The Green New Deal, as supported by most Democrats, envisions a U.S. power consumption market that is 100% served by renewable energy sources - primarily solar and wind renewables.
Is it hypothetically possible that either solar or wind, or some combination of the two, could deliver 100% of U.S. energy needs in the future?
Sure, but in reality it would not be practical, nor achievable, nor a desired outcome.
A very gigantic stumbling block to either wind or solar are the ludicrously huge land space requirements that are essentially insurmountable.
Using the total U.S. power 2017 consumption (estimated) as the goal to be met, either the wind or solar solutions would need to be able to generate 97.7 'quads' (97.7 quadrillion BTUs) on a yearly basis. That BTU figure converts to approximately 28,633 annual terrawatts, which in turn translates to an annual 28,633,000,000,000,000 watts consumed.
As the adjacent graphic indicates, whether it's a 100% wind renewable solution or a 100% solar solution, the approximate space needed in the continental U.S. would be astronomical for either, making these energy solutions politically and economically nonviable.
In contrast, even with current reactor technology, the land requirement for a nuclear solution (see green-filled rectangle on map) is a physical sliver of either solar or wind needs. In fact, the land needed by nuclear would amount to an approximate space as small as Connecticut.
And if the U.S. were to pursue a Gen-IV nuclear technology solution, such as molten salt reactors, the new reactors could be placed on the existing nuclear plant sites to use the old radioactive waste as fuel that is currently being stored at nuclear sites. Yes, Gen-IV technology can consume the old stored waste as fuel.
And because nuclear facilities produce energy 24/7/365, they do not require the same natural gas, pumped storage, or battery storage back up capability that wind and solar require, due to their being intermittent sources of energy. (The method of back up needed by renewables will also add to the the total land area requirements, which is not depicted on map image.)
Then there is the issue of new electrical transmission lines to be constructed. Because of geographical size of the solar/wind options, the number of new transmission lines to serve all the different wind/solar energy farms will be multiple times more than that required by the nuclear option.
Finally, as a plus, the Gen-IV technology is safe from melt down or potential containment vessel explosions due to its inherent design fundamentals. Conceivably, due to less risk, the total land needed for such technology might end up being less than the older nuclear plant sites.
Due to land requirements alone, it would behoove politicians of both parties to plan for and promote an industry standard design of the Gen-IV reactor technology to be adopted and installed as quickly as possible. It should become the nation's major source of electricity generation, along with smaller installations of solar and wind where locations favor their utilization - i.e., the sunny and windy regions.
Note: The land requirements for nuclear, solar, and wind were supplied from this NEI.org article. The adjacent table is a summary of the basic information used to calculate the land requirements assuming that all power consumption for all sectors would be in the form of electricity from non-fossil fuel sources, including transportation and heating. For the above U.S.map image, the square mile size of each U.S. state -- used to visualize the approximate land mass needed for each energy production source. Best case scenarios assumed for solar and wind capacity efficiency; industry average scenario used for nuclear capacity efficiency. Existing hydro power generation (about 2.9% of 2017 total) would slightly reduce amount of land required by wind, solar, and nuclear. Offshore wind farms could be utilized but they may ultimately be 2 to 3 times more costly; and will be exposed to greater natural weather and environmental stresses that cause more frequent operational maintenance/repair that will likely be difficult and lengthy.