PrintEnergy Transmission and Interconnection
One of the most important issues in the renewable energy transition is that posed by the ability of the grid to accept the great quantity of renewable resources required for decarbonization. The issues can be broken down into two major categories. The first is location. We have discussed transportation basis differential in previous lessons, and it plays an important role in the integration of renewable resources as well. It is simply a fact that the renewable resources are not necessarily located near the energy loads. Supply and demand are separated by space. (Much of the electric load in the US is located near the coasts, while much of the wind resource is located in the Mid-Continent or off-shore. There is a great solar resource in the desert of Arizona without a really significant load there.) Consequently, the interstate electric transmission grid will need to be built out to a significant degree for the loads intended to be met with electricity to be served. This is not always an easy process as transmission paths can be disputed and new transmission is expensive to build.
The second issue is variability. Intermittent renewable resources like wind and solar do not respond to grid dispatch commands the way that on-demand combustion and steam turbines do. Since most renewable resources are not currently dispatchable and actually may become available in large quantities at inconvenient times, there comes a place for increased levels of ancillary services provided by the transmission grid. These services take the form of frequency response, spinning and non-spinning reserve. Sometimes these services can be supplied by shifting loads, electric and thermal storage, but very often by dispatchable gas or diesel fired combustion turbines. These combustion turbines are often very carbon intensive, and if we are to reduce the carbon footprint of the electric grid, it becomes essential to try to move to supplying these ancillary services from other sources. This is one of the reasons we are starting to see greater deployment of battery storage with solar and wind.