Tag Archives: solar

relating to solar energy

Inexhaustible Flows?

Posted on by

Photo from Monash Universiry

I recently came across a statement to the effect that once we transition away from fossil fuels to renewable energy like solar, wind, and hydro, we would essentially be home free for the long run—tapping into inexhaustible flows. It is a very pleasant notion, to be sure, and one that I believe is relatively common among enthusiasts for renewable energy.

Naturally, I am concerned by the question of: what magnificent things would we do with everlasting copious energy? As an excellent guide, we can ask what amazing things have we done with the recent bolus of energy from fossil fuels? Well, in the course of pursuing material affluence, we have eliminated 85% of primeval forest, made new deserts, created numerous oceanic dead zones, drained swamps, lost whole ecosystems, almost squashed the remaining wild land mammals, and initiated a sixth mass extinction with extinction rates perhaps thousands of times higher than their background levels—all without the help of CO2 and climate change (which indeed adds to the list of ills). These trends are still accelerating. Yay for humans, who can now (temporarily) live in greater comfort and numbers than at any time in history!

But the direction I want to take in this post is on the narrower (and ultimately less important) technical side. All the renewable energy technologies rely on non-renewable materials. Therefore, inexhaustible flows are beside the point. It’s like saying that fossil fuel energy is not practically limited by available oxygen for combustion, so we can enjoy fossil fuels indefinitely. Or that D–T fusion has billions of years of deuterium available, when there’s no naturally-occurring tritium (thus reliant on limited lithium supply). In a multi-part system, the limiting factor is, well, the limiting factor. Sure, into the far future the sun will shine, the wind will blow, and rain will fall. But capturing those flows to make electricity will require physical stuff: all the more material for such diffuse flows. If that stuff is not itself of renewable origin, then oops. The best guarantee of renewability is being part of natural regeneration (i.e., of biological origin). If solar panels, wires, inverters, and batteries were made of wood and the like: alright, then.

Recognizing that biological organisms—plants and the animals that directly or indirectly draw energy from them—have already figured out how to tap into (essentially) inexhaustible flows—solar, primarily—I became interested in comparing the performance of the human animal to that of a solar panel or wind turbine, in terms of mineral requirements. After all, the biosphere gets by without mining the depths. So let’s dig into the material requirements of life.

Continue reading →

Views: 7011

Plans to Put PV to Pasture?

Posted on by

PV out to pasture?A colleague pointed me toward an article in the LA Times last week, which lays out a plan to remove financial incentives legally bestowed on solar photovoltaics (PV) to the detriment of utility power companies. The plan is spearheaded by the Koch brothers and their political action group, Americans for Prosperity.

In summary, they target two laws that give a big boost to solar: net metering, and renewable mandates. Both impart crucial advantages to solar installations that can change the economics by a large factor.

Continue reading →

Views: 1179

Blow-by-Blow PV System Efficiency: A Case Study for Storage

Posted on by

A short while back, I described my standalone (off-grid) urban photovoltaic (PV) energy system. At the time, I promised a follow-up piece evaluating the realized efficiency of the system. What was I thinking? The resulting analysis is a lot of work! But it was good for me, and hopefully it will be useful to some of you lot as well. I’ll go ahead and give you the final answer: 62%. So you could peel away now and risk using this number out of context, or you could come with me into the rabbit hole…

Continue reading →

Views: 1694

Solar Data Treasure Trove

Posted on by

I have not kept it secret that I’m a fan of solar power. Leaving storage hangups aside for now, the fact that the scale of available power is comfortably gigantic, that perfectly efficient technology exists, that it’s hard-over on the reality axis (vs. fantasy: it’s producing electricity on my roof right now), and that it works well almost everywhere—what’s not to like? Did you trip over that last part? Many do. In this post, we’ll look at just how much solar yield one may expect as a function of location within the U.S.

The ancient Mayans laboriously accumulated a substantial set of observational data on solar illumination across America well ahead of the present need. Okay, it wasn’t actually the ancient Mayans. It was the National Renewable Energy Lab (NREL), who embarked on a 30-year campaign beginning in 1961, covering 239 locations across the U.S. and associated territories. Imagine this. How many people were even cognizant of solar power in 1961? Yet the forward-thinking scientists at NREL appreciated the value of a solid baseline dataset way back then. This level of foresight seems akin to the Mayans constructing a calendar going all the way to 2012. That’s all I’m saying. It’s a gift from the past.

I have often consulted and enjoyed the product of this work over the years—called the NREL Redbook, or more formally, the Solar Radiation Data Manual for Flat Plate and Concentrating Collectors. But with a snazzy blog post as motivation, I have taken it up a notch and produced a variety of graphical representations of the dataset to explore what it can tell us. Let’s begin the guided tour.

Continue reading →

Views: 2583

My Modest Solar Setup

Posted on by

I have made repeated references in past posts to the modest off-grid photovoltaic (PV) system I built to cover a large share of our—again modest—electricity usage.  By popular demand, I’ll take you on a tour of the system: it’s history, its composition, and adaptation to my house.

In 2007, I acquired a single, second-hand solar panel—intent on doing something useful with it. Confronted with a variety of options, and eager to explore multiple paths, I purchased a second panel and proceeded to set up a dual system: two stand-alone off-grid PV systems mounted side by side. It was really cool. I was able to power my television console and living room lights off of the two systems, while experimenting with different components and learning to live (part of) my life on natural power. I wrote a comprehensive article about how to size and design such a system, which may be worth reading first. Since that initial success, I have incrementally expanded my system so that I now get more than half of my electrical power from eight panels sitting in the sun. This is their story.

I have enough to say about my solar setup (and PV systems in general) that I must break this topic into multiple posts. In this, the first, I will describe the components, functions, and evolution of the system. In a future post, I will present system performance data and an assessment of efficiency of the various components. Perhaps even later I can explore the impacts of panel orientation, tracking, horizon obstructions, and geographic location.

Continue reading →

Views: 3166

The Phantoms I’ve Killed

Posted on by

Two weeks ago, I described my factor-of-five reduction of natural gas usage at home, mostly stemming from a decision not to heat our San Diego house. We have made similar cuts to our use of utility electricity, using one-tenth the amount that comparable San Diego homes typically consume. In this post, I will reveal how we pulled this off…with plots. Some changes are simple; some require behavioral changes; some might be viewed as outright trickery.

Continue reading →

Views: 9899

Space-Based Solar Power

Posted on by

A solar panel reaps only a small portion of its potential due to night, weather, and seasons, simultaneously introducing intermittency so that massive storage is required to make solar power work at a large scale. A perennial proposition for surmounting these impediments is that we launch solar collectors into space—where the sun always shines, clouds are impossible, and the tilt of the Earth’s axis is irrelevant. On Earth, a flat panel inclined toward the south averages about 5 full-sun-equivalent hours per day for typical locations, which is about a factor of five worse than what could be expected in space. More importantly, the constancy of solar flux in space reduces the need for storage—especially over seasonal timescales. I love solar power. And I am connected to the space enterprise. Surely putting the two together really floats my boat, no? No.

I’ll take a break from writing about behavioral adaptations and get back to Do the Math roots with an evaluation of solar power from space and the giant hurdles such a scheme would face. On balance, I don’t expect to see this technology escape the realm of fantasy and find a place in our world. The expense and difficulty are incommensurate with the gains.

Continue reading →

Views: 9474

The Alternative Energy Matrix

Posted on by

[An updated treatment of this material appears in Chapter 17 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

Breathe, Neo. I’ve been running a marathon lately to cover all the major players that may provide viable alternatives to fossil fuels this century. Even though I have not exhausted all possibilities, or covered each topic exhaustively, I am exhausted. So in this post, I will provide a recap of all the schemes discussed thus far, in matrix form. Then Do the Math will shift its focus to more of the “what next” part of the message.

The primary “mission” of late has been to sort possible future energy resources into boxes labeled “abundant,” “potent” (able to support something like a quarter of our present demand if fully developed), and “niche,” which is a polite way to say puny. In the process, I have clarified in my mind that a significant contributor to my concerns about future energy scarcity is not the simple quantitative scorecard. After all, if it were that easy, we’d be rocking along with a collective consensus about our path forward. Some comments have  asked: “If we forget about trying to meet our total demand with one source, could we meet our demand if we add them all up?” Absolutely. In fact, the abundant sources technically need no other complement. So on the abundance score alone, we’re done at solar, for instance. But it’s not that simple, unfortunately. While the quantitative abundance of a resource is key, many other practical concerns enter the fray when trying to anticipate long-term prospects and challenges—usually making up the bulk of the words in prior posts.

For example, it does not much matter that Titan has enormous pools of methane unprotected by any army (that we know of!). The gigantic scale of this resource makes our Earthly fossil fuel allocation a mere speck. But so what? Practical considerations mean we will never grab this energy store. Likewise, some of our terrestrial sources of energy are super-abundant, but just a pain in the butt to access or put to practical use.

In this post, we will summarize the ins and outs of the various prospects. Interpretation will come later. For now, let’s just wrap it all up together.

Continue reading →

Views: 75967

Basking in the Sun

Posted on by

Who hasn’t enjoyed heat from the sun? Doing so represents a direct energetic transfer—via radiation—from the sun’s hot surface to your skin. One square meter can catch about 1000 W, which is comparable to the output of a portable space heater. A dark surface can capture the energy at nearly 100% efficiency, beating (heating?) the pants off of solar photovoltaic (PV) capture efficiency, for instance. We have already seen that solar PV qualifies as a super-abundant resource, requiring panels covering only about 0.5% of land to meet our entire energy demand (still huge, granted). So direct thermal energy from the sun, gathered more efficiently than what PV can do, is automatically in the abundant club. Let’s evaluate some of the practical issues surrounding solar thermal: either for home heating or for the production of electricity.

Continue reading →

Views: 23036

Wind Fights Solar; Triangle Wins

Posted on by

[An updated treatment of some of this material appears in Chapters 12 and 13 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

For me, the most delightful turn of events in the ultimate nerd-song “Particle Man” by They Might Be Giants, is that after introducing (in order of complexity) particle-man, triangle-man, universe-man, and person-man—and learning that triangle-man naturally beats particle-man in a match up—we pit person-man against triangle-man to discover that triangle wins—again. In this post, we’ll pit solar against wind and see who wins.

I will take my usual approach and estimate what I can—as opposed to researching the results of detailed studies. It’s part of the process of personal mastery of the big-picture issues, while also providing a sanity-check. In exploring useful reactions to the looming peak oil crisis (or pick your favorite rationale for weaning ourselves from fossil fuels), an appropriate strategy is to assess ballpark capacities of the various options. Some will prove to be orders-of-magnitude more prodigious than we need, others will be marginal, and many will show themselves to be woefully inadequate to match the required scale. So the goal is to perform this crude sorting process into abundant, useful, and waste of time.

Continue reading →

Views: 4180