Understanding the limitations of existing bulk Transmission System in the US

The existing bulk (230 kV and higher voltages) Transmission System is constrained throughout the Western United States.

According to Bob Stuart, Senior Director – Transmission, BrightSource Energy, the major constraints are nowhere more apparent than transporting power into the major load centers in California.

"The best solar sites are in the Mohave desert in Southern California, Nevada and Arizona.  There are several 500 kV and 230 kV transmission lines that import power from Nevada and Arizona into the Southern California load centers that are constrained by stability limits," said Stuart, who is scheduled to speak during CSPToday's 2nd CSP Summit US scheduled to take place in San Francisco on 30th September – 1st October this year.

Stuart is scheduled to address ` Your Transmission Capacity – A Bright Or Bleak Prospect?' session during the conference.

Stuart said that the existing bulk Transmission System was never designed to handle what potentially is over 10,000 MW of renewable resources. 

"The large solar thermal companies are mindful of this and have chosen sites as close to major transmission corridors as possible, however this still doesn't alleviate the need to install major transmission upgrades," he told CSP Today.com. 

He added that the focus should be on delivering the firm MW output of the renewable resources to the desired load centers in the most efficient and economic manner, though not an easy task. 

This effectively means redesigning the bulk Transmission System to accommodate the diverse and intermittent resources of wind, solar and biomass and integrating these resources with more traditional sources of electric power. 

"It is important to understand that a well designed and reliable bulk Transmission System is an integrated transmission and generation system. By utilising the best available technology and thinking outside the box will mean that transmission systems of the future will not have to be designed for MW of installed generation capacity.  For instance, solar and wind resources can complement each other because of the diversity of the resources," said Stuart.   

In case of Los Angeles Department of Water and Power (LADWP), it has three planning levels - local, regional and sub-regional. For example, in case of sub-regional planning, for LADWP, this consists of the interconnected electrical network spanning several states in the Southwestern U.S., including California, Nevada, Arizona, and Utah.

Assessing such approach from CSP perspective, Stuart said it makes sense to plan interconnected Transmission Systems from a regional perspective that could span several states. 

"It is not uncommon for utilities to sponsor regional transmission projects that involve several states.  There are several regional planning organisations such as Westconnect throughout the Western United States that do a good job of this.  We support this kind of regional planning from a CSP perspective as long as it is well thought out long term planning," said Stuart.

There is general consensus that California's existing transmission infrastructure is a barrier to increased development and use of renewable energy - new resources cannot be developed because they cannot deliver their power to California's load centers without incurring substantial upfront costs to construct the necessary transmission facilities.

For his part, Stuart again pointed out that the bulk Transmission System was never designed with a large concentration of renewable resources and California is no exception. 

"However, there is no question that the California Energy Commission, the California Public Utilities Commission, the California Independent System Operator, the three privately-owned utilities in California, the renewable resource industry and the Governor's office all are working toward a common goal of meeting California's Renewable Portfolio Standards. There are substantial upfront costs involved in redesigning and reinforcing the bulk Transmission System and there is not unanimity of opinion of how the costs should be allocated. It is felt that this issue will ultimately be sorted out amongst the various state and federal regulatory agencies.  The large scale thermal solar and CalWEA (California Wind Energy Association) believe that the costs should be directly born by the three large investor-owned utilities as it will provide a more efficient and better planned bulk Transmission System," shared Stuart.

Earlier this year, it was shared that Tehachapi Renewable Transmission Project will include a series of new and upgraded high-voltage transmission lines capable of delivering 4,500 megawatts of electricity from wind farms and other generating companies in Northern Los Angeles and Eastern Kern counties.

Assessing the overall situation from Renewable Transmission Projects perspective (Sunzia, TransWest, High Plains Express etc), Stuart said the Tehachapi Renewable Transmission Project is an excellent example of building new transmission that captures the benefits of large scale wind and other renewable resources that will be integrated into the bulk Transmission System. 

The Sunzia, Transwest and High Plains Express projects are in various stages of design and approval.  The Sunzia project will provide a new transmission corridor for connecting wind and solar resources in New Mexico to the load centers in Arizona and potentially California. 

The other two projects are designed to bring the wind resources in Wyoming and wind/solar resources in Colorado to the Arizona and New Mexico areas. 

Stuart expects the WREZ (Western Renewable Transmission Initiative) initiative to provide input and guidance into how some of these projects are integrated into the WECC (Western Electricity Coordinating Council) bulk Transmission System.

Before signing off, he says CSP is designed to provide the benefits of relatively firm power during the peak times and "shoulders" of the peak on a stand-alone basis. 

There are opportunities to integrate wind and solar with other resources to design a more efficient bulk Transmission System, concluded Stuart.

2nd CSP Summit US

Bob Stuart, Senior Director – Transmission, BrightSource Energy is scheduled to speak during CSPToday's second CSP Summit US scheduled to take place in San Francisco on 30th September – 1st October this year.

For more info, click here: http://www.csptoday.com/us/programme.shtml

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Contact:  

Sara Lloyd-Jones
Conference Director
CSP Today

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