The Qattara Depression Project was stupid but might make sense now

Does the Qattara Depression ring any bells to anyone? It’s a large depression below sea level in Egypt that is fairly close to the Mediterranean. However, it’s more well known as part of a hare-brained scheme to use 213 nuclear weapons to connect it to the Mediterranean, creating a large salty lake and generating electricity from the water flowing from the Mediterranean.

Now, for a cost-benefit analysis. The project would generate around 330-670 MW [1]. Yeah, that’s it, not even a gigawatt, the project called to blow up 213 megaton weapons for a 700 MW power plant. A nuclear power plant like say, Three Mile Island would generate more power with a lot less complexity for about 2 billion dollars. Aside from the nukes there would be other issues. The area was still mined from WWII, using saltwater would create corrosion issues. Pumped hydro storage was also proposed, however was not nearly as important as now when we are adding additional renewable power and trying to deal with intermittency.

So now, lets evaluate what we get now in an era of climate change and cheap renewables. Lets do some value stacking.

Firstly, one funny feature is that the depression is large enough to have an effect on work sea level. The depression is about 1200 cubic km and world oceans are around 361 million sq km. So the depression would, fully stored, lower world sea level by 3-4 mm which is about 1 year of sea level rise averted.  If we value global emissions at something like 2 trillion dollars in damage ($50/tonne) and maybe sea-level rise at 10 percent of that, that’s a cool 200 billion dollars.

Power-wise, we got the 700 MW which worth somewhere around $3-10 per W so $2.1-10 billion. Secondly, we got the immense storage capacity of 198 TWh (about 5 percent of US annual electricity usage). Using it as storage would negate the sea level decrease though. With that amount of storage the main challenge is needing to add a huge amount of generation to use it on a reasonable timescale, You’d need 20 GW or over 10 the actual generation capacity to use all that in a year! This might necessitate a wider channel and a huge cost there so, I’m not really sure how to value that but maybe somewhere around $1/kWh might be reasonable so $200 billion.

Another potential option to not be covered here for brevity is the project pairs very well with solar power in the area, using the depression to store the power for smoother deployment.

Now to the costs. The main cost would be the canal to connect to the Mediterrenean sea of 50-100 km. A Suez Canal expansion was completed recently in only one year at 23 m deep and 210 m wide and 35 km long for 4.5 billion dollars (surprisingly fast and cheap). Assuming this width is enough and doubling costs due to remoteness still leaves us with a reasonable cost of maybe 20 billion dollars. Given that this is the main uniquely high cost and it is much smaller than the benefits the project looks reasonable. EDIT: There are 200 m high barriers that would be expensive to pass. Edit: Taking the estimates here suggests even with optimistic estimates of canal costs we’d still only achieve something like $1000/kW  which is at the fringe of feasibility.

So to recap, the project’s initial reason, power generation via evaporation, for the project is largely garbage and only worth a few billion dollars. Evaporation is actually pretty slow and precipitation is a much more leveraged way to generate power (traditional dams). However in a world concerned about sea level rise and intermittent and cheap renewable energy, the storage and potential to lower global sea level raise the project’s value by an order or two of magnitude and render it viable again.

[1] My two wikipedia linked sources estimate 12,100 km^2 and 19200 km^2 area at 60m depth and about 1.41 m/year and 1.9 m/year of evaporation.

Another good source on the project