Colorado’s power pathway: balancing the need for renewables and grid expansion

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olorado’s Power Pathway is a $1.7bn to $2bn investment proposed by state utility Xcel Energy to improve regional power infrastructure. The project, which was approved by regulators in February, will have enough capacity to transmit 5,500MW of wind and solar energy to the electrical grid through new double-circuit transmission lines.

While the route for the new infrastructure is yet to be determined, it’s expected to span more than a dozen counties in a loop covering around 650 miles in eastern Colorado.

Xcel Energy says that the project will help the state meet its clean power plan, for which it hopes to ramp up new wind and solar power resources through to 2030. It will do this by solving the much-discussed ‘chicken-and-egg problem’: the need to build grid capacity before renewable energy projects ramp-up to avoid bottlenecks in the system.

Legacy grid infrastructure was originally built to transport energy from centralised coal and gas plants to residents nearby, but offshore wind and solar farms are, in comparison, dotted around, often in far-flung locations. They require a different approach altogether.

The result is that grid constraints can often mean projects stall or fail in the advanced planning stages due to connection challenges. Data from Berkeley Labs shows new power generation and energy storage in the transmission interconnection queues across America are rising, and reached a new record of over 750GW of generation and an estimated 200GW of storage capacity at the end of 2020.

As of May 2021, about 680GW of zero-carbon capacity were currently seeking transmission access. To overcome this challenge, Princeton University researchers estimate that the US’s high-voltage transmission capacity needs to grow by 60% by 2030 if it is to meet its clean energy goals.

Xcel Energy has said the new transmission lines built through the power pathway project will encourage construction of wind and solar farms for more low-cost electricity to help meet Colorado’s growing energy needs.

The region is believed to be one of the nation’s best areas for wind and solar, and the company has a separate proposal to build about 5,500MW of new wind and solar generation, along with additional battery storage.

The project, the first phase of which is expected to be in-service by 2025, with others to be complete in 2026 and 2027, has widespread backing from environmental groups, labour organisations, state agencies and solar companies.

But the Office of the Utility Consumer Advocate and others argued that Xcel Energy had not demonstrated a need for all segments of the project and that it was at risk of cost overruns onto customers.

The regulator ultimately disagreed, and a representative from Xcel Energy says the company is ”pleased” that the Commission confirmed the project’s benefits and the value it will provide to customers and communities.

“We have done a lot to engage the surrounding communities,” adds the representative. “Talking to landowners gave our project team insight into specific issues for areas to consider while developing the routes, such as current and expected land use and environmental factors.”

But the objection highlights the challenges grid expansion projects often face. To deliver its power pathway, Xcel Energy will have to work with over 700 landowners and manage environmental and other issues.

Across the global power sector, there is ongoing work to reduce the environmental impact of grid infrastructure. Several transmission network operators (TSO) in Europe, which is the leader for wind power generation and technology, have conducted research on ways to reduce costs and environmental impact of new grid infrastructure.

Companies, including the UK’s National Grid ESO and Germany’s TenneT, the largest TSO in Europe, determined that current offshore wind construction is inefficient. When large-scale offshore wind assets are built, single, point-to-point connections from wind farms to the onshore grid using traditional high-voltage three-phase alternating current technology will be inefficient, expensive and potentially less environmentally friendly.

Instead, many TSOs are looking at integrating high-voltage direct current (HVDC) cables, which allow for much higher levels of energy transported with fewer losses, and eventually connecting them up internationally, across the UK, Belgium, the Netherlands, Germany and Denmark.

National Grid ESO noted in a September 2020 report that adopting such an “integrated approach” for all offshore projects to be delivered from 2025 could save consumers approximately $7.9bn in capital and operating expenditure between now and 2050. The number of cables and onshore landing points required could also be halved, significantly reducing the environmental impact.

TenneT’s new 2GW program aims to put this notion into action. The program was created to better integrate Dutch and German grids and will construct six offshore grid connection systems, including new sea and land stations that will have twice the transmission capacity of previous 900MW systems, requiring half as many grid connections.

The new 525kV cable system also requires fewer cables to transport the energy onshore with less spatial and environmental impact.

Back in Colorado, Xcel Energy says it is not considering HVDC grid technology for the power pathways project as it would not be “a cost-effective technology for our overall needs for connection to renewable energy resources spread over a wide geographic area”.

Yet these European examples could have an impact, with the company instead designing the project using transmission technology that complements current infrastructure to “ensure we can operate and maintain the new lines along with our existing system".

This will include double circuit transmission lines that enable the transfer of more power over long distances. During consultations, some had suggested the use of advanced transmission technologies, in particular carbon-core conduits, that one proponent said could eliminate upwards of 500 transmission towers. But ultimately it was thought the technology not mature enough and too risky to make it a project requirement.

“New technology may provide benefits to our customers in the future, but we are confident our plans provide the best option for our customers as we pursue our carbon reduction goals,” the Xcel Energy spokesperson says.

This need to balance technological innovation with practical feasibility is at the heart of the pathway project. Xcel Energy says the project is currently waiting to be reviewed, which it expects to receive in a few weeks, as well as for potential approval for a new wind and solar project.

If all Xcel Energy’s plans are approved as proposed, the company’s renewable generation portfolio will double by 2030, as compared to its generation in 2005.

It hopes to begin construction in the first phase of the pathway project by the end of 2023. More details about permitting and pre-construction activities will emerge as it begins the more detailed engineering, design and procurement processes, it said.

The costs for grid expansion to meet the need for increasing renewables are high. Research by the International Energy Agency determined that annual investments in energy sector infrastructure and technologies will need to increase from today’s level of around $1tn to $4tn by 2030 to achieve net-zero emissions by 2050.

However, the industry is tentatively showing that, in addition to the zero-carbon benefits renewables provide, there are possibilities to reduce the overall physical environmental impact of new grid infrastructure and renewable energy projects.

What’s more, research from The United Nations Economic Commission for Europe found that wind and solar have one of the lowest total environmental impacts, with wind in particular scoring highly for land use impact.

But more needs to be done by traditionally conservative grid operators, possibly led by governments, to develop new approaches and technologies to reduce impact further. Indeed, consultancy firm McKinsey, and others, have said that in order to develop and build the clean infrastructure needed to meet climate targets, organisations will need to radically shorten development and construction timelines.