Stories tagged exergy


That's actually a tear: The potato just received some horrible news. But it illustrates how full of fluid potatoes are.
That's actually a tear: The potato just received some horrible news. But it illustrates how full of fluid potatoes are.Courtesy ZooFari
Here’s my impression of the future:

“Um, hey. How was lunch? Italian dunkers, eh? Nice. Gotta love the dunkers. Ate those right up, I see. Pretty good sauce too, huh? Got some extra sauce there, actually. Were you going to… can I have that sauce? Yeah? Oh, it’s SO good.”

Yeah, that’s the future for you. Man, is he hungry. Stuff you wouldn’t touch, the future will pound back like Captain Haddock with a bottle of Loch Lomond (before that fiasco in San Theodoros).

But the future is smart, because it realizes that Italian dunker sauce is in short supply, and it’ll take perfectly good extra sauce wherever it can get it.

Are you following the metaphor still? Were you thrown by Captaion Haddock?

Here’s what I’m saying: in the next few decades, we’re going to be super hungry for energy, food, and water, because there will be about 9 billion of us on the planet. So, in addition to coming up with new ways to produce of all of these things, we’re going to have to look for areas where they’re being wasted right now, like all those puddles of Italian Dunker sauce being shoveled into the cafeteria trash bins.

Example: drinking potato chip water.

Potatoes, as it happens, are about 75% water. When we turn them into potato chips, we get rid of all that water—we bake it, dry it, and fry it away. Considering how much we love dried potato products, that’s a lot of water wasted.

But that doesn’t mean we should stop eating potato chips. (NEVER!) Instead, some factories have been installing equipment to reclaim water that would otherwise be vented out of potato processing facilities as steam. One of the factories where the technology is being tried may be able to recapture as much as 3,000 liters of water an hour (about 790 gallons an hour). This water, already clean and pure, can be reused in the factory, or even sent back into the municipal water system.

Although the article doesn’t mention it, I’d be willing to bet that there’s another product being recaptured with the water: energy. Steam, after all, is just water with a whole bunch of heat energy in it. With the right equipment, heat can be extracted from steam, and reused for anything from cooking to powering heating and cooling equipment.

Do you see now? The future, with its peanut butter covered fingers and greasy South Park t-shirt isn’t quite the loser you think it is. It’s using all that Italian Dunker sauce, in ways that you never imagined possible.


…of climate control systems...

Ever notice the plumes of smoke rising from many buildings, factories, and power plants on a cold day? That smoke is actually water vapor, which still contains usable energy, muahahahaha! Our buildings use lots of energy. Electricity, for example, powers everything from lights to computers to copy machines to coffee makers. Electricity eventually degrades into heat—you can feel that heat coming off of electric appliances. Current building energy management systems expel this excess heat energy instead of using it for other purposes, such as building the ultimate tilt-a-whirl of doom. Dave Solberg, an energy miser and consulting engineer-ahem-secret advisor, wants to change all that using the concept of exergy. He envisions a future where energy is used as efficiently as possible, and he has been working with Xcel Energy and organizations in the St. Paul area to re-engineer buildings.

We all know that mad scientists with plans for world domination need money and power. Well, current climate control systems are expensive to build and operate, and they're bad for the environment. But retrofitting old buildings and creating the infrastructure to support Solberg's systems has a higher up-front cost than following the status quo. If Solberg can demonstrate the effectiveness and cost savings of his plan below at SMM, your regional science museum will become a model for climate control systems all over the world--I mean it will take over the world! HAHAHAHAHAHA!

At Science Museum of Minnesota, Solberg wants to make two big changes in the way we use energy:

Solberg's Plan - Phase 1
Like all large buildings, SMM takes in outdoor air, cools it to dehumidify it, then reheats the air and sends it throughout the building to control the climate. Unlike most buildings, which use giant air conditioners and boilers, SMM uses hot and cold water piped in from Saint Paul District Energy to do that job. You can learn more about District Energy in an outdoor exhibit to the left of SMM's main entrance--and you can see the building right next to us!

District Energy burnin' the biomass
District Energy burnin' the biomassCourtesy Andrew Ciscel

The first change Solberg proposes is to re-use the waste heat that SMM generates from cooling down fresh outside air. Currently, SMM's ventilation system cools outside air down to about 50 degrees F with cold water from District Energy, dehumidifies it, and then reheats that air back up to a comfortable indoor temperature with hot water from District Energy.

Solberg would have us cool the air with cold District Energy water, then use that same water (now warmer) to reheat the air back up to 65 degrees F on its way to the ventilation ducts. This change would eliminate the need to use hot water from DE to reheat air, and it would reduce use our demand on DE’s cooling system, because we would send water back to their chilled water plant at a lower temperature than we currently do.

Solberg's Plan - Phase 2
District Energy makes electricity by burning waste wood. DE then uses the heat energy still available after making electricity to produce hot and cold water, making District Energy 50% more efficient than coal-fired power plants. But at the end of the day, DE has 95-degree F water left over. Right now this excess heat is released into the atmosphere from cooling towers on top of the building (see the plume rising from the building in the image?), but that 95-degree water could meet most of SMMs heating needs. Solberg wants us to tap into that wastewater as our primary heating source, replacing the 180-degree water we currently get from DE. This would put an oft-wasted energy source to work, and it would allow the 180-degree water now being used by SMM to be used elsewhere within DE’s hot water distribution system.

This plan is so good it must be evil. In the long run, if the kinds of changes being pursued by SMM were replicated widely, they would amount to lower emissions and lower energy bills everywhere, which is ultimately healthier for our environment (not that mad scientists care about that sort of thing). In fact, we found out that if we had implemented this system when the current building was constructed, we could have saved $1.5 million in infrastructure (which we could have really used for that giant laser in the--end of message truncated--