Another Step Forward In Small Scale Electrical Generators

NicknamesAreStupid writes "Product Design & Development reports another breakthrough in small scale solid oxide fuel cells. This methane-fueled cell achieves about 50% efficiency at around 2kW, enough to power an average home. It does so by efficiently recycling its heat to perpetuate the process. Of course, this is not practical for most homes, which only have natural gas that contains nearly one fifth impurities. However, that could change if gas suppliers refined their product."

Re:How small is small?

[Anonymous Coward]

Could it be used on board an electric vehicle to provide power in lieu of a battery?

No. Even though solid oxide fuel cells work and are commercially available (in larger sizes), they have problems for automobile applications - to run efficiently, they operate close to 1000 degrees C, and they don't like being bounced around. Dealing with that kind of temperature in a car is a problem.

For mobile applications, PEM fuel cells [wikipedia.org] are far more likely to be practical.

Re:2 kW enough?

[JimCanuck]

Averaging it out, yes 2kW is probably typical in most homes. As gas furnaces are typical, and if you eliminate your stove, and instead use a natural gas stove, 2kW as a ceiling would be easy to maintain.

Personally for my own uses, 2kW/h nearly excessive, due to my gas furnace, gas water heater and gas stove, I'm averaging out approximately 1.25kW to 1.5kW per hour with a ceiling of 2kW. That includes running 2 TV's, a PC I set up as a file server, 2 other PC's, 2 fridges in the home and the Microwave running for me to hit that 2kW ceiling.

Classic problem with fuel cells

[Animats]

A classic problem with fuel cells is extreme intolerance to contaminants. [sciencedirect.com] Even trace amounts of contaminants tend to damage fuel cells. Hydrogen fuel cells need cleaner hydrogen than is normally available commercially. Research continues on making fuel cells more tolerant of contaminants, but it's hard. Fuel cells are surface chemistry systems. 40 years of research hasn't solved this problem.

Reverse osmosis water purification systems once had the same problem. Today they routinely take in raw seawater and pump out clear water. They just need a backflush cycle once in a while to flush the crud off the membranes. Fuel cells aren't there yet.

Re:2 kW enough?

[houstonbofh]

Unfortunately, air conditioning does not work as well off natural gas as a heater. My boat needed more than 2.5kw for the air conditioners. In Houston, most of the standby generators in case of hurricanes are 5kw to 7.5kw, and some larger houses have 15kw.

Re:2 kW enough?

[fa2k]

Electricity can be more than 100 % efficient if you use a heat pump ( http://en.wikipedia.org/wiki/Heat_pump [wikipedia.org] ).

Houses Need 5KW

[Doc Ruby]

The average American house consumes about 1.5KW electricity average across the days (and nights) through the weeks of a year. But they not infrequently peak demand in spikes over 2KW. A hairdryer or space heater draws about 1.5KW. A dishwasher (especially with extra washing or drying heat boost) will draw 1.5KW. An electric stove/oven can draw 4KW or even 7KW as it heats up. A vacuum cleaner can draw up to 1.5KW, especially if it's a strong one that gets jammed.

And all of those could happen at once. A couple happening at once is pretty likely at least once a year. Plus the rest of the 1KW regular demand, which is closer to 2KW max, averaged against quiet times closer to 0.1KW.

A home power supply should be close to half the 100A 120VAC panel, which is 6KW. A 5KW max supply is probably just fine. A 2KW fuelcell would need a battery that can output 5KW for at least a few minutes, perhaps while an alarm goes off warning the battery will drain down shortly and circuit breakers will snap.

Really all the residential fuelcells I've seen talked about are 5KW. A 2KW fuelcell seems like a good device for a yacht.

Re:2 kW enough?

[michael_cain]

The standard numbers that are tossed around for the average US suburban home (where a bit over 50% of the population lives these days), is 30 kWh per day, with a peak hour usage as high as 6 kWh, depending on location. IIRC, the peak hour tends to occur in the late afternoon and early evening, and varies somewhat between households: people coming home from school/work and turning on lights and A/C, parents firing up the washer/dryer, electric cooking, etc. We looked at converting to NG for cooking at one point; current code requires venting to the outside, which would in turn require some structural work. A contemporary single-family house in the US suburbs will be equipped with at least the equivalent of 125-amp 120-volt service (supports 15 kWh per hour max); the equivalent of 200-amp 120-volt service (24 kWh per hour) is not unusual.

Obligatory "Get off my lawn you damned kids!" anecdote. When my kids were in their early teens, I swear they could come through the front door and within 60 seconds, turn on 500 watts worth of assorted load each. Ever since, and after comparing notes with colleagues, I've claimed that one of the defining characteristic of dads who've had teenagers is a compulsive urge to turn things off and sit quietly in the dark.

Re:2 kW enough?

[Anonymous Coward]

Haha, no. kWh/hour = kilowatt, so it's power.