I'll try and do some more digging later on.
Please do. I'm sure alot of SPCR'ers would find a study like that really helpful/exciting.
found one!This 2004 study
The total energy and fossil fuels used in producing a desktop computer with 17-in. CRT monitor are estimated at 6400 megajoules (MJ) and 260 kg, respectively. This indicates that computer manufacturing is energy intensive: the ratio of fossil fuel use to product weight is 11, an order of magnitude larger than the factor of 1âˆ’2 for many other manufactured goods. This high energy intensity of manufacturing, combined with rapid turnover in computers, results in an annual life cycle energy burden that is surprisingly high: about 2600 MJ per year, 1.3 times that of a refrigerator. In contrast with many home appliances, life cycle energy use of a computer is dominated by production (81%) as opposed to operation (19%). Extension of usable lifespan (e.g. by reselling or upgrading) is thus a promising approach to mitigating energy impacts as well as other environmental burdens associated with manufacturing and disposal.
A Joule is 1 W*s.
--Â> 1 W*h = 3600 J
--> 1 J = 1/3600 Wh
--> 1 computer including 17" CRT is = 6400 MJ * (1/3600) Wh/J = 1.77 MWh
A 100W computer running 24/7 for a year = 0,876 MWh.
A 100W computer+17" CRT energy manufacturing cost = about 2 years of 24/7 use @ 100W
EDIT: Same author revisits his article and finds an energy use of 7320 MJ
Using hybrid assessment that combines process and economic input-output methods, the total energy and fossil fuels used in producing a desktop computer with 17-inch CRT monitor are estimated at 7,320 Megajoules (MJ) and 290 kg respectively. This indicates that the network of industries for manufacturing computers is energy intensive: the ratio of fossil fuel use to product weight for a computer is 12, an order of magnitude larger than the factor of 1-2 for many other manufactured goods. In contrast with many home appliances, life cycle energy use of a computer is dominated by production (83%) as opposed to operation (17%). The yearly life cycle cost of owning a computer is about 3,000 MJ/year, half again that of a refrigerator, a much larger appliance that uses far more electricity in operation. The short lifespan of computers and the variety of computing needs of users suggests that extension of lifespan, for example by promptly reselling to users who need less computing power, is a promising approach to mitigating environmental impacts.
What I dont understand if that he says tgat 83% of energy consumption is production vs 17% operation.. even though that production is 7320 MJ and 1 year use is 3000 MJ (if people keep them for 2 1/2 years then it's about 50-50).
Maybe that's because people dont actually run them 24/7