For those of us who work in transmission line design and construction, we know that a lot of work — up to 50% for some engineering firms — comes from building transmission lines to connect wind farms to the grid. For those of us whose jobs are directly tied to wind, the reality of green energy hits home. Transmission lines connecting wind to the grid tend to be shorter in length and lower in voltage, but that’s not always the case.
Consider the investment going into Texas to bring power into load centers from the Competitive Renewable Energy Zone (CREZ). Electric Transmission Texas, LLC (ETT) energized the first of seven 345-kV transmission lines. In West Texas, the Riley to Edith Clarke transmission line and the Edith Clarke switching station were connected to the Electric Reliability Council of Texas grid on July 31, 2013. This phase of the program represents US$141.5 million of ETT’s estimated total CREZ investment of approximately $1.5 billion.
The substation work generated by wind can be quite sophisticated as utilities work not only to connect renewables to the grid, but also to add stability to a grid that must deal with the inherent abrupt power swings associated with wind. One solution is the static VAR compensators we see being built in Texas to provide additional grid stability.
Solar can generate the same instability issues. Just ask San Diego Gas & Electric and Southern California Edison distribution design engineers who are battling the impact of a massive build out of rooftop solar.
Let’s take a look at the actual growth in wind and solar. According to data from Statista, the growth in wind output in the United States really took off, climbing 530% from 26.6 billion kWh of output in 2006 to 167.7 billion kWh in 2013. Similarly, total solar energy output has grown by 246%.
As the cost of solar panels drops and as state utility commissions increasingly set higher green penetration levels, investment in rooftop solar is also taking off. The total market value of rooftop solar has increased from $1.2 billion in 2011 to a projected $4.7 billion in 2016.
Add storage into the mix, and our electric utilities face several challenges in connecting and integrating renewables into the grid. Regardless of short-term trends, be assured that an increasingly sophisticated delivery system will be essential if we are to meet future energy needs.