Monday, May 27, 2013

More future think... PV for export AC for rent (and income diversification)

Like I wrote last time, I'm thinking about how a high temperature hybrid could change the way the economics work. It is a real exercise in imagination and takes me to some exciting possibilities.

For me, in my native/instinctive pattern of thought the problem is efficiency. I've taken to saying that 20% efficiency in PV systems (which is on the whole generous) "chaps my little green heart." But I should admit it is as much my thrifty/cheap heart as my green heart that feels the pangs. But that is just MY personal launching : cheat more from the sun.  But there are other perspectives. And they have some important contributions to make.

So let's give them a go...

Among the other, very important, perspectives I have considered over the last two years are those of installers, manufacturers and building owners.  They seem natural constituents to keep an eye on, right? But yesterday some other constituencies came to mind: utilities, PPA providers & aggregators. (PPA's, I should add, are Power Purchase Agreements and they have played an important role in the roll out of solar power in the US market.) Those financiers and their machinations are surprisingly important. Even more so in this cash strapped period. ( I understand that I should set aside China in this discussion since, I'm told, they have a much more straightforward finance approach: save and then buy gear to save more.)

But here in the USofA, and elsewhere, the financiers have a place at the table. And a similar place exists for power companies and a new breed of project developers that have moved in to drive the specification/finance and building of PV and wind farms in fields all over the place. But also on roof tops. These independent operators see the opportunity in creating powerplants and inserting them into appropriate places on the grid and they take care of the finance and management issues to capture the accelerated depreciation and then get into contract with the owner of the building that needs the power. Fairly complex but then so are a lot of modern economic arrangements.

But a hybrid, a hot-hybird at least, creates another opportunity: A virtualized power generation company could be created using this technology to diversify the income base.  A company of this type could agrigate a bunch of roof-tops in the following way...

Create a PPA with many building owners that sells them Shade, Heat and Air Conditioning Services... creating a mulit-source income stream (in effect, negative rent for the rooftop space/aka solar aperture.) The second income stream comes from selling the electrical production from the whole fleet of arrays. A fleet installed all over an incumbant power distribution utility's service area. The PPA company negotiates this product as a renewable insertion to the power supply (helping to meet renewable goals) and ties to it some sort of dispatchable power source (like a gas plant) to make it perform more like a base supply than a fluctuating renewable supply (and demand a higher, albeit wholesale, price.) As the market evolves, having the watts generated at or near the demand locations may allow for better deals on energy grid transport costs (short grid hops) or conversion to meter-bypassing hookups (to get retail prices.) 

What would be a meter-bypassing load? A shop with lots of air power tools could have two compressors (one DC and one AC even) and use the grid AC driven one as a backup. The renewable watts that drive the compressor would never have to touch the grid. Just one private transaction.

Additional streams of income can also come from:
  • credit for demand reduction from the HVAC services 
  • carbon credits etc 
  • and who knows what else different markets might provide
  • roofing service?
Yes, this is more economic complexity, but it is added to mitigate at least some of the hazards of a singular income/customer-base in the very competitive energy sector. Much nicer for a company to be on both the wholesale side as well as the retail side of the energy business. It also rationalizes things a bit in that almost nobody wants a power plant. What they DO want is power to do their work. So this puts the power plant onto the books of (and into the care of) those who really do want to make and sell power.  If you want to make money in power, doing it on a hobby-scale is a lousy business. At a larger scale it can work. This approach, to my surprise, makes the hot hybrid scalable to a degree I had not anticipated.

A while back, as an exercise, I thought about how a district heat system might work as a way to justify a large-field, utility-style array. Classic inventor-guy fantasy of their product paving acres and acres of land as far as the eye can see... But the relatively low temps and the infrastructure demands did not strike me as an obvious big win (a lovely fantasy but economically a bit dim.) And so I thought I'd have to leave the utility-scale installations to the flat panel PV folks. But now that I can see the role of mediators and aggrigators in the scene, maybe that is not too crazy after all! In the sunbelt, an array that runs efficiently even when the ambient temp is at its worse is worth a good deal all by itself. If it also supplied a small ice business or food processor with chilling and sanitary heat for water, how cool would that be? Plenty cool.

Do you have a thought about how a hot hybrid might be employed? Let me know!

Tuesday, May 21, 2013

Batteries are to PV what Tanks are to Thermal - Expensive Extras

My project is to develop a high temperature thermal collector that still generates respectable voltages (and thus maximized watts) for electrical service.

Sometimes I have to "game out" imagining how my new kind of collector would behave, once installed into the economic and energy ecosystem of today and tomorrow. And I find crazy (surprising) implications all the time. It makes communicating to people presently in the solar business tricky. They have a pretty darn good grip on what IS (to the detriment of seeing what could be.)

Take the title of the is post. In a thermal system the storage tanks are the batteries. Which is a fine analogy. Might not even be an analogy as battery is a word for storage and we've only recently confined it to electrical storage. Anyhow, storage is tricky. It is good if you gain (whatever it is) slowly and then use it in bursts. But there are losses in the movement to and from storage. The longer the storage the greater the losses. There is probably a law somewhere about the loss factor in storage and academics cranking out ways to reflect that loss factor into larger calculations. But first and foremost amongst the losses in storage systems is the cost of the container and collection system itself. What if you could do without? Then for the life of the system you don't have that cost (or the losses.) You get to skip buying it, financing it, disposing of it in the end, maintaining it, securing it, even thinking of it in some cases. This is the wisdom behind Just In Time ______ (fill in the blank.) It is trickier to manage in most cases but cost cutting on something you didn't really need is a big win if you can swing it.

That is an obvious thing these days right?

How does this apply to my hot hybrid? Well, if the coolant can run up to a high temperature then those BTUs can drive a chiller right away. No need to store the heat - put it to work immediately. This does two things:
1) Chops down the size of the storage requirements in the summer since the work is extracted as it becomes available.
2) Reduces the size of the thermal storage required in the winter (as the temps are higher the same energy can be stored in a smaller space.)

It gets better.

This same "higher temp is better" and "use it now" approach can be used in the winter as space heating support. High performance buildings might need to store the energy in classical tanks and "sip" the BTUs overnight but still others could load that heat into thermal mass within the building envelope and let it radiate through the night. By now you know I like dual purpose things so walls that store energy on the cheap (another value of mine) are winners in my book.

The big win on this immediate use is in the summer, however.  Many solar thermal systems have to be downsized to prevent summer stagnation and blowouts. But an immediate, high value use for those BTUs changes the game for what the solar specifier would pitch:

1) Less storage - AKA overhead.
2) More collection area with over-heat worries gone and a "more is better" model - AKA new income.

I wonder what else we don't have to buy if we re-imagine with abundance in mind. Nobody wants any of this gear - they want what it  produces: service. Are there other services heat can do beyond the HVAC world?

Also, are there better deals for a grid tied system owner than selling to the grid? This is part of the future we need to think about. If the generation during the day grows and subsidies go away it might be better to use the energy than sell it for too cheap. What if your house was smart enough to hold back electrical loads for some functions until the PV array was going full tilt? Or your system predicted the production and ran a mini-auction for the juice? (I'm starting to sound like an Enron Exec so I'll stop there) ugh.

Monday, May 20, 2013

Paul Saffo had a neat talk about forecasting.

Hey All,

Paul Saffo  SVForum about forecasting... One of the great pull quotes is "If you want an easy overnight success - find a technology that as been failing for 20 years." I wonder where we are on the 20 year curve for PV? and more importantly on distributed power and smart(ish) grid stuff.

If I am in the concentrator business, which I guess I am kind of am, the 20 years for this is pretty ripe (cf Amonix's history.)

OH i can save you a click:

Saturday, May 18, 2013

Another PV-T Hybrid pops up (and in the US of all places)

Solar Zentrum

They placed an article in "North American Clean Energy Magazine"

It looks like the print version is ahead of the online version (and that the author works at Solar Zentrum.) I had hoped to link to the story if they had posted it but maybe we have to wait.

I wanted to point out that they snuck in a very odd special case for their impressive info graphic, one that kind of points out the trouble with conventional hybrids. To generate their flattering "20% more" they used very cool rain water to knock down the heat. This is not uniformly, or even commonly available as a resource "in any climate zone." And it makes a huge difference. Getting a panel down to 77 degrees from 145 (F) is not a trivial thing. 1 gallon of water every two hours or so and remember it needs to exit at 77 (or below.) Rainwater turned into less cool rainwater, now what? water the greenhouse? Hardly a common scenario.

Kinda casts an unflattering light on on the magazine too. That info graphic is (along with being done with too small print and low contrast) troubling. Like why is the irradiance shown on such a small vertical scale? and why did it run for such a short time? Did they, like me, run out of rainwater?