How do we get from here to there?

REN-wilton-wind-092015.jpgMoving energy from rural renewables to urban consumers

More wind farms are coming on line and solar installations are sprouting across the country. While this is good news for renewable energy developers, there are looming issues on how power generated by renewables gets to power consumers. Since most renewable generation is done in more remote areas, this means expanding and upgrading transmission lines.

Traditionally, power lines connect to a substation near a power plant, with the power transmitted to another substation near consumers. With power from wind turbines and solar arrays, there is no true central power plant, and the power generated needs to make it to the substation from sources spread over a wide area. That means a somewhat different approach to transmission line planning.

“The grid is only as strong as its weakest link,” said Brandon Goltz, an engineer in Ulteig’s TD&C area. “Transmission lines can only handle a finite amount of power, and the problem with renewables is the power is not always being generated when the customer wants to use it.”

Renewable developers aren’t able to simply build a wind or solar installation if they are not able to transport the power to be sold. Planners need to account for multiple variables and potential growth in designing transmission lines. One of those variables is that generation from renewables isn’t a “plug and play” operation.

“Generation from the installation could be any voltage and would need to be stepped up to a higher voltage so it can be connected to a grid,” explains Goltz. “This requires large power transformers to match the voltage of the system they’re connecting to. Further collaboration with the system operators is needed for power factor correction, voltage control, frequency control, protection coordination and communication.”

With multiple generation sources, planning to get the power where it needs to be, at the appropriate voltage level, and with the right connections between sources, can be difficult to picture. Goltz compares it to a gravel road as opposed to a multi-lane freeway.

REN-max-wind-092015.jpg“A gravel road represents an old power system that can only handle a small amount of power and only goes from point A to Point B,” he explains. “The multi-lane highway represents an upgraded larger transmission system with multiple substations, or on- and off-ramps, if you will. They connect the grid together and help avoid traffic jams. Repairs would be minimal as these multiple paths of the power grid can be rerouted for outages and repairs. Distributed generation can be added to the system at the multiple substation locations along the path of the line.”

Adding more to the grid also means more detail to the elements that come from transmission line planning, from land acquisition, right-of-way, environmental impact, cost and who will build the line. Then add in route planning, topography, land owners and existing infrastructure. Goltz says it can make for complex and fascinating projects.

“The process of building a transmission line involves many people,” he sums up. “In short, the demand for the transmission line and its sources drives the design and land acquisition to build the line.”