# Research Needs for Realization of Zero-Carbon Power Grids with Selected Case Studies
## 4 Additional Research
### Electricity Market Design
#### 4.2.1 Changes in Electricity Markets  
In various algorithms and simulation tools, day-ahead, intra-day, and short-term market models have been widely explored to balance supply and demand and provide energy and grid services in a cost-effective manner. Given the increased installation and utilization of renewable energy resources, technological developments in the zero-carbon power grid context have greatly affected the design and operation of electricity markets, and vice versa [89; 90; 91]. For example, the replacement of traditional resources with new VRE sources is likely to remove the marginal cost of energy, significantly affecting electricity market structures and clearing mechanisms.  
Recently, interest in local market designs and peer-to-peer trading of various market services has grown [92]. Many efforts are being made to link local markets with each other and to bulk markets, particularly in regions where marked expansions of distributed, behind-the-meter VRE are expected. Horizontal and vertical interconnections within the electricity market are crucial to allow large- and small-scale interplay between VRE and flexible energy resources. It is challenging to develop local- and system-level market models that accurately consider low-voltage VRE growth.  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt}} \hline \hline
**Challenges** & **Research Questions and Requirements** \\ \hline Adequacy planning tools & \(\bullet\) _Inclusion of short-term supply-and-demand balancing when exploring the effects of forecast uncertainty_ on the optimal VRE mix. \\ \hline \multirow{8}{*}{Metrics and calculation methodologies} & \(\bullet\) _Use of several current metrics_, including LOLP, LOLE, and loss-of-load hours (LOLH), and _development of new metrics_ that consider societal needs and load and storage flexibilities. \\ \cline{1-1}  & \(\bullet\) _Use of different reliability levels_, such as an event occurring once in 10 years, as the common LOLP target and two events per year as a lower reliability target. \\ \cline{1-1}  & \(\bullet\) _Improving the calculation of adequacy benefits afforded when neighboring regions are interfaced and larger geographical areas are connected_ via transmission lines with limited capacities. \\ \hline \multirow{4}{*}{Contributions of emerging technologies} & \(\bullet\) _Improving representations of demand-side flexibility, energy storage, sector coupling, grid limitation, and expansion cost_, to better predict the investments required for grids with high VRE proportions and accurately determine the optimal VRE mix. \\ \hline \multirow{8}{*}{Modeling and data} & \(\bullet\) _Transmission networks and distributed generators_ should be modeled in a manner that accurately captures their contributions to adequacy. \\ \cline{1-1}  & \(\bullet\) The contribution of _demand and storage_ to adequacy must be determined accurately using models of real-world operating characteristics, including responses to electricity prices. \\ \cline{1-1}  & \(\bullet\) New models must capture how _sector coupling among electricity_, _transportation, heating, and natural gas affects adequacy_. \\ \cline{1-1}  & \(\bullet\) _More high-quality longer time frame (10+ years) data on supply and demand power_ are required to ensure precise and robust calculations of adequacy. \\ \hline \hline \end{tabular}
\end{table}
Table 14: List of research challenges in energy and capacity adequacy.