Jaquelin Cochran

Grid Integration and the Carrying Capacity of the U.S. Grid to Incorporate Variable Renewable Energy

In the United States and elsewhere, renewable energy (RE) generation supplies an increasingly large percentage of annual demand, including nine U.S. states where wind comprised over 10% of in-state generation in 2013. This white paper summarizes the challenges to integrating increasing amounts of variable RE, identifies emerging practices in power system planning and operation that can facilitate grid integration, and proposes a unifying concept—economic carrying capacity—that can provide a framework for evaluating actions to accommodate higher penetrations of RE. There is growing recognition that while technical challenges to variable RE integration are real, they can generally be addressed via a variety of solutions that vary in implementation cost. As a result, limits to RE penetration are primarily economic, driven by factors that include transmission and the flexibility of the power grid to balance supply and demand. This limit can be expressed as economic carrying capacity, or the point at which variable RE is no longer economically competitive or desirable to the system or society.

Integrating Variable Renewable Energy in Electric Power Markets. Best Practices from International Experience, Summary for Policymakers

Many countries -- reflecting very different geographies, markets, and power systems -- are successfully managing high levels of variable renewable energy on the electric grid, including that from wind and solar energy. This document summarizes policy best practices that energy ministers and other stakeholders can pursue to ensure that electricity markets and power systems can effectively coevolve with increasing penetrations of variable renewable energy. There is no one-size-fits-all approach; each country studied has crafted its own combination of policies, market designs, and system operations to achieve the system reliability and flexibility needed to successfully integrate renewables. Notwithstanding this diversity, the approaches taken by the countries studied all coalesce around five strategic areas: lead public engagement, particularly for new transmission; coordinate and integrate planning; develop rules for market evolution that enable system flexibility; expand access to diverse resources and geographic footprint of operations; and improve system operations. This study also emphatically underscores the value of countries sharing their experiences. The more diverse and robust the experience base from which a country can draw, the more likely that it will be able to implement an appropriate, optimized, and system-wide approach.

Overview of Wholesale Electricity Markets

This chapter provides a comprehensive review of four key electricity markets: Energy markets (day-ahead and real-time markets). Ancillary service markets. Financial transmission rights markets. Capacity markets.

GREENING THE GRID: Pathways to Integrate 175 Gigawatts of Renewable Energy into India’s Electric Grid, Vol. I—National Study EXECUTIVE SUMMARY

Author(s): Palchak, D; Cochran, J; Deshmukh, R; Ehlen, A; Soonee, S; Narasimhan, S; Joshi, M; McBennett, B; Milligan, M; Sreedharan, P; Chernyakhovskiy, I; Abhyankar, N | Abstract: The use of renewable energy (RE) sources, primarily wind and solar generation, is poised to grow significantly within the Indian power system. The Government of India has established an installed capacity target of 175 gigawatts (GW) RE by 2022 that includes 60 GW of wind and 100 GW of solar, up from current capacities of 29 GW wind and 9 GW solar. India’s contribution to global efforts on climate mitigation extends this ambition to 40% non-fossil-based generation capacity by 2030. Global experience demonstrates that power systems can integrate wind and solar at this scale; however, evidence-based planning is important to achieve wind and solar integration at least cost. The purpose of this analysis is to evaluate the operation of India’s power grid with 175 GW of RE in order to identify potential cost and operational concerns and actions needed to efficiently integrate this level of wind and solar generation.

GREENING THE GRID: Pathways to Integrate 175 Gigawatts of Renewable Energy into India’s Electric Grid, Vol. I—National Study

Author(s): Palchak, D; Cochran, J; Deshmukh, R; Ehlen, A; Soonee, R; Narasimhan, S; Joshi, M; McBennett, B; Milligan, M; Sreedharan, P; Chernyakhovskiy, I; Abhyankar, N | Abstract: The use of renewable energy (RE) sources, primarily wind and solar generation, is poised to grow significantly within the Indian power system. The Government of India has established a target of 175 gigawatts (GW) of installed RE capacity by 2022, including 60 GW of wind and 100 GW of solar, up from 29 GW wind and 9 GW solar at the beginning of 2017. Using advanced weather and power system modeling made for this project, the study team is able to explore operational impacts of meeting India’s RE targets and identify actions that may be favorable for integration. Our primary tool is a detailed production cost model, which simulates optimal scheduling and dispatch of available generation in a future year (2022) by minimizing total production costs subject to physical, operational, and market constraints. Our team comprises a core group from the Power System Operation Corporation, Ltd. (POSOCO), which is the national grid operator (with representation from the National, Southern, and Western Regional Load Dispatch Centers) under Ministry of Power, National Renewable Energy Laboratory (NREL), and Lawrence Berkeley National Laboratory (Berkeley Lab), and a broader modeling team that includes Central Electricity Authority (CEA), POWERGRID (the central transmission utility, CTU), and State Load Dispatch Centers in Maharashtra, Gujarat, Tamil Nadu, Karnataka, Rajasthan, and Andhra Pradesh. Our model includes high-resolution wind and solar data (forecasts and actuals), unique properties for each generator, CEA/CTU’s anticipated buildout of the power system, and enforced state-to-state transmission flows. Assuming the fulfillment of current efforts to provide better access to the physical flexibility of the power system, we find that power system balancing with 100 GW of solar and 60 GW of wind is achievable at 15-minute operational timescales with minimal RE curtailment. This RE capacity meets 22% of total projected 2022 electricity consumption in India with annual RE curtailment of 1.4%, in line with experiences in other countries with significant RE penetrations (Bird et al. 2016). Changes to operational practice can further reduce the cost of operating the power system and reduce RE curtailment. Coordinating scheduling and dispatch over a broader area is the largest driver to reduce costs, saving INR 6300 crore (USD 980 million) annually when optimized regionally. Lowering minimum operating levels of coal plants (from 70% to 40%) is the biggest driver to reduce RE curtailment—from 3.5% down to 0.76%. In fact, this operating property is more influential than faster thermal generation ramp rates in lowering the projected levels of curtailment. While this study does not answer every question relevant to planning for India’s 2022 RE targets, it is an important step toward analyzing operational challenges and cost saving opportunities using state-of-the-art power system planning tools. Further analysis can build upon this basis to explore optimal renewable resource and intrastate transmission siting, system stability during contingencies, and the influence of total power system investment costs on customer tariffs.

Greening the Grid Special Topic: Facilitating the Integration of Renewable Energy through Balancing Cooperation

The Greening the Grid animation shows facilitating the integration of renewable energy through balancing cooperation step-by-step.

Retrofitting Fossil Power Plants for Increased Flexibility

Increased renewable generation on the grid along with market deregulation has resulted in a significant increase in the cycling of coal and gas-fired power plant. This increase in cycling will result in increased wear-and-tear costs for units that were not traditionally designed for cycling. Asset owners can make operational changes to mitigate the wear-and-tear impact or alternatively retrofit existing units for improved flexibility. With retrofits, these plants can provide increased operational flexibility, or in other words cycle more, but this comes at an initial cost. On the other hand, increased flexibility in terms of faster starts, better turndowns and ramp rates also provides opportunity for the asset owners to recover their costs in the market. This paper evaluates the operational, as well as cost-benefit of retrofitting power plants for flexibility using a portfolio of generation resources in North America.© 2014 ASME