The importance of skipping steps

This might be an utterly pedestrian observation to somebody educated as an engineer, but a couple of examples I’ve run across lately have brought home to me how critical finding ways to “skip steps” is to dramatically increasing the efficiency of an industrial process.

The two cases are a clever means of using natural gas to run an efficient air-conditioner, and of using the gases from garbage to make electricity.

First, here’s a clip from James Fallows’ story (subscribers only, I’m afraid) a couple of Atlantic Monthlies ago on Zhang Yue, a Chinese tycoon who made his money in air conditioning:

The air conditioners most Americans are familiar with are compression coolers. They use electric power to compress a refrigerant such as Freon, and when the refrigerant expands, it cools the surrounding air. The nonelectric coolers instead use natural gas (or some other source of heat) to boil a special liquid, a lithium bromide solution, and when the vapors from that solution condense, they cool whatever is near them.

It sounds odd to use a flame to cool a building—and, indeed, when China’s premier, Wen Jiabao, visited Broad Town in 2005, he asked several times to have the principle explained. A company pamphlet that lovingly commemorates this historic visit calls the premier’s persistent curiosity a sure sign of his acumen. “If I spread a drop of alcohol on your hand, you will feel very cold,” Zhang told Wen, describing part of the cooling process. The account continues: “The Premier nodded in understanding and said, ‘Yes! Yes! For it evaporates and takes away the heat.’ The Premier is a specialist indeed.”

Zhang has never wavered from this technology, even when, in the early 2000s, market conditions temporarily turned against it and his sales force begged him to add normal, electric-powered air conditioners to Broad’s offerings. Its advantages all involve energy savings. Compared with typical compression systems, nonelectric air-conditioning as Broad makes it will always require less energy per unit of cooling, because when energy is converted from one form to another, some of it is lost. Electric-compression cooling requires more stages of conversion—fossil fuel to electricity at the power plant, electricity to mechanical power at the compressor, both stages very wasteful—than does using natural gas to boil liquid. Nonelectric cooling will also always be more adaptable to other sources of energy, since it is easier to apply a variety of heat sources, including solar power and biomass burning, to do the boiling than to use them to generate electricity in a remote plant and transmit it to the air-conditioning site. And this method of cooling helps reduce the costly peak loads imposed on the power grid, because natural gas is cheapest and most abundant in the summer, exactly when the demand for air- conditioning goes up. Indeed, since storing natural gas is expensive and difficult, in many countries the available gas is simply burned off—wasted—during the summer, when no one needs it for heating. In China, air-conditioning accounts for as much as 50 percent of the electric load during peak times in the summer. Zhang pointed out to me—as he has noted in countless speeches, and as is emphasized by the Harvard Business School case study—that with all of these advantages, his kind of air-conditioning can make both the electric and the natural-gas networks less wasteful while still keeping people cool in the summer.

And here’s a recording (MP3; there’s no transcript because we’re not made of money, but here’s a news report) of a meeting we had at the Citizen with Rod Bryden, the entrepreneur and former Ottawa Senators hockey team owner whose current project is a plasma-gasification waste-disposal company called Plasco Energy Group.

Plasma-gasification might sound like incineration but it’s quite different. Incinerators burn garbage to get rid of it; if they’re power-generating incinerators, they use the heat to boil water to generate steam to run generators.

Plasma-gasification blasts garbage with, essentially, lightning, and uses all that energy to blow the trash apart into its component molecules, which are then strained apart and separated. The gas is run through combustion engines, which burn it directly to generate power. The result is enough power to run the process for the next load of garbage and then some.

Bryden says Plasco’s plants can generate 1,400 kilowatt-hours of energy from a metric ton of garbage, while even the most efficient incinerators only get 800 kilowatt-hours out of the same trash. The key, he says, is pinching out that extra step of making steam. A process of his type will always be more efficient at generating electricity.

Incremental improvements — a little nip here, a little tuck there — are certainly important, but major advances in green technology are going to require our best engineers to find ways to skip steps.

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2 responses to “The importance of skipping steps

  1. Pingback: Running cars on coal is a bad idea: CMU researchers « The EcoLibertarian

  2. If only I had a quarter for every time I came here… Superb writing!

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