You think swapping your SUV for a Prius will save the world? Think again, says Peter Tertzakian, the guy who coined “energy break point” in his first best-seller. Last month, he launched his latest book, The End of Energy Obesity, and argued, among other things, that energy efficiency (Prius vs. SUV) and energy consumption (total number of cars) are two very different things.Since humans associate comfort with more energy consumption, we tend toward supply-side answers: finding renewable resources, creating more efficient forms of oil extraction, etc. Demand emerges, and supply materializes through some combination of human ingenuity and luck. But we have more power (as it were), Tertzakian argues, by curbing demand—instead of simply replacing incandescent bulbs with compact fluorescent bulbs, why not use fewer lights instead? At some point, we won’t be able to find new sources of energy fast enough, we’ll max out on efficiency improvements, and we’ll be forced to conclude, along with all reluctant dieters: consume less.In other words, we can be creative with our substitutes. Maybe install a skylight instead of another light fixture in a dark hall. Maybe ride the bus instead of driving a second car. Maybe use TelePresence instead of taking a 2000 kilometer flight. Cisco TelePresence gets considerable ink in Chapter 13: Dissolving Distance. Tertzakian describes the experience in glowing terms, noting “There was simply no comparison to that primitive ancestor, the videoconference.” Blush. But numbers are generally even more compelling, so I set about trying to quantify the substitution in Tertzakian terms, using barrels of oil equivalent (BOE). Here goes:- According to Boeing, their airplanes burn 3.5 liters of fuel per passenger per 100 km.- For a 2000-km flight, you would burn 70 liters of fuel per person, 140 liters for a round flight.- Converting liters to barrels of oil, this would be equivalent to 0.88 BOE.Now, for TelePresence in terms of barrels of oil:- According to the Power Requirements section of the deployment planning guide, a CTS 3000 unit is rated at 4536 watts.- Since you need at least two endpoints for a call, we double it to 9072W.- A two hour meeting consumes 18.14 kWh (9072 x 2 / 1000).- There are 1700 kWh in a barrel of oil, so this two hour meeting is equivalent to 0.01 BOE.So, if you’re on an energy diet, would you prefer to consume 0.88 BOE or 0.01?Of course, you can quibble with other factors, such as the Rebound Effect that Tertzakian notes (in this case, people would use more TelePresence for meetings that did not replace air travel), or get into the details of actual usage. All fair game. Let's hear from you.