President Joe Biden has called for major investments in clean energy as a way to stem climate change and create jobs. On September 8, the White House released a report from the U.S. Department of Energy that found that solar energy could generate up to 45 percent of the U.S. electricity supply in 2050 against less than 4 percent today. We asked Joshua D. Rhodes, an energy technology and policy researcher at the University of Texas at Austin, what it would take to achieve this goal.
Why so much focus on solar energy?
The Department of Energy’s Solar Futures Study describes three future paths for the US grid: business as usual; decarbonization, which means a massive shift to low-carbon and carbon-free energy sources; and decarbonisation with economy-wide electrification of activities now powered by fossil fuels.
It concludes that the latter two scenarios would require about 1,050-1,570 gigawatts of solar power, which would meet about 44 percent-45 percent of the expected electricity demand by 2050. For perspective, a gigawatt production capacity equates to about 3.1 million solar panels or 364 large wind turbines .
The rest comes mainly from a mix of other low- or zero-carbon sources, including wind, nuclear, hydropower, biopower, geothermal, and combustion turbines that run on zero-carbon synthetic fuels, such as hydrogen. Energy storage capacity systems — such as large installations of high-capacity batteries — would also expand at roughly the same rate as solar cells.
One advantage solar energy has over many other low-carbon technologies is that most of the United States has plenty of sunshine. Wind, hydropower and geothermal resources are not so evenly distributed: there are large zones where these resources are poor or non-existent.
Relying more on region-specific technologies would mean developing them extremely closely where they are most abundant. It would also require building more high-voltage transmission lines to move the energy over long distances, which could increase costs and draw resistance from landowners.
Is it possible to produce 45% of US electricity from solar energy by 2050?
I think it would be technically possible, but not easy. It would require an accelerated and sustained deployment that is far greater than what the United States has achieved so far, although the cost of solar panels has dropped dramatically. Some regions have reached this rate of growth, albeit from low starting point and usually not for long periods.
The Solar Futures Study estimates that production of 45 percent of the country’s electricity from solar energy by 2050 would require the implementation of approximately 1,600 gigawatts of solar production. That’s an increase of 1,450 percent from the 103 gigawatts installed in the United States today. For perspective, about 1,200 gigawatts of electricity generation capacity of all types is on the US electricity grid.
The report assumes that 10 percent-20 percent of this new solar capacity would be deployed on homes and businesses. The rest would be large-scale applications on a large scale, mostly solar panels, plus some large solar thermal systems that use mirrors to reflect the sun to a central tower.
If we assume that solar cells in scale of use require about eight acres per. Megawatts, this expansion would require about 10.2 million to 11.5 million acres. It is an area roughly the size of Massachusetts and New Jersey combined, even though it is less than 0.5 percent of the total U.S. land mass.
I think goals like these are worth setting, but it’s good to reevaluate over time to make sure they represent the most cautious path.
What are the biggest obstacles?
In my view, the biggest challenge is that driving change on this scale requires sustained political will. Other issues may also slow progress, including the lack of critical solar panel materials such as polysilicon, trade disputes and economic recessions. But the technical challenges are understood and quite straightforward.
Natural gas, coal and oil provided nearly 80 percent of the primary energy supply to the U.S. economy by 2020, including electricity generation. Replacing much of it with low-emission sources would also require the restructuring of most major U.S. energy companies.
Unless some agency, e.g. Federal Energy Regulatory Commission, has the power to approve new transmission lines, this kind of extension may be almost impossible.
Such a shift is likely to meet resistance, although some energy companies have begun to expand in that way. The Biden administration plans to use the Clean Electricity Payment Program, a $ 3.5 trillion budget provision awaiting Congress, to create incentives for power plants to generate more electricity from carbon-free sources.
Studies like this solar report also assume that there will be a lot of supporting infrastructure that is essential to meet their scenarios. According to the Solar Futures Study, the United States would need to expand its electrical transmission capacity by 60 percent-90 percent to support the levels of photovoltaic systems they envision.
Building long-distance transmission lines is very hard in the United States, especially when crossing state lines, which is what a massive solar rollout would require. Unless some agency, e.g. Federal Energy Regulatory Commission, has the power to approve new transmission lines, this kind of extension may be almost impossible.
One potential solution is to gain traction: to build transmission lines along existing road rights alongside highways and railways, avoiding the need to secure agreement from many private landowners.
How should the current system change to support so much solar energy?
Our electricity system currently gets about 59 percent of its electricity from coal and natural gas. These resources are generally, but not always, available upon request. This means that when supply customers require more power for their lights or air conditioners, companies can encourage these types of plants to increase their production.
Moving to a network dominated by renewable energy sources will require utilities and energy regulators to rethink the old way of matching supply and demand. I believe that the networks of the future will need much higher transmission levels, energy storage and programs that encourage customers to move the times when they use power to periods when it is most abundant and affordable. It will also require much greater coordination between North America’s regional power grids, which are not well configured now to seamlessly move electricity over long distances.
All of this is possible and will be necessary if the United States chooses to rely on a solar-heavy, decarbonized power grid to meet future demand cost-effectively.
This article is republished from The Conversation under a Creative Commons license.