Physics of Sustainability Lecture

Last week, I attended a presentation by Dr. Littlewood, Director of Argonne National Laboratory, who spoke on the physics of sustainability at a Energy Leader speaker series at Georgia Tech. Dr. Littlewood drew a crowd that packed an auditorium in the recently built Marcus Nanotechnology Building at Georgia Tech. The abstract is shown on the poster below. (No special permission needed for posting slides, according to presenter)

Here are my take-away notes and thoughts:

• All* renewable energy on Earth comes from the Sun... (*geothermal energy too?)
• There is only as much energy per square meter in each country (because of latitude, land available, general climate, hours of sunshine available)
• Renewable energy appears to be efficient, but... can renewables scale for each country?
• A few examples of orders of magnitude:
• Full scale photovoltaic (PV) to supply the entire USA (1TW at 300W/m2) would require covering an area of the size of New Mexico with solar panels (assuming 30% efficiency).
• Like those wind turbines? Fluid dynamics limits the spacing between wind mills and restricts the usable energy density to 6W/m2.
• Hydroelectricity from large water dams provides a 0.3W/m2 annualized.
• IT makes up 12% of all energy usage. CPU speeds are limited by heat.
• I have done a similar scaling exercise at Georgia Tech in the Energy Technology and Policy class, once taught by Prof. Valerie Thomas. Humans need to eat the energy equivalent of one rabbit a day to survive.

• New energy technology should focus on small-scale point-of-use. Efficient batteries and PV. Large power plants and transmission grids as we know them should be treated as an exception. It is quite unlikely that we will come up with an energy system of such large scale.
• Focus should also be on interfaces between energy systems. Examples include heat pump appliances (now underperforming by a factor of 100) and how to transfer energy from one environment to another.
• Energy = money. "The cost of things is their energy input," especially when considering the "payback" time for renewable sources, which the time until the energy produced by the source exceeds the energy needed to build the source. The speaker mentioned cheap solar sources made in certain countries that require inordinate amounts of energy (or pollution).  

Slides of the presentation will be made available at some point. Meanwhile, someone at University of Michigan taped a previous recording of this speech and posted it on YouTube.