The Energy Transition Ahead

The Age of Petroleum, which began in the nineteenth century and fueled the world economy through the twentieth, will almost certainly end in the twenty-first. Oil and oil products will likely be used after that, but petroleum as the dominant power source of humanity wil give way. The current high price of oil may not hold, but sometime fairly soon, it will. The twin billions of China and India, not to mention the rest of the developing world, will steadily increase demand for oil even as a major new field hasn't been discovered in decades. Add the environmental cost of burning fossil fuels, and the question becomes simply how to transition away from oil.

Of course, the inevitable could be delayed. Exploring ever more difficult regions of the world-- Siberia, the Alaskan Arctic, deep sea floors-- will probably discover more reserves, but that exploration will be expensive, and actually getting the crude out of such virtually inaccessible areas will kick the price even higher as the chain of companies involved try to make a profit on their expenditure. At some point, other energy sources will become competitive, and even preferable.

The ultimate source of power for a planetary civilization would be a fully mature solar power system based upon truly gargantuan orbiting satellites. The satellites, perhaps miles across, would collect energy streaming away from The Sun and convert that into safe beams at wavelengths that would do no harm as they sliced through Earth's atmosphere. The beams would land on rectenna farms on the surface, where the energy would be converted to electrical power and fed into the power grid. Such a system could deliver all the power needed, and it would be safe and clean. Such a system would also be almost impossible to cripple because of its decentralized architecture and the fact that the working part, the satellite, would be beyond any Earthly natural disaster and, hopefully, beyond the reach of any terrorist groups and most national military forces.

A fully mature SPS system, however, could take decades to complete even after everyone agreed it should be built. The near term problem is finding a way to get from an oil based energy regime to that SPS approach without suffering a collapse of the global economy. Nursing oil along might be necessary. More reliance on alternative sources of energy, such as wind, water, and geothermal, will help. Conservation will help. More nuclear fission plants, even with all their problems, may become necessary. Using solar energy on a large scale before moving to SPS may also be viable.

Solar power, of course, is already being used in many small projects. The problem at present is that solar cannot handle power intensive tasks, like powering a city. Even with better technology that can convert a high percentage of the energy it captures into electricity, huge areas will have to be covered in passive solar receptors to gather significant amounts of power. Luckily, there seems to be some areas that are suited for such use. The deserts of the American Southwest and northern Mexico, for example, have plenty of open land, and they annually receive over 300 days of sunshine. They are possible candidates. Depending on the local weather and the durability of the receptors, deserts in Africa and South America could also fit the bill. Floating skirts of receptors along continental coasts would offer an interesting engineering challenge.

The case can be made that the first major Western nation able to get a large percentage of its electricity from ground-based solar will be Australia. There, a relatively small population lives mostly along the coasts while the interior is dominated by an immense desert where, in some places, rain may not fall for years at a time. The Outback would seem to be ideal solar receptor territory.

Perhaps the most intriguing possible site for a receptor farm, however, is Saudi Arabia. Saudi wealth is based totally on the kingdom's oil industry. When the oil economy collapses, therefore, Saudi Arabia will be in a difficult spot even if it still has plenty of oil underground. The government that rules the Arabian Peninsula in the next few decades, assuming it's interested in the modern world, will pursue policies to maintain the wealth of the people in a post-petroleum world. Besides oil and its people, the greatest natural resource of the area is its vast desert. Saudi oil wealth can fund the transition to a Sun-centered power industry that could export vast amounts of power to Europe and Asia. Other nations in that dry, sunny region could similarly become energy exporters. That same Saudi wealth makes them potentially major backers, in decades to come, of SPS.

Ground-based solar systems clearly have many limitations. To produce significant amounts of electrical power, they need to be spread over huge tracts of land. To get the most direct sunlight, they are best suited to the equatorial belts, loosely defined. Bad weather could also be a problem. Of course, the biggest limitation is the day/night cycle of Earth. Any given installation will be down roughly half the time. One advantage of starting with a ground-based system, though, lies in the infrastructure that will need to be built to carry the electricity from the receptor farm to customers. Receptor farms could be converted to rectenna farms fairly simply, and could continue producing power through the buildup of a satellite system.

That brings us back to a space-based SPS. The U. S. Department of Energy has done one study of SPS. In 1979, the study concluded, SPS was technically feasible given the advance of technology then forecast, and the first satellite could be operational thirty years after commencement of the program. That study is almost certainly dated, but transitioning from oil to solar power will still be a central challenge of this century. It's a challenge, however, that can be met.