Add dynamic grid carbon intensity

content/en/docs/measuring/carbon/grid-carbon-intensity.md

@@ -18,9 +18,15 @@ Examples of available databases and services can be found on the Green Software
 
 ## Relevance for the Green Metrics Tool
 
-Grid carbon intensity is the **I** parameter in the [Software Carbon Intensity (SCI)]({{< relref "sci" >}}) metric. The Green Metrics Tool uses grid carbon intensity to transform the measured energy consumption into carbon emissions based on local grid characteristics.
+The Green Metrics Tool uses grid carbon intensity to transform the measured energy consumption into carbon emissions. It is also the **I** parameter in the [Software Carbon Intensity (SCI)]({{< relref "sci" >}}) metric.
 
-### Configuration
+## Configuration
+
+The Green Metrics Tool supports both **static** and **dynamic** grid carbon intensity:
+
+### Static Grid Carbon Intensity (Default)
+
+By default, GMT uses a pre-configured **static** grid carbon intensity value. This approach ensures **reproducible measurements** (results remain consistent across different measurement times) and **fair comparisons** (measurements on the same machine with the same configuration use the same baseline for carbon intensity).
 
 You can configure the grid carbon intensity as part of the [SCI]({{< relref "sci" >}}) configuration in `config.yml`:
 
@@ -29,10 +35,40 @@ sci:
     I: 334 # Grid carbon intensity in gCO2e/kWh (example value for Germany 2024)
 ```
 
-GMT calculates the operational carbon emissions by multiplying measured energy consumption by the grid carbon intensity value.
+You should set the grid carbon intensity to represent the typical or average value for your location.
 
-### Static vs Dynamic Values
+#### Dynamic Grid Carbon Intensity (Advanced Feature)
 
-The Green Metrics Tool uses **static** grid carbon intensity values rather than dynamic real-time data. This design choice ensures **reproducible measurements** (results remain consistent across different measurement times) and **fair comparisons** (measurements on the same machine with the same configuration use the same baseline for carbon intensity).
+GMT also supports **dynamic** grid carbon intensity that fetches real-time values during measurement runs. When enabled, this provides more accurate carbon calculations based on actual grid conditions at the time of measurement. But keep in mind, that your measurements are no longer fully reproducible as carbon values vary with grid conditions.
 
-You should set the grid carbon intensity to represent the typical or average value for your location.
+Dynamic carbon intensity is configured in the machine configuration file (`config.yml`):
+
+```yml
+dynamic_grid_carbon_intensity:
+  location: 'DE'
+  elephant:
+    host: localhost
+    port: 8000
+    protocol: http
+```
+
+**Supported location codes:**
+
+Only grid zone codes from [ElectricityMaps](https://portal.electricitymaps.com/developer-hub/api/getting-started#geographical-coverage) are supported (e.g., `DE`, `US-CAL-CISO`, `ES-IB-MA`, `GB`, `FR`).
+
+Note: Depending on the configured API provider in Elephant, not all zones may be supported.
+
+**Elephant Service:**
+
+[Elephant](https://github.com/green-coding-solutions/elephant/) is a small service developed by Green Coding Solutions that acts as a sidecar-container. It retrieves carbon intensity data from an external service like Electricity Maps or others. It is not part of the default GMT deployment and must be set up separately if you want to use dynamic carbon intensity.
+
+The repository includes a Dockerfile for easy deployment.
+
+**How it works:**
+
+When dynamic carbon intensity is enabled:
+
+- The static `I` value in `config.yml` is ignored
+- Carbon intensity is fetched from the Elephant service during measurement
+- Time-series carbon data is mapped to actual energy consumption timing
+- Requires access to a running Elephant service (configured within the `dynamic_grid_carbon_intensity` block)