Tipping point coming in photovoltaics?

A recent article in Engadget provides an exceptionally balanced and informative description of emerging technologies in the area of solar photovoltaic energy generation.  The amateur futurist in me is very tempted to suggest that we are seeing the first concrete evidence of a likely change of direction for renewables.

In the last few years, we have pinned a lot of hope on the evolution of PV to make possible building integration and distributed power generation.  Each is very attractive, the latter because it helps make the system potentially safe from single points of failure.

But there has always been a tension between that approach, and centralised systems feeding ever larger grids.  Wind power has gravitated towards 'bigger is better' because it is - bigger turbines are more efficient, and big wind farms are best located where the wind resource is the best.  With photovoltaics, big concentrator technologies have not had the same obvious compelling advantages.  But now it is emerging that they do have.

A team of IBM researchers in Switzerland is working on an implementation of a High Concentration Photovoltaic Thermal system, that will start with significantly greater electrical conversion efficiencies than BIPV technology.  But with well integrated thermal technology, it actually should be able to collect 80% of incoming sunlight and convert it to useful energy, while employing robust and low tech materials for its construction.

The actual solid state chips that do the electrical conversion remain high tech, as do the fundamentals of the extraordinarily effective cooling system, which is required to accommodate the heat generated by a concentration of 2000 to 5000 times the intensity of the incoming solar radiation. But the project team have thought through the rest of the system to replace expensive steel and glass with low cost concrete for the support structures, and simple pressurized metalized foils for the optics.

Emerging trends to district heating and even district cooling prompt the other synergies in the proposed technology.  The very high temperature fluid cooling is coupled with desalination or district heating potential, and with district cooling using absorption chillers.  Given thermal storage is already a well studied market, the promise of a centralised, but scalable solar/thermal generation is becoming very attractive.

IBM expects that the system would be approximately one third the cost third of current comparable technologies, but hasn't promised when the technology will emerge from its research phase to full prototyping.

Read more:

IBM solar collector will concentrate the power of 2,000 suns, keep its cool

The Greenest Building in the World

I sometimes like to enter a hyperbole into the Google search terms, just to see what it comes up with.  The headline of this blog is one of my favourites.  I do it partly because I know you can't expect Google to actually make a technical judgement; that I am only really getting whatever rises like froth to the top of Google's murky PageRank algorithm, sometimes no more than a measure of chutzpah.

And so it seemed this time.  The top-ranked page turned out to be an article by Neil Takemoto, writing for the SustainableCitiesCollective web page, about the Bullitt Centre in Seattle.  The Bullitt Foundation funds a variety of conservation projects, and committed itself to the rather ambitious Living Building Challenge for its newly built headquarters.  The first small crack in the credibility of 'the greenest' claim comes with the realisation that they really only mean it to be that in the company of conventional office buildings.

I should immediately declare that I feel terribly guilty. As one does for being at all negative about anybody's sincere efforts to truly test the envelope of business as usual.  The more especially because as I delved deeper I found that the Bullitt Foundation really has made an effort to give access to rich and useful information about the various initiatives and innovative technologies that the building employs.  More of that later.  Let me get the little negatives off my chest quickly.

In this case, the problem revolves around the contested terms that describe energy self-sufficiency.  Thus, the Bullitt Centre is described as Net Zero Energy, while the very first item in the bulleted list of its attributes states that it is "expected to use less than one fourth the energy of a typical building of its size".  Whether or not this apparent semantic contradiction confuses, relies on the reader having come across the variety of terms with their different system boundaries, which are used to describe the energy neutrality of buildings.  In this case, it is entirely possible that on the one hand the author is describing the energy demand, or energy load of the building, and that both the designers and the users have done well to very significantly reduce that demand.  If so, it is plausible that the big photovoltaic array, which tops the building like a peaked baseball cap, could just about generate the electricity portion of that demand.  Other initiatives, like the geothermal heating, would help with the rest.  Hence Net Zero Energy.  But even if that is actually the case, we would be well served by a little additional information: that most likely the building is grid connected and uses the rest of the city as its storage battery, or 'energy flywheel'.  My criticism in this regard is really of Takemoto's article.

As I often complain, short online articles give you a sort of hamburger patty version of a hearty T-bone steak and veggies.  In most such news items, even on the most committed web sites, fundamental claims for the performance of a building cannot be taken at face value. 

But the good news is that you can take the trouble to follow the link to the dedicated web page of the building.  If you more or less ignore the predictable vision, the tributes to the philanthropic partners, and the on-line leasing pages, you will find a blog.  This turns out to have an exhaustive photo record of the construction, with key technologies explained through a collection of informative articles.  There is a good selection, from geothermal drilling to the use of timber framing (where conventional office buildings would have steel or concrete).  While the information is still a bit ad hoc rather than systematic, it would be churlish to complain too much.

Finally, to give credit where credit is due, Takemoto makes no claim that the building is sustainable, and the web site is reasonably circumspect in its use of the word.  In this way, they are much more responsible than the many others who have so corrupted the term, as to make it almost useless.

It's worth linking to the original article, just for the panel that sums up the "20 imperatives of the Living Building Challenge.  Read it here.

For a quick primer on Zero energy buildings, you could do worse than Wikipedia here.

Yes, Virginia, photovoltaics do work

One of the headline snippets in today's in inhabitat news blog is that world installed solar photovoltaic generating capacity has surpassed 100 gigawatts.  Good news enough in its own right. Read about it here.

But for me, as an architect committed to buildings that gobble up less of that generated energy – or better still give back as much as they take – these big news always concentrate too much on the big items like fields of solar collectors working as centralised generators.

I personally think the real future is in building integrated photovoltaics, and the distributed generation which they make possible.  Quite frankly, I think that a building with good integrated photovoltaics is just much more sexy than a great big field of concentrating collectors.

Nevertheless, the central issue is how do all those dispersed BIPV integrate with the large-scale energy grid.  So I thought it was a good excuse to point interested readers at a surprisingly readable source of information, on how much progress has been made in the world's most committed and advanced market.

The European Photovoltaics Industry Association has put out a short version of 'Connecting the Sun'.  It is, as I say, a surprisingly readable report on the stuff that a normal architect, or possibly even a normal building engineer may dismiss as all too hard, all too big, and altogether too much somebody else's business.  This report is not specifically about buildings.  But if you want to bolster your faith in making the effort to integrate photovoltaics into a building that you design, it's well worth the added distraction to at least skim the eighteen pages or so.

Why the odd headline to this post?  Well, I live in hope that all those climate change skeptics try reading this little report, too.  At least then they would confine themselves to just arguing about the evidence of global warming, but would stop knocking the development of sustainable energy sources.  They are good for the planet, and good for us, regardless.

Download the short version of the report here.