en Route to a Greener Thermal Technology

It’s no surprise. Power levels in the data center keep rising. In fact, the cost of powering the computers in the data center is beginning to exceed the cost of the computers themselves. The computer architects have responded by designing systems that use multi-core processors. These processors can use less energy to perform the same workload as their single-core brethren by breaking up the code into smaller chunks that can be simultaneously processed by a number of simpler and lower power cores.

Computer engineers are beginning to think in terms of a power efficiency metric applied to computer systems: the power consumption per unit of computation. This, of course is a good thing. However, this view only accounts for the power consumed by the semiconductors themselves.

It is interesting to compare this response to that of thermal engineers. Long before green became fashionable, I have met countless thermal engineers who found it very painful to contemplate the incredible thermal inefficiencies in an air-cooled data center. The use of air, a very low heat capacity fluid, to transfer megawatts of power makes, of course, no sense from a system efficiency point of view. In fact, it has been estimated that in an air-cooled data center, up to 40% of the total power consumption is used to move air. The use of a liquid for the same purpose, would lower this number to around 2%. I’m glad to say that, at long last, the economics of energy have finally provided data centers with the incentive to begin the transition to energy efficient liquid cooling.

More than one thermal engineer, thinking not only of heat transfer within the data center, but also of the refrigeration costs, has joked about putting all data centers in the coldest climates, where refrigeration costs would be minimal, and then piping the data to the more temperate climes where the data consumers live. I haven’t yet seen the computer world catch up with this vision. However, I have heard of plans to locate some major data centers within the service areas of hydroelectric power plants to get lower cost electricity. So, perhaps this will be the next step.

The lesson here is that thermal engineers are trained to think of the thermodynamics of the data center as a whole and, by extension, the entire earth.

In light of the latest findings on climate change, we know that we should not only worry about the quantity of energy consumed but also its sources. However, greater energy efficiency in all aspects of the world economy can reduce the use of carbon-based fuels while alternative energy sources become established in the marketplace.

What can thermal engineers do to facilitate this change? We can begin by working to convert others to a more holistic view of energy consumption, so that we all understand the true energy costs associated with performing those tasks demanded by modern life. Furthermore, we can continue to do what we have done for decades: contribute to the development of electronics-based technologies that are energy efficient, not only at the device level, but also at the system and societal level.Looking ahead, there are many emerging technologies involving non-carbon-based energy sources that need the special talents of electronicscooling engineers to achieve success. It sounds like we’ll have our hands full, doesn’t it?