When looking at climate solutions for clean energy generation, it is prudent to look at all clean energy sources.

Nuclear power has the highest capacity factor of any energy source and is the most reliable, and efficient, source of energy. Clean energy solutions include both renewable energy (the obvious choice); as well as nuclear energy (which is non-renewable, and a not-so-obvious choice).

Nuclear Energy - The Most Energy-Dense Fuel

For the initial capital costs, nuclear is the most expensive form of energy. However, nuclear fuel (up to now - uranium, burned as fuel in current nuclear reactors) is an exponentially more dense fuel source than any other. Nuclear power represents by far, by a factor of a million - the most energy-dense energy source on the planet, based on a comparison of a similar quantity of nuclear fuel and coal (and coal is very energy-dense, but uranium is exponentially more energy-dense than all other fuel sources).

The Power of Nuclear and Politics

Even with the high up-front costs of developing nuclear power plants, Republicans tend to back nuclear energy, and so do most Democrats in Congress. Thus, nuclear energy is a potential area of bipartisanship for Congress and the U.S. Executive Administration.

Nuclear is a global incumbent energy source and is associated with a great deal of money and political influence worldwide. Therefore nuclear energy continues to have support from most politicians in the United States. The "good" thing about nuclear energy production is that there are little to no greenhouse gas emissions (no GHGs associated with the actual energy production from nuclear fuel, other than water vapor, in the form of steam).

However, it's necessary to find suitable locations to safely secure the radioactive waste produced from the combustion of nuclear fuel. Next-generation nuclear fuels promise to burn fuel significantly cleaner (Gen IV nuclear promises to run on spent uranium or thorium - much cleaner sources than uranium).

One other major consideration, to put it mildly, with current nuclear reactors is that we have to hope that there's not a Fukushima-type catastrophe. The solution is advanced nuclear reactors.

Gen IV nuclear promises to be safer, as well as cleaner, than current nuclear reactors. This is only theoretical at this point, as Gen IV nuclear is still in this design phase.

Gen IV Nuclear

4th generation nuclear promises to be safe, clean; and a source of cost-competitive and efficient energy. New reactors being planned in advanced nuclear designs can run on spent uranium and even thorium. 4th generation nuclear has entirely safe, cost-efficient designs. These reactors just need to get through R&D and demonstration phases, and become commercially viable alternatives in global energy mixes for countries.

Actually, the levelized cost of energy production from new, advanced nuclear reactors is looking viable. Nuclear is already a clean, efficient energy source - and future generations of nuclear energy production might prove to be perfectly safe, as well.

The major problems with the current generation of nuclear plants are the potential for another Fukushima-type disaster, nuclear weapons proliferation, nuclear waste disposal, and the very high up-front capital cost of building nuclear plants. The US Energy Information Administration estimated that for new nuclear plants in 2019, capital costs made up 75% of the LCOE.

Economies of scale (ideally) will drive down the costs of building the next generation of new nuclear plants - eventually over time. The remaining costs of developing and running a new generation of nuclear plants are projected to be cost-competitive with other "base-load" forms of energy generation, e.g. combined cycle gas turbines (CCGT). The probable, hopeful future cost-competitiveness of nuclear is another point that makes nuclear energy a viable energy solution for the future.

The following are snippets from articles listing reasons nuclear and renewable energy are the best options for future global energy sources:

"Nuclear power and hydropower form the backbone of low-carbon electricity generation. Together, they provide three-quarters of global low-carbon generation. Over the past 50 years, the use of nuclear power has reduced CO2 emissions by over 60 gigatonnes – nearly two years’ worth of global energy-related emissions."   FROM  -  iea.org/nuclear-power-in-a-clean-energy-system

"Levelized cost of electricity (LCOE) is often cited as a convenient summary measure of the overall competitiveness of different generating technologies. It represents the per-MWh cost (in discounted real dollars) of building and operating a generating plant over an assumed financial life and duty cycle. 4 Key inputs to calculating LCOE include capital costs, fuel costs, fixed and variable operations and maintenance (O&M) costs, financing costs, and an assumed utilization rate for each plant." - quote from the EIA.

* Examples of levelized costs of energy include:

up-front capital costs/ costs of initial investment (which are much higher for renewable energy than fossil fuel energy)

marginal cost of the fuel source (which is much higher for fossil fuels, and almost nothing for free, abundant sources of renewable energy like solar and wind energy, and very low cost for hydro, geothermal, and biomass)

cost of maintenance for the power plant/ energy farm/ dam, etc... 

cost of transporting the fuel (again, zero for most renewable energy)

costs associated with transmitting/ distributing the energy, insurance costs for the energy producing facility, etc...

Gen IV nuclear promises to have reasonable capital costs, and low marginal costs. Until Gen IV gets developed and deployed, we just have to hope the costs really are going to be low as advertised. So, other than a  relatively higher up-front capital cost than renewables, hopefully, the rest of Gen IV's LCOE data points should look roughly similar to renewable energy.

How Much Better Are Nuclear & Renewable Energy Than Fossil Fuels?

The reason that economic arguments tend to trump environmental arguments when finding solutions to anthropogenic climate change, is because many politicians are more likely to respond to economic arguments. You could simply say, "renewable energy is better than fossil fuels, because renewable energy is better for the environment, and is a more efficient energy source overall".

However, odds are politicians won't care until you also point out that the LCOE of renewable energy is less than the cost of fossil fuels. Many politicians already do want to support clean energy transition strategies. Finding ways to convince all politicians to support clean energy investment is important.

Republican politicians will also be needed to pass environmental regulatory laws - laws that support clean energy, and hopefully a majority of politicians soon support a federal carbon pricing system - that also supports clean energy.

Politicians don't necessarily have to want to protect the environment, or "give in" to the science behind anthropogenic climate change. Politicians can simply vote for energy policies that represent a cost savings; which tend to be clean energy investments. That includes supporting both renewable and nuclear energy.

Overall, the lowest cost of energy production are wind and solar (which also have zero negative externalities) This is followed by natural gas (which carries the cost of negative externalities). Natural gas is followed by more renewable energy sources, most significantly solar thermal and offshore wind.

Other than solar and wind, nuclear and hydroelectricity represent the past, present, and future of global clean energy on a large-scale basis. In fact, historically, nuclear and hydroelectricity have been the largest sources of global clean energy. Hydroelectricity also represents a relatively low cost source of domestic energy for the United States. 

When the costs of the negative externalities (damage to public health & the environment) associated with fossil fuel production are added in with the LCOE, the relative cost of renewable energy sources (as well as Gen IV nuclear) vs. fossil fuels is lower still. In fact, producing energy from coal is no longer cheaper than renewables or gas, and is very harmful to both the environment and public health (negative externalities).

The cost of producing energy with renewable fuel vs. fossil fuels is dramatically lower when just the cost of producing electricity (marginal cost) is considered. 4th generation nuclear promises to have a relatively low up-front capital cost, and a low marginal cost as well. Fuel for Gen IV nuclear designs promise to potentially run on spent uranium or thorium; which are cheap, abundant fuels that produce little waste.

Please see:

Nuclear Energy- One Necessary Energy Source to Fight Climate Change

..for more on how nuclear energy can be a climate solution, providing a clean, efficient, viable source of energy to power the modern, sustainable world.