An interesting article but like a number of commenters have stated, the worst case scenario depends on technology doing something it hasn't done in some time; remain static.

Fusion, the kind that is most energy experts (not fusion physicists and engineers, however) think of is the Tokomak which,if that continues to dominate the research landscape, will be big, expensive (at first), and slow in coming, but alternatives are emerging that take advantage of newer understanding of how to accomplish it and when they do they will do for energy what silicon did for information processing and communications.

As for solar energy developement never the less. I'm a big fan like many but I really am curious as to why so many think it will be earth-bound when the perfect place for a solar collector isn't some desert, it's out in one of the Lagrangian orbits. Scientific American last week said that Japan was committing 21 billion for a 1 gigawatt system to demonstrate its feasibility over the next few years. I'll be surprised if the Chinese and Indians don't do likewise. So far the launch systems have been an outgrowth of our early military ballistic missile program and need to send humans along with bulk payloads, but we know we can send humans in smaller packages without payloads and payloads which can endure high-g forces can be put into space using far cheaper and less polluting systems. Once there the advantages are not just lots of clean energy but also the ancilary technologies to explore and exploit the asteroids and eventually the Moon, Mars and the rest of our solar neighborhood. Mining for the metals we need, the energy for refining and transportation when undertaken in space become cleaner, cheaper and spare the wild undeveloped places on earth from the pressures to extract them in the old earth-bound ways.

I'm optimistic that if we use our remarkably robust industrial economy to take us beyond petro-fuels which both space based solar and fusion offer we will see a reduction in the kind of competition for resources that have fuelled wars and conflict for so much of our history disguised as wars of expansion of territory, ideology and religion, but all come down to people's desire for a secure source of the basics and the expression of cultural identity.

In so many ways R.Buckminster-Fuller was correct when he said that the only real shortage we face is a shortage of imagination.

One point that seems to slip by us in this discussion on the future of energy is that we seem to imagine that the leader in future energy will be the US and to a degree Western Europe. I suggest we think again. If speed in innovation and application is pivotal, and I think it will be, then the rapidly expanding industrial economies of Asia with their universities producing unprecedented numbers of engineers (not so many education majors and hedge fund managers) are going to lead the way while we sit on our well padded posteriors agonizing over how to untie the gnarled knot in our shoelaces we've so carefully crafted to be inextricable, before we take so much as a step. India, China, Korea, Japan who knows what other coalition of growing nations and transnational corporations are going to cut the gordian knot and see us a an rich vein of decadent consumers in a land of milk and honey just waiting to be catered to until our money's gone and we start selling off our previously frozen assets and treasures.

The challenges you mention are all real and I don't make light of them but we know how to solve them.

Sending tons of material to space while a man in a can sits on top like a delicate little sculpture made out of spun sugar and jello is a relic of the old military ballistic missile days. Astronauts will travel in lightweight crew vehicles seperately. Bulk materials, those not created in space using the materials available from the asteroids, will be driven to space using mass driving systems that reach escape velocity and orbit after being shot from their mile long barrel, not needing most of their weight just to get into low orbit. Instead of $100,000 per pound we're talking $5 per pound with zero emissions. Operating remotely in space will become far more sophisticated, effective and commonplace and when the massive components for a decent space station is assemled, including their solar panels we can create both the protection from cosmic radiation and with a carefully calculated rate of spin, the equivalent of gravity to keep our human physiologies happy and healthy.

Harsh environments? Connestoga wagons weren't too comfortable either, but to presume we wouldn't find ways to use the unparalleled abundance of energy and material in space for our immediate and long term use is to ignore the enormous energy there to use in what by earth standards would be an almost maintenance free environment..no rust, no dust, no wind, no gravity and ignores what humans have always done when given the chance and motivation every chance they've had.

In the mean time, 3 billion for cash for new clunkers, and 700 billion for bankers and trillions for Iraq and who knows how much for Afhanistan and yet we dont have money for NASA or more importantly we don't have even a couple of billion to act as a prize for an innovative American company to lead the way. Priorities are based on understanding of what's at stake and how technology can address our need, and our leaders seem to suffer from deficit in that area, in my opinion. Maybe it will be yours too. Cheers.