ONE PLANET — the environmental documentary radio programme of BBC World Service — last month broadcast (and podcast) a documentary which explored whether a future solution to Europe‚Äôs electricity supply problems might come from giant solar-thermal generating stations in the Sahara Desert, feeding hundreds of megawatts into the European grid through undersea cables while also bringing ‘an industrial revolution to the Southern Mediterranean,’ to quote one of the scheme’s supporters, Prince Hassan of Jordan.

What the programme didn’t mention is that the idea is at least five years old and is championed by TREC, the Trans-Mediterranean Renewable Energy Co-operation project, an initiative of the German association for the Club of Rome, together with the Hamburg Climate Protection Foundation. But what Miriam O’Reilly’s inverview with Professor Galal Osman revealed is that there are people in Egypt who see the construction of the pioneering solar-thermal power plant at El Kureimat on the Nile as possibly the first step towards realising that dream.

El Kureimat, a few kilometres south of Minya, is the site of a power generation centre that already has two gas-powered generators installed. Now under construction is a ‘Concentrated Solar Power’ (CSP) solar-thermal plant which will generate 20 megawatts of power, rising to 50 MW. Similar in principle to solar-thermal plants operating in the deserts of south west USA, the plant will feature an array of mirrored fifty-metre parabolic reflectors covering 100,000m2. These will focus the sun’s rays onto a vacuum-insulated heat collector tube running down the centre of each reflector, through which water pumped under pressure will carry the heat to a central facility where steam is generated and electrical power is produced using turbines.

Sun, water and salt

Photovoltaics, using for example silicon cells, is a completely ‘dry’ process, witness its efficacy in outer space and the surface of Mars. But CSP solar-thermal plants are the affordable technology when scaling production up to tens and hundreds of megawatts. One factor that might be seen as a hitch to implementing ‘desert power’, then, could be shortage of water; but there are plenty of zones around the desert edge where water is to hand, though it may be sea-water.

One vision for an integrated system to harvest the desert and make it blossom involves using CSP plants not only to make electricity, but also to desalinate marine and brackish water, for human consumpion and for agriculture. It has also been pointed out that if the solar arrays are constructed so that the ground beneath them is accessible, those shaded spaces could be ideal for agricultural and horticultural use.

Apart from cost, solar-thermal has another advantage over photovoltaics, in situations where a reliable constant energy supply is desired. Electricity is expensive to store — but harvested heat can be stored cheaply for use in overnight power generation. The 50 MW solar-thermal plant which Spain commissioned at Solucar near Seville a couple of years ago uses underground vats of molten salt to store up to seven hours’ worth of power-generating heat.

High tension

In the programme, Professor Osman, fancifully invoking a memory of Ancient Egyptian worship of the sun, also imaginatively sketched a vision of ten thousand square kilometres of desert covered with CSP mirrors, generating potentially much of Europe’s electricity needs. How would this be brought across the Mediterranean? The TREC plan calls for three High Voltage Direct Current (HVDC) cables under the sea: one from Libya to Sicily, a second from Tunisia to Sardinia, and a third across the Straits of Gibraltar from Morocco to Spain.

In the early 20th century, in the competition between rival electricity transmission techniques, it was Alternating Current that won out. AC, which reverses polarity fifty or sixty times a second depending on the design of the system, can be stepped up to very high voltages with cheap transformer technology — and high voltage is important, as this vastly reduces the amount of power lost to electrical resistance in the transmission cables.

However, developments in semiconductor technology never stand still. In recent decades the advent of high-energy solid state static inverter circuits has made it simple to ramp voltages up and down for direct current, too. And this has real advantages: less electrical power is lost per thousand kilometres in DC cables, and the cables are cheapoer to make and lay. The problem is that DC static inverter stations are still much more expensive to build than AC transformer stations; but where energy must be moved long distances, especially underwater, HVDC is the sensible choice. (The longest current HVDC power circuit is overland, however — it’s the 1,700-km line that runs from Congo’s Inga Dam hydropower scheme to the copper mines at Shaba.)

HVDC has another benefit where international sales of electricity are contemplated. AC grids can exchange power only if synchronised in frequency and in phase. When AC circuits go out of step, they can bring the system crashing down, with wide-area power outages. DC power flows constantly in one direction and can easily be distributed to AC local circuits through an inverter regardless of local phase and frequency. Indeed, sometimes HVDC links are incorporated into power grids just for the stability they bring.

Energy and security

In the BBC programme, Prince Hassan spoke about the benefits which widespread adoption of solar-thermal power could bring to the Middle East and North Africa, especially in terms of prosperity and development, industry and agriculture — and flowing from this, greater social and political stability.

However, a gloomy note was stuck by Open University֦s Professor Dave Elliot, co-Director of the Energy and Environment Research Unit. He pointed out that almost insurmountable obstacles have arisen in negotiations between European nations about cross-border sharing of power; how much more difficult would it be to negotiate prices and access for power from another continent?

European policymakers are also understandably nervous about energy security; the way Russia plays politics with its gas pipelines illustrate the dangers of dependence. It is said that one of former Congolese president Mobutu Sese Seko’s motivations for supplying the Shaba copper mines with electricity from 1,700 km away, rather than develop allegedly cheaper local hydropower sources, was the advantage to him of having his hand on a big switch to render Katanga province powerless should it rebel. How stable is North Africa?

‘We’ve got to get the balance right in the future,’ concluded UK Energy Minister Malcolm Wickes, ‘between the energy we’ll have to import — mainly oil and gas and coal at the moment, maybe one day solar — and the energy we can produce here in Britain and just offshore. Energy security will become an increasingly important component of a nation’s security, given the huge global demand, the global grab for energy in the 21st century, and all the difficult geopolitics around that.’


AS COMPUTER CHIPS get more compact and run faster, they also run hotter. Attaching radiator fins to their surface and blowing air over them are the usual solutions. But what happens when chips are stacked on top of each other to improve the flow of data between them in parallel processing? The heat-producing volume increases, while the heat-shedding surface gains very little.

The Economist Technology Quarterly, bound into the September 6th edition of the magazine, reports on IBM’s experiments in water-cooling such stacks of chips. Thomas Brunschwiler of IBM’s Zurich laboratory points out that processors stacked in this way generate heat at about two kilowatts per cubic centimetre, a greater density than in a nuclear reactor. Therefore the IBM team has developed a stacked processor through which water is pumped in channels, as thin as a human hair, etched in the process of silicon-chip fabrication. Nor need this heat be wasted: in compact multiple installations such as data centres, the heat can be exploited to warm community housing or other buildings.

Water cooling can also be applied to silicon-based solar cells. Another IBM researcher, Supratik Guha, has increased the efficiency of solar power by using mirrors to concentrate 2,300 times the normal intensity of sunlight onto a solar cell. Without water-cooling, the cell could reach 1,500 degrees Celcius and melt. The cooling system means that the cell is maintained at a safe temperature of 85 degrees C, and generates a record output of 70 watts per square centimetre: a very promising technology for economical electricity generation even in high-latitude countries.

GLOBALLY, COMPUTERS USE A LOT OF ENERGY; and given the dominant role of fossil fuels in electricity generation, computing is therefore responsible for a lot of the increase in carbon dioxide in the atmosphere. The ‘carbon footprint’ of computing is thought to equal to that of aviation (about 3% of global energy use); some put its burden as higher, and it is clearly increasing fast.

Targeting data centres and the desktop

Attention falls in particular on the impact of data centres, where thousands of machines are racked up to store data, host Web pages, process transactions etc. The density at which these machines are co-located means that for every watt spent on computation and data access, another watt is spent extracting heat, so they are sinners twice over. There has also been a tendency at data centres to ensure operation 24/7 by running the machines full time regardless of the computational load, by over-provisioning, and by adding a layer of uninteruptable power supplies to the infrastructure.

In March this year, at the Royal Society conference on ubiquitous computing, I heard an interesting presentation by Professor Andy Hopper of the University of Cambridge, on the subject of Computing for the Future of the Planet. More recently, Andy reprised this topic as the inaugural lecture of the UKCRC. I recommend visiting Andy’s site where you can find his presentation slides, and the paper he has submitted to the Royal Society for publication.

I found myself in agreement with Andy’s ideas about locating data centres close to sources of renewable energy and ‘moving the bits’ rather than moving electrical power long distance and suffering transmission losses. I also applaud the work his team is doing on virtualisation, moving jobs around the data centre so as to shut down as much of the system as possible when it isn’t needed. But I confess I baulked at his urging that the personal workstation, the PC as we have come to know it in the last quarter century, should be abolished in favour of network-centric storage and services accessed from ‘thin client’ machines.

Defra purges the desktop

I recently attended a meeting of the Carbon Footprint Working Group set up by the British Computer Society. CFWG harnesses the energies and expresses the concerns of the BCS’s Ethics Forum, the Data Centres Specialist Group and the Communications Management Association. Of particular note is the work being done on a voluntary code of conduct for data centre operators, and a project part-funded by the Carbon Trust to develop software to help data centre management model the energy use of their systems and play ‘what-if’ experiments to find ways of being more energy efficient.

However, CFWG’s concern doesn’t end with data centres. At that meeting, we heard an interesting pair of linked presentation by Bob Crooks of the British government’s Department of Environment, Food and Rural Affairs (Defra), and by Richard Lanyon Hogg of IBM UK which provides Defra with extensive IT support.

IBM helped Defra conduct an audit of the energy cost of its ICT systems, using meters and thermal imaging cameras. The results showed inefficencies in many unexpected locations. A frequent culprit was departmental print servers. The survey has led to many reforms, including the abolition of many desktop systems and their replacement by laptops: Richard showed off the Lenovo ThinkPad which is now his sole machine for portable, home office, desktop and hot-desk use.

A plea for the peripheral

Laptops are great things. The need for them to run on battery power has been a great driver in the direction of energy efficiency. I wrote most of this blog text on an Apple PowerBook G4 laptop, on buses and in hospital waiting rooms. But I wonder — what kind of compromises does one accept by trying to use a laptop for everything? Energy efficiency is a good thing; so is human efficiency.

There are three kinds of work I do that are more efficiently accomplished by being done on my ‘desktop’ machine (actually, my Apple Macintosh G5, the largest computer I’ve ever had, is a tower system that lives in a trolley beside my desk, not on it).

  • Media publishing work in Adobe Photoshop, Illustrator and InDesign. It is a great benefit to have as much display space as possible, for two reasons — to see the document being worked on, in both extent and detail; also to have rapid access to the horde of control palettes. Otherwise one wastes much time calling up and dismissing palettes, and scrolling around the document surface: not very efficient!
  • Video editing work. Here the actual products being edited do not need so much display area, but two 720 x 576 video previews need to be accomodated size by side, and editing efficiency is enhanced by seeing a big horizontal slice of the ‘timeline’ at reasonable magnification. Plus, video editing can require the simultaneous use of many peripherals: in my case, at least one large and fast external drive, and a FireWire link either to my camcorder or my Sony DSR-20P digital VTR. Desktop machines can support more simultaneous connections to peripherals.

Now, arguably these publishing applications are one for which even Andy Hopper would make an exception. Editing video on a thin client system is certainly out of the question. But of course, these are specialisms which it would be rare to find in an office environment.

However, consider my third scenario, which can hardly be unusual among knowledge workers:

  • Working across many windows — It’s not uncommon for me to be writing a paper or a contribution to an online discussion (or this blog), composing text in one window while referring to several Web sites, PDFs and emails, each in their own window. I arrange the windows so I can tell enough by the bits poking out which contains what. At the moment I find I have 15 applications running, which isn’t unusual for me; and 8 open windows plus 7 minimised to the Dock — again, not unusual for me. This behaviour, which I find efficient in terms of research and writing productivity, is supported by the ‘affordances’ of a 1680 x 1050 pixel Apple Cinema Display.
NEC-8201a laptop

NEC-8201a laptop, circa 1983 – 32k of storage and a comms link to my Mac

But, hey! I have at times to remind myself that in 1986 I was working on the 512 x 342 pixel monochrome display of a Mac Plus. Many dialogue boxes in modern applications are bigger than that!

And what about my first laptop? The NEC PC-8201a (see right) had just six lines of forty-column type display. That required something like an orator’s sense of what point you had reached in the argument evolving just to the north of your fingers.

Ironically, you don’t get much more space when composing text for WordPress…

As we may think

One thing I felt about the Defra/IBM response to the challenge of controlling energy consumption by IT, as expressed in the CFWG meeting, was that their choices about ‘End User Devices’ were effectively limited by what technology is currently on the market. What if we allowed ourselves the luxury of imagining the EUD of the future? Would it look like a Lenovo laptop? Would it look like a PDA?

I hope it would be more modular than a laptop, for the sake of the environment. On my bookshelf, for I can’t bring myself to get rid of it, is a nice white Apple G3 iBook whose motherboard got fried a few months ago. To repair it would be expensive. Yet destined for the grave along with it is a perfectly good XVGA colour LCD display, CD-writer etc. Seems a waste. (I guess I could prise out the RAM chips and put the hard disk in an external drive box.)

I’d like the EUD of the future to be a small core device that can be extended like crazy to suit the task and environment at hand. Maybe it would be about the form factor of the Asus Eee PC (see Flash presentation), with small tolerable keyboard and trackpad, wireless networking and Ethernet, a daylight/backlit energy-saving screen somewhat like in the One Laptop Per Child XO machine, and about 16 Gb of flash memory. I envisage a clip-on base that provides bulk storage, mains power, a secondary battery or fuel cell and more expansion ports. For efficient desktop use, a better keyboard and mouse could be attached.

But for me, the real breakthrough would be how my envisaged device would work with external displays. Some models of Apple PowerBooks already show the way in their ability to hook up to large external displays and run a fully interactive desktop and applications over two displays at once. Let’s explore this further. What about being able wirelessly to hook up to a number of displays, some of them forming part of the Desktop, some perhaps temporary repositories to which a document window could be copied for viewing and possibly some touch-screen interactivity?

In response to Andy Hopper, I guess what I am indicating is:

  • I want an environmentally responsible computer, or ‘End User Device’, and one the energy requirement of which scales according to how much work, and what kind of work, I am doing with it.
  • I don’t like the idea of entrusting my bulk storage to the Internet, and needing access to the Internet to do any serious work, which is what the ‘thin client’ model suggests to me.
  • I would like to look beyond the ‘one size [laptop] fits all’ approach that to me is implied by the choices Defra has made for its staff.

I guess I’m asking for a lot, but there’s nothing new there!


How is Defra tackling climate change? — page links to science notes.

Computing & Information Processing for the Future of the Planet — four-page op-ed paper by Conrad Taylor in PDF form, prepared for a meeting of the BCS Geospatial Specialist Group on 10 July 2008

On the radical energy-saving architecture of the XO laptop, see A Conversation with Mary Lou Jepson (hardware designer of the XO) in ACM Queue.

This week on the BBC World Service, a radio programme featured interviews with kids scavenging scrap copper and iron from broken computers, illegally imported from Western countries and dumped at the Agbobloshie waste site near Accra, in Ghana. On 5th August, an accompanying article by BBC West Africa correspondent Will Ross was posted, on the same theme.

Ghanaian kids were interviewed as they set fire to bundles of cable, then threw dirt on them to extinguish the acrid, toxic fires. They were looking for the copper to sell for scrap.

Greenpeace has taken the lead in researching the dumping of Western IT equipment in Ghana. Their researchers have taken soil samples from the Accra scrap market, finding high concentrations of such dangerous contaminants as lead, phlalates and dioxin.

The broken computers are landed in containers at the port of Tema: in the period of research, containers were seen being landed from Holland and the UK. There are international laws banning the export of computer waste, but the companies who engage in this poisonous trade get round it by falsely labelling the shipments as usable second-hand equipment. In fact, says environmental journalist Mike Anane, about 90% of the discarded equipment is useless, broken junk.

For me, the most gutting thing about this story is that many of the dumped machines showed clear markings revealing their previous ownership: Richmond upon Thames College, Southampton City Council, Kent County Council, London Guildhall University. Organisations like this had better wake up and ask the companies on whom they depend for equipment end-of-life management just what the hell they are playing at.