Residents of Hammarby Sjöstad, a district on the south side of Stockholm, Sweden, don't let their waste go to waste. Every building in the district boasts an array of pneumatic tubes, like larger versions of the ones that whooshed checks from cars to bank tellers back in the day. One tube carries combustible waste to a plant where it is burned to make heat and electricity. Another zips food waste and other biomatter away to be composted and made into fertilizer. Yet another takes recyclables to a sorting facility.

Meanwhile, wastewater is taken to a treatment plant, from whence it emerges as biosolids for more compost, biogas for heat and transportation fuel, and pure water to cool a power plant, which also runs on biofuels grown with the biosolids. Looking at a chart of all this is enough to induce dizziness. "In terms of what you can do at the local level for energy efficiency and renewable energy, it's incredible. It's just amazing," says Joan Fitzgerald, author of Emerald Cities (Oxford University Press, 2010).

After they are done district authorities hope Hammarby Sjöstad will produce about half its power independently, a task made easier by the fact that residents, thanks to a broad range of efficiency and conservation measures, will consume half the energy of the average Swede (who already consumes only about 75 percent as much as the average American). These intrepid Swedish urbanites are pushing the envelope on a phenomenon catching on in cities across the developed world: "distributed energy."

Though it takes many forms, distributed energy boils down to two basic strategies: The first is to harvest as much power as possible locally, close to where it is consumed, from small-scale, low-carbon sources. The second is to wring the maximum amount of useful work out of every unit of energy available. The overarching goal is to create resilient, self-reliant cities prepared for the economic and political volatility ahead in the 21st century.

More options than ever are available for local, low-carbon energy. Solar photovoltaic panels are falling steadily in price, and solar power plants are being scaled down to the range of 20 to 30 megawatts—small enough to occupy already developed urban land. Passive solar, the use of direct sunlight for water or space heating, is already a well-developed, low-cost practice. In countries such as Israel and in the cities of Dezhou and Rizhao in China, more than 90 percent of buildings have passive solar water heaters.

Geothermal energy for space and water heating is also well established. Boise, Idaho, has had a business district geothermal heating system since 1983; last year residents voted to expand the network. The U.S. Department of Energy has identified 271 cities within eight kilometers of geothermal resources sufficient to provide useful heat. Many cities that do not have access to solar or geothermal resources, like those in the southeastern U.S., have copious biomass available. And every city in the world produces a waste stream that can be used to make electricity, biogas or, like the Bowerman Landfill in Orange County, Calif., liquid natural gas to fuel transit systems. Natural gas fuel cells are also reaching viability at everything from the household scale to the district level. (For example, there is the recent, much-celebrated Bloom Box.)

At least for the foreseeable future, however, local generation is unlikely to supply the sheer quantity of energy that large fossil-fuel plants now provide, and urban populations are projected to continue expanding. Thus follows the second imperative of distributed energy: to maximize the utility of every bit of energy. By some estimates, more than two thirds of the primary energy that enters the U.S. economy is ultimately wasted. For virtually any urban area, "negawatts"—energy saved through intelligent use of resources—could become the largest source of local energy.

The best way to get more out of energy, by a fairly wide margin, is low-tech and unsexy: density. Living close together offers a number of inherent efficiencies: residents can take public transit, walk or bicycle rather than drive; and urban living spaces, which tend to be more compact than rural or suburban homes, are less energy-intensive to heat and cool.

Another key strategy is to make use of the extraordinary amount of heat that is wasted today. Virtually every industrial process, from smelting coke to generating power, creates heat as a by-product, and the vast majority is simply vented into the air or water. That heat can be used to create power or to warm neighboring buildings. So-called district heating, which uses one source to heat multiple buildings, may be the oldest, cheapest and most widespread distributed energy technology in the world. District heating systems have been in place in New York City, Detroit and Birmingham, Ala., for more than a century, and many other cities are now following their lead, including Portland, Ore. "The upside is competitive rates, green energy, long-run price stability, and reduced capital costs for developers," says Rob Bennett of the Portland Sustainability Institute.

The ultimate way to maximize efficiency, though, remains the most speculative, and that is the use of information technology for ubiquitous awareness and intelligence. Even as prices rise for concrete, steel, oil, coal and water, one commodity gets steadily and inexorably cheaper: computing power. As sensors and microchips become smaller, less expensive and more powerful, they will be integrated not only into the power distribution system (the "smart grid") but into countless appliances, buildings, vehicles and public resources.

The seeds of this approach have been planted in places like Boulder, Colo., and Austin, Tex., which have deployed thousands of smart meters. In its new Pecan Street Project, Austin is building houses wired with communications systems capable of managing the charging and discharging of electric car batteries based on the hour-to-hour cost of electricity. "The communication protocols being developed for the cars will transfer into energy management of every kind at the home level," says Larry Alford, manager of distributed generation at Austin Energy. The effectiveness of intelligent grids will be enhanced by new ways of storing electricity at the building and neighborhood levels. It is energy storage coupled with the smart grid, Alford says, "that enables grid security, grid stability and power quality."

One benefit of energy localism that is difficult to quantify but nonetheless significant is that it engages a city's residents in a more active civic role: People sort their trash, they manage their power consumption, they get involved. "You build it through city pride," Fitzgerald says. "It's a visible thing people feel proud about. Then they're more amenable to doing other things."

In many ways the evolution of centralized energy into distributed energy parallels the evolution of computers from central mainframes to PCs and smart phones, and it may have many of the same democratizing effects. Putting information technology in more hands enabled an explosion of innovation and experimentation. If cities can incubate a new round of innovation, spurred by the dispersion of energy technology, they will leave behind brittle 20th-century energy systems to create new models of resilient, self-reliant and sustainable prosperity.

8 Comments

1. 1. sethdayal 02:32 PM 6/15/10

   Great stuff for a fairly tale.
   
   The cost of most of it is so high that it makes Cape wind at 25 cents a kwh going to 35 cents look cheap. Can you imagine the cost of trucking heat from miles into a city from a power plant in giant insulated steam pipes, digging up streets and roads, and replacing everybody's furnace with a steam boiler.
   
   Average rooftop PV on imperfect roofs is 35 cents a kwh and unless there is a low cost breakthrough in cell efficiency that's about as low as it is going to get.
   
   With current cost of mass produced nuclear based on current Asian builds is dropping under 2 cents a kwh and as mass production begins is heading for 1 cent a kwh, the clean and green nuclear option is the obvious way to go.

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2. 2. 1citizen 05:34 PM 6/15/10

   It seems to me that it is important to fully pass the savings of negawatts onto the provider of those negawatts. For example, rooftop PV can provide power factor correction and should be paid to reflect the improved grid stability as air conditioning units start up in the area.
   
   By extension, if a housing unit uses less gas/day than the average, that house is helping the gas utility wring more profit from the existing gas lines (more customers on existing lines). Current billing doesn't fully pass this savings onto the individual rate payer.
   
   This is the glass-half-full side of the argument which is, essentially, high rate of consumption need to result in progressively higher billing rates from zero upwards so that current artificial billing floors are removed and every rate-payer can recoup the full cost of producing each negawatt.
   
   If the electric or gas bill has a floor independent of consumption, then the potential savings of better insulation, more efficient space heating, solar PV or solar hot water also have an artificial floor.
   
   Further, if I had a solar hot water system installed, I would like to be able to possibly virtually store and then sell my negawatts of gas back to the utility when the gas is being used to meet electrical peak demand later in the day. The premise being that my solar hot water system is subsidizing the utility's ability to sell electricity on the spot market.
   
   If these kinds of financial instruments were in place I believe a larger fraction of the expensive retrofits would make sense to consumers because the time to pay off the initial debt would be reduced.

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3. 3. Chinese 07:47 PM 6/15/10

   GREAT!

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4. 4. jtdwyer 03:21 PM 6/16/10

   I suggest that someone research the feasibility of large scale geothermal power generation using the energy produced by the Yellowstone magma chamber. I'd recommend keeping your distance, but there's a tremendous amount of energy available: reducing that energy could even postpone the future eruption (if we can avoid triggering it). If geothermal can't make it in Yellowstone, it can't make it anywhere...

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5. 5. out of the box 08:36 PM 6/16/10

   You live in a fantasy world. Like a deer following a spilled salt trail, Everything follows the real world of economics.

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6. 6. Jürgen Hubert 12:44 PM 6/17/10

   "You live in a fantasy world. Like a deer following a spilled salt trail, Everything follows the real world of economics."
   
   And economics reward efficiency. Green cities are the way to go.

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7. 7. Wayne Williamson 05:48 PM 6/17/10

   cool article...
   
   jtdwyer...I've often thought that same thing...a huge amount of energy sitting right there waiting to destroy...tap into and potentially defuse it and we get the energy...

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8. 8. GreenHornet in reply to sethdayal 11:16 AM 7/28/10

   The argument that Cape Wind produces more expensive electricity is relative. More expensive compared to what? the cost of traditional electricity? then yes. BUT, what most people forget is that traditional electricity carries significant hiddne costs, which we end up paying one way or another in the form of health conditions, respiratory illness, contaminated water, polluted rivers and oceans, degradation of plant and animal life, acidification of our lakes, rivers and oceans. Take all this into account and you will find that Cape Wind is a BARGAIN.

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