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There's a huge dependency chain you're not considering. Every valve, every sensor, every motor controller has a function and was put there for a reason: to make the systems work.

Want to stuff up an HVAC system? It's as simple as closing the drain valve or shutting off the power to the drain pump. If the drains back up, the drain-blocked sensor trips and the system tells the cooling unit to shut down. You've now temporarily disabled one of the cooling units to a building. Now repeat the attack and disable all the cooling units in the building, which should be easy because they're all on the same network.

While the HVAC systems may have some redundancy, they're not infinitely capable of cooling an entire building with a single functioning unit. Think of them like RAID drives. You can afford to lose one, but as soon as you lose two or more, you've got real problems.

In the case of a building, this leads to a condition called thermal runaway. The HVAC systems aren't just there to keep the office dwellers cool. They're cooling the heat emitted by the hundreds of light fixtures and desktop computers. I can count 240 ceiling light fixtures on my floor alone, each containing two 32 watt bulbs, which is 15kWh of heat energy that has to be removed. In a data center, they're pushing hard to remove the heat generated by dozens of server racks each consuming several kilowatts.

In a data center, a loss of HVAC can result in the self-protective shutdown of the servers in 120 seconds. http://www.activepower.com/fileadmin/documents/white_papers/WP_105_Data_Center_Thermal_Runaway.pdf

Consider that nobody is sitting in each building monitoring the electrical and heat systems. There's a central group that monitors all our building sites, watching for and responding to alarms, and they troubleshoot and dispatch technicians as needed. That means all these systems are online. And online means they're exposed to attacks.

And our offices are no different than anyone else's. Building managers around the country run their buildings and businesses the same way.

Our modern infrastructure is based on these systems, and just keeping these systems functional takes a lot of effort. Keeping these systems safe from malicious attackers is critically important.

Flywheels are attractive for short-term peak power delivery. They have low failure rates and easy fault detection (if the wheel is intact and spinning at the required speed, you know how much energy is available).

For long term loads (hours) flywheels aren't competitive with lead-acid batteries, let alone more exotic types such as the NaS battery the article describes. For example, the Active Power CSDC-500 flywheel storage system supplies 50kW for 138 seconds = 1.92kWhr. The cabinet is 78" x 54" x 34" and it weighs just over 3 tons. Four long-term loads, a system with two 12V 100Ahr VRLA batteries would be 14" x 14" x 10" and weigh 140 lb.

A flywheel based system has nowhere near the energy density of a battery storage system. Peak power density is the flywheel's forte.

What, you think those solar cells and batteries are made cleanly?

The best way around the pollution caused by chemical batteries is to stop useing them for stationary power supplies. Flywheels are so far advanced as a form of energy storage as to make using batteries for home power look almost laughable. Here's a nice comparison between the two technologies: http://www.activepower.com/solutions/cleansource-systems/flywheel-technology/flywheel-vs-battery.html

It's a shame that the gyroscopic effects make them unsuitable for transportation power.

There's a key advantage to using a flywheel/generator combination: your electricity supply is massively cleaned up because you're generating a new clean electricity supply, the inertia of the flywheel also smooths out most glitches in the mains.

Not only don't you need the UPS, you also do away with the problem of keeping the UPS cool.

The only issue is noise, these things aren't quiet.

A quick google found these people: http://www.activepower.com/

... battery... backup?

I'll take a flywheel UPS over a battery one any day. They take up less space, you don't have to have a dedicated AC unit for the room, and they actually filter the power.

(disclaimer: I work for a Caterpillar dealer, or rather will be when I get back out of school)

One method of energy storage I haven't seen anyone mention yet is flywheels.

You mean like this? They just make small ones (for data centers, hospitals, etc.), but still the same general idea.

I'm not sure so, though, that they can be as safe as you describe when something goes wrong. Yes, making them out of a softer material might help some, but even soft materials can cause a lot of damage if they are moving fast. The whole point of building the thing is to store as much energy as possible. If the thing breaks up or gets free of its bearings and goes spinning out of control, the energy has to go somewhere.

This system is based on technology from activepower. For line conditioning power from a DC bank of photovoltaics their CleanSource(R) DC product may be a better fit as it doesn't include all of the UPS addons that wouldn't necessarily be needed in such a setup.

This system is based on technology from activepower. For line conditioning power from a DC bank of photovoltaics their CleanSource(R) DC product may be a better fit as it doesn't include all of the UPS addons that wouldn't necessarily be needed in such a setup.

Here in Austin, TX, there's another company that specializes in that. See their web page.

Hmmm, a quick search on Google turns up plenty of hits for this stuff - it's not THAT new.

http://www.afstrinity.com/
http://www.activepower.com
http://www.acumentrics.com
http://space-power.grc.nasa.gov/ppo/projects/flywh eel/papers/powertrades-oct98/ - a NASA study from 1998

All with URLs displayed, for you who fear goatse.cx. Somehow, this doesn't look like that new of a technology. (And besides, I thought a REGULAR UPS was heavy!)

...especially with the short life span, but Wired ran a great story (available 2000.05.16) in the last issue about using Flywheels instead of lead-acid batteries. When can I get a Flywheel UPS?