a Power Consumption Ratio, 1:150

That is the energy consumption ratio of terminal v.s. networks.

I have been being curious to know how much energy is used for mobile communications.
Someone says data centers such as a service delivery platform and data ware houses are most dominant for that. Another one says power consumption for cell phone battery charge can not be negligible.

One occasion has come this time as an invitation to an academic workshop on Power Consumptions in Future Network Systems.
In investigating power consumption issues of a specific company, difficulty is to keep the company’s trade secrets for which the company doesn’t disclose the service “BOM (Bills of Materials).” BOM could be noted for this investigation as “BOE (Bills of Electricity). The BOE is the key to know the company’s operational structure.
Fortunately, NTT DoCoMo, which is the largest mobile telecommunication operator in Japan, has disclosed the figures to investigate the operational power consumption structure to some extent.
Let’s see it.

Japan's Ministry of Internal Affairs and Communications released a report from Ministry's Study Group on ICT System and Network for Reducing Environmental Impacts(in Japanese), March 2007. According to that report (Information and Communication Technology) equipment (e.g., routers, PCs, servers, network systems) is consuming about 45,000,000 MWh in 2006 which is 4% of the total electricity generated all over the japan (i.e., 1% of the country total energy consumption). Over recent five years, it has been increased 20% (See the figure below).

ICT System and Network themselves consume the energy on one hand. On the other hand, they save the total energy consumption of our daily lifeincluding logistics, commuting, business activities and so on. Please note that there are the two aspects when discussing the ecological impact of ICT equipment. I believe ICT System and Network, in total, bring the energy saving effect significantly. Anyway, let's continue the story.

Origuchi et al. has reported a comprehensive study on the third generation (3G) mobile communication systems in view of life cycle assessment and ecoefficiency evaluation. In their study, the result of the environmental impact evaluation indicated that approximately 50% of the total CO2 emission produced in the production stage, approximately 55% of that in the usage stage, and approximately -5% of that in the disposal/recycling　stage. CO2 emission from the 3G service mainly came fromterminals (cellphones) and base stations. CO2 emission from terminals　mainly occurred in the production stage. CO2 emission from base　stations mainly occurred in the usage stage.

According to NTT DoCoMo's environmental performance data report (in Japanese), the company used 2,278,853MWh in 2006 for all the telecommunication equipment, and that includes overhead such as lighting and air conditioning. 2,278,853MWh corresponds to the half of the energy power consumption of the mobile networks in the above figure. The other figure shown below summarizes the yearly energy consumption from 2003 to 2006. The figure also indicates the number of outdoor base stations of NTT DoCoMo. We can see the increase of energy consumption is proportional to the number of BTSs.2,278,853MWh can be decomposed into power consumption for each userper every single day, dividing the figure by 52 million users, 24 hours and 365 days, as 120 Wh

In early 90's when cellphone was becoming popular, the energy consumption at terminal side was 32Wh/day. Now it has been reduced to 0.83Wh/day that includes all the energy consumption of battery chargers and terminals. 0.83Wh is a small number in comparison with the network consumption 120Wh. The ratio is almost 1:150, and thus we can conclude the terminal energy consumption is negligible in operation.

I can conclude more about the mobile networks such as that base stations are consuming most　energy of the company, which is more than the other network elements　such as switches and data centers. The detail will follow at my presentation somewhere sometime later. Please wait my further report.