Introducing Synthwave

[alexose]

Introducing Synthwave

Now that we’ve validated the core concept, it’s time to spin Synthwave into its own mission with the goal of building a real, working, electrochemical Direct Ocean Capture machine.

In addition to all of the normal mission functions (recruiting, organizing, publishing, etc.) it will need to tackle three core engineering areas.

Degassing + Measurement

The ability to efficiently degas the electrolyte is the biggest unknown right now. How can we degas a given volume? How do we measure what kind of gas is being removed, and how much? If we’re removing CO2, how do we store it?

Being efficient is key, as I suspect the vacuum pump will be our biggest energy draw. The electrolyte needs to be degassed twice, and I suspect the resulting CO2 will need to be compressed.

Cell Design

The next biggest unknown is the design of the cell itself. It’s going to be tricky: We know there need to be two cells with two sets of electrodes. There are multiple steps to the process: How do we manage the timing?

It should be possible to design a flow cell. This should be the goal, although there may need to be a few intermediate steps along the way. Figuring out the development roadmap should be one of the first things we tackle.

Cost Optimization

There are two aspects to cost optimization: The overall cost of the ‘developer kit’, and the technoeconomic efficiency of the cell itself. Both are important, but for different reasons. Keeping the cost of materials low is key for recruiting other hackers and collaborators. Ensuring the process is cost-competitive is key to actual widespread adoption.

Where to go from here?

Ideally, we can recruit volunteers to help us on the above problem areas. We should aim to break experiments into small pieces (for example, we don’t need the full Synthwave setup to test our ability to degas water and measure the output).

In order to continue forward momentum, I’ll aim for weekly updates on this forum. Should we have enough interest, we can pull in some other project planning tools, but for now I’d prefer to keep our software load to a minimum.

Please reply here or contact me on Discord if you’d like to contribute!

[alexose]

Here’s a (very) rough diagram of Synthwave 1.0. Adding it here for posterity. Don’t make fun

[alexose]

Posting a preliminary Bill of Materials (since a few people have asked).

Note that this is very much a work in progress. Don’t treat this as a recipe for a working Synthwave. I haven’t built anything yet, nor have I written any software. Everything here is subject to change.

Also note that this design is terrible. It is not optimized in any way. It is failure prone. It would be much better to have a flow cell-- Ideally, one that avoided the need for all these redundant parts. The only thing this design is good for is demonstrating the concept.

Without further ado:

Pumps
2 DC 12V Water Flow Self Priming Diaphragm Micro Water Pumps $25.18 ($12.59 ea)
2 DC 12V Mini Vacuum Pump $51.98 ($25.99 ea)

Solenoids
2 3/4 inch NPS Thread 12V DC GRAVITY-FEED Plastic Nylon Solenoid Valve $25.98 ($12.99 ea)
4 12V Two-Position Three-Way Electric Solenoid Valve $20 (about $5 each)

Membrane Contactor
1 UDM-21110 Ultifuzor Degas Module ~$180 (I bought used for $75)
4 Luer lock to 1/4 barb fitting adapter $7.99 (10 pack)

Sensors + Electronics
1 SCD30 CO2 sensor $30.40
2 Gravity Arduino-compatible pH sensors $79.00 ($39.50 ea)
1 ESP32 Development Board with OLED $16.99
1 12V DC 2A Power Supply $11.99
1 Adafruit 4489 L9110H H-Bridge $5.18
10 TIP120 NPN 5A 60V Transistors $8.99 (20 pack)
2 LM2596S Adjustable Buck Converter $8.69 (5 pack)

Misc.
10 feet 1/4 ID silicone tubing ~ $5
2 830-point solderless breadboards ~ $5
Solid core wire
Wire strippers, needlenose pliers, soldering iron, etc.

You should expect everything to cost $370.38 total. Of course, it is much cheaper to source the parts from China if you don’t mind the wait.

The most expensive individual part is the membrane contactor. It would be interesting to come up with an alternative for this part, but I’m not sure what this would be. The pH sensors are optional, but very useful to monitor system performance.

There will also be a handful of 3D printed parts, which I am not including in the bill of materials for now.

With careful attention to price, it would be possible to build this device for around $200.

[alexose]

Quick update from Synthwave HQ!

The prototype is coming along nicely, with only a few changes to the BOM so far.

I’ve posted the 3D Models and software to GitHub. I haven’t had time to write any documentation yet, but I’ll get to that once I create a hackster.io page.

[alexose]

One loose end I probably won’t address until I build another one: How to secure all of these pumps and solenoids to the 3d printed shell.

The current design allows you to screw M2 screws directly into it. (I had to drill these out a tiny bit in order to get the screws to bite properly. But it works fine.)

I’d like to update the design to use theaded inserts. These are way more durable and user-friendly, but will require some trial and error to get right.