No single entity is responsible for, or has the authority to implement, a comprehensive approach to assure the resilience of the nation’s electricity system. Chapter 2 described the complex structure, asset ownership, and regulatory system of the current electricity system and how the changing nature of the electricity system provides both opportunities and challenges for system resilience. Because most parties are preoccupied dealing with short-term issues, they neither have the time to think systematically about what could happen in the event of a large-area, long-duration blackout, nor do they adequately consider the consequences of large-area, long-duration blackouts in their operational and other planning or in setting research and development priorities. Hence the United States needs a process to help all parties better envision the consequences of low-probability but high-impact events precipitated by the causes outlined in Chapter 3 and the system-wide effects discussed in Chapter 5. The specific recommendations addressed to particular parties that are provided in the report (especially in Chapters 4 through 6) will incrementally advance the cause of resilience. However, these alone will be insufficient unless the nation is able to adopt a more integrated perspective at the same time. Thus, this chapter provides a series of overarching recommendations that build upon the detailed recommendations contained within this report.
The first strategy that should be pursued to enhance the resilience of the system is to make sure that things already in place will work when they are needed. One of the best ways to do that is to conduct drills with other critical infrastructure operators through large-scale, multisector exercises. Such exercises can help illuminate areas where improvements in processes and technologies can substantively enhance the resilience of the nation’s critical infrastructure.
Overarching Recommendation 1: Operators of the electricity system, including regional transmission organizations, investor-owned utilities, cooperatives, and municipally owned utilities, should work individually and collectively, in cooperation with the Electricity Subsector Coordinating Council, regional and state authorities, the Federal Energy Regulatory Commission, and the North American Electric Reliability Corporation, to conduct more regional emergency preparedness exercises that simulate accidental failures, physical and cyber attacks, and other impairments that result in large-scale loss of power and/or other critical infrastructure sectors—especially communication, water, and natural gas. Counterparts from other critical infrastructure sections should be involved, as well as state, local, and regional emergency management offices.
The challenges that remain to achieving grid resilience are so great that they cannot be achieved by research- or operations-related activities alone. While new technologies and strategies can improve the resilience of the power system, many existing technologies that show promise have yet to be fully adopted or implemented. In addition, more coordination between research and implementation activities is needed, building on the specific recommendations made throughout this report. Immediate action is needed both to implement available technological and operational changes and to continue to support the development of new technologies and strategies.
Overarching Recommendation 2: Operators of the electricity system, including regional transmission organizations, investor-owned utilities, cooperatives, and municipals, should work individually and collectively to more rapidly implement resilience-enhancing technical capabilities and operational strategies that are available today and to speed the adoption of new capabilities and strategies as they become available.
The Department of Energy (DOE) is the federal entity with a mission to focus on the longer-term issues of developing and promulgating technologies and strategies to increase
the resilience and modernization of the electric grid.1 At present, two offices within DOE have responsibility for issues directly and indirectly related to grid modernization and resilience.
Overarching Recommendation 3: However the Department of Energy chooses to organize its programs going forward, Congress and the Department of Energy leadership should sustain and expand the substantive areas of research, development, and demonstration that are now being undertaken by the Department of Energy’s Office of Electricity Delivery and Energy Reliability and Office of Energy Efficiency and Renewable Energy, with respect to grid modernization and systems integration, with the explicit intention of improving the resilience of the U.S. power grid. Field demonstrations of physical and cyber improvements that could subsequently lead to widespread deployment are critically important. The Department of Energy should collaborate with parties in the private sector and in states and localities to jointly plan for and support such demonstrations. Department of Energy efforts should include engagement with key stakeholders in emergency response to build and disseminate best practices across the industry.
The U.S. grid remains vulnerable to natural disasters, physical and cyber attacks, and other accidental failures.
Overarching Recommendation 4: Through public and private means, the United States should substantially increase the resources committed to the physical components needed to ensure that critical electric infrastructure is robust and that society is able to cope when the grid fails. Some of this investment should focus on making the existing infrastructure more resilient and easier to repair, including the following:
- The Department of Energy should launch a program to manufacture and deploy flexible and transportable three-phase recovery transformer sets that can be pre-positioned around the country.2 These recovery transformers should be easy to install and use temporarily until conventional transformer replacements are available. This effort should produce sufficient numbers (on the order of tens compared to the three produced by the Department of Homeland Security’s RecX program) to provide some practical protection in the case of an event that results in the loss of a number of high-voltage transformers. This effort should complement instead of replace ongoing initiatives related to spare transformers.
- State and federal regulatory commissions and regional transmission organizations should then evaluate whether grids under their supervision need additional pre-positioned replacements for critical assets that can help accelerate orderly restoration of grid service after failure.
- Public and private parties should expand efforts to improve their ability to maintain and restore critical services—such as power for hospitals, first responders, water supply and sewage systems, and communication systems.3
- The Department of Energy, the Department of Homeland Security, the Electricity Subsector Coordinating Council, and other federal organizations, such as the U.S. Army Corps of Engineers, should oversee the development of more reliable inventories of backup power needs and capabilities (e.g., the U.S. Army Corps of Engineers’ mobile generator fleet), including fuel supplies. They should also “stress test” existing supply contracts for equipment and fuel supply that are widely used in place of actual physical assets in order to be certain these arrangements will function in times of major extended outages. Although the federal government cannot provide backup power equipment to everyone affected by a large-scale outage, these resources could make significant contributions at select critical loads.
In addition to providing redundancy of critical assets, transmission and distribution system resilience demands the ability to provide rapid response to events that impair the ability of the power system to perform its function. These events include deliberate attacks on and accidental failures of the infrastructure itself, as well as other causes of grid failure, which are discussed in Chapter 3.
Overarching Recommendation 5: The Department of Energy, together with the Department of Homeland Security, academic research teams, the national laboratories, and companies in the private sector, should carry out a program of research, development, and demonstration activities to
1 The Department of Homeland Security, the Federal Energy Regulatory Commission, and other organizations also provide critical support and have primacy in certain areas.
2 As noted in Chapter 6 and in the next section of this chapter, the DOE Office of Electricity Delivery and Energy Reliability is supporting the development of a new generation of high-voltage transformers that will use power electronics to adjust their electrical properties and hence can be deployed in a wider range of settings. The committee’s recommendation to manufacture recovery transformers is not intended to replace that longer-term effort. However, the new DOE advanced transformer designs will not be available for some time, and in the meantime the system remains physically vulnerable. While in Chapter 6 the committee notes several government and industry-led transformer-sharing and recovery programs, the committee recognizes that high-voltage transformers represent one of the grid’s most vulnerable components deserving of further efforts.
3 In addition to treatment, sewage systems often need to pump uphill. A loss of power can quickly lead to sewage backups. Notably, a high percentage of the hospital backup generators in New York City failed during Superstorm Sandy.
improve the security and resilience of cyber monitoring and controls systems, including the following:
- Continuous collection of diverse (cyber and physical) sensor data;
- Fusion of sensor data with other intelligence information to diagnose the cause of the impairment (cyber or physical);
- Visualization techniques needed to allow operators and engineers to maintain situational awareness;
- Analytics (including machine learning, data mining, game theory, and other artificial intelligence-based techniques) to generate real-time recommendations for actions that should be taken in response to the diagnosed attacks, failures, or other impairments;
- Restoration of control system and power delivery functionality and cyber and physical operational data in response to the impairment; and
- Creation of post-event tools for detection, analysis, and restoration to complement event prevention tools.
Because no single entity is in charge of planning the evolution of the grid, there is a risk that society may not adequately anticipate and address many elements of grid reliability and resilience and that the risks of this system-wide failure in preparedness will grow as the structure of the power industry becomes more atomized and complex. There are many opportunities for federal leadership in anticipating potential system vulnerabilities at a national level, but national solutions are then refined in light of local and regional circumstances. Doing this requires a multi-step process, the first of which is to anticipate the myriad ways in which the system might be disrupted and the many social, economic, and other consequences of such disruptions. The second is to envision the range of technological and organizational innovations that are affecting the industry (e.g., distributed generation and storage) and how such developments may affect the system’s reliability and resilience. The third is to figure out what upgrades should be made and how to cover their costs. For simplicity, the committee will refer to this as a “visioning process.” While the Department of Homeland Security (DHS) has overarching responsibility for infrastructure protection, DOE, as the sector-specific agency for energy infrastructure, has a legal mandate and the deep technical expertise to work on such issues.
Overarching Recommendation 6: The Department of Energy and the Department of Homeland Security should jointly establish and support a “visioning” process with the objective of systematically imagining and assessing plausible large-area, long-duration grid disruptions that could have major economic, social, and other adverse consequences, focusing on those that could have impacts related to U.S. dependence on vital public infrastructures and services provided by the grid.
Because it is inherently difficult to imagine systematically things that have not happened (Fischhoff et al., 1978; Kahneman, 2011), exercises in envisioning benefit from having multiple groups perform such work independently. For example, such a visioning process might be accomplished through the creation of two small national power system resilience assessment groups (possibly at DOE national laboratories and/or other federally funded research and development centers or research universities). However such visioning is accomplished, engagement from staff representing relevant state and federal agencies is essential in helping to frame and inform the work. These efforts should build on the detailed recommendations in this report to identify technical and organizational strategies that increase electricity system resilience in numerous threat scenarios—that is, by preventing and mitigating the extent of large-scale grid failures, sustaining critical services in the instance of failure, and recovering rapidly from major outages—and to assess the costs and financing mechanisms to implement the proposed strategies. Attention is needed not just to the average economy-wide costs and benefits, but also to the distribution of these across different levels of income and vulnerability. It is important that these teams work to identify common elements in terms of hazards and solutions so as to move past a hazard-by-hazard approach to a more systems-oriented strategy. Producing useful insights from this process will require mechanisms to help these groups identify areas of overlap while also characterizing the areas of disagreement. A consensus view could be much less helpful than a mapping of uncertainties that can help other actors—for example, state regulatory commissions and first responders—understand the areas of deeper unknowns.
National labs, other federally funded research and development centers, and research universities do not operate or regulate the power system. At the national level, the Federal Energy Regulatory Commission (FERC) and the North American Electric Reliability Corporation (NERC) both have relevant responsibilities and authorities.
Overarching Recommendation 7A: The Federal Energy Regulatory Commission and the North American Electric Reliability Corporation should establish small system resilience groups, informed by the work of the Department of Energy/Department of Homeland Security “visioning” process, to assess and, as needed, to mandate strategies designed to increase the resilience of the U.S. bulk electricity system. By focusing on the crosscutting impacts of hazards on interdependent critical infrastructures, one objective of these groups would be to complement and enhance existing efforts across relevant organizations.
As the discussions throughout this report make clear, many different organizations are involved in planning, operating, and regulating the grid at the local and regional levels. By design and of necessity in our constitutional democracy,
making decisions about resilience is an inherently political process. Ultimately the choice of how much resilience our society should and will buy must be a collective social judgment. It is unrealistic to expect firms to make investments voluntarily whose benefits may not accrue to shareholders within the relevant commercial lifetime for evaluating projects. Moreover, much of the benefit from avoiding such events, should they occur, will not accrue to the individual firms that invest in these capabilities. Rather, the benefits are diffused more broadly across multiple industries and society as a whole, and many of the decisions must occur on a state-by-state basis.
Overarching Recommendation 7B: The National Association of Regulatory Utility Commissioners should work with the National Association of State Energy Officials to create a committee to provide guidance to state regulators on how best to respond to identified local and regional power system-related vulnerabilities. The work of this committee should be informed by the national “visioning” process, as well as by the work of other research organizations. The mission of this committee should be to develop guidance for, and provide technical and institutional support to, state commissions to help them to more systematically address broad issues of power system resilience, including decisions as to what upgrades are desirable and how to pay for them. Guidance developed through this process should be shared with appropriate representatives from the American Public Power Association and the National Rural Electric Cooperative Association.
Overarching Recommendation 7C: Each state public utility commission and state energy office, working with the National Association of Regulatory Utility Commissioners, the National Association of State Energy Officials, and state and regional grid operators and emergency preparedness organizations, should establish a standing capability to identify vulnerabilities, identify strategies to reduce local vulnerabilities, develop strategies to cover costs of needed upgrades, and help the public to become better prepared for extended outages. In addition, they should encourage local and regional governments to conduct assessments of their potential vulnerabilities in the event of large-area, long-duration blackouts and to develop strategies to improve their preparedness.
Throughout this report, the committee has laid out a wide range of actions that different parties might undertake to improve the resilience of the United States power system. If the approaches the committee has outlined can be implemented, they will represent a most valuable contribution. At the same time, the committee is aware that the benefits of such a contribution—avoiding large-scale harms that are rarely observed—are easily eclipsed by the more tangible daily challenges, pressures on budgets, public attention, and other scarce resources. Too often in the past, the United States has made progress on issues of resilience by “muddling through” (Lindblom, 1959). Even if the broad systematic approach outlined in this report cannot be fully implemented immediately, it is important that relevant organizations develop analogous strategies so that when a policy window opens in the aftermath of a major disruption, well-conceived solutions are readily available for implementation (Kingdon, 1984).
Underlying the Overarching Recommendations are the numerous, more targeted recommendations presented throughout this report. Here, the committee summarizes and sorts these recommendations by the institutions to which they are directed.
Recommendations Directed to the Department of Energy
DOE plays a critical role in enhancing the resilience of the grid through research, development, and demonstration programs as well as convening and engagement activities. Much progress has been made, and DOE should sustain and expand many of these efforts.
Recommendation 1 to DOE: Improve understanding of customer and societal value associated with increased resilience and review and operationalize metrics for resilience by doing the following:
- Developing comprehensive studies to assess the value to customers of improved reliability and resilience (e.g., periodic rotating service) during large-area, long-duration blackouts as a function of key circumstances (e.g., duration, climatic conditions, societal function) and for different customer classes (e.g., residential, commercial, industrial). (Recommendation 2.1)
- Conducting a coordinated assessment of the numerous resilience metrics being proposed for transmission and distribution systems and seeking to operationalize these metrics within the utility setting. In doing the review, engagement with key stakeholders is essential. (Recommendation 2.2)
Recommendation 2 to DOE: Support research, development, and demonstration activities, as well as convening activities, to improve the resilience of power system operations and recovery by reducing barriers to adoption of innovative technologies and operational strategies. These include the following:
- Coordinating with federal and state utility regulators to support a modest grant program that encourages utility
investment in innovative solutions that demonstrate resilience enhancement. These projects should be selected to reduce barrier(s) to entry by improving regulator and utility confidence. (Recommendation 4.1)
- Initiating and supporting ongoing research programs focused on the operation of degraded or damaged electricity systems, including supporting infrastructure and cyber monitoring and control systems, where key subsystems are designed and operated to sustain critical functionality. (Recommendation 4.6)
- Convening transmission and distribution system owners and operators to engage the Federal Aviation Administration proactively to ensure that the rules regulating operation of unmanned aerial vehicles support the rapid, safe, and effective applications of unmanned aerial vehicle technology in electricity restoration activities, including pre-disaster tests and drills. (Recommendation 6.5)
- Continuing to support research and development of advanced large power transformers, concentrating on moving beyond design studies to conduct several demonstration projects. (Recommendation 6.7)
Recommendation 3 to DOE: Advance the safe and effective development of distributed energy resources (DERs) and microgrids by doing the following:
- Initiating research, development, and demonstration activities to explore the extent to which DERs could be used to help prevent large-area outages. (Recommendation 4.2)
- Supporting demonstration and a training facility (or facilities) for future microgrids that will allow utility engineers and non-utility microgrid operators to gain hands-on experience with islanding, operating, and restoring feeders (including microgrids). (Recommendation 5.6)
- Engaging the manufacturers of plug-in hybrid electric and fuel cell vehicles to study how such vehicles might be used as distributed sources of emergency power. (Recommendation 5.12)
- Evaluating the technical and contractual requirements for using DERs as part of restoration activities, even when these assets are not owned by the utility, to improve restoration and overall resilience. (Recommendation 6.3)
Recommendation 4 to DOE: Work to improve the ability to use computers, software, and simulation to research, plan, and operate the power system to increase resilience by doing the following:
- Collaborating with other research organizations, including the National Science Foundation, to expand support for interdisciplinary research to simulate events and model grid impacts and mitigation strategies. (Recommendation 4.3)
- Supporting and expanding research and development activities to create synthetic power grid physical and cyber infrastructure models. (Recommendation 4.4)
- Collaborating with other research organizations, including the National Science Foundation, to fund research on enhanced power system wide-area monitoring and control and the application of artificial intelligence to the power system. Such work should include how the human–computer interface and visualization could improve reliability and resilience. (Recommendation 4.8)
- Leading efforts to develop standardized data definitions, communication protocols, and industrial control system designs for the sharing of both physical and cyber system health information. (Recommendation 4.9)
- Developing a high-performance utility network simulator for use in cyber configuration and testing. (Recommendation 6.12)
Recommendation 5 to DOE: Work to improve the cybersecurity and cyber resilience of the grid by doing the following:
- Embarking on a research, development, and demonstration program that results in a prototypical cyber-physical-social control system architecture for resilient electric power systems. (Recommendation 4.10)
- Developing the ability to apply physics-based modeling to anomaly detection, which provides real-time or better physics models that derive optimal power flow and monitor performance for more accurate state estimation. (Recommendation 6.8)
Recommendations Directed to the Electric Power Sector and the Department of Energy
There are thousands of operating utilities and electricity system asset owners across the United States, with diverse characteristics and institutional structures, including private investor-owned utilities, cooperatives, and publicly owned entities. These organizations, and the people they employ, are the foundation of a reliable and resilient grid, and many promising demonstrations and initiatives are ongoing across the sector. The industry and DOE have benefitted from a strong relationship, and the committee encourages further collaboration on projects to increase the resilience of the grid.
Recommendation 6 to the electric power sector and DOE: The owners and operators of electricity infrastructure should work closely with DOE as follows:
- Develop use cases and perform research on strategies for intelligent load shedding based on advanced
metering infrastructure and customer technologies like smart circuit breakers. (Recommendation 4.5)
- Explore the feasibility of establishing contractual and billing agreements with private owners of DERs and developing the ability to operate intact islanded feeders as islanded microgrids powered by utility- and customer-owned generating resources to supply limited power to critical loads during large grid outages of long duration. (Recommendation 5.10)
- Work together to analyze past large-area, long-duration outages to identify common elements and processes for system restoration and define best practices that can be shared broadly throughout the electricity industry. (Recommendation 6.2)
- Identify those components and corresponding events for which pre-event de-energizing of selected assets is the lowest risk strategy and develop regulatory, communication (especially with customers), and other plans that allow such protective action to be implemented. (Recommendation 6.4)
- Expand joint cyber-physical recovery exercises that emphasize, among other things, the maintenance of cyber protection during the chaotic period of physical restoration. (Recommendation 6.14)
Clearly, some of these recommendations will require greater degrees of DOE engagement than others.
Recommendations Directed to the Department of Homeland Security and the Department of Energy
Because emergency response and management is central to power system resilience, the committee makes several recommendations that call for collaboration between DHS and DOE.
Recommendation 7 to DHS and DOE: DHS and DOE should work collaboratively to improve preparation for, emergency response to, and recovery from large-area, long-duration blackouts by doing the following:
- Working with state and local authorities and electricity system operators to undertake an “all hazards” assessment of the natural hazards faced by power systems on a periodic basis (e.g., every 5 years). Local utilities should customize those assessments to their local conditions. (Recommendation 3.2)
- Developing and overseeing a process to help regional and local planners envision potential system-wide effects of long-duration loss of grid power. (Recommendation 5.3)
- Evaluating and recommending the best approach for getting critical facility managers to pre-register information about emergency power needs and available resources. (Recommendation 5.5)
- Renewing efforts to work with utilities and national, state, and local law enforcement to develop formal arrangements (such as designating selected utility personnel as “first responders”) that credential selected utility personnel to allow prompt utility access to damaged facilities across jurisdictional boundaries. (Recommendation 6.1)
- Building off of existing efforts to manufacture and stockpile flexible, high-voltage replacement transformers, in collaboration with electricity system operators and asset owners and with support from the U.S. Congress. (Recommendation 6.6)
- Developing a model for large-scale cyber restoration of electricity infrastructure. (Recommendation 6.9)
Recommendation 8 to DHS and DOE: With growing awareness of the electricity system as a potential target for malicious attacks using both physical and cyber means, DHS and DOE should work closely with operating utilities and other relevant stakeholders to improve physical and cyber security and resilience by doing the following:
- Working with operating utilities to sustain and enhance their monitoring and information-sharing activities to protect the grid from physical and cyber attacks. (Recommendation 3.1)
- Continuing to work with the Electricity Subsector Coordinating Council and operating utilities to enhance the sharing of cyber restoration resources (i.e., cyber mutual assistance agreements), including personnel, focusing on peer-to-peer collaboration as well as engagement with government, industry organizations, and commercial cybersecurity companies. (Recommendation 6.10)
- Working with the electricity sector and representatives of other key affected industries and sectors to continue to strengthen the bidirectional communication between federal cybersecurity programs and commercial software companies. (Recommendation 6.11)
- Redoubling efforts to reduce the vulnerability of the power system to terrorist attacks in close collaboration with FERC, NERC, and other representatives of the electric industry. (Recommendation 6.13)
Recommendations Directed to State Offices and Regulatory Bodies
State offices and elected officials have an important role in increasing the resilience of the nation’s electricity system, including through planning and regulatory decisions as well as emergency preparedness and response. Several of the committee’s recommendations encourage various actors in state government to take action.
Recommendation 9 to state offices and regulators: Work with local utilities and relevant stakeholders to increase investment in resilience-enhancing strategies, including the following:
- State emergency planning authorities should oversee a more regular and systematic testing of backup power generation equipment at critical facilities, such as hospitals and fire stations, and ensure that public safety officials include information related to electrical safety and responses to long-duration power outages in their public briefings. (Recommendation 5.1)
- Utility regulators should work closely with operating utilities to assess their current interconnection standards as applicable to DERs, consider the costs of requiring new installations to use enhanced inverters, and determine the appropriate policy for promoting islanding and other related capabilities. (Recommendation 5.7)
- State legislatures and utility regulatory bodies should explore economic, ratemaking, and other regulatory options for facilitating the development of private microgrids that provide resilience benefits. (Recommendation 5.9)
- Utility regulators and non-governmental entities should undertake studies to develop guidance on how best to compensate the owners of distributed generation resources who are prepared to commit a portion of their distributed generation capacity to serve islanded feeders in the event of large outages of long duration. Additionally, the National Association of Regulatory Utility Commissioners (NARUC) should establish a working group to advise members on the issues they will likely have to address. (Recommendation 5.11)
Recommendations Directed to the National Association of Regulatory Utility Commissioners and Federal Organizations
NARUC is uniquely capable of convening and disseminating information to regulators from diverse states while providing a single point of contact with federal agencies.
Recommendation 10 to NARUC and federal organizations: The committee recommends that NARUC work with DHS and DOE as follows:
- Develop model guidance on how state regulators, utilities, and broader communities (where appropriate) might consider the equity and social implications of choices in the level and allocation of investments. (Recommendation 5.2)
- Develop guidance to state regulators and utilities on (1) selective restoration options as they become available, (2) the factors that should be considered in making choices of which loads to serve, and (3) model recommendations that states and utilities can build upon and adapt to local circumstances. (Recommendation 5.4)
- Undertake studies of the technical, economic, and regulatory changes necessary to allow development and operation of privately owned microgrids that serve multiple parties and/or cross public rights-of-way. (Recommendation 5.8)
Recommendation Directed to the Federal Energy Regulatory Commission and the North American Energy Standards Board
The growing interdependence of natural gas and electricity infrastructures requires systematic study and targeted efforts to improve coordination and planning across the two industries.
Recommendation 11 to FERC and the North American Energy Standards Board: FERC, which has regulatory authority over both natural gas and electricity systems, should address the growing risk of interdependent infrastructure by doing the following:
- Working with the North American Energy Standards Board and industry stakeholders to improve awareness, communications, coordination, and planning between the natural gas and electric industries. (Recommendation 4.7)
Recommendation Directed to the North American Electric Reliability Corporation
Following large-scale outages, detailed investigations are essential to support the learning phase of resilience. NERC, with authority delegated from FERC, has conducted several such investigations.
Recommendation 12 to NERC: Review and improve incident investigation processes to better learn from outages that happen and broadly disseminate findings and best practices by doing the following:
- Engaging relevant regional and state-level organizations to improve the investigation process of large-scale losses of power, drawing lessons from the National Transportation Safety Board and others, with the objective of disseminating lessons across geographical and jurisdictional boundaries. (Recommendation 6.15)
Fischhoff, B., P. Slovic, and S. Lichtenstein. 1978. Fault trees: Sensitivity of estimated failure probabilities to problem representation. Journal of Experimental Psychology: Human Perception and Performance 4: 342–355.
Kahneman, D. 2011. Thinking Fast and Slow. New York: Farrar, Straus, and Giroux.
Kingdon, J.W. 1984. Agendas, Alternatives, and Public Policies. Boston: Little, Brown, and Company.
Lindblom, C.E. 1959. The science of muddling through. Public Administration Review 19(2): 79–88.