“There will be a price for carbon,” data center energy expert Jonathan Koomey said last Monday in his keynote at the Uptime Institute Symposium 2010. “We have to start thinking about how that price affects the economics of data centers. Carbon taxes will have an impact on where you locate your data centers.” He also said that this issue of the impact of a “carbon tax”is “not on the radar screen” of corporations yet. This issue was also echoed by other speakers at the Uptime event. “It’s not a question of if (carbon regulation) will happen. It will definitely happen” according to Mike Manos, the Vice President of Service Operations at Nokia.
One of the market-based approaches to control and reduce carbon emission is cap and trade, see Wikipedia. This mechanism is used in Europe. It has now the largest emission trading for greenhouse gases in the world, the European Union Emission Trading Scheme with The European Climate Exchange (ECX) in London as the leading marketplace for trading carbon dioxide (CO2) emissions in Europe and internationally.
If we can foresee that there will be a price for carbon produced by data centers and the mechanism are already in place, what will be the impact on Data Center Power Usage and Carbon Usage and Money spending? Is it worthwhile to monitor energy usage and the carbon footprint of a data center?
In my blog entry ‘Data Center Power Usage and Money savings‘ I made a rough estimate on money savings based on the precept that every kilowatt of computing related load saved (or wasted), equals 8760 kWH per year or about 35 Megawatt Hours over 4 years. Inspired by the Uptime Institute Symposium I now extended this rough estimate by including the cost of carbon and including a PUE conversion.
All power generation systems have a ‘carbon footprint’. There is some debate about how large these footprints are, but for an estimate I used some figures from the Parliamentary Office of Science and Technology of Great Britain:
- Conventional coal combustion systems result in emissions of the order of > 1000gCO2eq/kWh.
- The average carbon footprint of oil-fired electricity generation plants in the UK is ~650gCO2eq/kWh.
- Current gas-powered electricity generation has a carbon footprint around half that of coal that is ~500gCO2eq/kWh.
For the price of carbon I used the EU carbon price from the European Union Emission Trading System (EU ETS). According to Reuters “Prices have averaged 13.66 euros in the first 5-1/2 months of 2010, meaning they will have to hold at current levels or rise further if they are expected to reach an average of 15.40 euros.”
To make a rough estimate of electricity costs I took a table of electricity prices from Wikipedia and used the exchange rate of 1.00 USD = 0.733783 EUR.
The PUE of data centers is very different, the EPA Estimated PUE Values for 2011 are between 1.2 and 1.9.
A “worst case scenario” is used, where 1kW of dirty electricity (1000 gCO2eq/kWh) is producing 8760 kg CO2 per year or about 35 000 kg CO2 over 4 years. For the data center a PUE of 1.9 (to deliver 1 kW for the IT equipment you have to use 1.9 kW) is used. The carbon price that is chosen is based on the 13.66 euro average price of the European cap and trade market. In this way we can get a first impression and a sort of upper limit. But be aware that the carbon price is dynamic and the EU carbon price is relatively low in comparison with 2009. Further in reality how green the supplied electricity is, is much more complicated and depends on the location of the data center and the power supplier. The PUE is a dynamic efficiency measurement because of the dependency on the workload that is being processed.
In the table below you can see the yearly and four yearly cost of 1 kW of electricity and the associated carbon costs, the total yearly and four yearly cost (electricity + carbon), the index on yearly electricity cost and total cost and the last column shows the rise of cost because of the adding of the carbon footprint. As you can see, you can save a buck with thinking 8760.
Electricity and CO2 costs
Problems are looming up
This table is all about kW and CO2, so to be more practical let us go one step further. We have servers in all kind of flavors that have a different power consumption. Making use of the report ”Estimating total power consumption by servers in the U.S. and the world” of Jonathan G. Koomey of Stanford University the power usage of low, mid and high range server are estimated on 180, 420, and 4800 Watt. So thinking 8760 this means:
- low range server = 180/1000*8760 = 1576.8 kWh/year
- medium range server = 420/1000*8760 = 3679.2 kWh/year
- high range server = 4800/1000*8760 = 42048.0 kWh/year
For a data center in Canada this give the following cost increase:
CO2 cost increase
To get an impression what this means, let’s make a use case. If we take, for example, a data center of 5000 servers, with 50% low range, 25% medium range and 25% high range servers and we take the lowest electricity price (Canada), we can see the following cost increase:
- low range server = € 102 310,-
- medium range server = € 119 362,-
- high range server = € 1 364 142,-
Total € 1 585 815,- per year
Houston we got a problem!