3 ms·

The separation itself is not the only thing that makes the economics favorable. It's important that changing the separation makes the process electricity only o

The separation itself is not the only thing that makes the economics favorable. It's important that changing the separation makes the process electricity only overall, and this is a big deal. We can run intermittently, allowing low renewable power costs, and since there is no pressure or heat in the system, we can use inexpensive components. When the capex is low, it allows for a lot of other things to not be ideal starting out. Current densities aren't going to be as high as water splitting electrolyzers or aluminum production, for example, but that's ok in this context.

thereisnospork 7y ago
Electricity costs more than heat, as a rule. (electricity = heat at pretty much 100% efficiency) Intermittent operation blows up CAPEX costs. There's no heat in the system until you start dumping electricity into the resistive heating of your cells - you won't ever be able to run at scale at room temperature. A gallon of gas per second unit - something nicely sized for intermittent operation at a gas station - would need to vent approximately 120 megawatts of heat. Current densities are 1-2 OOM lower than water electrolyzer. Cell CAPEX isn't nearly as catalyst dependent as the daily 'We've invented a replacement for platinum in fuel cells' papers would make you believe. Nafion, balance of hardware, and assembly man-hours are $$$. I've been where you are (more or less): beware the superficially justifiable assumptions.
- rmcginnis 7y ago
  It's true that running part of the time is not as good as running continuously, but if the capital is low enough, it's ok to start out running intermittently until we get to the point where we have low cost dedicated power and can have a higher uptime. We will have to shed heat from the system to the environment, but that can be done passively. Current densities are likely going to be substantially lower, but our capital costs are also going to be much lower. We don't need to operate at 30 bar for example, nor further compress our product. Our capital costs aren't magic, they're just good enough in balance with everything else.
  - acidburnNSA 7y ago
    Hook to nuclear and hydro electricity and you can get your uptime much higher while remaining carbon free. That should give you a good 2x boost on capex at least.
    - pfdietz 7y ago
      Building nuclear plants to save on electrolyzer capital cost is not a good idea at all. Penny wise, pound foolish.
      - acidburnNSA 7y ago
        Hook to existing plants to help them load follow where intermittent renewables are at high capacity.
  - Zenbit_UX 7y ago
    If you base yourself in QC you'll have access to cheap and 100% green hydro electricy 24/7.

thereisnospork 7y ago

Electricity costs more than heat, as a rule. (electricity = heat at pretty much 100% efficiency) Intermittent operation blows up CAPEX costs. There's no heat in the system until you start dumping electricity into the resistive heating of your cells - you won't ever be able to run at scale at room temperature. A gallon of gas per second unit - something nicely sized for intermittent operation at a gas station - would need to vent approximately 120 megawatts of heat. Current densities are 1-2 OOM lower than water electrolyzer. Cell CAPEX isn't nearly as catalyst dependent as the daily 'We've invented a replacement for platinum in fuel cells' papers would make you believe. Nafion, balance of hardware, and assembly man-hours are $$$. I've been where you are (more or less): beware the superficially justifiable assumptions.

rmcginnis 7y ago
It's true that running part of the time is not as good as running continuously, but if the capital is low enough, it's ok to start out running intermittently until we get to the point where we have low cost dedicated power and can have a higher uptime. We will have to shed heat from the system to the environment, but that can be done passively. Current densities are likely going to be substantially lower, but our capital costs are also going to be much lower. We don't need to operate at 30 bar for example, nor further compress our product. Our capital costs aren't magic, they're just good enough in balance with everything else.
- acidburnNSA 7y ago
  Hook to nuclear and hydro electricity and you can get your uptime much higher while remaining carbon free. That should give you a good 2x boost on capex at least.
  - pfdietz 7y ago
    Building nuclear plants to save on electrolyzer capital cost is not a good idea at all. Penny wise, pound foolish.
    - acidburnNSA 7y ago
      Hook to existing plants to help them load follow where intermittent renewables are at high capacity.
- Zenbit_UX 7y ago
  If you base yourself in QC you'll have access to cheap and 100% green hydro electricy 24/7.