I don't believe there is too much confusion in terms of what alternative energy source work or do not. There are, however, plenty of entities pushing forward their interests.
For a quick run-down on the truly viable alternative sources:
Solar power:
* Works, it's sustainable, it will only get better. It has already reached grid parity in many markets, this trend will absolutely not reverse but continue. * Is nowhere near it's optimal efficiency, has tons of room for optimization of both cost efficiency and conversation efficiency (basically reducing the area required to reach a desired power output). * Requires a grid that is built with solar power in mind. Requires baseload generation, of which nuclear and natural gas are the best candidates (assuming the natural gas glut continues on).
Wind Power:
* Works, proven technology. It has reach grid parity in more markets than solar. * Is nearly at the limits of it's theoretical efficiency. There are pretty much only manufacturing cost and economy-of-scale gains to be had here, which I think really hurts wind power's future unless some sort revolutionary change happens in manufacturing process takes place. * Also needs a grid that plays nice with, with baseload assistance.
Hyro:
* Not much to say here, it's capped, very little room to grow. Extremely economically efficient but serious ecological effects.
Geothermal:
* See hydro, but will less serious ecological effects.
Biomass:
* Total crapfest. Until such time as we can bio-engineer some plant that turns sunlight directly into petrol or the like, biomass offers a a net gain to carbon emissions, especially in the case of corn. Sorghum/Sugar Cane is more interesting but hasn't panned out as of yet, mostly because of it being picky where it grows (it seems unwise to turn rain forest area into sorghum fields in the name of alternative renewable energy).
Nuclear:
* Massive amount of energy in a small form factor. * Potential for very bad accidents. (see: black swan event) * Nuclear proliferation concerns, nuclear waste to manage. * Decent economic efficiency. * Nuclear has a niche but can hardly be the world's power source. Would you want every country to be full of nuclear plants, including those whose governments change monthly, are prone to extreme corruption, etc. There are plenty of trade groups they are lobbying for support of "safe" nuclear technologies such as Thorium based breeder reactors, but the truth is these designs are almost entirely vaporwear, and have faults and dangers of their own.
I feel rather strongly the solar is the way forward, with nuclear in stable well-regulated countries for base load, with natural gas/hydro/wind/geothermal filling in the rest.
Meanwhile, me I live in corn country. And yes, biomass is a total crapfest, but it's extremely popular with the legislation around here because a lot of moneyed interests stand to make a whole lot more money by convincing legislators to subsidize it. And it's easy enough for them to complete the deal and sell it to the public by choosing a green color scheme for those "10% ethanol" stickers they put on gas pumps. Witnessing those shenanigans firsthand is what makes me extremely suspicious of any forms of subsidy. Excise taxes certainly aren't manipulation-proof, but they seem to be much more resilient to it than subsidies are.
Fuck subsidies. I believe solar/Nuclear/fusion(heh) will rule the future with or without them. Subsidies tilt the market to and fro without a care about reality, often supporting the wrong ticket.
Which means that if there is a market distorting subsidy to one market that you hate (e.g. coal/fracking at the federal level), often the only way to deal with it is create a subsidy or tariff in another (e.g. solar at the local level) as a counter-distortion.
It's also worth bearing in mind that "fuck all subsidies and tariffs" and "let free markets rule" are ideas pushed by carbon-industry funded think tanks (e.g. CATO) when it serves their agenda, but is swept under the carpet when it doesn't (the only solar panel tariffs CATO complained about was the feed in tariff).
Some examples:
Tidal tech here and now:
http://energy.gov/articles/maine-project-launches-first-grid...
http://www.theday.com/article/20130331/NWS01/303319909/-1/NW...
Near future:
More:
The U.S. Navy has committed to get half of its energy from renewable sources by the year 2020. One element of that strategy will be looking to extract energy from tides, currents and waves:
http://www.washington.edu/news/2014/10/24/u-s-navy-awards-8-...
I also think you failed to mention that nuclear is too expensive. That's why places like France (who have had success with nuclear in the past) are transitioning towards alternative energy (like offshore wind) instead of building new nuclear plants.
http://cleantechnica.com/2012/03/26/nuclear-power-too-expens...
More sources of evidence that show why nuclear is too expensive:
http://v1.apebble.com/static/clean/CSI_Nuclear_Power_Fact_Sh...
http://www.smh.com.au/federal-politics/society-and-culture/n...
http://www.forbes.com/sites/jeffmcmahon/2012/03/29/exelons-n...
http://www.ucsusa.org/nuclear_power/nuclear_power_and_global...
http://www.psr.org/resources/nuclear-power-factsheet.html
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We really don't need to build new nuclear plants to transition and we should work to responsibly phase them out over time. Here's results from a Stanford researcher whose study shows the world can be powered by alternative energy in 20-40 years:
http://scienceblog.com/65427/the-world-can-be-powered-by-alt...
More:
Mark Z. Jacobson - Energy Policy
http://web.stanford.edu/group/efmh/jacobson/Articles/I/JDEnP...
Here's for New York (with more numbers):
http://web.stanford.edu/group/efmh/jacobson/Articles/I/NewYo...
http://news.stanford.edu/news/2013/march/new-york-energy-031...
Jacobson doesn't just throw numbers around, he makes some very salient points along with strategies as well.
We should also factor in advances in decentralized battery storage that are bound to offset current baseload issues. For example, breakthroughs in graphene production, etc.:
http://delta.tudelft.nl/article/making-graphene-affordable/2...