Mexstan

As some of you know, I am doing some work at a large orphanage here and they have asked me to check into the feasibility of obtaining a diesel powered generator and taking them completely off the grid except for when the generator is down. Electricity here is very expensive and continuously going up in price.

Any ideas how to size this thing? Of course I could count all the lights, fridges, office equipment etc, add the wattages, but that is a big job. Is it possible to work backwards from the monthly bill to calculate what is needed? I checked the last few months and see that they use between 4,500 & 5,800 kWh's a month. It will go up in the future as they add more buildings.

FiverBob

Stan - - interesting concept, but probably not very practical. By the time you consider the cost of the generator, cost of maintenance and cost of fuel, it will not be as cheap you might think. Your concept of trying to determine the size of a generator by the monthly bill will not work. Trying to average out the usage/hour will not work unless everything in the building is running at the same time over the same period of time everyday. The probability is something quite hoggish could run for 2 or 3 hours once in a while yet not the rest of the day. You still have to size the generator for that hog plus the everything else. You have to assess the amount of current being drawn at the highest point and size for that. Does the building have AC? Does it have heat? What kind - - electric? Any motors running? Any cooking done on electric stove? Electric water heater(s)? Can you shut the generator down at night? You have to consider the worst, then size for that. The other option is solar. You have lots of sun most every day. Initial cost would be more, maintenance much less.

Just some thoughts to tickle the mind. There are possibly some changes that could be made to reduce the runtime of a generator - - be creative with that thought. Could a smaller solar unit run things most of the day and at night and a generator standby for heavier usage at a set time each day?

Bob

railroaderone

Is there a flowing stream near by a water powered generator is a possibility.

If not I would check on solar.

Mexstan

Thanks Bob & RR1 for the replies.
Bob, that is exactly what I figured, but I was asked to check into that in spite of it not looking very practical.
RR1, no flowing water anywhere close. In fact, this place is sort of out in the country and there is not even any city water. They have a large amount of cisterns and water tanks and all water is trucked in daily by large water truck. They own the water truck and the driver is part off the staff. He makes many trips every day to pick up water at a central point where many water trucks go.

There is no A/C in any of the buildings, as it is not required. A few portable electric heaters for occasional winter use. Quite a few fridges. All cooking is done on gas stoves. Electric stoves are not common in Mexico. Water heat is a combination of solar and gas for a few areas, but most so far have only gas heaters. One of my future jobs is to install about 10 new solar water heaters which will be paired with the gas heaters. They are waiting for approval on a government grant to purchase the units. We have to install them. There is a fairly constant wind, so small wind generators are a possibility. In fact, they have 4 running already. One unit has 2 wind generators combined with solar that charges a rack of batteries with an inverter. Was looking at it yesterday for the first time and discovered that it has never worked correctly, so as soon as I have a chance will see if I can figure the thing out. No circuit diagram, so will see if the installer can supply one.

Solar for both electricity and water heat is very practical here. Solar electrical is a bit pricey at the moment due to too few dealers and they tend to gouge a bit. One day hope to sit down an figure out a system and then maybe take a trip to the states and buy what I need there. Even with the duty it may work out cheaper.

Lots of things to think about. Too many fires for me to put out at the moment to even think about stuff like this for now.

Thanks for suggestions. Keep 'em coming.

Justwannabeme

I was thinking military surplus gen sets. they have to operate a company base of 4 platoons (240 men), computers, ac, water system filter and pumps, lights, perimeter accessories, vehicle systems.

just came from PA and have a military auction ID, so I can check on line.

figuring 2500-5000 dollars on a skid unit. contractors love 'em.
hubby is not here today, so I can't get the kilowatt usage without checking online...he is the electrician. wiring up a friend's house..

hey! I should send him to you! heh heh warning: you have to feed him.

Mexstan

Heidi, not a bad idea. Will certainly keep that idea as an option for if the decision is made to go that route.

No problem on feeding your husband. We will just warn the kitchen to prepare an extra 4 or 5 meals a day, just for him.
BTW, the director of the school there could be your sister because every time I see her, I think about you.

Colo_River_Ram

Stan,

Tell me about you gas supply, is it propane or tied into a system? I know of some micro-turbine gen set out there..

Mexstan

It is propane. Large tank filled by truck. Easy to add another tank.
Very few places in Mexico are tied into a system
A micro-turbine sounds very interesting. Can they be sized small enough for residence ie my house?

Justwannabeme

Capstone micro- 30 kilowatt would be the smallest multi fuel. plenty for a single house off grid. do not know what the cheapest fuel would be.....

great thing is so many members with acute experience here.....love to hear from da Colorado explorer...

peak use is a good estimate for (wattage times buildings used) off the cuff.

says the hungry man....yes, use solar banks, gen back up.

Tallguy67

Mexstan,
The company I work for believes in Corporate Social Responsibility. They also believe that access to energy is an important part of life. We have run a set of projects over the past 4 years to make energy available in under developed parts of the world. At least the last 3 projects have been to places in Chile where there is no access to electricity, propane or natural gas. So, our volunteers go into these villages and put up these really cool solar setups in homes and schools. We put solar panels on the roofs or somewhere else appropriate and then we put storage batteries and LED light sets inside the buildings.
The feedback we get is that in places like the schools having access to reliable lighting is a game changer.

Mexstan

Sean, that is very commendable.

Don't know if this project would qualify for help from your company in that electricity and gas is available, but it is just so darn expensive. The problem is that the orphanage relies on volunteers (like me) and donations, so any and all help is very much appreciated. Every now and then work groups come down from Canada and the US and they bring a lot of 'stuff' and complete various projects. The tools they bring with them are frequently left behind for use by the orphanage maintenance staff. The next group are Canadian Mennonites (very good and knowledgeable workers) and they will be here in January.

Would it be possible to get your company involved in a project (ie reducing electrical costs) at the orphanage? What do they need to do to get the ball rolling?

I just returned from working there this morning. My 'to do' list is getting longer, no matter how fast I run. Help is badly needed. If anybody wants to come down for a few days, a few weeks or even a few months, you will discover that helping less privileged people, especially these kids is a very humbling and satisfying experience. Beware: you may go home a changed person.

Colo_River_Ram

Good Call

Link to the system:

http://www.capstoneturbine.com/prodsol/products/

With trucked in propane I'm not sure it would payout as the primary electrical source. I would contact them and give them your scenario see what they say ..

There is an Oasis on the Salmon River in Idaho called 5 Mile Bar. They are located at the bottom of the canyon near rivers edge. They have the hydro-turbine piping ran up the side of the canyon next to one of the may streams of that area. The effluent from the turbines feeds the many gardens that are lined with grass for ease of kneeling while tending to what they refer as the grocery store.

Mexstan

Thanks for the suggestions. That Capstone turbine looks very interesting, especially if it can heat water as well as generate electricity. I will contact the company and see what they suggest.

AlpineRAM

Hi Mexstan!

I am not a guru in this but have some experience with stuff like that.

Just doing a raw calc based on Austrian figures:

10 sq meters with 1kW peak give about 900-1100 kwhrs/year, so your 6000kwhrs/month are 72000 kwhrs/year. Or approximately 720 square meters of PV.
One kW peak is approximately 1500-2000 US$ as an investment- so as a wild guess this would be somewhere around 100 k US$ for your consumption, battery farm is extra.

With a genset you will run into the following problem- if you take it big enough to satisfy your peak consumption you will have it "idling" most of the time.
At peak efficiency a genset will take about 180-200 grams of diesel per kWh- at half load it will be 30% more, and depending on the genset you will have about 3 kg/hr for a 200kW genset as an idling consumption(Very modern genset with electrical coolers etc). So if you use this genset to charge your cellphone the cost per kWh is astronomical!

If you have use for the heat generated by the genset and you would produce said heat by burning oil in a furnace instead the equation gets slightly more attractive.

If you want to do something like this you will need to think of 2 parameters-

Total energy consumed per month or year. This will give you the sizing for stuff like PV and wind turbines etc, and also your "storage" sizing.

Peak power demand- this will determine how big you have to go with an inverter, a genset or whatever- so this is the demand on the infrastructure, and this is also what makes electricity expensive.
If you can manage to get your peak consumption down by load management (EG adding a bit of mass to the refidgerators and forcing them to only work at different times) you can get your peak load down significantly.
Your figures imply an average use of about 4500-5800 kwhrs/Month, so an average load of only 8kW.
So if you have to do it by diesel I would suggest investing in a big battery bank as used for solar and a big enough inverter to satisfy your peak power needs and then selecting a genset that has it's sweet spot while delivering said 8kW. This would get your consumption close to the mentioned 180-200g/kWhr. This would still mean about 1400 liters of diesel per month.

If you were to use an old genset with 200kW for the task you would be somewhere around 3600 liters per month idling consumption + about 1400 liters of actually generating electricity. (I would not really recommend that... )

The main advantage of the small genset plus battery solution is that you can add alternative inputs to the storage later on without having to care too much about compatibility. So an additional wind turbine or a new PV panel or the ergometer in the gym can all be added as time and funds permit.


Hope that helps


Markus

Mexstan

Markus, thanks a lot for the great answer. Yes it does help. Our research is still ongoing and your answer goes along with what what we have looked at so far. One day hope to be able to post our solution.