Currently oil is the fuel that provides much of society's energy. However, finds of new terresterial fields of crude oil are now extremely rare. Most of the "new" technology oil is much more difficult to both extract and process.

The off-shore fields are extremely expensive to develop. The tar sands are expensive to both mine and process. The "fracked" fields are expensive to process and the individual wells have short lives.

The Texas and California fields that provided plentiful, inexpensive oil through the first half of the twentieth century are now in permanent decline. The giant fields of the Middle East have been supplying oil for fifty years. They are now showing signs of decline.

The price of energy has shown a corresponding increase that has little likelihood of being reversed.

The time has come to admit that the energy infrastructure that powered the twentieth century will not be able to similarly power the twenty-first century.

The monograph on solar power discusses the need for a solar power infrastructure.