New engine sends shock waves through auto industry

[CosmicCowboy]

Ok, I know that a 12 kwh system doesn't necessarily produce that much, but why won't that large of a system take care of all of your power needs (that summer 340 dollar cps bill you referenced above) especially since you referenced 4k per month above.


Incidentally, when I checked into it in late 2009 a 4 Kwh system was 50k (or 16k after tax credits) so that is a pretty dramatic price drop in a short period of time.

Correction: I said 12kwh system and that is incorrect...it's actually a 12kw system, meaning it will produce 12kw per hour in direct sunlight. In San Antonio we get and average of 5.3 hours of direct sunlight a day (obviously more in the summer and less in the winter) so on average it will produce 12 X 5.3 X 30 or 1908 kwh a month. I picked a 12kw system for my comparisons because my lowest usage is currently November-February (I have gas heat) where I use an average of probably 1200kwh but I'm also planning to add another 1000sf to my house (currently about 3000sf)

[Wild Cobra]

Where's your highly-efficient combustion engine/turbine so we can asses you know what you're talking about?

Did I say it was highly efficient?

I was making a point that scale makes a difference. If this guy's design is using sonic compression, then that may have a very hard time scaling.

I meant to do some searches in the past when you asked, but must have been busy. Still not going to spend much time, but here is the technology I speak of:

MILLIMETER-SCALE, MEMS GAS TURBINE ENGINES

[Drachen]

Correction: I said 12kwh system and that is incorrect...it's actually a 12kw system, meaning it will produce 12kw per hour in direct sunlight. In San Antonio we get and average of 5.3 hours of direct sunlight a day (obviously more in the summer and less in the winter) so on average it will produce 12 X 5.3 X 30 or 1908 kwh a month. I picked a 12kw system for my comparisons because my lowest usage is currently November-February (I have gas heat) where I use an average of probably 1200kwh but I'm also planning to add another 1000sf to my house (currently about 3000sf)

Ok, sorry, completely missed that too. I have gas heat too so those "winter" bills are great. Just looked at my last bill, and the little graph and it turns out that 1908 kwh a month would actually completely cover every month outside of two months (my house is 2.5k sq ft). I think I will wait another year or so to really look into it.

[CosmicCowboy]

hmmm....doing more research the rule of thumb is that you get 10 watts per square foot of panel so I don't have room for 12kw. Looks like 8kw at most is about all I can cram up there on the new roof.

[Drachen]

hmmm....doing more research the rule of thumb is that you get 10 watts per square foot of panel so I don't have room for 12kw. Looks like 8kw at most is about all I can cram up there on the new roof.

LOL, expand your patio for the express purpose of solar panels.

[CosmicCowboy]

LOL, expand your patio for the express purpose of solar panels.

meh...I could probably put another 400 sq. ft on the front of the house too but don't really want to sacrifice the look...

[Wild Cobra]

Looking for more recent material. Haven't had much luck, of course the newest material will be proprietary.

Here are a few interesting articles on the designs:

COMBUSTION TESTS IN THE 6-WAFER STATIC STRUCTURE OF A MICRO
GAS TURBINE ENGINE

Modeling, Design and Analysis of Micro-Scale Rankine-Based Systems

Experimental Development of the Rotating Subsystem for a Macro Rankine Power System

Now I don't have a password for this site. The article is February 2011. Anyone?:

A Silicon Microturbopump for a Rankine-Cycle Power Generation Microsystem—Part I: Component and System Design

Anyway, for mm or cm scale development, this is pretty good:

They are integrated to enable the microsystem design by satisfying force and power balance conditions on the rotor. Considering our previous thermodynamic cycle analysis on the Rankine micro power generation system, which is aimed at generating a few watts of electric power for applications in portable electronics or waste energy harvesting, we have designed a centimeter-scale demo turbopump device delivering 4.7 W of turbine mechanical power and 71% of turbopump efficiency in order to demonstrate the effectiveness of the component design models and system design principles.

Now on the lighter side... found this interesting device of the searching. You know those leaks in your house... Plug them with these, and generate power:

CM-SCALE AIR TURBINE AND GENERATOR FOR
ENERGY HARVESTING FROM LOW-SPEED FLOWS

[Wild Cobra]

They did their academic paper in early 2011, and said that they would have some better prototypes by the end of 2012.

Seriously. Scaling something like that is not an easy task. It uses a sonic wave to detonate the fuel if I recall, which will change in characteristics with the chamber size as you change the scaling.

Anyone who understands waveguide theory can understand how this poses a problem.

[CosmicCowboy]

Seriously. Scaling something like that is not an easy task. It uses a sonic wave to detonate the fuel if I recall, which will change in characteristics with the chamber size as you change the scaling.

Anyone who understands waveguide theory can understand how this poses a problem.

I'm not sure what the scaling issue is? If 33hp is the maximum practical scale per unit then they can just stack them in multiples if more power is required.

Am I missing something?

[Drachen]

I'm not sure what the scaling issue is? If 33hp is the maximum practical scale per unit then they can just stack them in multiples if more power is required.

Am I missing something?

This is kinda what I was thinking. Especially since they are relatively small.

[CosmicCowboy]

[Wild Cobra]

I'm not sure what the scaling issue is? If 33hp is the maximum practical scale per unit then they can just stack them in multiples if more power is required.

Am I missing something?

That's one way of doing it, but then you have twice as many components when one larger one is only slightly more money. I'm referring to the scaling of physical size.

[RandomGuy]

hmmm....doing more research the rule of thumb is that you get 10 watts per square foot of panel so I don't have room for 12kw. Looks like 8kw at most is about all I can cram up there on the new roof.

http://solarbythewatt.com/2009/04/19...r-square-foot/

Interesting bit.

NREL has a good starting point that gives an equation.

http://www.nrel.gov/rredc/pvwatts/ch...arameters.html

If space is more of a limiting factor than cost, you can get panels that are 50% more efficient per unit area or higher.

http://howsolarworks.1bog.org/sunpower-solar-panels/

SunPower makes the most efficient solar panels on the market. That means that if you put a SunPower panel side by side with another panel of the same size, the SunPower panel will convert much more sunlight into electricity that you can use. A typical solar panel may have an efficiency between 11-15%, but SunPower makes panels with 18% and even 19% efficiency.

I imagine these are more expensive.

As time goes by, output per square foot has gone up, and will likely continue to do so. FWIW.

You can get really cheap per watt stuff, but it takes up a LOT of space. You can get stuff that doesn't take up space, but it is expensive per watt. It is a trade-off.

Personally, I kind of wonder what effect on cooling bills putting a layer of PV cells between the sun and the roof has. This would provide a cooling effect from the shade alone. Add in an attic fan to keep the attic cooler, and it might have an add-on effect in reducing summer time power needs, not insubstantial in Texas in July.