Predictions about energy and energy-efficient innovations come and go. What are the timelines for some of the more popular or unique predictions?
The Renewable 70s
An intense interest in renewable resources began in the 1970s when the industrialized world faced two energy crises. The first was in 1973, caused by the Arab oil embargo of OPAEC, and the second was in 1979, resulting from the Iranian revolution. 
This resulted in a spike in interest in renewable resources, including solar and wind.
In the 1970s, solar energy was expected to contribute 21% of the primary energy requirements by 2000. However, just two years before that milestone, in 1998, the United Nation’s World Energy Assessment said that solar accounted for .04% of the world’s primary energy use. 
The graph to the left shows the available energy from renewable sources as compared to global consumption.
Interest and investment in solar, however, continues to grow, and substantial progress in solar technology has been made. By 2007, grid-connected photovoltaic electricity was the fastest growing energy source, and the installation of photovoltaic solar panels had increased by 83% in 2009. At the end of that year, the total installed capacity was 15 GW. Less than .02% of available resources are sufficient to entirely replace fossil fuels and nuclear power. 
Photo source: upload.wikimedia.org/wikipedia/commons/7/7a/Available_Energy-4.png
Another promising renewable energy resource coming out of the 70s was wind. In fact, one Dutch company, working with The Netherlands Organization, felt that a prototype for offshore wind harvesting could be built, and construction of an off-shore wind power plant could begin around 1983. The company predicted that 56 such plants could be up and running by 1985, supplying 50 to 70% of electricity demands in the Netherlands, as well as producing hydrogen and desalinating water. However, results of wind power have been negligible until recently. 
Finally, wind power is developing fast. As of 2009, wind power supplied approximately 1.9% of the world’s electricity consumption. While wind power is expanding in the United States, Europe continues to take the lead in this renewable resource. In Denmark, 19% of electricity is generated by wind, while Spain and Portugal derive 9% of electricity use from wind, and Germany and Ireland each get 6% of their electricity from the resource. 
There has been strong interest in renewable resources for centuries, and particularly so since the 1970s. Despite the pressure applied that resulted from energy crises, the development of renewable resources remains in its early stages. 
Photo Source: Treehugger.com/files/2009/09/offshore-wind-farms-europe.php
Thorium is a naturally occurring, slightly radioactive element. Much like plutonium and uranium, thorium can be used to fuel nuclear reactors. 
As a fuel source, thorium is clean and safe, and according to Australian science writer Tim Dean, it has no possibility of a meltdown. Furthermore, there is enough thorium in the United States to meet all its energy needs for 1,000 years. 
Abundance is a huge advantage. It is plentiful in the earth’s crust, and is 5,000 times more abundant than gold. According to the U.S. Geological Survey’s 2006 Mineral Yearbook, the United States has about 20% of the world’s supply of thorium.
In light of the events unfolding in Japan, it is also important to note that Liquid-Flouride Thorium Reactors (LFTR) have significant safety advantages over traditional nuclear reactors. LFTRs burn nearly all of their fuel, and as a result of this, 83% of LFTR waste is safe within 10 years and the remainder is safe after within 300 years. This is compared to traditional nuclear waste, which is estimated to be safe after 100,000 years.
Additionally, the LFTR uses uranium and thorium dissolved in lithium and beryllium, both fluoride salts. The salts are impervious to radiation damage and do not corrode their containment vessels.
And cost is a factor. It is estimated that the cost of an LFTR could range from 25 to 50% less than that of a traditional nuclear reactor. 
In the 1960s and 1970s, Molten Salt Reactors (MSR) were tested by the United States in Oak Ridge, Tennessee. A prototype reactor, using thorium fluoride-salt in lieu of fuel rods, was built and operated successfully for about five years. In 1976, the government halted funding of thorium research, as the uranium powered facilities product plutonium, which can be used in nuclear weapons. 
The image to the left shows that the Liquid-Flouride Thorium Reactor uses a chemically-stable salt as the medium in which nuclear reactions take place.
However, in recent years there has been a resurgence in the interest in and study of thorium. India is expecting to bring online the Kaprapar-1 reactor this year. This will be the world’s first reactor to use thorium rather than plutonium to achieve power flattening in the core. The nation also plans to meet 30 percent of its electricity needs with thorium reactors by 2050. 
The HT3R reactor, near Odessa, Texas, which is designed to be a “teaching and test reactor” will use thorium-coated beads for its fuel source. 
Photo source: Bravenewclimate.com/2008/11/28/hansen-to-obama-pt-iii-fast-nuclear-reactors-are-integral/
Is There Room for Cold Fusion?
In “The Saint,” a 1997 film starring Val Kilmer, the title character is hired to steal a cold fusion formula that would replace oil as the world’s primary energy source. In the hit “Back to the Future” movies, the time-traveling DeLorean is run by a cold fusion power module, and cold fusion has even served plot lines in television shows such as the “Twilight Zone” and “Dr. Who.” Cold fusion is fun stuff in Hollywood, but does it have real potential?
The idea of cold fusion gained real attention in 1989 when two chemists, Stanley Pons and Martin Fleishmann, reported the production of excess heat in an electrolytic cell that they concluded could only be produced by a nuclear process. This claim was based on a large amount of energy being produced, and over the years, other similar claims related to nuclear reactions have been made. 
Several laboratories in multiple counties tried, and failed, to repeat the results of Pons and Fleishmann. 
Photo Source: famous-cars.net/2010/04/delorean-time-machine/
A review panel organized by the U.S. Department of Energy stated in 1989 that results presented “did not present convincing evidence that useful sources of energy would result from phenomena attributed to cold fusion.” 
Research in cold fusion has continued over the years, but most mainstream sources remain skeptical of results to the point that some scientists call cold fusion a pseudo-science.  The skepticism of the scientific community stems chiefly from an inability to reproduce cold fusion results, and the theoretical unlikelihood of cold fusion.
Research into cold fusion continues, and as recently as January, 2011, researchers at the University of Bologna claim to have demonstrated cold fusion. However, interest seems to be waning, as evidenced by a 2004 decision by the U.S. Patent Office to no longer accept patents for cold fusion devices. 
Jean-Louis Naudin claims to have replicated the cold fusion reactor by researchers Tadahiko Mizuno and Tadayoshi Ohmori from the Hokkaido University in Japan.
Photo source: http://jlnlabs.online.fr/cfr/html/cfrdatas.htm
Nanotechnology and Solar Energy
The technology to harness the sun’s power is expensive and the development of more efficient and more affordable devices to do just that is a great challenge of solar power and billions of dollars are being invested to achieve that goal. 
One option that has been presented is to use nanotechnology to make a thin-film solar panel that is more efficient and more affordable than what has been offered in the past. However, many are arguing that the claims of improvements in energy efficiencies need to have less hype.
In 2004, physicists argued that more than one electron-hole pair could be pulled from one photon with semiconductor nanocrystals. This, physicists say, would double the charge, increasing solar energy efficiency.
However, some are disproving that theory.
“Our theory shows that current predictions to increase efficiencies won’t work. The increase in efficiencies cannot be achieved yet through Multiexciton Generation, a process by which several charge carriers (electrons and holes) are generated from one photon,” Professor Eran Rabani of Tel Aviv University’s School of Chemistry wrote of his research on the topic. 
However, freed of hype, scientists and researchers can continue to look at nanotechnology and approaches to develop more realistic improvements in solar panel efficiency and affordability, as well as other energy-saving innovations.