Friday, August 31, 2007

Heating with Flops

Greetings, fellow old-world primates.

Today I'm going to flesh out an idea a dear friend of mine had: that waste heat from high-performance computer facilities could be used to heat cold regions of the world.

We humans evolved our big brains in Africa, where it's nice and warm. For better or for worse, these big brains have allowed us to develop means of keeping our bodies at African temperatures even at polar latitudes, allowing us to conquer the planet.

Technology (be it fire or clothing) has always been a factor in allowing our spread into frozen zones; today I'm going to look into something a little higher-end.

Computing in Vegas

A friend of mine works for Cafe Press, an online clothing-designing company which recently moved their main data centers to Nevada. The reason for this move was an unusual one: proximity to the Hoover Dam means cheap power to run the site's computational muscle.

In fact, data centers can generate an enormous amount of heat. A thousand processors working at 100 W each consume 100 kW of electricity: about 50 households' worth. With electricity costing 15¢ per kWh, that's over $130 000 per year in electricity costs alone, and that's before factoring in cooling costs.

Computing in Siberia

Suppose instead that data centers were built where you want to generate a lot of heat anyway. that same 100 kW data center could potentially provide heat most of the required heat to a shopping mall. How economically feasible is this? Let's look into two possible scenarios. For the sake of simplicity I'm going to assume enough people will soon do the Cafe Press trick that electricity costs even out globally around 15¢/kWh.

Scenario A: 1 fixed data center in a place cold in winters.

Here, you'd build a 1000-CPU data center for $500 000, and half of the year you'd be able to use 80% of the waste heat from the data center to heat a mall. Together, you and the mall would save $52 560 in heating costs per year of operation; more if you can use some waste heat more than half the year. Even in the summer, data centers could be used to provide hot water.

Scenario B: 1 data center in a shipping container, moving from pole to pole

Sun Microsystems' "Project Blackbox" will build you a data center in a shipping container already. Imagine having a deal with two different malls, one in each hemisphere, so that the waste heat of the data center could be used always. You'd have two extra expenses: container shipping expenses (about $10 000 for the round trip) and four weeks annually of down-time, but you'd save $100 000 in heating costs. Overall, you'd have to spend 8% more (or $40 000 as a one-time expense) on your computer hardware to compensate for the downtime, but that should be just-about recouped after the first year of operation.

Three Moore's Laws

Technologically, the use of waste heat is only going to make more sense in the future. There are three relevant Moore's laws here: performance/watt, performance/$ and bandwidth/$.

The most familiar Moore's law statement is that computing power doubles every 18-24 months, but one should also look at power efficiency and bandwidth trends. Power efficiency has been climbing slower than computing efficiency, so today's $1500 PC uses more energy than a $1500 PC from a decade ago. Conversely, bandwidths have been doubling more frequently than CPU speeds. Therefore, in the future, bandwidth (especially on the backbone of the Internet) will be too cheap to matter, and the ratio of power expenditure to computer hardware expenditure is only going to increase.

Therefore re-using computer waste heat is only going to become increasingly lucrative in the future, so it's a technology that should be on the up-and-up.


It's already cheaper to operate data centers where power is cheap. I think now it's also cheaper to coƶperate with public buildings (which tend to be big enough to act as thermal flywheels to smooth out diurnal heat supply needs) to supply waste heat from data centers. I haven't worked in the added costs of the data center's floorspace, so it's not yet a complete no-brainer to use computers instead of /along side of traditional furnaces, but future trends certainly seem to be pointing in that direction.

Yoursfor a Greener Cyberspace,


PS This post printed with 100% recycled electrons

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