For many reasons, the 21st century will experience a sea-change in energy related technologies. With the current world-wide population of 7 billion bodies, all of whom will want to consume energy at the rate of your typical New York Capitalist, "kilowatts" of anything is now too small a quantity to count.

The anticipated massive investment in replacing petroleum guzzling automobiles with electric powered cars is going to drive the existing AC-based power grids (currently located mostly in the world's major population centers) to glow red hot, melt and literally explode. Recharging a Chevy Volt-200 at night, for another 200 mile Los Angeles county round-trip commute (every day) is not practical for the typical 100amp/110V home service measuring " kilowatt-hours" of energy demand at the meter. By some magic, existing coal-fired steam turbines (which today make 50% of the electricity in the USA and almost 90% in the emerging very large population countries like China) might be made to operate at full power, all the time, while still sequestering the trillions of tons of carbon emissions. However, the world-wide grid's wiring infrastructure of AC-distribution transformer-substations cannot handle the loads using the installed, and rusting 20th century technology.

What is never discussed is that the world's energy, transportation, and climate problems are really over-population problems that are ACTUALLY caused by the 20th century's failure to stop the concentration of most of the earth's population into overly dense and massive cities. Everywhere, people have moved from small towns to big cities to get access to the energy "efficiencies" of electric power generation and distribution/consumption of carbon fuels for heating and transportation. It all was a very good idea back in mid-20th century. NO MORE!

However, with unavailable access to limited supplies of coal/petroleum/natural gas world-wide (be that for political, or economic, or environmental-control reasons) BIG cities are not going to survive. Contrary to the logic of conventional wisdom, Cities are no longer "efficient." Previous caluculations to determine "efficiency" did NOT include major cost components (your list might be longer than mine)

Rather, for reasons of safety and personal comfort, the 21st century will see a slow exodus from super cities back to small-concentration living environments, made possible in part by the communication technology revolution. Very rich movie stars, leave over-populated Los Angeles to build their dream homes in the mountains of Idaho, and Colorado, complete with domestic energy generating systems. THEY are the canaries in our virtual (atmospheric) coal mine. Cars, running gasoline, or on battery juice, are already in grid lock everywhere in the world. Radical innovations in massive "mass transit" (and there are many idealistically proposed) can work only if population densities get even inhumanly worse.

Thankfully, the failure of 20th century technologies to save the 21st century, has created the opinion that the real energy solution has to come from "low-density" highly distributed energy inputs primarily from sun and wind capture. Those technologies are NOT simpatico with the existing 20th century constructions in massive cities where very few people are living on top of hundreds of other people below. The world has a very large unusable land mass if you assume we MUST use 20th century ideas of energy and transportation.

Rather, if people re-locate to be nearer this 21st century's to-be-built-energy-farms, then the unit of energy produced and consumed will be measured in "GIGAWATTS" of local generators. Part of the real problem of living in "unusable" lands (defined as mountains, swamps, deserts, and jungles), is the issue of water, and/or its lack/over-abundance there-of. If we can develop a radically new approach to generating energy, we might be able to "import" (or even "export") sea-water in ways never before dreamed of. SUN is the best, most efficient, desalinization process energy. A warmer world climate will case more rains and snows to be blown into what were "unusable" spaces. Nobody is modeling their super computers to define the positive effects of a warmer world temperature (they exist). The first principle of environmentalism is that everything is connected to everything else. And the second corollary is: the only thing constant is CHANGE. Human migration is at the core of human evolution. The last 10 centuries has seen the migration TO a bigger city, thereby creating the benefits AND problems with 20th century technology.Trying to invest monies (that we do not have) is a philosophy of "stasis." It is self-defeating.

The history of human evolution has put population centers on, or next to, modes of transportation (mountain valleys, river junctions and sea-shore harbors). And later, man learned to live along the multitudinous railroad paths that crisscrossed unused land. Rather today, where you choose to live is a function of how close you are to a "super-highway" or a regional airport. PERHAPS in the future, how close you are to a super-high-speed intercity train station will determine where a few can live.... NOT.

ALL that changes if the 21st century mode of transportation becomes possible for private aircraft capable of Vertical Take-Off flight. NO, not noisy, dangerous, difficult to pilot, costly, and slow HELICOPTERS. That was a 20th century definition of "aviation". The 21st century generation of personal transportation can be something radically NEW, CHEAP, EFFICIENT, and FAILSAFE provided we all have easy access to gigawatts of electrical power generation. The future of aviation is NOT super-sonic jets or rocket powered sub-orbital tourist flights across entire continents. The REAL future of travel is going to be electric powered aircraft of many different missions and design strategies. GIGMEDIA CONSULTING knows how that will be done this century.