Once synonymous with oil, Texas now leads the US in renewables generation, with wind and solar contributing 40% of the state’s power mix.
With generous tax breaks and the Environmental Protection Agency’s efforts to shut down most of the country’s coal plants, the US, at least in the pre-Trump era, has been an unsung champion of renewable energy.
From west to east
But it is not simply a matter of building capacity and plugging in. Although Texas is blessed with abundant sun and wind, these resources are mostly in the western part of the state, where relatively few people live. So the challenge is getting the power from where it is generated to where it is needed.
Traditional thermal generation tended to be closer to the cities and as these plants are retired power delivery is becoming a big issue. This requires new transmission lines in Texas and across the US, which is good news for companies providing power delivery services.
Another challenge relates to patterns of air circulation: the wind rarely blows in the afternoon in western Texas. Turbines are therefore idle when people come home from work and the demand for power is at its peak. This demand is being met by traditional coal-fired power generation. One solution to this conundrum is to spread wind generation around different areas. The wind on the coast of the Gulf of Mexico in Texas blows consistently between 4pm and 7pm, so with a recent surge in renewables developments, electricity generated there is being transmitted to other parts of the state. Another option is to mix wind and solar generation. The sun continues to shine in west Texas during the late afternoon peak, even if the wind has died down.
Combining wind and solar
Across the US, solar plants are now being built near wind generation sites – mixed-use facilities are now mandated in California. Large-scale solar generation was until recently lagging way behind wind, but is now fast catching up, bringing down the cost. Meanwhile, battery storage is crucial to addressing the challenge of balancing a grid reliant on renewables and meeting peak demand. Mott MacDonald has worked with battery storage companies across the US and has designed multiple facilities in four different states and on Caribbean islands for one major firm.
The increase in renewable generation in the US has led to significant investment in transmission infrastructure. Texas recently completed its US$9bn competitive renewable energy zones (CREZ) programme to move the power from the west of the state to four major cities, Houston, Dallas, Austin, San Antonio. And there is much more to come.
With transmission distances increasing, projects are moving away from using alternating current. One is a 1100km high-voltage direct current (HVDC) transmission line running through Oklahoma, Arkansas and into Tennessee. Another runs from Texas through Louisiana and Mississippi. We are providing services for the latter and expect similar projects to emerge over the next five years.
Engineering innovation
When working on new technology, such as HVDC transmission, battery storage or balancing the grid for a greater contribution from renewables, there is no template. “You have to put innovative engineers who think out the box on these kinds of projects,” says Bob Beckage, programme director in the US.