Modelling Solar Overcapacity

Solar generated electricity, along with wind power is cheaper than fossil fuels.  These renewable energy sources are being deployed rapidly at many scales.  We’ve been working toward these developments for the last seventy years.

Solar power has one very challenging feature:  it is, by definition, intermittent.  We can generate all the power we want—while the sun is shining.  This creates a difficult problem for existing 24/7 grid systems: how to economically integrate vast amounts of intermittent generation into a reliable, always there, grid.

Obviously, batteries and other storage technology can help smooth out the supply, and there is plenty of work on these technologies.  Even so, grid operators will still want to work with a mix of sources, and getting the mix right is a complicated optimization problem.  Different technologies have their own characteristics, and economics.

This summer researchers at Clean Power Research report a study of an alternative approach, relying on “Overbuilding & curtailment” [1].

The basic idea is that the economics of cheap and abundant solar and wind energy turn conventional wisdom on its head.  Grid operators are generally constrained by the immense costs of building and running generating capacity.  Therefore, it is economically necessary to build only “enough”, and to fully use generators.  Idle plants are a financial disaster.

The new study shows that, in the case of intermittent solar power, it can be cheaper to “optimally” over build and curtail.  The basic idea is that it is cheap enough to build enough PV generation so that most of the time you have enough to meet the target load.  This means that a lot of the time, you have “too much”, more than needed–so you just don’t use the excess.  This concept works even better with a combination of solar and wind.

Basically, this approach deliberately “wastes” both capital plant and output.  So how can this be good?

The main point is that when renewable energy is cheaper than alternatives, it is cost effective to “waste” the renewable resources in return for minimizing the use of costly alternatives.  (Note that this also upends the “renewable augments conventional fuels” paradigm, for a “conventional sources fill gaps in renewable generation” apporach.)

The thrust of the paper is modelling to demonstrate that an optimal combination of overbuilding and curtailment can be cost effective for grid operators.  Their study indicates that a solar-only system is “feasible”, but including wind and small amounts of natural gas could be even cheaper.  (The details will depend a lot on local conditions.)

I like this approach, if only because it leans on the idea that “solar power is almost free”.  Nothing is free, but sunlight is as close to infinitely free as we are likely to get.

In this approach, the economics of the renewable generating plant (as opposed to the whole grid) are a bit more complex, because the overproduction isn’t sold to the general market.  But, as the researchers point out, this “unused” electricity is still valuable, and can add additional value to the overall system.  They suggest that “curtailed” production might go to something like desalinization or generating hydrogen for fuel.

  1. Marc Perez, Richard Perez, Karl R. Rábago, and Morgan Putnam, Overbuilding & curtailment: The cost-effective enablers of firm PV generation. Solar Energy, 180:412-422, 2019/03/01/ 2019.


Book Review: “Gather The Fortunes” by Bryan Camp

Gather The Fortunes by Bryan Camp

Camp’s latest is a sequel to The City of Lost Fortunes, picking up what happens to Renaissance Raines after the dramatic end of the earlier story.

She has been resurrected as a psychopomp, tasked with ushering the dead into the underworld.  She seems only partly aware, and there is a whole lot that she doesn’t understand, though she doesn’t seem to question things even after five years.

But weird stuff starts happening, including a young man who somehow avoids his own death (is that even possible?, she wonders with good reason).  This can’t be good, and the arrival of the Hallows—the three days around Halloween and All Saints—means that the barriers between living and dead will be open.

Thing get even more complicated as we learn that resurrected Renai is very special case indeed. Just who is she, and what is her role in whatever bad stuff is happening?

Renai regains herself, and must  try to fix things, if she can.  Her path takes her around New Orleans and down into the underworld.  There are so many spirits, gods, and magicians that it’s hard to keep track, which is not made easier by the skullduggery and deception of many of these entities.

In the lands of the dead, there are horrible, violent, dark events and entities, but there are good people and there is hope.

Camp is a fine writer, and he is writing of the city he clearly loves.  I have never been to NO, but I’m sure that the places are recognizable to natives.

I look forward to more from Camp.  (I hope there is more music and food in  future stories. : – ) )

  1. Bryan Camp, Gather The Fortunes, Boston, Houghton Mifflin Harcourt, 2019.


Sunday Book Reviews

Lighting Up Navaho Homes

Eighty five years ago, the US made a great push to connect rural areas to the electric grid.  That massive effort generally stopped at the boundaries of Indian reservations, and, to date, many residents of tribal land still have no electric power, or only local generators.

Setting aside possible historical reasons for this neglect, things are slowly changing, with progress from a number of directions. As Maria Gallucci reports, “Parts of the Navajo Nation Are Still Off the Grid—but That’s Changing [1] .

Gallucci reports on a “pilot” project that connects 600 rural homes on the Navaho lands to the grid.  This still leave tens of thousands to serve.

The problem, as always, is that it costs a ton of money to run wires out to remote locations, and it’s difficult to justify the expense for just one or two homes.  The particular project mentioned is supported by volunteers and donations—not necessarily scalable. (Light Up Navaho!)

Of course, tribal lands in the Southwest US have a valuable asset:  lots of sunlight.  In recent years, this has fostered considerable development of solar power on tribal landsAs in many places, tribes are following an “all of the above” strategy for solar—at many scales, all at once [2].

In the past, projects have installed hybrid solar/wind off-grid generation for individual homes.   Other tribes are booting up community solar, and even large arrays.  These projects not only improve the standard of living, they also provide economic development and job opportunities for local people.

The article quotes Sandra Begay about the advantages of continuous grid power, when it can be available.  Interestingly, she notes that an off grid system that provides a few hours of electricity at night is OK for “old people” like me, but younger people need and expect more power around the clock.  (TV? Computer games?  Streaming?)

Last summer I had a very pleasant lunch with Sandra Begay and some of her bright young interns. The conversation made clear that solar power is very attractive to trible communities for many reasons.  Sustainable, clean energy appeals to indigenous traditions, and there is every reason why the innovation will work so much better when led by people from the community.

  1. Maria Gallucci, Parts of the Navajo Nation Are Still Off the Grid—but That’s Changing, in IEEE Spectrum News – Energy. 2019.
  2. Patty Garcia-Likens and Deenise Becent, NTUA, SRP and Navajo Nation Leaders Celebrate Groundbreaking Ceremony for Kayenta II to Celebrate Commitment to Develop Renewable Energy Projects on Navajo Nation. 2018.
  3. Robert E. McGrath, Think Heliocentrically, Act Locally, in The Public I: A Paper of the People. 2019.

Molecular Magic: Manipulating Atoms

Whoa!  As I always say, “If you let me manipulate individual atoms, I can perform black magic!”

So, I really wanted to read about “A Faster Way to Rearrange Atoms” [1]:  “scientists can now rearrange individual impurities (in this case, single phosphorous atoms) in a sheet of graphene by using electron beams to knock them around like croquet balls on a field of grass.”

It sounds so simple:  use the electron beam of a Scanning Tunneling Electron Microscope to quickly and accurately push specific atoms around a graphene sheet.  The trick is, the “push” in question is a complicated billiard shot.

The MIT researchers report on the theory of these maneuvers [2].

“Controlling the exact atomic structure of materials is an ultimate form of engineering “ ([2],, p.1)

Ya think?

One interesting aspect of their approach is that they control the “dopant” atom by zapping a neighboring Carbon atom, which swaps place with the target atom.


There are a lot of variables involved, and, needless to say, I don’t understand the details of the physics, not even a tiny bit.

What I do understand is that (a) the electron beam is fast and scalable (you can have more than one beam) and (b) the “billiards shots” are a complicated, but algorithmic collection of steps.  You many need to create a code book for different atoms and substrates,and you may need some clever planning software to string together the best moves, but it all should plug right in to the same STEM technology.

In other words, this could be a technique for literally programming the layout of atoms, one by one.

Sigh me up for some of that stuff!

  1. Mark Anderson, A Faster Way to Rearrange Atoms Could Lead to Powerful Quantum Sensors, in IEEE Spectrum – Nanclast. 2019.
  2. Cong Su, Mukesh Tripathi, Qing-Bo Yan, Zegao Wang, Zihan Zhang, Christoph Hofer, Haozhe Wang, Leonardo Basile, Gang Su, Mingdong Dong, Jannik C. Meyer, Jani Kotakoski, Jing Kong, Juan-Carlos Idrobo, Toma Susi, and Ju Li, Engineering single-atom dynamics with electron irradiation. Science Advances, 5 (5):eaav2252, 2019.

More Nakamotoan Engineering

I think that one of the paths to winning the Crypto Tulip of the Year award is through exemplary Nakamotoan Engineering.

As discussed many times here, Nakamotoan systems are “decentralized”, which means that there is no authority in charge.  In addition, the “consensus” protocol ensures that software engineering, including bug fixing, proceeds along one, rather peculiar path.

  1. (optional) a change is proposed, often through a web “white paper”
  2. someone, could be anyone, hack up implement proposed changes.
  3. Revised code is put out on test net, and then pushed to main code.
  4. Users of the code decide whether to accept the modified code. When “everyone” on the network picks up the code, the change is official.  This is a “vote” on the change.

Note that there is no guarantee when a fix will be picked up, if ever.  Many people may continue to use the old, often buggy and insecure software.  There are other peculiarities, such as no formal testing, and options for “conditional execution” based on voting or elapsed records id (timestamps).

(To be fair, this methodology was not invented by Satoshi Nakamoto. It is common in open source software.)

As I have remarked before, this is a heck of a way to run a software project!

I have commented on all the ways Ethereum has been exploring the joys of Nakamotoan engineering.   And, of course, Bitcoin and other cryptocurrencies have similar challenges.  It’s an awful mess, but a lot of crypto enthusiasts seem to either not know any better, or truly believe that this is a feature not a bug.

The Crypto Tulip judges are particularly impressed by the incredible lengths developers are willing to take to do the right thing, even when it is impossible because of the Nakamotan ideology.

This month, I read of yet another classic move “Crypto Developer Komodo ‘Hacks’ Wallet Users to Foil $13 Million Theft” [1].

This case involves one of the numerous “wallets”, client-side apps that reside on user’s devices.   Developers discovered a bug in Javascript (a notoriously buggy language) which opened a potential back door in one of Komodo’s wallets.  Hackers could exploit the bug to take control and steal whatever cryptocurrency the user held (by stealing keys).  Note that this has nothing to do with Komodo, Bitcoin, Ethereum, or any other core protocol or blockchain.

The Komodo developers were informed of the problem, and confirmed that users were exposed (and, it became clear, were already being robbed).  What to do?

In Nakamotoland, the company can’t stop transactions, or even revoke keys.  Transactions, including transfers of stolen funds, are unchangeable.

The best response would be for users to move to updated products, which they should have done already, but didn’t because who has time to update apps?  Like many apps, it wasn’t possible to quickly update all the copies out on users devices, and in any case the already stolen information would enable the theft.

The Komodo people did something that is both clever and deeply disturbing.  They counter hacked the hacker, and use the stolen information to summarily “steal” the remaining exposed customer funds into secure locations [2].  This certainly stopped the crime.  It also was done without permission or notice, which is disturbing.

So, let’s recap.  The company sells “secure” software that isn’t secure (using Javascript borders on negligence here), and when a serious hack occurred had no mechanism to protect the customers.  So they improvised an intrusive counter hack that did save their customers, at some inconvenience.

Of course, the blog post assures us that their other products are, and I quote, “completely secure” [2].  And their new product is even more secure, because “it only utilizes dependencies that are reviewed by security experts.“.

Trust us.

The Crypto Tulip judges note that the core Nakamotoan principle of “decentralization” is supposed to make things more secure (as well as “trustless”), but obviously does not really address end-to-end security.

We don’t know why the company released product with dependencies that were not reviewed.  We suspect that they thought that the “secure” blockchain was sufficient.

The judges also take note that the company is striving to maintain the trust of its customers, while providing products that are based on the principle of “trustlessness”.  This cognitive dissonance about “trust” is the essence of Tulip-ness.

I think we’re going to have to enter “Nakamotoan Engineering” as a competitor for the Crypto Tulip award this year.


  1. Benedict Alibasa (2019) Crypto Developer Komodo ‘Hacks’ Wallet Users to Foil $13 Million Theft. Coindesk,
  2. Daniel Pigeon, Update Regarding Vulnerability Recently Discovered In Komodo’s Agama Wallet, in Komodo Blog. 2019.


Cryotocurrency Thursday


Drones Over Tanzania!

I’m more than a little skeptical of the widely ballyhooed commercial use cases for UAVs, deliveries basically, local reconnaissance.  And I’m especially skeptical of neo-colonialist assumptions that places like Africa are not so much poor as blank slates, which can be “fixed” by the magic of technology.

So I was interested to read Evan Ackerman and Michael Koziol’s article on the local “drone industry” in Tanzania [1].  There’s a lot of interesting stuff going on in Africa, not least because it’s Africans doing it, not “experts” from Silicon Valley.

For one thing, commercial products, even hobby grade UAVs are too expensive for Africa.  Fiberglass and carbon fiber are aerospace materials—sexy, but hardly the stuff for a small business in Africa.  And who needs it anyway?  The article reports on drones made with bamboo and zip ties.  There is sexy software inside, but the outside is cheap and easy to repair.

Even more interesting, Tanzanians are pioneering uses “that aren’t even on the radar for the United States and Europe.”

One use case is land surveying.  Where I live, things have been surveyed to death centuries ago—and important tool of appropriation. (When you steal a continent, you want to keep careful records of which thief owns the swag.)  But much of Tanzania has not be ground surveyed.  Satellites aren’t very detailed, and small aircraft are expensive.

Commercial and hobby-grade drones are very expensive.  So why not operate a rent-a-drone service?

A second use case is the classic delivery service.  In my town, drone delivery is competing with motor vehicles in the last ten miles, which are pretty efficient and benefit from enormous amounts of infrastructure.  In Tanzania, many places rely on motor bikes over limited roads.  And, of course, there are islands and other isolated spots with even less connectivity.

So delivery drones make a whole lot more sense in Tanzania, at least outside the main towns, which is a lot of the place.  Of course, it remains to be seen how much business there is for a kilo or two of “urgent” cargo.  Obviously, low cost, locally repairable aircraft would be an asset, and maybe a swarm might lift larger loads that could make a difference to the equation.

Now, to be sure, this article is mainly about enthusiastic drone-heads (is there a term in Swahili for this? : – )) , and they’re pretty much the same everywhere. These use cases face similar economic challenges in Africa as elsewhere.  Just how much business is there for aerial surveying or delivering priority packages?  I dunno.

These projects are in very early stages, and there is a lot that might happen.  For starters, unlike developed areas, government policy in Tanzania has yet to be set.  And, this being Africa, there is a possibility of corruption distorting policy.  Depending on how policy and law comes down, local entrepreneurs could win or lose big time.

Assuming these businesses continue and thrive, they may have major side-effects.  The land-surveying services are based on defining firm property boundaries, for the purposes of establishing formal ownership, obtaining loans, and transferring property.  In the past, these legal processes are predominantly used by wealthy and privileged people.  Spreading the use of these legal protocols to wider populations could create wealth, but also can create inequality (displacing poor people who can’t prove title), and conflict (disputed titles, foreclosures, etc.)

And, of course, there are other, darker uses of surveillance drones.  Police, gangs, and militias might make use of low cost, locally made drones. Putting an air force in the hands of any group that has a few thousand dollars might be dangerous and destabilizing anywhere, and Tanzania is no exception.

So, it will be interesting to see what happens as Tanzania boots up local drones and drone-based businesses, and maybe exports them to neighbors, too.

  1. Evan Ackerman and Michael Koziol, Tanzania Builds a Drone Industry From Local Know-How and Bamboo, in IEEE Spectrum – Robotics. 2019.


Robot Wednesday

One Last Black  Hole Simulation at NCSA

Another installment of “winding down the National Center for Supercomputing Applications” (other posts here and here).

NCSA was literally created in order to do black hole research, and through the years astrophysical simulations have always been going on.

So it is fitting that the last years of NCSA should support important block hole work.

This month an international team of researchers report a new simulation that has a 45 year old hypothesis about black holes.  (I’m not astrophysicist, so I’m taking the science at a pretty shallow level.)

Bardeen and Petterson predicted that in a spinning black hole, ”the inner parts of a thin disc would align with the [black hole] midplane.” ([1], p.551)

The paper discusses the technical difficulty of simulating this effect, which, I gather, is pretty hairy, requiring high resolution simulation of the black hold and the accretion disk as they move.

The new study was able to achieve higher resolution, including effects of magnetism, which is important [2]

From my own perspective, and the part I understand better, is that this new result was made possible by porting the simulation codes to the Blue Waters supercomputer at NCSA.  In particular, they used the GPU vector coprocessors with a 3 billion point grid.

The paper doesn’t indicate the exact configuration of the computer (c’mon guys, that’s the most interesting part! : – )), but they could have used thousands of processors in parallel.  (Allocations are measured in “node-hours”.)

Now, I know very well that it ain’t that easy to get a simulation like this to run on such a hybrid architecture, let alone run as fast as possible.  So I know they did a lot of fussy work to make sure that everything worked—correctly!—on this massive system.

Altogether, this is a fine capstone to black hole research at NCSA in the last year of operation (as far as I know).

Over the years, NCSA achieved quite a bit, much of it not contemplated in the original proposal (contributions to networking, security, the world wide web, applications from Art to Zoology).  But, as I said, what is was intended to do was advance black hole simulations.  And it did that superbly.

  1. M. Liska, A. Tchekhovskoy, A. Ingram, and M. van der Klis, Bardeen–Petterson alignment, jets, and magnetic truncation in GRMHD simulations of tilted thin accretion discs. Monthly Notices of the Royal Astronomical Society, 487 (1):550-561, 2019.
  2. Jackson Ryan, Haunting black hole mystery solved with most detailed simulation ever, in CNET – News. 2019.


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