Enhance documentation with detailed findings from analysis report

- Add clustered vs isolated facility comparison to README
- Expand infrastructure insights with hyperscaler energy strategies
- Document additional database tables (opposition cases, IM3 projections, utility rates)
- Enhance research ideas with specific watershed names and grid saturation data
- Add data quality notes about EIA longitude corrections
- Reference loaded but unused tables for future analysis

README.md

@@ -40,12 +40,23 @@ Compared to the US average, data center host communities are:
 - **Better connected**: 94.9% broadband (vs. 89%)
 
 ### Infrastructure Insights
-- **89% of data centers are in metropolitan tracts** (vs. 80% of all US tracts)
+- **89% of data centers are in metropolitan tracts** (vs. 80% of all US tracts) - only 1.11× over-index
 - **Non-metro data centers (11%)** are dominated by hyperscalers:
   - AWS (67), Meta (22), Microsoft (10), Google (4) = 55% of non-metro facilities
   - 66% are in Oregon + Washington (Columbia River hydro corridor)
-- **Energy infrastructure**: 4 states have >2/3 of generation within 50 km of a data center:
+- **Grid saturation**: 4 states have >2/3 of generation within 50 km of a data center:
   - New Jersey: 83%, Nevada: 75%, Tennessee: 70%, Oregon: 68%
+- **Hyperscaler energy strategies** (non-metro sites):
+  - AWS: 114 GW wind + 66 GW hydro
+  - Microsoft: 13 GW nuclear (Palo Verde co-location)
+  - Meta: 16 GW solar
+
+### Clustered vs. Isolated Facilities
+Facilities in DBSCAN clusters differ significantly from isolated sites:
+- **$35K income gap**: Clustered sites in tracts with median income $108K vs. $73K for isolated
+- **+18 pp education**: 51% bachelor's+ vs. 33%
+- **More diverse**: 25 pp less non-Hispanic white
+- **2× energy infrastructure**: 89 vs. 40 generators within 50 km
 
 ### Submarine Cables
 - **Data centers are NOT systematically closer to cables** than ordinary US cities
@@ -194,10 +205,18 @@ python3 make_internet_cables_map.py
 ## Data Quality Notes
 
 1. **Incomplete power ratings**: Only 5.9% of data centers have power ratings (108/1,833)
-2. **Operator fragmentation**: String variations ("Meta" vs. "Meta, Inc.") inflate distinct-operator counts
+2. **Operator fragmentation**: String variations ("Meta" vs. "Meta, Inc.", AWS variants) inflate distinct-operator counts
 3. **45 facilities** use city-precision fallback coordinates (approximate tract assignment)
 4. **7 facilities** failed RUCA join (Puerto Rico / non-US)
 5. **Broadband subscribers** are a coarse benefit proxy (actual cloud users are global)
+6. **EIA longitude correction**: 2008-2010 generator coordinates had sign errors, corrected in flat-table build
+
+## Known Limitations
+
+- **Power capacity**: Only 5.9% populated - nearby EIA generator capacity used as proxy
+- **Operator strings**: Need deduplication (50 of 190 non-metro facilities have null operator)
+- **Benefit measurement**: Broadband subscribers are an imperfect proxy for cloud computing benefits
+- **Universe**: Limited to 46 DC-host states (excludes DC-free states from ACS comparison)
 
 ## Research Ideas & Future Work