Add unit conversion methods to Energy type

RELEASE_NOTES.md

@@ -16,6 +16,7 @@ Commiting the API definitions and preparing the repo to the pass all CI tests.
 - Commiting the electricity trading api specs.
 - Rename PublicOrders to PublicTrades
 - Add a python client with pyton wrappers for methods & classes and support for streaming orders.
+- Add unit conversion methods to the Energy type
 
 ## Bug Fixes
 

py/frequenz/client/electricity_trading/_types.py

@@ -144,6 +144,46 @@ def to_pb(self) -> energy_pb2.Energy:
         decimal_mwh.value = str(self.mwh)
         return energy_pb2.Energy(mwh=decimal_mwh)
 
+    def as_watt_hours(self) -> Decimal:
+        """Return the energy in watt hours.
+
+        Returns:
+            The energy in watt hours.
+        """
+        return self.mwh * Decimal(1e6)
+
+    def as_kilowatt_hours(self) -> Decimal:
+        """Return the energy in kilowatt hours.
+
+        Returns:
+            The energy in kilowatt hours.
+        """
+        return self.mwh * Decimal(1e3)
+
+    @classmethod
+    def from_watt_hours(cls, watt_hours: Decimal) -> Self:
+        """Initialize a new energy quantity from watt hours.
+
+        Args:
+            watt_hours: The energy in watt hours.
+
+        Returns:
+            A new energy quantity.
+        """
+        return cls(mwh=watt_hours / Decimal(1e6))
+
+    @classmethod
+    def from_kilowatt_hours(cls, kilowatt_hours: Decimal) -> Self:
+        """Initialize a new energy quantity from kilowatt hours.
+
+        Args:
+            kilowatt_hours: The energy in kilowatt hours.
+
+        Returns:
+            A new energy quantity.
+        """
+        return cls(mwh=kilowatt_hours / Decimal(1e3))
+
 
 class EnergyMarketCodeType(enum.Enum):
     """