A recent study done for parties including Minnesota electric utilities has found plenty of opportunities for expansion of renewable energy capacity in the state.
General Electric’s (NYSE: GE) Energy Consulting business served as the lead technical consultant for the recent Minnesota Renewable Energy Integration and Transmission Study (MRITS), performed by the Minnesota utilities and transmission companies in coordination with the Midcontinent Independent System Operator and directed by the Minnesota Department of Commerce. The study demonstrated that Minnesota’s power system can accommodate renewable generation, representing up to 40% of retail sales in total with certain upgrades to existing transmission. The study also found that even with these higher levels of renewables, the overall system could continue to operate essentially as it does under normal conditions today.
The study also determined that this level of renewable generation in Minnesota could be reliably achieved with only about 2% curtailment of renewable energy, often cited as a challenge when considering whether to develop renewables projects. When moving towards 40% renewable penetration on the Minnesota system, there is modest change in energy from Minnesota’s conventional generation, General Electric noted.
“GE Energy Consulting’s findings will help Minnesota develop and continue to achieve its renewable energy strategies and goals,” said Minnesota Department of Commerce Commissioner Mike Rothman in a Nov. 24 statement. “We appreciate Energy Consulting’s technical analysis, showing renewable energy is a viable and reliable resource to meet Minnesota’s energy needs.”
One of the concerns often raised with the introduction of high levels of renewable generation onto the grid is the impact on the grid’s stability and its ability to adequately respond to system disturbances. This study, along with several others conducted by GE’s Energy Consulting business, demonstrates that higher levels of renewable penetration do not negatively impact grid stability and further, can actually enhance resiliency when equipped with grid-friendly controls, General Electric said. The Minnesota study showed that wind and solar resources contribute significantly to voltage support and dynamic reactive reserves. Additionally, the fast response capabilities of wind and solar inverters can help with voltage recovery following a system fault.
This Minnesota study builds on several similar studies that GE’s Energy Consulting business has conducted across the United States and Canada over the past several years using GE’s PSLF modeling software—including the recent study of the Eastern Interconnect (EI) of the U.S. for the National Renewable Energy Laboratory (NREL). That study considered the impact of 25% renewable penetration on frequency response on the EI system, finding that renewables at this penetration level could actually help with grid resiliency.
“While 25 percent renewable penetration on the Eastern Interconnection is an aggressive target overall, the fact that Minnesota’s system could reasonably accommodate 40 percent renewables penetration demonstrates the importance of evaluating the role renewable energy can play in the generation mix at regional and local levels,” said Doug Welsh, Technical Director, GE’s Energy Consulting business and GE project manager for the Minnesota study. “Not all electric power systems are created equal, and taking into account the unique aspects of individual systems can create a better understanding of the role renewable generation can play across the U.S. and around the world.”
The study was mandated in 2013 by the state legislature as part of the Omnibus Energy Bill. This legislation required that all Minnesota utilities and transmission owners, in coordination with MISO, analyze transmission reliability if the Minnesota Renewable Energy Standard (RES) increased to 40% by 2030 and to 50% thereafter.
The MRITS results show that the addition of 1,931 MW of wind and 914 MW of solar generation needed to supply 40% of Minnesota’s annual electric retail sales can be reliably accommodated by the electric transmission system by 2030, provided that currently planned transmission projects are completed as planned, and upgrades are made to 54 existing transmission facilities. The cost of these 54 upgrades totals about $373m.
Great River Energy notes that the study, by design, didn’t cover several issues
Great River Energy said Nov. 18 that it and its members have worked hard through years of planning and strategic investments to prepare the transmission system for an evolving generation mix and continued reliable service to the region.
“Approximately 750 miles of new transmission 200-kilovolts and above have been added to the system in this region since 2011. Other large expansions will be energized by 2017,” said Gordon Pietsch, Great River Energy’s director of transmission planning and operations. These projects include the remaining CapX2020 projects, one being the Brookings County-Hampton project slated for energization in early 2015.
At first glance, the MRITS results can be misleading in terms of how easy it would be to adjust to a higher RES, Great River Energy noted. Transmission reliability is only one component to consider in any discussion of an increase in the RES.
“We think the right transmission investments are being made,” said Pietsch. “But MRITS is a reliability study – a conceptual plan, based on where solar and wind developers might site their facilities. There are significant factors that the legislation did not require be studied.”
In particular, future EPA regulations, such as the recently proposed Clean Power Plan 111(d), were not modeled nor considered in MRITS. In the 40% scenario, the study assumes neighboring states’ RES requirements remain the same.
Great River Energy Resource Planning Manager Laureen Ross McCalib said: “MRITS provides important insight into the ability of the transmission system to accommodate 40 percent renewable energy in Minnesota. Additional analysis is needed to understand the full economic and rate impacts that would result from such a change.”
The legislation did not require an evaluation of the cost of adding new generation sources, or to identify the impact these new generation sources would have on the MISO energy market. The legislation did not require the study to include costs associated with cycling coal facilities in ways for which they were not designed. This coal plant cycling was shown to be required to accommodate the additional renewable resources. The legislation also did not require that non-fossil hydro energy be included as a renewable energy option; however, MRITS did assume the installation of Manitoba Hydro‘s Keeyask hydroelectric dam.
“To meet Minnesota’s existing 25 percent RES requirement, Great River Energy will need to build approximately 600 megawatts of wind beginning in the late 2020s. If the Minnesota RES requirement were to increase, we would need to build even more renewable generation, even though our members do not need capacity or energy until the 2030s,” said McCalib.
In 2013, Great River Energy received 11% of its energy from renewable resources and an additional 13% from hydro resources.