This is part 2 of 3 in finding high IRR hydropower sites with an aggressive tariff using HydroDesk. Please feel free to jump to the other parts below:
we are now going to design a hydropower plant around the pink and yellow segments we found. In a
HydroDesk Project Folder, there are many structures you need to fill in before you can
Simulate a project. In this post, only the following structures are discussed in detail:
- the Headrace
- the Dam
- the Access Road / Transmission Line
Let’s check the slopes of the banks to see if they are crazy. First we turn on the
Contours Layer Let’s assume there will be no tunneling and we will be placing all structures on the surface.
It seems the contours are not that dense between
550m to 600m, which is where our pink segment begins. However the left bank (right side of image) has a valley. So on a glance it seems our headrace will be on the right bank.
Second, to see what kind of slopes our headrace might pass through, we draw a sketch line along the
575m contour and turn on the
Terrain Slope layer. We can easily see what kind of challenges we face within seconds:
Let’s remove the Satellite basemap so that we can see a clean white canvas. Then turn
Contours back on again.
Its becoming more evident that the right bank (left side of image) is better. The left bank (right side of image) has at least 2 to 3 valleys and hills. Furthermore, farther downstream the contour veers off “into the mountain” (see X symbol on image below):
Seems like the right bank is the right choice!
We are going to try a covered channel as our primary headrace (also called a box culvert). In HydroDesk, we don’t have to draw this manually! We use a tool called
Flattest Path for this purpose.
You place two points of the same elevation, click the “Run” button and HydroDesk will automatically finds the flattest path for you between these two points:
You can also easily get the elevation and excavation profile of your headrace by just clicking on the respective tabs in the toolkit:
We see that
Flattest Path managed to find a flat path within a
Cross Section Excavations
The cross section excavations will eventually lead to calculating of the largest cost components of our project: Earth Works. On the bottom right corner of each section, you will find the cut fill volumes needed. After you have “Simulated” the project (in Part 3), you can adjust the benching parameters in great detail.
There are many more things we can do by analyzing the cross section excavations, including changing the alignment of the headrace. However, for this exercise, we will move on to site the dam.
We are going to turn on the
Contours Layer again. There are two possible locations where the river flattens out for a little bit. There seems to be nothing particularly special about either so I will choose the one downstream for now:
Once you draw the dam (by crossing the river line), HydroDesk will immediately ask you for the
Dam Height. After that, the inundation and catchment is immediately generated. If your dam height is very tall, the inundation could take a while. I placed only
10m in this case:
One of the features that is a work in progress is to show you visually whether the dam inundation a) affects communities upstream due to flooding and b) how it affects downstream communities in a PMF (probable maximum flood) dam breach situation. This uses artificial intelligence methods on satellite imagery to detect homes, structures and farms.
In addition to just finding out what the catchment area shape is, HydroDesk also works in the background to perform rainfall-runoff calibration against known flow gauge stations in our proprietary database together with decades long historical satellite rainfall data.
We are working on some features that will soon be able to provide you insights into the catchment area’s
Land Use Pattern using AI based computer vision on satellite images, as this affects the integrity of our
Flow Duration Curve over the years to come.
Previously we used the
Flattest Path tool which insisted on a grade of
0 (flat) for concrete channels. However, for roads and transmission lines, they don’t need to be on a flat grade. Roads can be up to up to
20 degrees (or
10 degrees if turbines are passing through) and transmission could go as far as
We have a tool called
Least Cost Path for this particular situation. Below you can tweak your maximum slope as well as whether you would like to minimize distance or slope. Sometimes if you put the maximum slope value too low, HydroDesk will complain that it found no viable paths with such aggressive parameters.
The animation below shows permutations of several access road candidates with different slopes:
The access road is only about 1km, the
Least Cost Path tool works for very long lines too. For example, a transmission line to the nearest city could be 40km long:
The other project structures do not impact CAPEX severely so we will skip them for this post. Now we can simulate the entire project to view the financial results of this project!
Simulation in HydroDesk will perform the following:
- Calculate dam costs from the ground up based on the river profile
- Calculate headrace, penstock, access road, transmission line structure costs
- Calculate earth works costs (cut and fill) of all structures
- Calculate power generation based on the river flow and catchment (including rainfall and flow gauge station calibrations)
- Gather all the intermediate outputs and put it into a project finance model with reasonable default assumptions
When the Simulation completes, it will ask you to go to the “Optimize” page to view the results.
We are going to stop here for Part 2. Here’s a summary of what we did:
- Turn on the Contours layer to check for obstacles along both banks of the river.
- Draw a candidate headrace line, turn on the Terrain Slope layer and check for more obstacles.
- Draw a covered channel headrace using the Flattest Path tool.
- Check out the cut and fill excavation profiles along the headrace.
- Generate the catchment and inundation characteristics of our dam.
- Generate some transmission line and access road permutations.
- Put everything together into a Project and Simulate it.
In Part 3, we review the results of our simulation and tweak some inappropriate default values to the correct ones. Part 3 is the most exciting part as we finally see what the project returns are going to be like.
Disclaimer: Any resemblance to any schemes or projects under development in the particular area used in this post is entirely a coincidence.