Energy for the Second Half of the 21st Century

Obviously, we need to be ready with cost-effective alternatives when fossil fuels actually reach the decline stage.  While hundreds of billions of dollars have been spent on so-called Clean Tech investments over the past 25 years, resources have also gone into other "not yet ready for commercialization" technologies including nuclear fusion and so-called low energy nuclear reactions (LENR).  What is LENR?  Does it have any real merit?  What are its implications?  We'll provide our best answers.