We live in a world where humanity's decisions are increasingly affecting the physical landscape of our world, both for the good and the bad. The Industrial Revolution was built on the bedrock of society's increasing fossil fuel consumption, and we're going to be feeling the consequences of that for generations to come. But it also led to our civilization reaching heights not seen at any other point in history and developing technological advancements that would have been thought impossible by humans even 100 years ago.
However, we are finally starting to see green energy solutions to longstanding problems facing our planet gain momentum in mainstream culture. The ethos of environmentalism is no longer embodied by classic liberal/hippy stereotypes. Sustainability should be a bipartisan issue, as it is our best bet to create continued prosperity and maintain a livable ecosystem on Earth. Fossil fuels are finite resources, and even the least aggressive timelines predict that they are going to run out in approximately the next 100 years.
The problem with the above theory assumes that the planet will be livable for that long under the continued practices we're employing now. I would strongly suggest reading the article linked directly above this chart in its entirety, but the ending should drive the point home nonetheless.
Quick Synopsis of Renewable Energy Sources & Viability for Individual Energy Divestment
Depending on the study you're using, solar is either #1 or #2 in the race to be the cheapest form of renewable energy on a kWh scale. It also happens to be the easiest type of green energy system for individuals to implement for their personal use, and the celebrated futurist Ray Kurzweil has predicted that the solar industry will dominate energy over the next decade. The cost of installation is relatively cheap after tax rebates and when considered as a long term investment. A solar energy system will not only pay for itself over time, but can also eliminate your energy bill entirely and make you a profit vs. your original investment. Additionally, there are a multitude of community solar initiatives taking off around the country for people who either do not have solar-viable homes, or those that cannot or do not wish to install solar energy systems on their own property.
The energy department published a goal of sourcing 20% of the US's power from wind energy by the year 2030. Wind energy is, in many places, also as cheap as solar. However, a turbine requires a lot higher investment total than a photovoltaic panel system. Similarly to solar, there are community wind programs that allow you to source your energy use from wind farms here in the US, or at least purchase wind energy RECs. Wind and solar combined are going to be the easiest and quickest avenue for individual consumers to divest their energy consumption from fossil fuels. They also represent the most insulated green job growth against the Trump administration's fossil fuel push, as the economic benefits of renewables easily seen in a spreadsheet.
Hydropower is a safe, reliable, non-emissions creating way to generate electricity once a hydroelectric facility is constructed. However, one huge barrier to using hydropower is the high entry cost, basically meaning this type of energy cannot be implemented by individual citizens on a large scale. Also, the environmental consequences also need to be taken into account whenever we consider investing in this type of energy.
Biomass represents a relatively small percentage of the renewable energy that is generated currently in the US (5%). It would require significant technological advancements in order for this to be more than a niche product, and most ways of capturing biomass energy involve burning raw materials.
In theory, it would be ideal to exhaust every possibility in our search for energy independence simultaneously and immediately. However, due to the various concerns involved with capturing energy through this process and the speed with which we need to act to stem climate change, it would be wise to first build up our wind and solar energy infrastructures before focusing on processes like harnessing energy from biomass.
The United States is the largest producer of geothermal energy, of the 20 countries that currently engage in this process. One of the great things about geothermal energy is that it is "always on". Although it is getting easier to store renewable energy whenever the sun is not shining or wind isn't blowing, theoretically a prolonged absence of either would lead to an inability to produce energy via those means. That's not a problem with tapping into a constant source like the earth's temperature, and it is very inexpensive once a plant is built. However, the various disadvantages of this energy source make it hard for many individual consumers to utilize this type of system in their homes. Basically, this avenue of energy production shows a lot of promise as a supplementary option to solar and wind, however it will require significant additional investments by governments and the private sector to achieve full efficacy.
Generally, Hydrogen technology is one of the least understood types of renewable energy. It requires a knowledge of chemistry to understand the process of separating naturally-occurring compounds into more basic elements that are then able to be used as fuel sources. Since Hydrogen is the lightest, simplest, and most common element in the universe, it would seem to be a great candidate for sourcing our energy. NASA has even used Hydrogen engines to power some of the world's most advanced technology for the last 4+ decades. Yet, obstacles to the mass utilization of Hydrogen energy are going to be hard to overcome without massive improvements to transportation methods, cost-efficiency, technology, and infrastructure. It remains a volatile resource when insufficient precautions are taken and can be very dangerous.
Ocean, or Marine energy, is similar to Hydropower in many ways, the biggest being that they both (primarily) generate power from the kinetic flow of water. Additionally, it has a minimal carbon footprint and will never run out. Marine energy also has many of the same downsides as Hydropower, including disturbing natural aquatic habitats, geo-specific viability, and high entry costs for building a plant capable of converting power. Being able to use a resource that takes up 2/3rds of our planet as a means of producing energy represents a huge opportunity for human civilization in the future, and "recoverable" wave energy capacity right now is equal to almost 1/3rd of the electricity the United States uses every year. Right now though, our capabilities in this renewable technology are insufficient to harness the full power of our oceans and meet the world's energy demands.