The finalists include a lot of inspiring ideas, but my favorite by far is the proposal to have menacing 3,000-foot-tall robots stomp into suburban villages, rip the homes out of the ground, and install them in bleak, Matrix-like hives.

“By radically retrofitting suburbs, the old methodology of horizontal sprawl is supplanted with a scheme of vertical-core sprawl freeing the suburbanite from the demands of automotive travel.” Unless, of course, the suburbanite feels like traveling from his prison tower to one of the neighboring prison towers. The project is green because the robots will drill into the earth to tap geothermal power, which is a great idea for suburban villages that happen to sited on top of active volcanoes.

I’d be remiss if I didn’t also mention Vehiforce: “Generate Energy With Your Parked Car!” This isn’t some pie-eyed scheme to tap into the battery pack on futuristic electric vehicles. No, this is a straightforward idea to put plain old gravity to work by capturing the energy embodied in the weight of your parked car.

I know what you may be thinking: there is no useful energy embodied in the weight of a parked car. And you’re right, but so what! Perpetual motion machines may violate the laws of nature, but they don’t violate the rules of the Reburbia design competition. As one far-sighted commenter says, “I wonder what credentials those ‘physics professors’ possess?” Indeed.

Most of the rest of the entries are variations on the twin themes of slapping lots of windmills all over suburbia and slapping lots of cornfields all over suburbia. (I really like the vision of suburbia as a wine bar/greenhouse in which chefs, small dogs, and young professionals meet to admire fresh produce.)

I gather that the purpose of such exercises is to stretch the imagination a bit, not to put forth strictly practical proposals. The problem here is that entries in the Reburbia competition aren’t imaginative. They’re either totally loopy (turn your parked car into a power plant), totally trivial (put median strips to better use), or totally reductive (replace the local Wal-Mart with a biofuel factory).

Fact is, solutions to climate change are mostly boring and don’t require much imagination. That’s a good thing. For example, making more extensive use of our existing natural gas-fired power plants would do a lot to lower carbon emissions. Waste heat capture is proven technology that could greatly reduce fossil fuel use. Both of these really boring solutions to climate change can be deployed at low cost and massive scale in the near term.

Ending deforestation could solve 20% or more of our emissions problem. Forests aren’t exactly boring, but neither are they a hotbed of radical innovation. Maybe we should send the giant robot towers into the Amazon.

Cement manufacture is a huge source of emissions, one that hasn’t been adequately addressed despite lots of exciting research. And by “exciting,” I mean excruciatingly dull to anyone who’s not a material scientist.

Energy efficiency! Building codes! Who wants to talk appliance standards? Anyone? Hello?

The steady progress in electric vehicles and renewable energy sources is pretty interesting, at least if your tastes run that way. Ironically, though, these cleaner versions of existing technologies may help to perpetuate suburbia, not eradicate it. After all, if your car runs on electricity, and your electricity comes from the sun, and your McMansion is built to the Passive House standard, then your suburban lifestyle is suddenly looking a bit less malign.

Fixing our energy problem presents a deep and long-term challenge, one that requires a steady and fundamental transformation of our infrastructure. Fortunately, we already have many or even most of the tools we need to effect such a change.

Several studies have looked at the climate impact of internet infrastructure and information technology, and other studies have attempted to compare the relative efficiency of internet retailing vs. traditional bricks-and-mortar stores. A new study takes a different spin on the subject, comparing the energy embodied in physical products with their digital, network-based counterparts.

The result is hardly shocking, but it’s kind of fun nonetheless: a life cycle analysis reveals that downloading music digitally creates less than one sixth the carbon emissions of buying it from a retail store (pdf).

The study compares six scenarios:

1. Music purchased from a traditional retail store
2. Music purchased from an online retailer and delivered by truck
3. Music purchased from an online retailer and delivered by plane
4. Digital music purchase (e.g., via iTunes or Amazon.com)
5. Digital music purchase burned to CD
6. Digital music purchase burned to CD and then stored in a plastic jewel case

Even when the consumer burns the downloaded music to writeable CDs, the digital version of an album is environmentally friendlier than the physical version, despite the electricity consumed by the internet delivery infrastructure and the shopper’s computer.

Note that well over half of the emissions of the album purchased from a physical store come from the car ride to the store. This portion of the footprint will vary dramatically based on the purchaser’s proximity to the store and choice of transportation. In the best case — a trip on foot or by bicycle — buying a CD in a physical store has about the same impact as downloading it, burning it to CD, and storing it in a jewel case.

In semi-related news, several universities are experimenting with using the Amazon Kindle electronic reader to deliver electronic textbooks to students — and they’re claiming sustainability as a primary motivation. This notion rubs some people the wrong way. Books are low-tech, durable, and ostensibly derived from renewable resources. Electronic readers are cheap-looking plastic devices that need to be plugged into an outlet and presumably will end up in a landfill when newer models come out.

It’s not clear to me, though, which way the scales tip. Book are not, of course, completely benign. Energy goes into their manufacture, transport, and disposal. Beyond that — and here I speak as a Kindle owner — electronic readers do result in at least some energy savings by supplanting computer use. I suspect that physical books retain an edge over their digital cousins, possibly a substantial one. But I’d be curious to see some actual numbers.

Chevy Volt

GM isn’t the only company to make such claims. Tesla has long stated that its electric roadster gets 135 “MPG-equivalent.” Nissan has responded to GM’s claims by announcing that its all-electric Leaf, also slated for sale in 2010, gets the equivalent of 367 MPG.

Where do these numbers come from? For Tesla, the calculation is straightforward, but that doesn’t make it any easier to interpret:

the total energy used for a full charge of the Roadster’s battery is 62.3 kWh (assuming a 15 percent loss). That’s equivalent to 1.85 gallons of gas for the 244 miles that the Roadster can go on a full charge – 244 miles divided by 1.85 gallons gives us a little less than the equivalent of 135 MPG.

This method of calculating “MPG” has the benefit that it’s completely independent of the energy source. You could apply the same calculation to the space shuttle running on liquid oxygen or to a steam engine running on coal. The enormous drawback is that the number is meaningless to car buyers. No one really cares how many kilowatt-hours are needed to move a car around. Rather, people care how many dollars are needed to move a car around, and they might secondarily care how much carbon dioxide is created in the process.

Using some standard figures for the average cost of electricity, the average cost of gasoline, and the average CO2 emissions per kilowatt of electricity, I translated the Tesla electricity usage into miles per gallon based on both cost equivalence and carbon equivalence with gasoline: 89 MPG and 57 MPG, respectively. These are good numbers — well, OK, they’re great numbers, particularly for a high-performance sports car — but they’re not as eye-popping as Tesla’s original claim.

Nissan’s game of one-upmanship is both brash and, by all appearances, totally bogus. The Leaf comes by its reported 367 MPG by way of multiplier of 6.67. This “incentive adjustment” from the Department of Energy is meant to reward auto-makers for producing all-electric vehicles. Whether or not the multiplier makes for good public policy, it surely has no effect on the fuel economy experienced by the car’s owner. Removing the multiplier knocks the Leaf’s rating down to 55 MPG. Whatever that means.

The figure for the Volt is also hard to interpret, but at least GM comes by it honestly. GM claims to have tested the Volt using a “tentative” methodology developed by the EPA. Although the EPA is staying quiet on the matter, many have speculated that the company wouldn’t be bragging quite so loudly if it didn’t have some tacit support from the agency. According to the informed speculation at Edmund’s, GM’s test methodology was to drive 40 miles on an electric charge alone (0 gallons of gas), followed by an additional 11 miles using the internal combustion engine (0.22 gallons of gas). The total of 51 miles on 0.22 gallons of gas yields a mileage of 231 MPG.

Fine. The problem here is that the Volt operates in two dramatically different modes. In the all-electric, limited-range mode, the car uses no gasoline and so gets an effective gas mileage of infinity. Once the battery is drained, the internal combustion engine kicks in and the Volt gets a more conventional 50 miles per gallon. The blended mileage is exquisitely sensitive to the percentage of time spent in each mode. If GM had decided to test drive the Volt for 80 miles rather than 51, the result would have been a rating of about 100 MPG — still great, but a massive step down from the marketing claim. On the other hand, if GM had chosen to drive only 42 miles, the result might have been a fuel economy rating higher than 1,000 MPG.

A four-figure mileage number would have evoked howls of derision, and the Tesla example shows why these howls would be justified. Along the metrics that consumers care about — $/mile or CO2/mile — the inflated figure would be wildly misleading.

So what’s a better metric? Arguably, for all-electric vehicles, we should ditch MPG altogether. Companies can make all the goofy marketing claims they want, but I don’t see much reason for the EPA to get in on the act. Miles per kilowatt-hour will do nicely, along with charging time and miles per charge, to define a vehicle’s performance. Even better, though, would be kilowatt-hours per mile, which scale linearly with the vehicle’s efficiency.

Plug-ins like the Volt, on the other hand, are a tough case. Because they marry two different energy sources (and possibly two different drive trains), the only thing you can really say about their efficiency is, “It depends.” Some have suggested the cars should carry two numbers: the range in all-electric mode, and the average MPG when the combustion engine is running. Using multiple numbers is not terribly consumer-friendly, but then, neither is using a single number that doesn’t mean anything.

Finally, as Hank at ecogeek reminds us, whatever method we use to measure the performance of electrics and hybrid electrics, these are all very fuel-efficient cars.

The unexpected popularity of the cash-for-clunkers program has sent congress scrambling to find more funding. About 250,000 people have taken advantage of the incentives to trade older cars for ones with better fuel efficiency, burning through the first billion dollars in about a week.

The price tag of the program has given politicians something to argue about, but I’m interested in a more basic question: does it work? The last time I looked at this question, I came up with a somewhat equivocal answer: cash-for-clunkers is an interesting experiment, but it’s tough to pass judgment without some hard data.

Hard data has arrived, and Geoffrey Styles beats me to the punch on crunching numbers. The average trade-in resulted in a better-than-feared 10 mile-per-gallon increase in fuel efficiency:

The corresponding CO2 reduction would be around 700,000 tons per year, which if you figure the cars removed from the road by this program likely only had a few more years of high-intensity usage left in them yields a CO2 abatement cost in the region of $475/ton. As climate policy, this wins no prizes.

He also beats me to the punchline: cash-for-clunkers isn’t strictly an environmental program, it’s a stimulus effort, and on that score it looks to be pretty successful. Nevertheless, given that demand for the rebates has outstripped supply, one obvious way to ratchet up the green value of the program while still pumping money into the economy would be to require even greater fuel efficiency gains. Right now, you can qualify for a rebate by buying a car that gets only 4 miles-per-gallon better fuel efficiency than your clunker. Given that the average fuel efficiency gain has been far higher than this, why not raise the threshold for participation?

In semi-related news, here’s a cash-for-clunker program environmentalists can really get behind: all across the country, states are offering rebates to residents who trade their ancient refrigerators in for more energy-efficient models. Fridges are often the most energy-hogging appliances in your house, and new Energy Star models are vastly more efficient than ones from a decade ago. The rebate programs ease load on the electrical grid, and, in the case of really old fridges, help to clean up ozone-destroying CFCs. In a nice touch, about 95% of the material in the old fridges can be recycled.

The Wall Street Journal weaves the finding into a sort of grand unified theory of the financial crisis:

Maybe what happened to oil prices had something to do with credit markets seizing up. The housing bubble saw people of lesser means traveling further afield to buy homes. That gave them long commutes that they were able to afford when gas was $2 a gallon, but maybe they couldn’t at $3. Housing in the exurbs got hit hardest, and one reason why is that high gasoline prices made it hard for people to lived in them to keep up with their mortgage payments, and hard for them to sell their homes without taking a steep loss. In some meaningful way, that has to have contributed to mortgage problems.

Other, more complicated theories have been offered. It’s surprisingly difficult to to ascertain the causes of a recession, and I can’t stress enough that Hamilton’s paper is in no way conclusive. In fact, the current financial crisis was almost certainly sparked by an interlocking set of problems.

But it’s worth pulling these threads, because the implications for energy and environmental policy are stark. Environmental considerations aside, we may not want to couple our prosperity to a volatile commodity whose price is only expected to rise in the long term. Matt Yglesias makes this point about as well as it can be made:

Today’s economy is built on the idea that the atmosphere can safely absorb ever-increasing levels of carbon dioxide, and that ever-increasing quantities of cheap oil can be extracted from underground. Neither, however, is true.

It also goes to show how fleeting conservative support for “market-oriented solutions” like cap-and trade is. A lot of the liberal enthusiasm for cap-and-trade over the past decade has been based on the idea that it might be more acceptable to conservatives than a straight tax, but obviously that hasn’t turned out to be the case. Basically, they just don’t want to do anything, full stop.

I get the point of this story. It’s supposed to demonstrate the bad faith of opponents of climate change legislation. “We gave you what you asked for, and this is the thanks we get?” While I’d hardly argue the general point, there are a couple of problems with the narrative.

First, a nitpick: a carbon tax and a cap-and-trade system are both “market-oriented solutions” to climate change. Occasionally carbon taxers like to pretend otherwise, in the hope that “market” has become an even dirtier word than “tax.” But, technically speaking, this bit of revisionism doesn’t wash. A carbon tax puts a price on carbon directly and lets market participants decide whether they’d rather pay the tax or reduce emissions. A cap and trade system puts a limit on the total amount of carbon and lets market participants decide whether they’d rather bid for carbon permits or reduce emissions. If these systems sound similar in principle, it’s because, broadly speaking, they are. They’re both market-oriented (or, alternatively, price-oriented) ways of reducing pollution.

More problematically, this narrative implies that liberals came around to a fundamentally conservative policy approach primarily as a sop to their political opponents. But carbon pricing isn’t a defensive crouch on the part of environmentalists — it’s the substantively correct position. The interest group known as “people who don’t want to roast the planet” came around to market-oriented environmental policies because they’re the best shot we have at curbing carbon emissions. Obviously I’m eliding a considerable diversity of opinion here, but the fact is both liberals and conservatives who support carbon pricing do so on the merits.

Next up, there’s the subtext that environmentalists secretly prefer a carbon tax, but they made a pact sometime in the ’90s to back the horse they thought could win. In reality, a large majority of people from whichever end of the political spectrum couldn’t begin to explain how either a carbon tax or cap-and-trade system works, much less parse the differences between the two. Of the significantly smaller group that is fluent in the details, you can find good-faith partisans of all sorts of different policies.

Finally, it bears mentioning that the central conceit of the narrative — cap and trade is more politically acceptable than a straight carbon tax — happens to be true. I’m pretty sure no one ever said cap and trade would unite all interest groups for a rousing chorus of kumbaya. After all, most of the organized opposition to climate change legislation isn’t ideological in nature. The issue, as ever, boils down to money. Any meaningful restrictions on emissions — carbon tax, cap and trade, command and control, whatever — are going to push costs onto polluters, and are therefore going to encounter considerable resistance. But a carbon tax never had a snowball’s chance of passage, and here we are in 2009, with climate legislation looking more likely by the minute.

None of this is to suggest that opponents of action aren’t feckless or opportunistic or whatever. But it’s hardly the case that environmentalists got played on this issue.

Says Scott Segal, chairman of the Electric Reliability Coordinating Council:

… the bill’s silence on a method for allocating credits leaves open the option of an auctioning system that could double up the impact on energy consumers. Those living at or near the poverty level or on fixed incomes, and institutions like schools and hospitals are likely to be particularly hard hit.

Although Segal makes no mention of the fact, credit auctions could also have particularly dire consequences for orphanages and ice cream trucks.

The issue at hand is how carbon credits will be allocated to industry under a cap-and-trade bill. Segal and the companies he represents want them to be handed out for free, rather than sold via auction. His claim is that a credit auction will “double up” the impact on consumers. Both economic theory and real-world experience in Europe suggest that this is not true. The consumer impact is the same in either case.

But a carbon auction allows the government to raise revenue that can be put to useful ends. Such as, for example, providing relief to pensioners, schools, and other groups adversely affected by higher energy prices. Weep not, gentle power companies. Permit auctions are good for consumers.

Way back in 2001, Oregon recognized the problem that many state legislatures are now staring down: gas tax revenue is falling inexorably as vehicles become more fuel-efficient, threatening transportation budgets. The state launched a task force that investigated 28 alternative funding mechanisms before selecting a mileage tax as the one that best met a wide range of criteria: fairness, efficacy, ease of implementation, public acceptance, enforceability, privacy protection, etc.

In 2006, the state recruited 299 volunteers for participation in a year-long trial of a prototype system. Because any real-world mileage tax will be phased in over a long period of time, it has to harmonize with the existing gas tax. The Oregon experiment neatly solved this problem with a pay-at-the-pump system:

• A small GPS receiver in participants’ cars tracked miles driven.
• When participants went to the gas station to fill up, a wireless scanner at the pump detected the GPS receiver and recorded the car’s current mileage, which was then sent to a central database to determine miles driven since the last payment. No specific location data was transmitted.
• The payment system at the gas station applied either the standard gas tax (for cars that didn’t have a GPS system) or the mileage tax (for participating cars). The experiment was designed to be revenue neutral, so fees were about the same in either case.

The other day, I used the fanciful example of $50,000-utility bills to illustrate how cap-and-rebate schemes can inspire energy efficiency and conservation. The numbers were deliberately exaggerated, but they highlight one of the features of cap-and-rebate that I like: the robustness of the system in the face of higher carbon prices.

The political battle over climate change legislation is mostly a battle over cost. Who pays and how much? Even the arguments that seem to turn on fine policy points (safety valves, offsets, circuit breakers, permit auctions, etc.) really boil down to cost. While a high price of carbon isn’t per se a goal of effective climate legislation, a high price may nevertheless be necessary to bring down carbon emissions quickly and steeply. A good system will accommodate high prices without exploding.

Americans have an average carbon footprint of 24 tons per year. As a thought experiment, imagine I offered you the following deal: every year, I’ll charge you $2,000 per ton of your personal emissions. I’ll also offer you a guaranteed $48,000 annual rebate. Would you take the deal?

I bet most Americans would. Think about the behavioral changes that would follow. Every gallon of gas now costs you about $20. Of course, you’ll be able to afford it because I’m handing you a huge check every year. But that Prius is starting to look a lot more attractive, to say nothing of your bicycle. A single cross-country flight is now going to set you back about $2,500. Again, you can swing the expense. But is there something else you’d rather spend $2,500 on? Maybe it’s really important for you to spend Christmas with your family. Or maybe you can send them an e-card.

Of course, we’re not going to see a $2,000 per ton carbon price in my lifetime, which is a good thing. For lots of reasons, such a high price would in fact cause the system to explode. But, at least in theory, most consumers could bear it pretty well under a cap-and-rebate system, and might even end up significantly richer. Given that $100 per ton of carbon might not be too far off, a rebate will not only ease the pain for taxpayers, it will also ease the pressure on our political system to sacrifice the environment for short-term relief.

Who, in this scenario [carbon revenue rebated to consumers], has any new incentive to shift to low-carbon electricity or efficiency?

Short answer: everyone.

Let’s say I’m your utility, and I raise your energy prices so that, at present rate of consumption, your bill will rise to $50,000 per year. Pretend that energy here means everything: heating oil, electricity, natural gas, everything encompassed in a carbon cap. Then I hand you an annual rebate check for $50,000. You can do two things.

1. Give the money right back to me to pay for energy. Money is shuffled. Nothing changes.
2. Use part of the $50,000 to install a solar hot water heater, put in triple-glazed windows, and replace your light bulbs. Then you set your programmable thermostat two degrees lower, throw away your second fridge, and hang a clothesline. All of this will cost you a few thousand dollars, and you’ll slash your energy use in half. Now, year after year, you pocket $25,000 from the rebate check.

This is, obviously, a toy example, but it helps to show where the “money shuffling” criticism of cap-and-rebate goes wrong. When you change the relative prices of things, people shift their consumption patterns, even if they have more money to spend.

Update: Note, also, that your behavior doesn’t really depend on getting that rebate check. If I raise your annual energy bill to $50,000, you’d be a fool not to install the solar water heater and clothesline regardless. The rebate just changes the distributional consequences of the carbon cap. Under a rebate scenario, you actually wind up richer. Under a permit giveaway scenario, the utlity winds up richer.

Another problem with the money-shuffling theory: it ignores the action of the cap. If for some reason people don’t change their energy consumption patterns when they get their rebate checks, then the cap is going to bite. Carbon permits will become more expensive. Prices will rise until people do change their consumption patterns.

A third problem: David says, “Business costs rise, but they get that money back by raising prices for consumers.” This is the persistent fallacy that businesses can pick whatever price they want, so they don’t care about costs. In the real world, businesses care about costs an awful lot. Fortunes are made and empires built on the ability to squeeze costs out of the supply chain. When carbon carries a price, businesses that can find efficiencies or switch to non-carbon sources of energy will be able to pass those savings on to their customers. Then their competitors will go out of business. Then environmental bloggers will do little happy dances, writing about the smart green companies that are growing rapidly, hiring new employees, and wringing a profit from the new green economy. Hoo-ray!

(Note that the logic above also applies to David’s Netflix example. Most people would quit Netflix, pocket the $5, and either join a competing service or watch something on cable. The key thing here is that, under cap-and-rebate, you get to keep the rebate even if you’re no longer a Netflix subscriber.)

Update 2: Other bloggers are piling on. We’re all saying the same thing, but for the record, I was first.