## 3 Demand-Response Aggregator Frameworks in Future US Electricity Markets
### Open Research Questions for Future Demand-Response Aggregators' Operations  
This paper introduced the environmental goals for 2030 and 2050 in the US and analyzed the role that DR aggregators will play in future US electricity markets, for which their mechanisms are expected to be revised by policymakers in order to better compensate clean technologies and grid reliability support providers. To facilitate the large-scale deployment of DR aggregators and registered distributed loads (prosumers) in future US electricity markets, DR aggregator operation frameworks will need to have the characteristics shown in Figure 4, the achievement of which remains an open research question, as observed and analyzed in Sections 2 and 3. In short, we refer to this as the FCUPS evaluation scheme for any DR aggregator and prosumer framework, and we next justify how these operational changes in future US electricity markets will facilitate the 2030 and 2050 goals (Section 1):  
* **Flexibility (F)** with the type of prosumers (residential, commercial, and industrial), their behavior (strategy, rationality, bidirectional flow of energy and information, etc. ), their device constraints, their distributed load types, and their operational capabilities through their HEMS/BEMS: Ideally, a flexible DR aggregator prosumer framework would model, in detail, the prosumer's distributed load mix (Figure 3), data pipelines, settings, and controls via an HEMS/BEMS to ensure the feasibility and optimality of the DR aggregator prosumer solution, utilizing technologies introduced in Section 2.3. Flexibility is important to the 2030 and 2050 goals in order to operate a grid with significant renewable resources, according to Section 1's points 1 and 6. * **Competition (C)** between the DR aggregator and prosumers, as well as between prosumers, to incentivize prosumer engagement: Competition of the DR aggregator with other market players to maximize profits. Ideally, the DR aggregator and prosumer framework should model the underlying competition type, considering the types of competition analyzed in Section 3.1. Competition consideration is important in order to ensure that the prosumer's interests are also taken into consideration, considering prosumers as active market players with preferences and rewards, unlike numerous previous approaches (Table 6). In this way, the distributed load is incentivized to participate in market-based DR, which can facilitate the 2030 and 2050 goals according to Section 1's points 1 and 2. * **Uncertainty (U)** quantification in multiple areas, such as the demand and generation profiles of the prosumers and the market and market prices for the day-ahead and spot markets to reduce unexpected costs: Ideally, the DR aggregator and prosumer game would be modeled as a Bayesian, stochastic, or RL game to allow mixed strategies and uncertainty quantification to be included in decision-making while still considering competition modeling in the framework. Uncertainty consideration is important for better scheduling in electricity markets and helps prevent supply shortages, large demand and price variations, or unexpected costs inflicted on the DR aggregator and prosumer, resulting in more reliable grids and markets, as well as financial prosperity and risk management for market participants. The aforementioned facilitate the 2030 and 2050 goals according to Section 1's points 3 and 9. * **Privacy (P)** preservation of the prosumer with respect to any for-profit market entities, such as the DR aggregator, hardware manufacturer, software developers, etc. : Privacy preservation includes PI data, prosumer preferences for comfort, device models and the mode/frequency of operation, load types and operational choices, demand and generation forecasts, etc. Ideally, the prosumer's strategy, PI data, settings, preferences, controls, objectives, and structural details of the HEMS/BEMS would not be shared with the DR aggregator, a goal that aligns with the Department of Energy's Energy Independence and Security Act (Section 2.5).