Solar is inefficient, mostly because the best solar panels can't make the best of the sunlight they do catch, even amorphous solar panels are only 25% percent efficient. You'd need to make the incentive for home owners to put them on their homes and feed excess energy into the grid. With the stat of American power companies and the way they work, fat chance of that. Solar farms, even with solar thermal collection towers take up far more land space than they deserve for the output they have. Not to mention that much of North America isn't as sunny as people like to believe it is, especially concerning the Northern states and mountainous areas. The deserts are alright, but most places get just enough sun to make solar worthwhile only on a personal use basis.
Wind... Even the biggest wind farms only put out a tiny spark compared to most modest hydroelectric dams, again they're a massively inefficient use of land space for the power they generate. Also due to the number of moving parts, per-turbine, they're massive maintenance hogs on an individual basis, meaning wind farms are under constant maintenance, making them expensive. Wind turbines increase the cost of electricity when power companies try to focus on wind farms, this adversely effects the poorer populations served by them. But all that aside environmentalists who bellow about climate change caused by man, which the caused by man part is a bold faced lie in my mind[footnote]We have a huge geological record that shows climate change happens naturally and often at rates far more rapid than we're seeing.[/footnote], are the same people who want to ban wind turbines. This is because wind turbines are known for being a hazard to birds, especially the likes of bald eagles. Then you have the rich who cry at length about "man caused" climate change, but they won't let wind turbines be set up because they own the beach houses that are near ideal coastal locations, but they don't want to actually see wind turbines. Even if it saves the planets, freaking hypocrites.
Hydroelectric dams have the issue of environmentalists hating them to the point where it's nearly impossible to build new dams, this despite their durability, reliability, and massive generating capacity. Which is a shame because they could reduce our dependence on coal and petroleum by a massive amount. They do have one down side, their requirement of a significant source of flowing water. We just don't have enough rivers, creeks, and the like that to cover all of our power demands and the expansion of power production that we need. At least not by them selves.
Tidal power generation is a fantastic idea that generates a goodly amount of power. The down sides are that they're complicate, need to be watched, require a decent amount of maintenance to keep them working, and said maintenance is difficult due to the capturing devices being undersea. Along with that being undersea means sea life just loves to latch on to them, jamming them up with barnacles and coral. They also present a hazard to sea life, which is something animal rights activists and environmentalists will use against them in the long run.
Next up: Geothermal, this stuff is great, there are an abundance of sites where it can be done, even if the areas are fairly localized. They still require lots of attention be paid to them though, mineral build up reduces their efficiency over time, meaning the heat collectors eventually need to be replaced. That aside there is the potential of them becoming objectionable because they require pretty complicated construction projects, which "ruin the scenery", a complaint environmentalists and land preservation types will exploit.
Thermonuclear fission generation is a good one, produces lots of power, France in fact gets about 75% of it's electrical power from nuclear fission. The most obvious issue is that it's a complicated and expensive way of boiling water just to spin turbines to generate electricity. Also there is public opinion, with the likes of Chernobyl, Fukushima, and Three-Mile Island[footnote]Three-Mile island is a stupid one, it was a non-incident where they had to release a bit of radioactive steam that hurt no one. *sigh* People are idiots.[/footnote]. This is a major problem, environmentalists who detest any power generation get a strong argument with the very few catastrophes from nuclear power. Totally in spite of it's actual relative safety compared to traditional and newer renewable sources of power generation. Nuclear still has an image problem in the eyes of the public, this allows power companies who want to maximize profits and environmentalists who want to stop development an excuse not to use it. An excuse to regulate the market to a point where it's untenable to make new reactors to help power the country.
There is one final possibility, but it needs funding to complete research and start maturing the technology. This solution is contained nuclear fusion power, but for it to happen we need to focus on actually making sustained fusion possible, and collecting the energy it puts out. It can be done, but no one to puts in the investment to get the ball rolling. But this is a cheap form of energy, power companies don't want it to happen because they don't see a huge profit margin in it. Environmentalists I'm sure will also find something about this to complain about too and attempt to drown the baby before it can even walk, sadly...
We do have a far larger issue here in the United States is the state of our power grids. Texas has a fantastic grid all to it self, but the grids in the western and eastern sides of the country? Those decrepit inefficient dinosaurs, they loose way too much power, can't handle the strain we already put on them, and are unable to handle our further growth... They're a large chunk of the problem all by themselves. The biggest problem is no one wants to do more than the bare minimum required to keep them limping along. We're looking at a billion dollar, or more project to update them and rebuild them to standards we can cover our current needs and future growth with. There is the biggest problem of all, no one wants to cover the costs of full overhaul and updating, not the power companies and not the federal government. All the alternative renewable power the world can support won't be worth dick if we continue to try to limp along with a aged power grid that has one foot in the grave...
So if we update and rejuvenate the grid then put in a combination of all of the alternatives I've mentioned, we might, just maybe, be able to get fully sustainable renewable power by 2050... The problem is I don't see any of that happening at all. On the business side, the power companies seem just completely content to kick the can down the road on the grid and renewable. At the same time efficiency on most alternative renewable sources, is pitiful for the resources they require to run and the land space they take. Then you have the environmentalist concerns, which are by far the largest roadblock, they'll continue dumping regulation on the problem for the foreseeable future, making power more expensive and expansion basically impossible. Looking at things as they are, we won't be 100% renewable by 2050, we'll be lucky if we're half way there by 2150 at the rate we're going.
