Greenhouse Water Condenser/Energy System

I have been thinking a fair amount lately about the potential of stacking in a symbiotic manner several functions into greenhouses.  The greenhouse below is one such idea for this concept.  Its central function is to act as an atmospheric condenser.  The air is drawn in the four inlets and as it cools in the descending underground pipes it hopefully cools to the point of condensation.  The condensation is then trapped in a buried storage tank.  To drive air through this process a black 3' tube in the center of the greenhouse acts a passive solar air heater, this is ducted over the inlet draw tubes and the natural convection of the cycle acts as a fan to draw air through the condensation cycle.  As is also illustrated their is a parabolic concentrator to increase the temperature and effect of the convenction action.  I have not done calculations but it may even be worthwhile to place a small 200w air turbine horixontally in the tube to extract some energy from this stream. 
Though it is not in the drawing I think that adding thermal earth mass around this tube would further enhance the cold weather growing capabilities of the submerged greenhouse.  More ideas and refinement on this concept to come....
http://www.flickr.com/photos/58298476@N04/7707418084/in/photostream
http://www.flickr.com/photos/58298476@N04/7707418550/in/photostream

Oh one further addition to this concept may be possible.  The incoming air could be further cooled through an expansion process if each air inlet tube had a valve that cycled between open and closed states.  When those valves are closed the air inside the inlet pipe would expanded by the upward solar chimney draft, this expansion would cause cooling in the pipe and aid in the production of condensation.

More Thoughts on Bridging the Economic Gaps...

It seems to me that contests such as the $300 house  are a good sign that the larger tides are turning and we collectively will start evolving low cost infrastructure for non industrialized parts of the world and the soon to be post industrialized parts of the world.

Low cost renewable energy powered infrastructure that still keeps us integrated into global communications seems very feasible and imminent.  Yet there are plenty of social barriers that will make it a challenge to implement in the west.  In my last post I mentioned some of the biggest barriers I see to this movement, land prices, zoning ordinances and taxes on said land. All of that makes it somewhat unlikely that even if one attains high degrees of self sufficiency with some product surplus  to sell that you'll be able to afford the mortage, unless you came in with a good chunk of cash prior to the venture.  With a deeper recession/depression imminent and most potential "homesteaders" or "unpluggers"  approaching these ventures with no savings and probably some debt to service, this economic hurdle becomes a big one.

Obviously one can try and find work outside, but depending on your choosen "unplugged" location this can be challenging and often conflicting with your unplugged job ethics.  What seems to have the most potential is figuring out a decent way to plug into the online economy.  Elance and other online markets are a start but somewhat a race to the bottom as labor markets are international.  So the open ended question I have now is whether we can build openly collaborative firms that are working in alignment with solar autonomy and also bridging the economic gap?

Solar Bellows Engine, Will this work?

I'm having trouble communicating a potentially unique and simple, stirling engine concept. I might also be missing something, but here it is...
My goal is to make a low energy dense, stirling engine (passive solar) that is also low cost on a kwhr basis. 
To do that I need a very high volume, low speed engine (reduce drag losses).  It would be expensive to build a typical metal engine with say 10" cylinders for 500watt.  However an insulated rubber expanding bellows in place of a displacer and power piston might be an answer.  Here are some sketches to the concept.

This configuration is really simple as the expansion piston and compression piston work against each other.  This is also bad as it fixes the phase angle.  There are fixes to that, the main point is to ask the question of whether or not a bellows engine could be made to work for low temp solar applications?  Without pressurizing the system the cylinders will not see more than 10psi.  Any old inner tube can hold that.  Temperature is an issue 200 deg F will be common.  I think though there is rubber that can withstand those temps.  It may also be possible to insulate the rubber on the inner sleeve to protect it. 
Feedback or criticism would be most appreciated at this point.  Want to get glaring problems out of the way before researching more or prototyping.  Thanks

Economic barriers to solar autonomy, and how we can break through

As the world moves simultaneously both down resource extractive curves (oil, rare metals, phosphate) and up population curves. We will increasingly need to seek answers from beyond current industrial economic paradigms. Centralization, and accompanying long just in time supply chains, which proved to be optimal strategies for maximizing production in a resource abundant era(minimized labor input per unit/ maximized productivity) will prove to be poor, vulnerable ways to carry vital societal infrastructure in the coming years. Long term what will be required of societal infrastructure are systems that are solar driven (whether wind/biomass), ecologically integrated (as opposed to ecologically dominating) featuring high degrees of autonomy and resiliency  from the bottom up. Current approaches towards solar economies which rely on centralized complex industries (PV's, current wind turbines), may prove to be overly dependent on the old fossil based industrial system. What is needed now are technologies that form a bridge between the resilient solar economies to come, and the existing industrial economies that currently exist.

Building these bridges is not an easy task. Once one realizes the core of the problems with industrial society it is tempting to simply opt out and build a post modern society from scratch (see OSE). Though this work is very important for our medium-long term future, we are still left with the puzzling question of how to economically integrate it now, particularly as the global economic crisis comes to a head. Building solar driven earth brick resilient communities sounds like a great solution, but who will first buy into these communities, who will first rewrite building codes, food codes, ect and even more importantly who will buy the products that are aimed exclusively towards these very communities? There is a problem of exclusivity between current economic paradigm (corporate consumer driven monopoly) and any other alternative form of economy. At the heart of this conflict are land prices, land ordinances, and land taxes. I'm speculating a bit , but I suspect that agricultural land prices (the land needed for RC development) are primarily held as high as they are because of the massive fossil fuel subsidy that conventional ag utilizes. If it weren't for this subsidy that land could not produce enough to be valued at such prices. Property use ordinances (building codes, FDA) ect further act to support the existing fossil fuel ventures, they may have evolved that way to guarantee investors that their ventures will be the only game in town? So as I see it this exclusivity of land uses needs to be tackled before we can expect to see large scale solar driven movements.

My thoughts on moving forward on this problem are two pronged. The first prong of attack is to develop a suite of resilient technology that maximizes ones odds of being autonomous from the the global economic system in which we wish to emerge from.

In order to do this a very difficult balance must be struck on multiple fronts. First for a given piece of land solar energy flows must be transformed into enough product to stay financially afloat (mortage, taxes, ect). We must come to see ourselves not as industrial consumers, but instead as solar farmers and producers, turning solar BTU's into food, fuel, fiber, and energy for manufacturing ventures. This must be done in such a way that you are not entrapped within current global industrial paradigm.

The second prong of attack is perhaps the more critical and difficult. It is the accompanying social and cultural revolution which must usher in and create broader acceptance and support for these new sets of values. What is needed here at this moment are synthetic visionaries who can grasp the complexities of our current system, where we must head and why. The challenges on this front are enormous as I suspect that there are problems, and answers that currently exceed our linguistic abilities to communicate. The tools though at hand are impressive, the information age is at hand. Small agile intelligent groups can leverage this media to produce news content, cultural narratives, and other trans formative tools that were formerly only afforded by all but the most well funded, linked in media companies.

In this blog I aim mainly to discuss the first prong of attack.

In the next post I'll begin exploring my plans on developing one core piece of infrastructure needed for solar autonomy, the home. I intend to work collaboratively and build on the open source hexayurt project , founded by Vinay Gupta.  Stay tuned....

Low Cost Low Tech Solar Thermal Engine

I've been fascinated by air engines in general and stirling engines in particular for there potential for solar electrical energy production.  Though in studying these systems a couple of drawbacks stick out. 

1. Low energy density per unit of material used.
2.  Correspondingly difficulty in manufacturing the large tight tolerance cylinder that is required to make up for said low energy density.


I've also observed that though concentrated solar will produce far superior efficiencies, its associated complexities and poor performance in all but the clearest skies lead to less than stellar $/kwHr figures. 

To address these issues how about a passive solar stirling cycle with a bit of a twist?  The twist being that the passive absorber is an air diaphragm that is also the working piston.
Here is a rough schematic of this idea.

 The air cylinder could maybe be a canvas fabric to withstand heat with a plastic outer layer for zero porosity.  The material requirements really would be basic as the engine would not see more than 5 psi and 250 deg.  However in order to develop useable amounts of power the cylinder would be large, as would the force transfered onto the hydraulic piston. At even low temperatures this force would be significant, for a 9' diameter cylinder at 3 psi roughly 27,000lbs would be transfered to the piston. To handle this force transfer I was thinking steel cables could be woven in a concentric pattern on the outside of the air cylinder.  These steel cables would then connect to a center steel collar to transfer the force to the hydraulic piston.   This way force concentration is transfered to the steel cables, and the fabric only endures around 5psi max.  The hydraulic cylinder will then act as both the power piston and the displacer piston.



Here are a few quick calcs on efficiency.  Assuming 150-160 deg average temp, 55 deg heat rejection, and 55% of carnot ideal, we'd get something like 8.9% efficient engine, perhaps 6-7% is even more realistic.  Not good by normal heat engine standards but look what might the $/kwhr metric look like?

Intro

I'm starting this blog under the premise that the energy infrastructure we are currently committed to will no longer remain viable in the future. We are obviously fossil fuel dependent and our continued reliance on these forms will continue to flare geopolitical instability, marked economic dispartities (due to the highly centralized nature of fossil energies), and of course environmental problems. Perhaps though greater than any of these individual problems is the overall emergence of an increasingly brittle energy infrastructure. One only needs to look at how vulnerable both electric grids, and oil pipelines have proven to be in countries of instability to realize this point. Though in the US we probably needn't worry about these direct attacks (yet) we do need to worry about the indirect results. In a world of tight energy interdependence these problems will affect us all.

I hope to initiate a pragmatic discussion of what realistic sorts of possibilities we can develop. I'll be sharing some general approaches and ideas I've come up with you in hopes that through the power of networks we can perhaps create a couple of useful emergent ideas.

First though let me share my philosophy and approach to the problem. Since highly centralized energy infrastructures seem vulnerable to both breakdowns and economic control and that renewable energy is by very nature distributed I am biased towards localized renewable energy systems.  Given that neither small wind or PV systems seem to have proven succesful in this arena I am trying to really think outside the box.  My constraints are:

1. Needs to be able to reproduce locally, therefore readily available and abundant materials must be used in construction.

2. Cost per kwHr produced (not cost/kW installed) is most important economic metric.

3. Should not rely on other potentially unstable centralized technologies.

4.  Construction must be accomplished through readily available means (cnc mills, lathes ect).

Those constraints are not final of course, but do set the stage for explaining some of the energy system ideas that follow.  So that being said lets brainstorm a little on low cost solar thermal systems.