Feeling our way to Flexibility

A flowery spring sunset in the foothills.

Flexibility is the name of game at this point. Since arriving on site six weeks ago, we have been gathering layers and layers of information that could come from nothing other than our own observations and measurements, conversations with our client, and iterative dialogue with the individuals who have been managing the development of this farm and will continue to do so long after our consultancy team is gone. A few of the bigger discoveries and our attempts to design them into our project:

1) We discovered that there is a significant volume of water in the form of springs and wells located high above the plantation. Our idea? Maybe we don't need to pump at all! In fact, through some number crunching, we discovered that there was enough gravity-fed water for this year's demand and more; certainly a more sustainable option than fancy solar pumps and expensive PV panels. But time constraints and pressures to install the already purchased equipment ruled out this 'keep it simple' option for the time being. Unfortunately, we can't exactly hop in the car with our six pumps and 32 solar panels, drive back to the store, and ask for a refund.

The Lagoon, our primary water source, with pomegranate trees in the far background.

2) The projected watering demands per tree turned out to be half of what we planned for when we designed the initial system and bought the equipment. What a great surprise, right? Well, not really from a sustainability perspective, if it means we've purchased far more equipment than we need. So now we have enough water for a farm with three times as many trees. Result? A happy client who will plant as many trees as we can provide water for. Disaster averted.

3) Turns out that our original idea to bring two water sources (a lagoon and deep well) together and then send all that water up to the four tanks that feed the trees won't work based on the limited power input (and thus flow rate) that these solar pumps can take. We shift our approach to equalizing the flow rate from the sources to each tank. This system requires water from only one of the two main sources, leaving us with an extra pump and untapped water source. Anybody in the market for a Grundfos SQFlex 11-2 water pump?

FOR SALE: One solar powered water pump, best offer, you pay shipping from Chile! =)

4) Our solar grid tie exploration was educational and interesting, but ultimately a dead end. We won't give the exciting details about the complexity of combining PV arrays with different voltages or expound on the illogic of powering a home that is rarely occupied. Oh yeah, forgot to mention, grid tied renewable energy systems are not yet feasible in this community in the first place. So we're back to pumping water...

"Where does sustainability reside in all these ideas and explorations and conclusions?" you might ask. Hmmm ... good question. Our group process requires that we discuss such a deep and profound question all together and decide by consensus what our answer will be. So we'll get back to you on that one. =)

Project Site

Welcome to La Aurora de Curacavi, our little valley tucked in between the mountains west of Santiago, Chile. The pomegranate trees have just been planted and can be seen on the slope in the distance. The primary source of water is at the bottom of the slope near where the above photo was taken. Sunshine abounds, especially during the long, dry summers here, making a photovoltaic approach to generating power an obvious choice.