3 ms·
For the same reasons you mention, ICEs are also crucial to heavy-duty mobile robots (see e.g. Boston Dynamics).
by alcubierredrive 11y ago
For the same reasons you mention, ICEs are also crucial to heavy-duty mobile robots (see e.g. Boston Dynamics).
- dredmorbius 11y agoSeems fuel cells might also fit in there. Though yes, powerplant design (and noise/exhaust) are limiting factors. Also: stored-energy locomotion. Fully-powered walking is expensive.
- eru 11y agoFrom an energy and CO2 emission point of view, fuel cells are no different than an internal combustion engine.
- millstone 11y agoCan you elaborate on this? I thought hydrogen fuel cells produce only water, not CO2.
- eru 11y agoHow do you generate the hydrogen in the first place? Hydrogen is only a battery. An inefficient and cumbersome battery. I was thinking of hydrocarbon fuel cells, to be honest.
- dredmorbius 11y agoWhether you're looking at hydrogen or hydrocarbons, you need some chemical energy carrier mechanism. In the long run, either will have to be formulated, and yes, there's about a 50% efficiency hit straight off the top in elecrolysing hydrogen. But if you're trading an abundant, variable energy source (say, peak solar which is otherwise wasted) for a scarce but valuable and useful store, that's a net win. Note that whether you're formulating H2 or hydrocarbons, the energy cost is about the same (the carbon sequestration from seawater mentioned above is low energy cost), though it requires fairly substantial capital investments.
- eru 11y agoYes. One other alternative is the Li-Ion batteries that we already have. In any case, I am just reacting to the hype we sometimes see about an `H2 energy future', as if hydrogen was a source of energy.
- dredmorbius 11y agoFuel cells: 1. Run silently or near silently. They're generating electricity via redox reactions, not combusting. 2. Have effectively no moving parts. Again, no noise or vibration. 3. Product electricity directly. For powering electronics, this means no secondary generation required. 4. Utilise extremely expensive catalysts. The reason you don't see fuel-cell automobiles (excluding very small numbers of test vehicles) is that the engines cost, literally, on the order of $1 million, as opposed to a few hundred for a typical ICE. This price premium has proven difficult to overcome. 5. Operate better delivering fairly steady-state power, from what I understand. A tremendous benefit of ICEs is that they can scale output in a second or few seconds, with very little throttle lag. Yes, straight-up electric motors are even better at this, but straight-up batteries tend to not store much power. A fuel cell is essentially a battery whose electrolytes you fill rather than recharge or replace. This offers the advantages of fuel-based systems (high energy capacity) and batteries (direct electrical output). Unfortunately, it introduces the disadvantages of fuel cells (cost, power delivery profile).
- eru 11y agoI was thinking of hydrocarbon fuel cells (hydrocarbons in, CO2, water, useful energy and heat out). In any case, I agree with your analysis.
- dredmorbius 11y agoYes, that's one option. I'm a little shakey on the specific function, characteristics, and reaction materials, but some form of redox and electron flow is what you're aiming for.