What will transitioning the energy economy to prepare for the future entail, specifically with regard to renewable energy and the political and economical barriers that prevent the transition?

The main barriers to renewable energy goals and other eco-friendly solutions are social and political, rather than technical or economical. This claim is supported by Mark Z. Jacobson, a Stanford University Professor of Civil and Environmental Engineering. He is also the director of the campus Atmosphere/Energy Program.
The fossil fuel energy structure has been in place for a century, as oil giants have poured millions of dollars into lobbying against alternative energy sources. Both Republican and Democratic politicians accept huge campaign donations from the oil industry and its investors, although several Democratic politicians have been leaders in promoting the transition to cleaner energy, particularly in western states.
One of the main hurdles to cleaner energy is mass media, since many big news outlets profit from advertising revenue that originates from oil-based companies. Lack of media coverage on the benefits of solar and wind energy, as well as electric vehicles and other sustainable solutions, pushes the topic to the background in the minds of many consumers.
Renewable energy studies, for example, rarely make headlines, such as a joint study by Stanford and the University of California which found that costs for a 100% transition to renewable energy were over 60% lower than those of the traditional energy system. The study projected that clean energy transition would create a net gain of over twenty million jobs globally.
Despite lack of mass media coverage, solar and wind power reached a level of accounting for 10% of all electricity generated in the United States in 2017. The main economic barriers are huge upfront costs to build solar and wind farms. At the same time, solar panel costs have dropped dramatically, particularly in China, which has helped fuel the global solar revolution. Trump's tax tariffs, however, have increased the prices of imported products and materials.
Since solar and wind power can be decentralized energy sources, it's possible for community developers to avoid the higher costs of building huge power plants and instead invest in smaller power generation and distribution systems. Much of the solar revolution in states such as California has been driven by utility companies investing in solar power. The state is a model leader in renewable energy transition; for example, in December 2018, the California State Energy Commission mandated solar roofs on all new homes under three stories starting in 2020.
In December 2018, Stanford announced that the school would be powered by 100% solar energy by 2021, which outpaces California's goal of establishing a carbon-free grid by 2045. Stanford's solar power will come from an 88-megawatt solar plant based in Lemoore, which is southeast of the San Francisco Bay Peninsula. It's the school's second solar generating station; the first has already significantly reduced greenhouse gas emissions.
https://news.stanford.edu/press-releases/2018/12/03/stanford-go-100-percent-solar-2021/

https://www.ecowatch.com/mark-jacobson-barriers-to-100-clean-energy-are-social-and-political-no-1882122292.html