Scientific American presents "A Path to Sustainable Energy by 2030" in its November issue. In many ways, it sounds good. But let's think about the details: What would the end result look like? Would it really be sustainable? What would the costs really be? Is there any way we could afford to do what is proposed?

The authors of the article, Mark Jacobson and Mark Delucchi, propose substituting wind, water, and solar (WWS) energy for all other forms of energy by 2030, not for just the US, but for the world. The types of energy sources that would be eliminated include the following:

• Petroelum (including gasoline, diesel, propane, heating oil, etc.)
• Natural gas
• Coal
• Liquid biofuels, such as ethanol
• Wood and other biomass
• Nuclear

All that would remain would be wind, wave power, tidal energy, hydroelectric, geothermal, and solar. Because of the ambitious timeframe, the only techniques that can be used are ones that work at large scale today, or are very close to working.

If we want to plan for truly long term sustainability, it seems to me that we need to plan from a base of zero in terms of fossil fuel usage, rather than from present day usage. This is very much a change from most thinking--how we can make tweaks to our current system to use less oil or gas. Over the long term, we know our current system won't work, so at some point we need to be thinking where we want to head, while we still have resources in hand that we can use to make changes.

We are so unaccustomed to thinking local, that it is hard to even contemplate the idea. What can be made with strictly local inputs, besides simple things like baskets and bricks? It is hard to even contemplate the idea, if one has to put all of the necessary steps in place, like transporting the raw materials to an area where they can be worked on, then working on the raw materials, and distributing the finished products to new locations.

Joseph Tainter, a Professor in the Department of Environment and Society at Utah State University, and author of the seminal work "The Collapse of Complex Societies", recently gave a speech on complexity and resource use at the 94th Annual Meeting of Ecological Society of America in New Mexico: (Conference theme: Human Macroecology: Understanding Human-Environment Interactions Across Scales). The speech, 'Human Resource Use: Timing and Implications for Sustainability', based on a forthcoming paper, is reprinted below with the authors permission.

The kitegen concept: high altitude wind power based on kites. In this configuration ("stem"), the kite reaches altitudes of the order of 1000 m; pulling on a power generator located on the ground. High altitude wind power promises to be a low cost and widely available technology able, in principle, to provide amounts of energy comparable, and even superior, to the present production based on fossil fuels. (See here an animated representation of how a stem works)