Please Help!! A few Questions on building a System?

System

Hi,

Can someone please help me with the following sizing calculations?

I am new to Solar Energy and would like to build a simple Solar Thermal System capable of generating 5KWp AC to help a few folks in a rural area. I should be able to add additional capacity on a as needed/funding available basis by simply adding more units later.

The Alternator will be coupled with a Steam Engine of appropriate capacity...


My Questions are:

1. What should be the capacity of the alternator to output 5KWp? Specifically, at what RPM should it rotate to generate the required electricity?

2. What should be the Capacity of the Steam Engine in HP to be able to power the Alternator at required RPM?

3. If the RPM from the Steam Engine varies based on the Steam input variances what happens to the Alternator Output...I'm looking for RPM and Output in KW
numbers.

4. Any suitable Off the shelf Steam engines and Alternators that I can simply purchase? A few brand names would tremendously help.

Not sure what additional information can I provide to help me build a system.

Thanks for your help.

hermit

Re: Please Help!! A few Questions on building a System?

why steam? expensive equipment, quality steam required in a determined range of dryness, constant exhaust drained to? supply of steam from? added future capability (bigger initial turbine) fluctuating steam supply (pressure/dryness?) alternator that likes varying speeds and keep at freq? who will monitor/maintain turbine? steam is not a source of energy to use unless you are qualified. anything can be made to work but at what cost and how much time to run and maintain. good luck.

System2

Re: Please Help!! A few Questions on building a System?

hermit wrote: »

why steam? expensive equipment, quality steam required in a determined range of dryness, constant exhaust drained to? supply of steam from? added future capability (bigger initial turbine) fluctuating steam supply (pressure/dryness?) alternator that likes varying speeds and keep at freq? who will monitor/maintain turbine? steam is not a source of energy to use unless you are qualified. anything can be made to work but at what cost and how much time to run and maintain. good luck.

To keep the cost down I am trying to go with low cost equipment given that this is for a Rural area on a charity basis.

So the equipment I have in Mind is a Closed Loop Tesla Turbine ( http://www.youtube.com/watch?v=e7nFga2BpGU )

or

a Green Steam Engine ( http://www.youtube.com/watch?v=GZ41rKx8XoM&feature=related )

These engines seem to require less maintenance. Parts are easily replaceable.
Maintenance is not a huge concern as the maintenance costs in this region are not that much.

Also, to generate Steam I'm thinking of using a Fresnel Lens and a Flash steam boiler.

Am I not thinking about this right?

BB.

Re: Please Help!! A few Questions on building a System?

You kind of have two threads going here with the same questions--Steam Vs Stirling--although they have taken separate paths... We can merge the two or leave them separate--see how they go.

Regarding live steam--boilers and live steam is dangerous... People get killed.

This is something that a few people without knowledge and licenses (at least in the USA) are going to be able to create/run safely and successfully.

Is there some specific application you are trying to address (location, fuel sources, co-generation, etc.)?

Small steam systems have pretty much disappeared in the US (and much of the world?) because of the issues of safety, maintenance, water, and fuel requirements (low fuel efficiency vs diesel, as an example).

-Bill

icarus

Re: Please Help!! A few Questions on building a System?

"I am new to Solar Energy and would like to build a simple Solar Thermal System capable of generating 5KWp AC to help a few folks in a rural area."

Perhaps the oxymoron here is " a SIMPLE 5kw system"! I know of no such thing except a diesel generator.

Tony

mike95490

Re: Please Help!! A few Questions on building a System?

Simple 5KW system is about 6KW of solar panels. Put them on pole mounts, and manually aim at sun. After system losses, you will have 5KW or so. Use 2 inverters, slaved together.
Could add batteries if you need some night time power.
Daily aim of panels is only maintenance.

BB.

Re: Please Help!! A few Questions on building a System?

An interesting news article on Solar Thermal electrical generation in Arizona:

New rays of hope for solar power’s future:

Boulder City, Nev.
From five miles away, the Nevada Solar One power plant seems a mirage, a silver lake amid waves of 110 degree F. desert heat. Driving nearer, the rippling image morphs into a sea of mirrors angled to the sun.
As the first commercial “concentrating solar power” or CSP plant built in 17 years, Nevada Solar One marks the reemergence and updating of a decades-old technology that could play a large new role in US power production, many observers say.

But, it is mostly foriegn companies coming for a 30% investment tax break, and looking for $0.15-$0.17 per kWhr (not cheap) to compete against Natural Gas fired power plants.

Lots of numbers to play with in article (size of installation, costs, MW/GW output, etc.).

-Bill

System2

Re: Please Help!! A few Questions on building a System?

BB. wrote: »

You kind of have two threads going here with the same questions--Steam Vs Stirling--although they have taken separate paths... We can merge the two or leave them separate--see how they go.

Regarding live steam--boilers and live steam is dangerous... People get killed.

This is something that a few people without knowledge and licenses (at least in the USA) are going to be able to create/run safely and successfully.

Is there some specific application you are trying to address (location, fuel sources, co-generation, etc.)?

Small steam systems have pretty much disappeared in the US (and much of the world?) because of the issues of safety, maintenance, water, and fuel requirements (low fuel efficiency vs diesel, as an example).

-Bill

Bill and Others,

Fist of all, Thanks a million for not flaming a new bee like me and answering all questions...

Let me provide more details on what I'm trying to accomplish and that may help in building a cost effective system.

Goal:

The ultimate goal is to power up a few rural areas during the day time mostly. Hence, No power storage is needed as Storage costs add up significantly to the overall system cost.

The system could also be possibly connected to a Grid at a later time once it is stable and generates meaningful power.


Location Details:

The places are located in an area where SUN shines 2600 - 3200 hours per year with a daily average solar energy incident ranging from 5 to 7 kWh/m2.
So Sun Availability is not a problem.


Labor & Manufacturing costs:

Labor and manufacturing costs are VERY cheap. So the system modules could be replicated cost effectively to add more power once is it built.


Funding:

State and Local Authorities provide some financial assistance for such system and I'm planning to get additional help from some Charitable organizations.

With all this assistance I estimate that the cost of 1 KW-Hour of electricity could go up to $0.15-$0.18 and still the system might be viable.


Maintenance:

Maintaining the system should not be a problem as I'm trying to workout various options and you can assume for now that resources with necessary technical skills can be brought on site for ongoing operations and maintenance.


Now, the path I chose to do this is to start off small and build a system that can be replicated later over a period of time to increase the output.

Since I'm new to the Solar energy field, I'm trying to learn as much as I can and trying explore multiple options like Striling, Steam Etc. Hence my questions in multiple directions.

The main objective is to build something utilizing the local resources at a reasonable cost.

System Options based on what I read so far (Although, some of the posts already indicated that some of these options may not work):

1. Fresnel Lens -> Steam Engine (Tesla or other large ones) -> Alternator
2. Fresnel Lens -> Stirling type Engine -> ALternator
3. Large Reflector -> Steam Engine -> ALternator
4. Parabolic Through -> Steam -> Alternator

To give an example of costs, a large 8m² Reflector Concentrator module can be built for about $800 that generates

Max temperature reached at focal-point 1000°C
Max optical efficiency 70-80%
Size of the Reflector 8m²
Cost of one reflector $800 USD


Or another example,

A 1.8m² Reflector capable of boiling 4.5kg of water in 30 minutes at an average Insolation of 700 watts/m².

Cost : $90 - $100 USD

Similarly, The boiler, Steam engine and alternators could possibly be obtained at much lower prices.

On the subject of Photovoltaics:

I'm avoiding Photovoltaics so far because of the high costs of the panels. From what I read the Photovoltaics cost much more than Solar Thermal hence I'm leaning towards Solar Thermal.

Lastly, on a small scale if the system is not viable given the above details and I'm open to any and every suggestion on what other approaches may work better in this situation.

While providing suggestions If I may request you all to kindly provide some numbers as I work better with numbers that would be wonderful.

Again, thank you for your kindness.

System2

Re: Please Help!! A few Questions on building a System?

hermit wrote: »

why steam? expensive equipment, quality steam required in a determined range of dryness, constant exhaust drained to? supply of steam from? added future capability (bigger initial turbine) fluctuating steam supply (pressure/dryness?) alternator that likes varying speeds and keep at freq? who will monitor/maintain turbine? steam is not a source of energy to use unless you are qualified. anything can be made to work but at what cost and how much time to run and maintain. good luck.

I would love to avoid dealing with Steam altogether, If I can make a Stirling engine work...Something similar to this...Even though I may never be able to reach the same level of efficiency these systems operate at....

http://www.stirlingenergy.com/technology/suncatcher.asp

Photovoltoics are just too costly for my purpose. See below.

nigtomdaw

Re: Please Help!! A few Questions on building a System?

Solar Thermal to produce hot water for domestic use is a lot cheaper than PV Solar Electric.

However Solar Thermal + Thermal Engine then generation of electric power may be more costly than PV Solar, certainly more maintainance and more unreliable .

IMHO Nigel

BB.

Re: Please Help!! A few Questions on building a System?

Solar Novice,

You did not give any information on your load other than it is AC...

Assuming you mean just standard 50/60 Hz at 120/240 VAC--a stand-a-lone solar PV or Solar Stirling AC generator without storage is going to be a very difficult system to make successful...

The problem is that most AC devices/appliances are designed and operate under the fact that the AC electricity is "unlimited" and steady throughout its operating period. And that the outlet can supply large surges in power.

A simple AC alternator (solar thermal) or inverter (solar PV), just cannot meet these expectations and run near 100% output for 5-8 hours a day... Take a refrigerator--simple AC motor powered system. If the power is cut (cloud passing, another heavy load starts), the motor will stop/stall, and it must site for 5 minutes or so to let the freon pressure inside the heat exchangers drop so the motor can restart. Also, if there is not enough "sun", the voltage (or frequency, or both) will sag and you will have a brownout condition--causing the AC motor to draw too much power and eventually will burn itself out ("in the old days", utilities use to brown out when they had problems--now, they just cut the power until they can restore 100% service to prevent these sorts of problems).

I understand your concerns about storage--This can easily increase your power costs by 2-4 times... But, if you are using standard appliances designed for utility power--your choices will be limited. Either install storage (battery, hydro/pump system, etc.) or make your "generator/collector" much larger than needed to support surge/low light situations.

In the end, you are stuck in the typical engineering rock and a hard place--Either you design your energy source to feed the expectations of loads designed for utility power--Or you look at the entire "sun" to application and possibly redesign both to be more cost efficient/appropriate for the location (example, say your load is a large refrigeration/freezer type application. Design for variable speed DC powered refrigeration pump and use water/salts/wax to allow you to over cool during the day and the "cool" storage of the water/etc. to keep things cool at night and during cloudy weather--or you use DC power for variable speed water pumps to pump and store excess water during the day and use gravity and/or small hand/battery pumps for water the other 20 hours per day).

My humble opinion--you will fall into a trap if you don't look at both the power source and power consumer when trying to design/build your technologically/locality appropriate system.

In the end, for small systems--solar PV electric with batteries is probably going to be your only workable solution to your application. Anything else to going to be to expensive/complex to implement on the small/distributed scales you are asking about... Unless you have some specific local energy source (like stream/lake with significant water flow and drop) available.

Other issues like building a complex central power source (like a 5 kW unit suggested here) and probably distributing the power using copper/aluminum wire is an issue in itself--in many places, having $50,000 piece of equipment (assuming $10 per watt cost to build/install) and distribution network (lots of recyclable metals that can be sold for cash) becomes a security issues in itself.

Sociological issues/changes can also be a big problem too... Central power either attracts more people to a location (food/infrastructure/social friction) or, if in a refugee camp, keeps the people concentrated instead of returning home--with all of those issues.

As another example, from a small book (actually a kid's book I was reading while waiting for my kids)--A child from Ontario Canada ended up raising money for a well in an African village--very inspiring story--in the "middle" the story was very successful. Village had clean water and prospered--healthy. Then a year or so later, the local "rebels" came by, kidnapped the young boys to be sold to other "rebels" and stole/destroyed/scattered everyone else. End of the story--family found the young African child who had initially exchanged letters with the US student after he escaped from the slavers and helped him immigrate to the US (adopted?). The well projects are still ongoing (as I last read)--but the problems can be huge.

So--in the end, your project needs to address an entire range of issues (which you undoubtedly know better than I) for it to be successful.

-Bill

PS: Found the book Ryan and Jimmy and the Well in Africa That Brought Them Together.