Here’s a good article on a recently completed solar thermal tower (aka concentrated solar power or CSP) in the desert between Las Vegas and Reno, NV.

The thing to like about solar thermal, as we’ve often discussed here, is that it affords us a fairly low-cost way of storing energy and delivering it when the sun isn’t shining. This is due to the fact that in today’s world, we can store heat energy (in vats of molten salt) far less expensively than we can store electrical energy (in batteries). Thus solar thermal installations can be treated as baseload, delivering power on a consistent 24X7 basis.

That’s the good news.

The bad news is that they’re still expensive – in the neighborhood of $5 – $7 per Watt.

Yet those of us who favor solar thermal believe that costs will fall dramatically as these technologies mature. Solar thermal is really in its infancy, lagging several decades behind photovoltaics (PV) and wind in terms of its development. The plummeting cost of PV (to about $1 per Watt) wouldn’t have happened in a million years without the support of an enormous number of public and private agencies. I’m among those who hopes that solar thermal will be given the same chance.

This subject came up in detail in the interview I conducted with Dr. David Mills for the chapter on the subject in my book. It was clear to me at the time that molten salt has a long way to go if it is to scale to the extent that it will move the needle in terms of facilitating the penetration of renewables. However, this is a true breakthrough.

I only wish Sicily were in my travel plans; I’d love an excuse for a visit at this momentous occasion.

1) Moving large amounts of energy around a large land mass (like the lower 48 states) in a way that would compete with electrical. (Proponents point out that a great deal of this piping infrastructure is already in place.)

2) Storing large amounts of energy locally in a way that would compete with molten salt, batteries, and pumped storage hydro-electric reservoirs, compressed air energy storage (CAES), and

3) Storing small amounts of energy in portable devices, potentially solving the battery cost, energy-density, and charging infrastructure issues in electric transportation.

Yet it seemed that, for all this technical and economic merit, precious few people had any familiarity with the subject at all. But, in response why “thinking out loud” here, I got a phone call this morning from a bright young man in Indiana, Daniel Miller, who led me to the a great deal of information on the website of The Leighty Foundation. And here’s a real treasure trove from Iowa State University, which hosts an annual meeting on the subject.  Interested readers will be kept out of trouble for quite a while coming up to speed on this fascinating idea.

Craig, you seem to think that there should be a single best solution for clean energy. I would agree with you if you qualified your assertion to state that there is a single best solution for a given site. For example, a mountain top with high steady winds may be crying out for a a wind farm, but a wooded valley location with almost no wind would probably benefit from a low head hydro plant…..

I acknowlege that I am in a slim minority of those who do not favor a wide variety of renewables. I’m optimistic that we as a civilization will find our way out of the mess we’ve created for ourselves. But I find it hard to believe that this solution will come in the form of 8 – 10 different renewable technologies.

You raise a good point, of course, in that different sites lend themselves to different renewable energy technologies: the plains support wind, the mountains geothermal, the deserts solar, etc. And if you’re truly a “don’t put all your eggs in one basket” type of guy, maybe you really DO want all of them. But I ask: Why?

Let’s keep our eye on the ball.  All we need to do is harvest and distribute 1/6000th of the sun’s energy. I grant that this can be done through a variety of means, but if we can choose one or two that meet all our criteria (low-cost, scaleable, safe, clean, etc.) do we really need to develop and support them all?

Of course, all this does presuppose a cost-effective way of distributing power around the continent.  As I’ve written elsewhere, I believe that we have to upgrade our grid — even in the absence of deeper penetration of renewable energy.  As an integral part of this upgrade, I favor high voltage DC power transmission (VHDC), minimizing line losses over long distances.

I’m not a futurist by trade. But I’ll go on record right now and make a bold prediction. Long before the midpoint of this century, the technology surrounding solar thermal will have matured to such a point that it will represent a clean and bankable path to the end of the world energy conundrum.  At a certain point soon thereafter, 90+% of the Earth’s population will enjoy low-cost and very clean energy brought about by a combination of solar thermal (concentrated solar power), molten salt energy storage and VHDC power transmission.

“That was an interesting article. I didn’t know a combined cycle could be made to be that efficient… What about simply heating water with molten salt in a heat exchanger, and running that through a turbine, then recovering left over heat from the condensate? I know that all conventional plants can only convert 30 to 33% of the thermal energy to electric. In fact each of my units produce about 3600MW Thermal but we only generate about 1200MW. Of course these were built between 1971 and 1986, but even the new nukes are only claiming a maximum of 36% efficiency.”

This molten salt technology is actually far simpler that what you’re describing, and the efficiency of the storage itself is huge – up to 99%, according to this report by Sandia Laboratories. Obviously, the process of concentrating the sunlight, generating steam, turning the turbine, etc. is far less efficient, but the issue doesn’t lie with the storage medium/system.

Overall, solar thermal has about 17% total conversion efficiency in terms of incident solar energy to electricity. Of course, the industry is working hard to improve this, but still, a solar thermal farm that would occupy 3% of the Moroccan desert would generate more than enough power for the entire continent of Europe. This really IS the answer, it seems to me.

“Craig, do you know if a Stirling engine would be more efficient than making steam for a turbine?”

To which I reply:

I don’t know know much about Stirling engines; I need to learn about these.  But it sounds like you may be comparing apples and oranges.

I’m sure you’re aware that devices that simply store energy (e.g., molten salt, batteries, capacitors) and devices that convert energy form one form to another (e.g., motors, turbines) are two different things. And as far as the latter is are concerned, electric motors, even using the technology of the very first ones 120+ years ago, are quite efficient; in fact, the AC induction motors that are used in today’s electric vehicles are close to 90% efficient. What’s not to like about that?

Thus, it seems to me that the real question is how to generate, store, and distribute the electricity.  Coincidentally, I was writing my book’s chapter on basic physics last night, in which I noted the following about the conservation of energy:

Once one really wraps his wits these basic ideas, one is in a terrific position to understand most discussions of energy. Here are two examples to make this clear:

Hydrokinetics: Every day, the energy from the sun evaporates water into steam that is later condensed into clouds, the precipitation from which forms rivers, some of which are in high altitudes. The kinetic energy of the water flowing back downhill can be converted into electrical energy. But the conservation of energy tells us that the most electricity one can possibly hope to generate from this water is the potential energy it had before it started to flow (which equals the weight of the water times the height of the elevation from which it fell). This is for this reason that hydrokinetics cannot provide a significant amount to the overall energy picture, regardless of how many dams, how efficient the turbines, etc.

Solar: On the other hand, the earth receives 6000 times more energy from the sun every day than mankind currently uses for all its purposes: transportation, heating, air conditioning, etc. Put another way, if we had the capability of capturing and distributing 1/6000^th of the sun’s energy, we would not need to burn another lump of coal, spilt another atom, or pump another ounce of gasoline. This fact alone forms the rationale for our interest in solar energy.

I encourage readers to review all assertions about different forms of power generation — renewable or otherwise – to this discussion on the conservation of energy. When someone says, “This car runs on water,” ask yourself: water? Isn’t water already “burned” hydrogen and oxygen, i.e., the result after these two elements release energy by joining together? That’s like saying, “Let’s build a fire using those ashes for fuel.” Sorry, they’ve already been burned, meaning that the chemical energy that was once stored in the carbon bonds of the wood has already been converted into the heat, light, and sound of a fire. The ashes are the low-energy result of that process.

I got an email from a friend announcing a miracle car that runs on air. As it turns out, it actually runs on compressed air. The energy required to compress the air is stored in a tank and converted into kinetic energy. Trust me, there is not one bit of energy delivered to that car’s wheels that didn’t going into compressing the air in the first place.

At the end of the day, I think the energy direction of the planet is very clear:

Generation: solar, especially concentrated solar power (CSP).

Storage: molten salt (Note that storage is somewhat less important for solar than say, wind, as solar tends to be generated in congruity with times of peak need). Note also that solar it’s already heat energy; there is no need to convert it to something else.

Transmission: High voltage direct current (HVDC). This requires a build-out of our ancient power grid, but we need to do that anyway.

Thanks again for writing, Peter.  I hope this was useful.

You assume that “molten” salt is universally available over the entire power grid? Get real!

Apparently, I’m not describing this as clearly as I thought I was. As shown in this diagram on molten salt energy storage these devices wouldn’t need to be universally available over the entire power grid; units are located within solar thermal farms to store energy for distribution back onto the grid during the hours that the sun is not high in the sky. In other words, it’s part of the power generation plant, like a subsystem within a coal or nuclear plant.

Having made that clarification, if you’re referring to the expense of the migration to renewables in general — or to molten salt energy storage in particular, you have a point; I can’t say that this whole process will be cheap. But I do believe two things:

• This is the least expensive (and most secure, reliable, and scaleable) alternative, and

• We literally do not have a choice.

I don’t want to come off as an alarmist, but I do not believe that our civilization with survive the run-up of oil scarcity that it inevitably faces — not to mention the long-term environmental damage associated with consuming 100 million barrels of oil a day — until we run out.

The current technology of Wind and Solar tends to provide power when and where it is needed the least. The transmission of power from wind and solar farms to population centers is extremely expensive, and superconducting transmission lines are still a future dream, so the answer lies elsewhere…

Thanks, Peter. I appreciate your comments, but I respectfully disagree. I favor the build-out of the grid with high voltage DC to conduct power from solar thermal farms with molten salt energy storage in the southwestern desert to the east and west coasts. While you are correct that this will not be inexpensive, in my estimation, it’s a program we should embrace immediately. When the total cost of burning fossil fuels is considered (including national security, healthcare, long-term environmental damage, etc.) it’s the deal of the century. And it carries with it the considerable benefit of putting people to work on a project that will solve one of mankind’s thorniest problems now and forever.

Solar thermal is safe, scaleable, reliable, affordable, environmentally sensible, and easily protected from attack, as it can be distributed across the vastness of the desert (criteria all of which need to be met before we can take any renewables technology seriously).

So what about wind, geothermal, and hydrokinetics? I think they all hold considerable promise, though I can’t see how they can compete effectively with solar thermal when all the considerations named above are fully thought through.

Normally, I would do my best to add something positive to the discussion. Quite frankly, I feel that the transportation industry in the USA is already positioning itself to inflate consumer expectation and subsequently slam them into the embankment as hard as is possible.

Thanks, Arlene. Sometimes I read things that cause me to agree with you 100%. I know I’ve been hugely pessimistic – even cynical – about the direction that renewable energy and electric transportation is going. But strangely, I have a good feeling about this overall. And it’s not because of positive intention and honesty of our corporate and government leaders, but rather the strength of the business case. The cost of all this is crashing like a stone, and, fortunately for mankind, I don’t see that anyone can do anything about that.

I’m looking at dozens of business plans, some of which feature truly transformative technology. Yes, they need funding – and in some cases, huge amounts of it. But the numbers in some of these cases are so compelling that they will ultimately receive the capital they are requesting, enabling the generation of clean power at a fraction of the cost of energy that comes from dirty and/or dangerous sources. I know it’s too early to declare victory, but I’m feeling very good about the transportation and energy industries.

I’m under NDA on a lot of these, but look at technologies that are already on the streets, like solar thermal with molten salt energy storage. The lies that Big Energy are spreading include the notion that this may be nice, but solar is inappropriate for baseload power. This is simply not the case. My point is this: That lie has a finite shelf-life. It’s just a matter of time until the truth gets spread so broadly that the lies will evaporate like the morning fog here in valleys of Central California.

To present a few of the basics on electric power:

• The availability of renewables fluctuates during each 24-hour cycle, and thus it’s normally assumed that they are inappropriate for providing baseload power.

• The cost of building the plant is independent of the cost of the fuel to operate the plant.

• Where solar and wind can be switched on and off in seconds, fossil fuel and nuclear plants cannot.

• The cost of pollution needs to be included in the calculations.

While I don’t dispute any of this, there are important aspects of the discussion that I feel need to be brought forward:

1. The reason that we believe renewables cannnot provide baseload power is not intrinsic to the generation method per se, but to our perceived inablility to store energy inexpensively. However, molten salt technology, which stores energy as heat and coverts it to electricity on demand, is a proven method of removing this objection. I urge readers to note the work of Ausra, the US leading solar thermal company, based in Northern California. Yesterday, I had the pleasure of interviewing Dr. David Mills, the company’s founder, in preparation for my book on renewables.

1. The actual cost of building these plants is almost never anywhere near the projected budget.  Readers may want to Google “nuclear plant cost overrun,” and read a few of the 54,700 articles they’ll find on the subject. Here’s one that refers to a certain nuclear project as “satanic,” based on the the actual amount of the overrun ($6.66 billion). The Florida utility, FPL Group, now estimates the cost of building a new nuclear power plant at over $9 billion, nearly double their previous estimate.

1. The nuclear industry and its lobbies have carefully confused us about the costs and safety of shipping and storing nuclear waste, which remains dangerous for as long as one million years.

1. As noted, the author of the article above mentions the cost of the pollution, but does not suggest any real way of quantifying it. While I’ll grant that this is not a straightforward issue, it’s really crux of the matter.

As I’ve written many times in the past, if the price we pay per kilowatt-hour of electricity (or for a gallon of gasoline) included the cost of addressing the lung disease and long-term environmental damage to our skies and oceans, the math would be changed completely. Society’s desire to continue to mine, process, ship and burn coal and oil would be gone in the blink of an eye.