life in suburbia is more a function of the shape of the overall economy (e.g. the earning power of suburbanites) than it is a function of gas prices in isolation.
What are the options to commuting? First, looking at the graphs above, it should be clear that eliminating a suburban family’s need for one of their two cars will have a greater effect than doubling the miles per gallon of both of their cars. There are many ways to do this: ride sharing, mass transit, and telecommuting are the most obvious.
Ridesharing (Carpooling): For all the talk about improving vehicle efficiency, there are few solutions that are simpler, more elegant, and more practical than putting more than one person in each car. For our hypothetical suburban family in the example above, if the happy couple can drive to work together and only maintain, insure, and park one car, they would save $697 after-tax dollars per month--and this is assuming no reduction in car-miles driven. Similarly, workers can organize car-pool clubs, etc. The downside of ridesharing is inconvenience. It’s convenient to only go straight from your house to work and not pick anyone up along the way. It’s convenient to pick when you commute. It’s convenient to have access to a car while at work in case you need to run an errand, etc. If, for our hypothetical family above, they can afford $32/day and the convenience gained is worth more than that, then it probably makes financial sense to drive alone (ignoring environmental arguments, etc.).
Mass Transit: Mass transit is another option for most suburbanites. Again, the viability of mass transit is a matter of weighing the cost savings against the inconvenience. In some cases, mass transit may actually be more convenient, but for most suburbanites it 1) takes longer, 2) is less flexible, and 3) doesn’t address the “last mile” and still requires one car (and its associated costs) per commuter.
Telecommuting: Working from home, one or more days per week, is another approach to making suburbia viable. This is already a common practice, and the ability to expand upon it has been explored here before.
I sense that, at this point, many readers will be a bit baffled by my focus on the base cost of commuting rather than the variable cost of commuting caused by higher gas prices. This is, after all, an article about peak oil and suburbia. I think it’s critical to focus on this differentiation—-the base cost of commuting vs. the variable cost.
If the variable cost (as gasoline gets more expensive) of commuting is what will kill the finances of suburbanites, then urbanites will be far better positioned to adapt to the impact of peak oil. They don’t have these long commutes, they often don’t have a need to own one car per family, let alone 2+. However, if it’s the base cost that is the primary issue (as I argue here), then we need to envision the scenario where suburbanites can no longer afford this base cost. This is even more true to the extent that America’s auto fleet gradually improves in efficiency (a topic I have largely ignored).
As long as suburbanites maintain their present income levels, they should be able to afford their present costs of commuting--in most cases rising gas prices won't break the bank, and can largely be addressed through improved efficiency. However, a sharp economic downturn has the potential to dramatically reduce these income levels. Here’s the key: a sharp economic downturn will most likely reduce urbanites’ income levels by a similar amount. So while these economic troubles may make life in suburbia much more difficult, it will also make life in urban areas much more difficult. Precisely because the issue is base cost of commuting, not variable cost, this economic impact is felt equally in suburban and urban areas. In fact, because there are so many viable (if inconvenient) options for suburbanites to reduce base commuting costs (outlined above), it may be easier for suburbanites to adapt to a sharp economic downturn than urbanites. Cutting down from two commuter cars to one could cut a suburbanite's total expenditures by 10-20%+ per month without great change. That's a large chunk of suburban budgets that is quite elastic, and lends a great deal of resiliency to suburbanite finances. How many urban households can cut expenses by this much merely by doing something as simple as carpooling?
My purpose in writing this series is not to make a partisan stand in favor of suburbia. Rather, my intent is to push the debate beyond “suburbia sucks” to the more important question of how we will address its weaknesses. As I argued last week, it isn’t practical to think that we’ll simply abandon suburbia in favor of some preferable urban option. This week, my conclusion is that suburbia may actually be no worse situated to deal with the economic impact of peak oil than urban areas. It is the base cost of commuting, not the variable cost, that most impacts suburban finances—-suburbanites have already (by definition) budgeted for this cost, and have more viable options to reduce this cost than urbanites have viable options to comparably reduce their expenditures. Next week I’ll argue that suburbia may be more than on equal footing with urbia—-it may actually be better positioned to deal with the more extreme potential impacts of peak oil such as food shortages, water shortages, and energy shortages.
Monday, November 10, 2008
Many argue that suburbia was a terrible idea—a giant waste of land, capital, and culture. I largely agree. But there you have it: suburbia happened, with no refund available. It is a sunk cost—not only the millions of homes, but the vast infrastructure for transportation, employment, governance, and distribution that is fundamentally intertwined with the suburban model. Looking into a future of energy scarcity and economic challenge, it is time for the discussion to shift from “suburbia sucks” to “what are we going to do about it?” Is it possible to build a vibrant, sustainable, and self-sufficient civilization on the framework of existing suburban development? More importantly, is there any viable alternative? This four-part series will take a critical look at suburbia in an environment of peak oil, beginning with this post’s discussion of sunk costs and credit markets as they impact our options.
This series will consist of four separate posts: 1) this post, on sunk cost and credit, 2) a discussion of the suburbia’s economic prospects and the challenges of commuting and production after peak oil, 3) the potential and limitations of producing food, water, and energy in suburbia, and 4) the impact of decentralization, self-sufficiency, and lessons from history as they inform our “solutions” to suburbia.
In this first post, I will develop the argument that sunk cost and the current credit crisis prevent any the development of any meaningful alternative to suburbia. Specifically, suburbia presents a Catch-22 situation where the theoretical viability of an alternative effectively destroys our ability to either leave suburbia or build that alternative. This is a crucial foundation to this exploration of suburbia: because there is no alternative that is both theoretically viable and realistically implementable, we must focus on adapting suburbia to a post-peak oil future.
For most readers, the threat posed to suburbia by peak oil and generalized resource scarcity is clear. I won’t detail the exhaustive arguments in support of this proposition, but briefly: peak oil threatens our ability to commute from suburbia and transport supplies to suburbia; suburban civilization is dependent on cheap energy to heat, cool, light, and transport and purify water supplies; suburban America represents too large a population for any viable, unified version of America to continue if it truly “fails” without a suitable alternative.
Suburbia in light of its alternatives: I think that we can all agree that suburbia is imperfect, perhaps even fatally flawed. What I propose is that the task, going forward, is not whether suburbia is “bad,” but rather an evaluation of our options informed by a realistic appraisal of the alternatives to suburbia. It’s fine to say that suburbia is too dependent on long, oil-powered food supply lines. What is the alternative? It’s fine to say that suburban residents will soon be unable to commute to work, and that will render suburban living untenable. What is the alternative. In the initial phases of a debate, it is valuable to refine criticism, to point out flaws. We must now move past that. Most of us understand the flaws of suburbia, but we are now at the point where it is only productive to point out a flaw if we do so to argue why a specific solution is preferable.
What are the alternatives? For my own purposes, I’ve divided the spectrum of choices into re-urbanization, re-ruralization, and clustering, but I’m interested to hear how others would categorize our choices. I will discuss each of these in a later post, but first it is necessary to outline the key hurdles facing any effort to shift to an alternative: the sunk cost of suburbia and the paucity of credit to finance such a shift.
Sunk cost is the economic concept that some costs, if they cannot be recovered once they have been incurred, have significant effects on our decision making. What is the sunk cost of Suburbia? Individual homes, for individual buyers, may not entirely represent “sunk cost” if they sell immediately, though to the decline in prices over the past months does represent sunk cost. If everyone in suburbia wanted to leave, however, then the entire suburban project--tens of trillions of dollars--would represent a sunk cost.
In layman’s terms, if you bought your house for $200,000 but can only sell it today for $50,000, then your sunk cost is $150,000. Even if you didn’t have a mortgage, that would represent a significant disincentive to selling. If your mortgage is $185,000, and you have no savings to make up the difference, you are in an even more inflexible situation. However, from a societal standpoint, the sunk cost in suburbia is even greater than the sum of its home values. There is a tremendous amount of energy invested in these homes and in the infrastructure to support them. While suburbia may be highly energy-inefficient, at some point in the not too distant future (possibly today) it will no longer be possible to replicate that kind of energy investment to create a sustainable alternative.
As the example above illustrates, declining housing values make suburbia more inelastic. As prices go down, people are less able to move out of suburbia to an alternative. To the extent that rising energy prices make suburban house values decrease, they also act to make it more difficult for suburbanites to move to more energy-efficient locations.
Similarly, as credit markets remain tight, it is increasingly difficult to both afford a move to a more energy-efficient home, as well as it is increasingly difficult to finance the development of more energy-efficient projects (whether “new urbanism,” condos, light-rail systems, or energy-retrofits of existing suburban homes).
There is a feedback-loop between declining house values and tight credit markets. Declining home values and increasing foreclosure rates (one result of declining home values) undermine the viability of mortgage-backed securities (and send shockwaves into the credit default swap markets). This makes credit tighter, decreasing the pool of people able to buy homes, which leads to further home value declines, ad infinitum. This is the core of our current financial crisis.
The even more critical problem, however, arises when that feedback-loop process interacts with peak oil. Absent the challenges of peak oil, the above cycle can eventually be “solved” through some combination of market forces and government intervention. However, if we accept that peak oil presents a challenge to suburbia, a Catch-22 situation arises. To the extent that suburbia retains its value over the long-term, we can afford to build an alternative to it that addresses the energy challenges facing suburbia. But if suburbia does maintain its value, where’s the motivation to do so? To the extent that energy challenges undermine the viability of suburbia, causing a desire to move to an alternative and a decline in the value of suburban homes, our ability to finance that alternative is destroyed.
That’s exactly the catch: to the extent that we need to end the suburban experiment, we aren’t able to do so. To the extent that early adopters “get out” soon and buy in to more sustainable alternatives, the vast majority who are left behind are increasingly stuck. For this reason, suburbia isn’t going anywhere—at least not in my lifetime. This is not to say that suburbia won’t undergo dramatic change. It will, but we're stuck with its basic existence. The potential and great challenge of making something sustainable and life-affirming out of the fact of suburbia will be the topic of the rest of this series.
Monday, November 03, 2008
Sunk cost fixedenss: In the '90s and early part of this millenium, the United States invested in massive natural gas-driven electricity generation capacity. Now, with natural gas much more expensive, that sunk cost is forcing up the price of electricity. Likewise, while it is certainly possible to generate the power needed to get our cars and trucks from point A to B, we've invested in a hugely expensive fleet of liquid-fuel driven vehicles. There is a great deal of fixedness introduced by this sunk cost, and it is slowing the transition to both electric-powered vehicles, and to our transition away from single-commuter modes of transportation.
Project timeline fixedness: Additionally, the increased volatility in energy supplies is wreaking havoc with the long time-lines to plan, permit, and build our energy infrastructure. Not only does it take years to get a project off the ground, that project must operate for years to decades to be financially viable. Because we effectively lock in energy choices a decade or more in advance, the volatility of supply and demand for different types of energy, and the volatility for demand at different locations is causing serious problems. It has taken over a decade to get a liquid natural gas terminal operational in Baja California (to serve San Diego and Los Angeles), during which time the viability of LNG, the global demand, and the supply, have all dramatically shifted. It takes over a decade to bring a nuclear plant online in the US--how certain are we about our supply of uranium 10+ years from now, especially when China can (and is) bringing on new nuclear plants in two to three years, meaning the demand picture will shift significantly before our plant ever gets online. The credit crisis--both in terms of capital availability and the illiquidity of long-range derivatives to hedge energy supply isues--is only exacerbating this issue.
Geopolitical fixedness. If oil (or gas, or coal, or uranium, or rare earth metals used in photovoltaics, etc.) was equally available from anywhere, then geopolitics wouldn't enter into the discussion of supplies. But because resources are increasingly located in geopoliticaly challenging locales, the worlds of geopolitics and energy are increasingly interrelated. Europe is largely dependent on Russia and North Africa for its supply of natural gas, for example. Because of the massive investment necessary to bring trans-national pipelines to operation, long-term commitments to certain geopolitical alliances are required. Additionally, because these infrastructure assets represent fixed-targets, they incur very fixed vulnerabilities for consumers.
Now, it's important to point out that energy fungibility as it existed in the 20th Century was truly a historical anomaly. The utter dominance of the West over global trade routes and the temporary surplus of high energy-surplus, easily transported, and truly interchangeable crude oil created a "golden age" of energy fungibility. This didn't exist in the Middle Ages, in Rome, at the height of the Caliphate, or at any other time in our historical past. In fact, the level of free energy that we enjoyed during the 20th Century was a huge historical abberation. It funded the explosive growth in population and in the "middle class." It has come to an end. Oh, there will be plenty of energy around for quite some time to come, but phenomena such as decreasing fungibility of that energy will make our access to it--and our enjoyment of the benefits it provides--far more intermittent, far more regionally concentrated, and far less certain.