I Had No Idea -- High Voltage DC Transmission Lines In North Dakota -- June 28, 2018

First the graphic, look where the only US high voltage DC transmission lines are in the US:

The link: at the EIA --

A new study commissioned by EIA examines the role of high-voltage direct current (HVDC) lines in integrating renewables resources into the electric grid. The review indicates that, although applications in the current electric transmission network are limited, HVDC lines have a number of potential benefits including cost effectiveness, lower electricity losses, and the ability to handle overloads and prevent cascading failures. These attributes mean that HVDC lines could, if properly configured, help mitigate some operational issues associated with renewable generation.

Renewable resources can be categorized into two types of generating sources—dispatchable and non-dispatchable. Dispatchable generators can respond to real-time system operator instructions to increase or decrease output. Among renewable power plants, those fueled by geothermal and biomass resources are considered dispatchable.

Non-dispatchable renewables, such as those fueled by solar and wind energy, are dependent on the availability of naturally occurring resources. As a result, these technologies have a limited capability to respond to dispatch signals. Hydroelectric generators fall between these categories; they can typically respond to dispatch signals, but they often have seasonal operational limitations that prevent them from being completely dispatchable.

Go to the linked article to see why high voltage DC transmission lines are being considered for renewable energy.