Friday, January 21, 2011

An Opportunity for Underground Electricity Transmission?

Electricity transmission is a significant barrier to ramping up renewable capacity. The New York Times published a story this week about Texas where the Public Utility Commission has struggled to site 2,300 miles of new transmission lines. Much of the battle revolves around citizens unhappy with the prospect of lines degrading the quality of public and private property. Utilities are also constrained and looking to avoid costs associated with circuitous routing and permitting.

Controversies over electricity lines always leave me envious of the Germans. In Germany, a country that stands near the top of world rankings for total wind capacity, distribution lines are mostly underground – a considerable factor in mitigating localized power outages caused by downed trees. Destruction of infrastructure during WWII explains why Germany has a more modern and reliable electricity system compared to the US. Germany is also exploring underground transmission options through a pilot project near Bremen. Historically avoided due to premiums on installation and maintenance, underground transmission lines may be a solution to overcoming stateside NIMBY battles.

What exactly are the barriers to placing transmission lines underground? An operational barrier, emphasized by the American Transmission Company, is the fact that electricity transmission creates heat, which must be dissipated for safe and reliable delivery of power. While air is a much more effective medium for heat transfer relative to soil, releasing heat into the atmosphere is a waste of a valuable resource. If heat is released into the soil, however, the challenge of heat dissipation may be an opportunity for efficient heat capture. Capturing electricity transmission waste heat is a concept I’ve not heard about. Geothermal heating and cooling, a process that uses convection and heat pumps to capture ground warmth, is the obvious comparison.

There seem to be opportunities for coupling underground transmission development with heat capture, or combined transmission and heating. Namely, a chief inefficiency in the electrical grid, unused electrons, can be transformed into a revenue generating tool as heat is captured and sold to customers. This benefit alone may be enough to overcome the cost barriers associated with placing transmission lines underground. On the other hand, it seems like a bad idea putting fluids in close proximity to an electrical current. An additional concern is infrastructure requirements (I.e., electrical and fluid piping) under the principle of placing people close to heat sources to minimize heat loss, but away from electrical currents to minimize health risks.

I believe that is as far as my hair-brained idea should go without consulting experts. What are your thoughts? Has this concept been introduced before?