Bury the Lines
Please read this article by engineer Andrew Ballentyne on how and why Maine can use high-voltage DC underground.
First, a little background:
We are hearing from legislators that there are as many as a dozen corridors in the works.
The LS Power corridor proposed through some of the best farmland in central Maine is likely the first of many.
Massachusetts’ ambitious net zero goals appear to rely on northern Maine’s supply of future wind and solar.
We can meet those goals AND preserve Maine’s natural beauty by using buried high voltage DC lines.
Stop Gateway Grid - Let’s plan ahead. Please read the article below and inform your legislators.
Download the article:
By Andrew Ballentyne:
Informative Bulletin:
Impact of Clean Energy Goals on Electrical Corridors
Andrew Ballantyne, PE 9/6/2023
The “Massachusetts Clean Energy and Climate Plan for 2025 and 2030” establishes a goal of 70% reduction in carbon emissions by 2030 and a 100% reduction by 2050.(1) Based on this, along with energy use data provided by the State of Massachusetts, it is estimated that the King Pine wind project and associated Aroostook Renewable Gateway corridor will provide roughly
1/7th of MA energy goals by 2030 and 1/12th of what is needed by 2050. This transmission line, contracted to LS Power in the Fall of 2022, will bring the power from the King Pine wind farm to Coopers Mills’ substation in Windsor Maine using 150ft tall overhead 345KV high voltage alternating current (HVAC) transmission lines. The majority of the proposed 150ft wide corridor will not utilize existing corridors. Instead, it will carve its way through over 100 miles of rural Maine; impacting hundreds of Maine landowners, many of which utilize the land for agriculture.
Perhaps more troubling is the fact that, as mentioned, this transmission line would only carry a fraction of the power that is needed to support our neighbors in Massachusetts, who consume seventeen times more power than they generate. (2) Massachusetts carbon emission goals, coupled with their increasing demand for electricity, will likely require additional renewable projects to be contracted in Maine, bringing with it more transmission lines and electrical infrastructure to our rural areas.
LS Power has already stated publicly that they have a long list of developers waiting to tap into their new corridor once it is completed, which will further impact surrounding Maine landowners in the next several years.
The good news is that there are much less intrusive ways of doing this that are better for the environment, provide better resiliency to the electrical grid, and can be done at a similar cost through existing Maine right-of-ways (ROWs). In the last decade, advancements in modern technology have allowed High Voltage Direct Current (HVDC) transmission to insert itself as a more favorable way of moving electricity over long distances. From a technical perspective, the major reason for this is the fact the HVDC can be buried underground in a ROW that is only 5ft deep x 5ft wide. This means that a HVDC underground corridor takes up only 3.3% of the same space that a 150ft wide overhead HVAC transmission line does. Even if someone doesn’t understand the technical differences between HVAC and HVDC, they can understand how much deforestation and visual pollution is reduced.
The primary drawback of HVDC is the cost to create a “converter station”. These stations are constructed to transform the power from Alternating Current to Direct Current or vice-versa. This process uses electronics (solid state devices) to convert the power, which up until the past decade has not been economically viable. However, in recent years, advances in technology are making these HVDC transmission lines the future of bulk power transmission over longer distances. In fact, a recent study conducted in the State of Minnesota, entitled “NextGen Highways Feasibility Study for Minnesota Department of Transportation – Buried High-Voltage Direct Current Transmission” estimates the cost of a 1GW converter station has fallen from $300M to $200M in recent years. Cable costs have also fallen from $3M per GW-mile to $1-2M per GW-mile. (3) This reduction in price allows the benefits of HVDC to outweigh the costs. NextGen recognizes this in their report writing, “Buried HVDC transmission is comparable in cost to overhead AC transmission while providing additional reliability and resilience benefits.” (3) Because of this reduction in cost, more projects utilizing HVDC are on the horizon. Some great examples of this are the NECEC project, which will utilize HVDC in Maine, and also the Twin States Clean Energy Link, which utilizes underground HVDC for approximately 75 miles. (4)
The study by NextGen also researched the societal benefit to the State of Minnesota by considering permitting costs, carbon emission reduction, and capacity of renewable energy that could be transmitted. The findings of this research concluded that by using HVDC transmission lines underground along existing ROW’s, the societal value would equate to an estimated $1.01B dollars. It should be noted that this benefit greatly outweighs the cost of the HVDC converter stations previously mentioned. Furthermore, the study points out that using underground transmission lines has a significant advantage compared to overhead AC transmission lines when it comes to public safety and environmental impacts. Underground lines are not susceptible to damage caused by ice storms, high winds, or fallen trees. With Underground HVDC you also do not need to worry about electrical fires starting because of fallen lines. On page 69, the report uses the Kincade Fire in 2019 as an example of how underground HVDC is a safer option than overhead AC transmission lines. The Kincade Fire was started in the State of California due to a Pacific Gas and Electric (PG&E) transmission tower that “broke in high winds, fell, and arced against the tower. The arc caused molten material to fall into vegetation and ignite below the tower. It took CalFire 15 days to contain the fire. The blaze burned more than 120 square miles and destroyed 374 buildings.”3 This should be a significant concern here in Maine as well. Installing new transmission line corridors through rural areas that have lots of vegetation is a potential safety hazard that should be taken seriously.
Like the steps taken by the State of Minnesota, I would urge our legislature to look to our engineers to develop a long-term solution for this. A great first-step would be to hire an engineering firm, such as NextGen, to conduct a feasibility study of utilizing existing ROWs in our state for underground HVDC. Until such time that a study is performed and a well thought out electrical grid archetype is designed, I appeal to our legislature not to allow any large-scale transmission lines be constructed in this State. We owe it to current and future generations of Mainers to take the appropriate amount of time in reaching a solution that will sustainably harness and transport power throughout the State of Maine.
Attached Appendix A you will find calculations I performed related to the anticipated required generation for the State of Massachusetts by 2030 and 2050. Attached Appendix B you will find an “Introduction to Buried High-Voltage Direct Current (HVDC) Transmission for DOTs.
1 https://www.mass.gov/doc/clean-energy-and-climate-plan-for-2025-and-2030/download
2 https://www.eia.gov/state/analysis.php?sid=MA
3 https://nextgenhighways.org/wp-content/uploads/2023/01/NextGen-Highways-Feasibility-Study-Minnesota-DOT.pdf
4 https://www.webster-nh.gov/sites/g/files/vyhlif4021/f/uploads/twin_states_energy_handout.pdf
Appendix A:
Download the PDF For Appendix B:
Protect this land: bury the lines.
LS Power has current experience in High Voltage DC projects as is evidenced by:
http://www.lspgridcalifornia.com/metcalf/
“The project includes two new high voltage direct current (HVDC) terminals, which provide the ability to control power flows. The northern HVDC terminal will include a 115 kV alternating current (AC) gas-insulated switchgear (GIS) switchyard and will interconnect to the existing San José B substation. The southern HVDC terminal will include a 500 kV AC GIS switchyard and will interconnect to the existing Metcalf substation via a new approximately two mile 500 kV underground transmission line. A new approximately 14 mile ±320 kV HVDC underground transmission line will connect the two terminals.”
http://www.lspgridcalifornia.com/newark/
“The project includes two new 320 kV high voltage direct current (HVDC) terminals, which provide the ability to control power flows. Each terminal also includes a 230 kV alternating current (AC) gas-insulated switchgear (GIS) switchyard. The northern HVDC terminal will interconnect to the existing Newark substation via a new 230 kV AC overhead transmission line. The southern HVDC terminal will be located near the existing Los Esteros substation and will interconnect to the existing Northern Receiving Station via a new approximately four miles 230 kV AC underground and overhead transmission line. A new approximately eight mile ±320 kV HVDC underground and overhead transmission line will connect the two terminals.”
