The Gigaton Throw Down has published a 150 page report on their view of the big energy bets for the next ten years. (see it at http://gigatonthrowdown.org/files/Gigaton_EntireReport.pdf
They analyze nine energy technologies that have the potential of displacing at least a billion tons of CO2 each within the next ten years. A gigaton by their calculation is 205 gigawatts of installed power, which is about 5% of US energy consumption. Some of their analysis is pretty good, some a bit over-optimistic, and they forgot a few biggies.
Biofuels: yes, but a close reading shows that ethanol, in any flavor, really does not make much economic sense on a macro scale. Ignores/understates the additional cost of erosion and fertilizer for cellulose ethanol, assumes a near zero cost for those feed stocks, and assumes a huge amount of currently non-agricultural land can be used in the future with some unspecified technology. Does not address that simply burning the feed stocks of cellulose alcohol produces more energy (as electricity) than ethanol, and a lot less expensively. Biodiesel is mentioned, but no explanation of how it will become an important part of the energy picture energy. Algae is considered a lot father away than ten years.
Building efficiency: yes, major requirement is change in the building codes.
Concentrating solar: yes.
Construction materials: yes, mostly focuses on concrete manufacture which consumes huge amounts of energy. Talks of low-energy cement, but with little background of how that would actually work or be implemented.
Geothermal: qualified yes. I think it overstates some of the risk associated with it.
Nuclear: qualified yes. Does not discuss "mini-nuclear" (sub 10 MW plants) for distributed energy production at lower risk. Also does not mention waste disposal issues, or the use of the Mariana trench.
Plugin electric vehicles: big no, and quite realistic analysis.
Solar photovoltaics: yes.
Wind: strong yes, underestimates wind resources of deep water offshore wind and high altitude.
Does not include any information on OTEC (Ocean Thermal Energy Conversion), which can produce many times current world total energy.
Does not include any information of hydrokinetic (waves, tides, and currents). The estimates for the amount of capturable energy in these resources vary tremendously, but the high estimates are many times the entire world's requirements.
Does not include any information on anhydrous ammonia. While not technically a fuel but an energy carrier, it can bridge the gap from making electricity and using it as a transportations fuel. Ammonia can run in most internal combustion engines with some modifications. Ammonia burns cleans; it's exhaust is water vapor and nitrogen gas. Ammonia and its byproducts are not greenhouse gases, and already is produced in a huge scale. One hundred and twenty millions tons were produced last year, about 50 pounds per capita worldwide. It is the most produced chemical in the world, other than petro-fuels. The technology of storing and distributing is already well known, and there is a significant infrastructure in place already. There are over 3,000 miles of ammonia pipelines in the US - compare that to zero miles of ethanol pipeline. The biggest use of ammonia is as a fertilizer, and it is used very widely as a refrigerant gas.
Since the report limits the horizon to ten years, it does not mention extra-terrestrial solar, or fusion (cold or hot). There are, of course, many niche energy solutions that may have good investing opportunities, but cannot be expected to produce a substantial amount of energy.
Disclosures: no stocks mentioned. Long a number of renewable energy technologies.