Power Electronics

Energy Efficiency Demands a System-Level Approach

Industry leaders, academics, consultants and government representatives regularly invoke the energy-efficiency hot button at industry conferences, appealing to engineers — particularly power-system designers — to produce products that save energy and help stave off the effects of global warming. To me, such appeals have always seemed a bit like preaching to the choir, even as they reassure power-supply engineers that their work matters.

Then, too, many appeals to engineers concerning energy efficiency serve to advocate for particular new technologies, such as energy-saving motor controls, lights and transportation. However, that was not exactly the case when Alex Lidow, CEO of International Rectifier, singled out these application areas in a talk he gave at last month's PCIM Europe conference in Germany. Lidow pointed out that fluorescent lamps, motor controls and hybrid cars have the potential to save 30% of the world's energy consumption (quoting Al Gore in his documentary). However, Lidow used these technologies mainly to frame a larger discussion about how we need a more sophisticated understanding of energy efficiency to assess the real impact of new technologies.

To that end, Lidow presented what's essentially a model that engineers can use when assessing the energy savings to be accrued from new products. This model takes into account not only the energy saved during a product's operating life (its operating cost or energy cost), but also factors such as acquisition cost (total cost of the end product) and the user experience.

To explain his model for energy savings, Lidow depicted a triangle with the top corner labeled operating cost, another corner labeled acquisition cost and a third identified as user experience. Taken together, these factors determine energy savings as well as the adoption rate for new technologies.

For example, in Lidow's model, energy savings can be calculated in monetary terms by taking the operating cost delta (dollars saved by the new product over its operating life) and subtracting the acquisition cost delta (how much extra the user paid for the new, more efficient product). Lidow noted that this equation ought to be applied without counting subsidies, which obscure the true energy savings, or lack thereof.

This calculation alone is not sufficient, however, because the user experience with an energy-efficient product ultimately will determine whether the product is adopted or not.

And energy-saving technologies, which are not adopted, cannot make a difference. Lidow cited compact fluorescent lamps and washing machines as examples of energy-efficient products, which have been received very differently in the marketplace because of their contrasting user experiences.

Although what I have described here is an oversimplification of Lidow's approach to analyzing energy savings, his underlying message is a simple one, which he summarized as, “You can't look at energy savings without considering how much it costs to save the energy.”

In essence, Lidow is asking engineers and others to look at the big picture, to make decisions about technologies based on their actual energy-saving value and to develop products that truly save energy over a product's lifetime, while also meeting the customer's expectations.

In other words, take a system-level approach to saving energy, and weigh all of the related factors that affect energy savings and influence product adoption. Though we might take issue with certain details of Lidow's energy-savings model, it would be hard to argue with the idea that a system-level approach must be brought to bear when striving for energy efficiency.

As our understanding of energy-efficiency issues grows, I expect that we'll want to expand this system-level approach to consider other issues. For example, can the performance of digitally controlled products be improved in the field through software upgrades? Or, how might future requirements for disposal or recycling of electronic waste influence our understanding of energy savings? No doubt engineers will have many such issues to address in the future as society at large gains a more sophisticated understanding of energy-efficiency issues.

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