Storage Water Value
| Units: | $/GWh |
| Mode: | Input Only |
| Multi-band: | True |
| Default Value: | 10000 |
| Validation Rule: | Any Value |
| Key Property: | No |
| Description: | Incremental price of water released from storage |
| Detail: |
Storage Water Value is the price of water at the end of each simulation step (or end-of-horizon for a single step simulation) It can be used as an alternative to setting the End Effects Method. Water Value defaults to units of $/GWh for the Storage "Potential Energy" Model. When using either the "Volume" or "Level" model it is more convenient to use Energy Value ($/MWh) and Energy Value Point (GWh) in combination with the conversion factor (either automatically calculated or input via Downstream Efficiency) so that the energy value can be converted to native volumes of water in storage.
Example:
| Storage | Property | Value | Units |
|---|---|---|---|
| Pukaki | Max Volume | 1300 | GWh |
| Pukaki | Initial Volume | 900 | GWh |
| Pukaki | Water Value | 45 | $/MWh |
Here the storage remaining at the end of the step is valued at $45/MWh.
Given uncertainty in natural inflow the Water Value is not constant for all volumes of storage. The lower the storage the higher the water value since the risk of running short is high. Likewise when the storage nears full the water value is low due to the risk of spill. You can define a multi-band water value function that discourages release when the storage is low and encourages extra release when it is near full. This is done using the Water Value or Energy Value in combination with Water Value Point as in the following example:
| Property | Value | Units | Band |
|---|---|---|---|
| Max Volume | 50 | GWh | 1 |
| Initial Volume | 41 | GWh | 1 |
| Water Value | 35 | $/GWh | 1 |
| Water Value | 10000 | $/GWh | 1 |
| Water Value | 9000 | $/GWh | 2 |
| Water Value | 500 | $/GWh | 3 |
| Water Value | 250 | $/GWh | 4 |
| Water Value | 125 | $/GWh | 5 |
| Water Value | 90 | $/GWh | 6 |
| Water Value | 50 | $/GWh | 7 |
| Water Value | 37.5 | $/GWh | 8 |
| Water Value | 35 | $/GWh | 9 |
| Water Value | -100 | $/GWh | 10 |
| Water Value Point | 5 | GWh | 1 |
| Water Value Point | 10 | GWh | 2 |
| Water Value Point | 15 | GWh | 3 |
| Water Value Point | 20 | GWh | 4 |
| Water Value Point | 25 | GWh | 5 |
| Water Value Point | 30 | GWh | 6 |
| Water Value Point | 35 | GWh | 7 |
| Water Value Point | 40 | GWh | 8 |
| Water Value Point | 45 | GWh | 9 |
| Water Value Point | 50 | GWh | 10 |
The above example defines 10 storage volume bands at various prices
with higher prices for lower storage volumes leading up to negative
price for very high volumes. The above example is simplified in that
the Water Value bands are constant over time. A more realistic
assumption would be that the values are sculpted over time with high
penalties for release during periods of low inflow, and vice versa for
periods of high inflow.