Computing With Waste Energy

06 February 2011

Interview with

Professor Andy Hopper, Cambridge University

Sarah -   As the internet and our reliance on computers grows, so does the amount of energy that this industry consumes, which means significant CO2 emissions.  But is there a way to make the process more environmentally friendly?  Computer Scientist Professor Andy Hopper from Cambridge University has been working on a way to turn waste energy into useful computer processing around the planet.  Hello, Andy...

Andy -   Hello there.

Sarah -   To put some numbers on the problem first, how much energy are we looking at and how much CO2 does running the internet consume?

Andy -   Well, about 3, 4, 5, or 6% of global energy use goes into computing one way or another, so it's not a huge number at the moment, but it's going up fairly quickly.

Sarah -   And what sort of volume of CO2 is that?  I mean, compared to other industries, how does that then compare?

Andy -   Well, the aviation industry would be probably two or three times that, so we're catching up on it.  Maybe in due course, it'll be comparable.

ComputerSarah -   What's the solution that you've been working on to help counteract this?

Andy -   Well, what we're trying to understand is the notion of taking computing to energy sources and using energy which would otherwise be lost because it cannot be transported to the place where it can be used.  So the notion is to transmit bits around the planet rather than energy around the planet, and see if you can be a kind of a sponge for either surplus energy or, perhaps more importantly, energy that cannot get to houses or to trains or to situations where it can be used in a more obvious fashion.

Sarah -   So this means running processes in an area of the world where it's not being used locally, so it's night-time and there's not a whole lot going on, and you can then use that downtime for an area where it's during the day, and you've got a lot of traffic going on.

Andy -   That's right.  So it's either the windmill has speeded up somewhere or it's night-time and there isn't much local use for whatever reason.  What we're trying to find out is to what extent is this possible, what actually is the energy cost of shipping the data and the problems to these potentially remote places because it must be a win rather than lose.  But fibre optic communication is a marvellous technology because essentially the further you go, the more energy you don't really use.  So you can go much, much further without paying an energy price.  It's almost like magic.  And then seeing at what level of granularity, what sort of problems, what sort of tasks can be done in this way, and soak up this surplus energy, so that in due course, when 10 or 15 or 20% of the world's energy is going on computing, we can say, "That may be 3 or 4% of energy that would otherwise be lost."

Sarah -   What sort of tasks are you looking at that will be suitable?  I'm guessing ones where you want an instantaneous reaction, so e-commerce and things like that, they aren't necessarily so suitable as things where you don't necessarily need that instant feedback?

New York Stock Exchange Trading FloorAndy -   That's right.  So anything that requires an instant response, that is interactive, is less suitable to this sort of approach.  But nevertheless, you can go a reasonable way, it's constrained by the speed of light, so it's not that it has to be just around the corner.  It might be at the other end of your country, up in Shetland or wherever.  But nevertheless, we're trying to divide up the tasks into those that are interactive and require an immediate solution, and perhaps others which are cataloguing tasks, recognition tasks which can be done more slowly, and therefore, amenable to this sort of treatment.

Sarah -   How realistic is this?  You mentioned the advent of fibre optics.  Are our current networks able to deal with this?  Are they fast enough at the moment?

Andy -   Well, to some extent, it is already done, in that you place server farms close to cheap energy sources and ship data there and get the answers back.  But you know, it is appropriate to be slightly fanciful, not completely unrealistic, but slightly fanciful in one scenario, and looking maybe 10 or 15 years out where the networking around the world is perhaps somewhat different.  There is much more fibre communications.  We have server farms in perhaps what today are unusual places, in the middle of the oceans where it's very windy, from which you most definitely couldn't get the energy back to heat a house, but you might be able to do the computing jobs.

Now you have to be very careful about this.  You mustn't cheat, so you have to take into account the energy cost of getting the computing there, so to speak, building that plant, including the embedded energy cost seen in the manufacturing of it, maintaining it, and then recycling it or shutting it down in an appropriate way at the end of its useful life.  So you have to take the whole picture, but nevertheless, with that in mind, and the notion that distance doesn't matter so much with fibre optics, I think the world may be a different place.  One other comment that follows on from
Mike's contribution earlier, I think it's energy proportional computing and communications that is very, very important going forward.  That, rather than over provisioning, over engineering, over dimensioning which has traditionally been the case, and is now being less important in mobile communications, spreads to everything.  Every computer on the planet [should be] either doing useful work or is shut down or in at least in very deep sleep mode.  Now, one way of helping to understand this is looking at this and chasing the energy, because if you move a job somewhere else then the one that was originally destined for that job can be switched off.

Sarah -   What is the scale of the saving in energy that we're looking at?

Andy -   Well to be quite honest, I don't know!  That's the challenge we have because to be realistic about this, we have to postulate some kind of model of how the networks will work, take current jobs, divide them up, and so on.  But initial results suggest that it's not going to be just 1 or 2%.  There is a reasonably good opportunity here for improving the way computing works and so, ask me back in about 5 year's time and I might not hesitate to give you an answer.

Sarah -   I suppose, even though it may be a certain amount of percentage now, with time moving on, it'll become more important as we become more reliant on the internet, but will we expect to see this sort of thing being implemented any time soon?

Andy -   Well, the beginnings of it are happening now, but let me just point out another kind of win-win.  Not only using energy that would otherwise be lost, but also in many cases, using that energy to compute things about the real world which save even more energy, optimising the physical world by using energy in the digital world and that energy itself, being so to speak 'free lunch' energy, now that would be a wonderful scenario.  But as I say, I am paid to be slightly fanciful, and there it is!

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