So fast, in fact, that it would take only one-third of the solar and wind energy projects that have already been proposed to almost entirely phase out coal in the state, according to a new study by researchers at Houston’s Rice University.

That’s huge news, considering President Joe Biden’s goal for the U.S. to have a carbon-free power sector by 2035. 

But there is a big catch: The state’s energy grid is a mess, and it is standing in the way of a faster transition in Texas away from coal and toward renewables. 

“Transmission lines are the leading bottleneck that is slowing down the growth of wind and solar,” Daniel Cohan, one of the study’s coauthors, told Fortune.

The energy-rich state

As the top U.S. producer of crude oil and natural gas, Texas is easily one of the most energy-rich states in the country.

But it has a whole lot more than just fossil fuels going for it.

It leads the nation in wind power generation, which accounts for around 20% of Texas’s energy usage, while the state’s solar power industry is also growing fast.

But while the potential for renewable energy in the state is massive, Texas is also the country’s largest coal consumer, according to the U.S. Energy Information Administration.

Coal is considered to be the dirtiest fossil fuel, and its phaseout is key to achieving U.S. President Joe Biden’s ambitious climate goals.

As the nation’s largest coal consumer, and biggest electricity consumer in general, how coal is phased out and replaced with clean energy in Texas would be crucial to meeting any nationwide climate agenda and to lead other states in the inevitable energy transition.

A troubled power grid

Since June 2020, dozens of the new renewable energy projects have been approved, and the number of new proposals for solar and wind farms has doubled.

But there’s one big problem: The state’s electrical grid is a mess. 

Different parts of the state can generate more energy at different times. Winds are strongest at night in west Texas, for instance, but tend to pick up during the afternoon in coastal southern regions of the state. You need a power grid to connect all those areas. 

“Simply put, it’s not always windy and not always sunny, but it’s almost always windy or sunny somewhere in Texas,” the study’s authors wrote in the paper.

But without an extensive and up-to-date network of transmission lines to connect the electricity generated at these farms to cities, Texas’s energy transition will have to wait.

In February 2021, Texas was hit by a historic deep freeze that led to prolonged power outages across the state. Although lawmakers blamed wind power and renewable energy for failing during the storm, the major culprit was the electrical grid’s dated infrastructure and aging transmission lines. After the storm, ERCOT, the private company that manages Texas’s electrical grid, came under fire for reportedly cutting corners and loosening regulations, leading to outdated and ill-equipped infrastructure.

Nationwide, aging electrical transmission infrastructure could soon be updated. In Biden’s recently approved infrastructure bill, the president laid out a financing plan worth over $15 billion to construct thousands of miles of new lines and upgrade existing ones.

While Texas’s ERCOT has historically remained stubborn against integrating with the national grids, it is beginning to intertwine itself more with neighboring power systems, such as through the ongoing $2 billion Southern Cross Transmission project.

But Cohan believes that even though the infrastructure bill is a good start, more attention and investment is needed to sufficiently update the country’s power system.

“The infrastructure bill was only a very small step forward for transmission,” he said. “It has some funding for a few projects and some funding for studies, but it’s nowhere near the scale of what’s needed nationwide to expand our transmission infrastructure.”