Thursday, January 7, 2021

Open Letter to Secretary Kerry


Congratulations on being picked to be the Czar for Climate in President-elect Biden’s administration. I heard you speak about your role on a couple of different news shows and am pleased to note that you recognize the shortcomings of the Paris Agreement.

The only effective solution that scientists like James Hansen are telling us to embrace, is nuclear power. Nuclear power is the one source of clean energy that is scalable to the levels needed. It is also the has safest record (fewest fatalities per TWh generated) and the smallest environmental footprint, both in terms of area covered and tonnage of commodity materials required per unit of electricity delivered. Yet, our current policies such as subsidies and portfolio standards, and the manner in which electricity is marketed is making nuclear power uncompetitive. The unfounded fear of radiation and years of anti-nuclear misinformation has placed such strict and expensive standards on the nuclear power plants that they are being priced out. In many states even fully functioning nuclear power plants are being shuttered. We have a shortfall of clean electricity, and we are digging ourselves deeper in the hole!

As climate Czar, I hope you will address the market distortions that are at the root of the nuclear power plant closures. Instead of closing them down, we should be extending clean energy credits to them, support their expansion, and invest in demonstration of newer walk-away safe nuclear power plant designs.

Getting the public to embrace nuclear power presents a formidable challenge. Public opposition to nuclear power has its origin in the debunked idea that there is no safe dosage of radiation, and the improper application of the LNT (linear, no threshold) hypothesis to estimate cancer in large populations exposed to low levels of radiation. Without public acceptance of nuclear power, we have no chance to achieving net-zero emissions by 2050 or curbing the devastating effects of climate change. What is urgently needed is a sustained public education and outreach program that undoes the decades of anti-nuclear fear mongering. An office of energy education and public outreach dispelling the fear of nuclear power. There are trade-offs with all energy systems, but the benefits from nuclear power far outweigh the risks.

Good luck to you in your new role!


Ripudaman Malhotra, PhD
Fellow, American Chemical Society

Friday, November 20, 2020

A New Life for Spent Nuclear Fuel


My friends at EnerChemTek, a Toronto-based consulting company, recently brought to my attention a technology by a company called Infinite Power for harnessing the energy from the radioactive decay of a strontium[1] isotope, 90Sr. (Infinite? Immediately, my skepticism goes on high alert!) The company’s website promotes the technology, which was invented by scientists at the University of New South Wales, as a solution to global energy crisis. It promises abundant (almost inexhaustible) source of inexpensive clean (i.e., carbon-free) electricity that can power the world! My curiosity was piqued.


If true, and it is a big IF, the claims by Infinite Power would constitute a giant step forward for the power-hungry planet. To be sure, deployment of any technology at global scale takes decades, but having a scalable clean technology is a step in the right direction. 


Devices for harnessing energy from decaying radioisotopes are often referred to as nuclear batteries, although they are not electrochemical cells. Such batteries produce electricity through various processes: thermoelectric, thermionic, or photovoltaic. Radioisotope thermoelectric generators of RTGs have been used for long duration space exploration missions. Cassini and Galileo probes were powered by a plutonium oxide RTG. The device described by Infinite Power is different and falls under the category of a photoelectric nuclear battery. It uses the electromagnetic emissions resulting from the radioactive decay to produce electricity with photovoltaic (PV) materials.


There were not many details about the technology on the company’s website, which is understandable. After all, if the company is sitting on a gold mine, they would not want to disclose all their secrets. They do mention the basis of their technology, which is that they have fabricated “hardened PV cells” to produce electricity from the radiation emanating from radioactive strontium. The “hardening” allows these PV cells to capture and convert even high energy radiation, exposure to which degrades the garden-variety PV cells. 


90Sr has a half-life of 28.3 years and thus it would take a century for its radioactivity to subside to less than a tenth its original intensity. 90Sr decays by emitting a beta-particle (an electron) and forms 90Y, an isotope of yttrium. In turn, the daughter 90Y decays by another  beta-emission to stable 90Zr, zirconium. 90Y is extremely radioactive and has a half-life of only 64 hours. The energy of emitted b-particles from 90Sr and 90Y are 0.5 and 2.5 MeV (million electron-volts). Combined, the energy from the radioactive decay of the two isotopes amounts to about 3 MeV. Not all of this energy could be converted to electricity, but this figure places an absolute limit to what is realizable. So how much energy does that represent? How many cubic miles of oil? Or how many TWh of electricity could possibly be generated by this source? 


To answer these questions, we need to know (i) how much 90Sr is available—the resource potential, (ii) how the energy of the emitted particles is transformed into electromagnetic radiation, and (iii) the fraction of that energy that is captured by the “hardened PV device,” and finally convert the MeVs into kWh or other commonly used units of electrical energy.


90Sr is not present in natural strontium, but it is present in the spent nuclear fuel. Nuclear power plants have been operating commercially since 1956 when the Calder Hall plant in England began operation. This was a small facility, only 50 MW of capacity; since then, over 400 nuclear power plants have been built and the global installed nuclear capacity has ramped up to over 350 GW. A typical 1-GW nuclear plant generates about 25 to 30 tons of spent fuel each year. While about a third of the spent fuel is being reprocessed in countries like France, Russia, Japan, and the United Kingdom, most of the spent fuel is stored in dry casks at the power plants. The World Nuclear Association estimates the global stockpile of spent nuclear fuel in 2013 to be 250,000 tonnes (metric tons).[2] Isotopes of uranium and plutonium comprise over 95% of the spent fuel. The amount of 90Sr in the spent fuel is on the order of 1%, for a total of 2,500 tonnes. At 3 MeV per decay, the total energy amounts to 2,230 TWh.[3] While 2,230 TWh is a lot of energy (potentially worth over $100 billion), it is less than a tenth of annual global electricity consumption. In 2018 alone, the world consumed 26,000 TWh of electricity. 


Clearly, the technology is not the “(a)nswer to climate change” as proclaimed by Infinite Power. However, the fact that I do not know enough about their technology and could be missing a big factor, I am not inclined to simply dismiss their claims mere corporate hype. This technology can still be a significant component of a broader portfolio of clean technologies. As described, the technology is highly modular and lends itself to addressing energy needs under a wide range of situations, such as powering remote villages, industries, and charging stops for electric vehicles, including trucks. There are probably many applications for which this nuclear battery would be particularly suited and therefore be of interest to investors and technology developers.


In this analysis I have assumed that the entire inventory of Sr in the spent fuels is accessible. While methods for chemical extraction of Sr from spent fuel have been developed—for example, the Idaho National Lab has published a processes for extracting almost 100% of 90Sr from the spent fuel with dilute nitric acid—access to the spent fuel will likely present several jurisdictional barriers, and thus limit the overall supply. Reprocessing has been banned in the USA since 1976. Furthermore, a major factor in the cost of the extraction process will be the implementation of safety protocols for handling radioactive materials.


Another important consideration would be the fraction of energy from the decay that could be converted into electric power. I reviewed a patent underlying the company’s technology, but it was very light on details. It says that their technology as being able to use high energy photons from the decay. As mentioned above, 90Sr and 90Y both decay by emitting high energy electrons. The emitted electrons can cause excitation of electrons in other atoms, which would then emit photons that could excite electrons in a PV cell to produce electricity. However, the patent gives no idea of the spectrum of the radiation from their 90Sr source nor the bandwidth of the PV material. Such information would be essential for determining the fraction of the total available energy that can be realized as electric power. 


All in all, I find this technology extremely intriguing and hope that further R&D is conducted to answer some of the questions before the technology is advanced to commercialization.


[1] Strontium has chemical properties similar to calcium and is situated right below it in the periodic table. Natural strontium is not radioactive and non-toxic. However, certain isotopes of Sr that are formed during nuclear fission of uranium are radioactive. Although the b-emissions are readily blocked and can penetrate only about 1 cm through the skin, the chemical similarity of strontium and calcium allows 90Sr to get incorporated in the bones, where it can do damage and thus potentially cause cancer.


[3] One eV is the energy released one a charge of a single electron drops by 1 Volt. It is equal to 4.45 x 10-23  Wh. To obtain an estimate of a gram mole of eV we multiply the 4.45 x 10-23  Wh by the Avogadro’s number, 6.02 x 10-23 , to get 26.8 Wh. The 2,000 tonnes of 90Sr correspond to 22.2 million g-moles. Multiplying the moles of 90Sr with the amount of energy per eV, and then multiplying that with 3 x 106  (for 3 MeV per decay) I get 1,800 TWh as the energy released from decaying 90Sr and its daughter 90Y.

Friday, June 26, 2020

Role of Bioenergy in Achieving Sustainability

I was recently invited to give a keynote address at an international conference on Bioenergy and Sustainability. Because of the Covid-19 pandemic the conference was held virtually over Zoom. What follows is an abstract of my presentation; the full lecture can be accessed here.

The word sustainability shares its root with sustenance. In the case of modern society sustenance comes from use of energy, which is derives from many sources: oil, coal, natural gas, hydroelectric, nuclear, wind, solar, and biomass. Annual consumption of global energy is equivalent to 4 cubic miles of oil (cmo), about 3 of which are obtained from fossil sources: oil, coal, and natural gas.


The dominance of fossil energy in the global mix has been longstanding—ever since the dawn of the industrial revolution in the mid nineteenth century. As a result, the concentration of carbon dioxide in the atmosphere has increased from 280 ppm to over 400 ppm and continues to rise. CO2 is a greenhouse gas and it and now threatens life as we know it from the resulting climate change. To avert devastation from climate change or constrained energy supply, the world desperately needs sources of clean, carbon-free energy that together can scale to cmo levels.


Much emphasis has been placed in recent years on resources like wind and solar to provide clean electricity. Technological advances have led to dramatic reductions in their costs and their advocates now propose a future powered entirely by them. However, these costs do not include the cost of storage, currently provided by natural gas, nor do they consider the environmental cost of mining for the materials needed for their installation. Scaling them to a 100%-renewables scenario will strain the global supply of commodities like steel, concrete, glass, and aluminum; clearly not a sustainable scenario.


Burning biomass has been proposed as a fuel source; indeed, prior to the industrial revolution the world once derived 100% of its energy from bio sources. Unlike wind and solar, bioenergy sources are storable and do not suffer from intermittency. However, biomass use also results in emitting CO2. The only reason these emissions are not counted is that the regrowth of the biomass would take an equivalent amount of CO2 out of the air. For this assumption to hold, it is important that we consider harvesting only rapidly growing biomass or annual crops.


Global biomass production is substantial; it is estimated that 75 Gt (gigatons, or 109 tons) of biomass are produced annually. Most of the biomass is in the forests and oceans and not readily recoverable, nor is it desirable to cut down this “sequestered” carbon and burn it. The estimate for recoverable biomass resource is only 3 Gt/y. At a heating value of 15 GJ/t (gigajoules/ton) the energy from these 3 Gt of biomass would correspond to only 0.3 cmo. The low energy density of biomass translates into large areas over which the biomass to be harvested and transported to the power plant: 160 sq. miles of fast growing trees each year to power a single 100 MW plant.

Clearly, we cannot rely on biomass to meet global energy demand for clean energy. Yet, there are some applications where energy from biomass is uniquely suited. Production biofuels is one such example, and many conversion of starch in grains into bioethanol is a thriving business—thanks in large part to the support the industry receives from various state agencies. There are also processes for converting lignocellulosic wastes into biofuels, although there deployment has been hampered by high costs. The main reason for using biofuels is to reduce greenhouse gas emissions; however, on a life-cycle basis the biofuels reduce greenhouse gas emissions between 20% and 40%!

Co-firing biomass, particularly waste biomass, may provide only a limited amount of energy, but it would help enormously with waste management since many municipalities are running out of landfill space. Likewise, utilizing agricultural waste in an engineered system rather than open-field burning would go a long way in reducing urban pollution in many countries.

True sustainability demands a scalable source of clean and cheap electricity. Nuclear power can deliver that. It has the smallest environmental footprint and the best safety record, but public concerns over plant safety, long-term storage of waste, and cost are considerable obstacles. Getting the public to embrace nuclear power is a Herculean task, but it must be undertaken. We have to (i) educate the public (ii) stop closing functional nuclear power plants; (iii) expand the fleet of nuclear power plants; and (iv) develop and deploy the next generation of walk-away safe plants that can also use the spent fuel as a resource.

Thursday, April 30, 2020

Planet of the Humans: A Review

Michael Moore’s documentary Planet of the Humans was released on YouTube in conjunction with Earth Day, 2020—a casualty of the Covid-19 pandemic as a theatrical release was precluded. I had heard of the movie and knew that it was about the limitations of renewable energy sources. I was glad that a renowned documentarian like Moore was putting a spotlight on the shortcomings of “renewables,” because the public has been largely seduced into believing that wind, solar and biomass can provide us with all our energy needs while averting climate change. Last weekend, I finally got to see the movie.

I had mixed reactions as I watched the documentary. Although Michael Moore is the Executive Producer, he does not appear in the film. The film is narrated by Jeff Gibbs who tells his journey of disillusionment with the green movement. I liked how effectively Gibbs dispenses with the myth that wind and solar lead to reduced emissions! Reducing greenhouse gas emissions should be our main objective, not simply installing renewable energy sources. Gibbs points out the massive amounts of steel, concrete, and other materials required for any wind turbine, which would last for only 20 years. Similarly, large quantities of commodities are also needed for a solar farm. Production of the commodity materials requires tons of fossil resources, which cut into the “greenness” of these installations. All the mining necessary to obtain the raw materials also degrades the environment.

Gibbs loses credibility when he asserts that it takes more energy from fossil sources than what is produced by wind and solar power plants. Many reputable life-cycle analyses show that these sources are net positive energy producers after five to seven years. By overstating his case against wind and solar and not acknowledging their contribution to carbon-free electricity, he leaves himself open to easy criticism by advocates of renewable “green energy.” And he has been criticized for that by many environmentalists.

That said, Gibbs is right in his overall criticism. Life-cycle analyses do not count emissions from sources needed to back up wind and solar. Those emissions are counted as emissions from coal or natural gas plants, even though in many instances these plants are expressly built to support a new wind or solar farm. The necessity to back up intermittent sources is the reason why Germany’s greenhouse gas emissions did not decrease even though the country spent over $500 billion on its Energiewende (Energy Transformation) program.

Another fallacy of the “renewables” is that it considers biomass carbon neutral. Burning wood chips (actually forests, as the movie points out) is not good for the environment and is ruining habitat. It also can take a hundred years or more for new trees to grow and offset the carbon dioxide emitted during the burning of wood chips. Gibbs dwells a lot (indeed, too much for my liking) on the environmental damage done by growing biomass for fuel or devoting farmland for growing crops to make biofuels.

Gibbs next turns his attention to the moneyed interests behind the “green” movement. He exposes many promoters of green energy as deeply vested in fossil energy sources. The reason fossil companies support wind and solar installations is that they know the renewables will have to be backed up by new natural gas plants or the predominately coal-based grid. [i]

Gibbs portrays many leaders of the environmental movements such as Bill McKibben and Al Gore as being in the pockets of fossil energy companies. Without convincing evidence, such portrayal is sure to raise the ire of the green movement. The movie seems to make the case that nothing good will come if we rely on market forces, forgetting the counterpoint that profit motive is exactly what drives innovation and solutions.

I was particularly disappointed by the documentary because it offered no solutions. It completely ignored nuclear power and just harped on the Malthusian theme that we humans are the problem since we have so increased in numbers and each of us is consuming too much! The last part of the movie showed scenes of rampant environmental damage and an orangutan clinging on to a lone tree surrounded by devastated landscape. Pure environmental porn; ugh!  

The movie leaves the viewer hopeless, and with a sense of despair that can lead to inaction, when what the world needs is rational thinking and concerted action. In an interview with Stephen Colbert, Michael Moore said that his objective in producing this film was to raise the alarm and motivate the younger generation into action. I am afraid, by not offering any hope the movie fails on that front.

So, what are we supposed to do?  Revert to 17th century lifestyles? That seems to be the message but recall that back then life expectancy was barely 40 years and infant mortality was ten times higher than today, and people spent almost all their time in the drudgery of procuring food and fuel rather than other pursuits. The world population in the 17th century was less than 1 billion; today it is 7.5 billion and about half are living in unacceptable poverty without access to electricity, clean water, and adequate food. It will take energy to lift them out of poverty so they too can lead healthy, productive lives. Where is that energy going to come from?

Incidentally population growth, a theme that the movie touches, is best addressed by raising living standards. The need for copious quantities of clean energy is evident.  The movie makes it amply clear that the required energy cannot be produced through the magical thinking of 100% renewables. It will require a substantial expansion of nuclear power—the one clean source that is safe, scalable, and cheap enough for global deployment.

As an antidote to the movie, I suggest watching this interview by Michael Killen of me and Alex Cannara.

[i] Battery storage just does not scale to provide the required back up; besides it too is fraught with issues of materials supply.

Monday, November 18, 2019

An Open Letter to Jane Fonda

Dear Ms. Fonda,
Kudos to you for rising up to draw attention to the crisis of climate change. You are an inspiration! I read the story about your protests in the NY Times and also watched your interview with Judy Woodruff.

You clearly articulated the gravity of the problem and say that we should listen to the scientists. As a scientist, I was gladdened to hear you say that. I hope you will also lend your voice to the only effective solution that scientists like James Hansen are telling us to embrace, namely nuclear power. To the extent that your movie, “The China Syndrome,” contributed to the public fear of radiation and nuclear power, your coming out in support of nuclear power would go a long way.

Image result for james hansen nuclear energy
Climate change is also a matter of social justice as it most adversely affects those who can least afford it and who contributed the least to bring it on. People need energy to lead healthy productive lives, and currently about half the world’s population does not have access to adequate energy. Social justice demands that the global supply of energy be increased to rectify this situation. However, burning fossil fuels, which are the easy source of energy, aggravates climate challenge.

Most champions of social justice movements call for rapidly expanding renewable energy sources like wind and solar. However, these intermittent, low-energy density sources cannot meet the energy demand while reducing greenhouse gas emissions. Germany’s experience with Energiewende makes that amply clear. They spent over $550 billion but their greenhouse gas emissions are rising, because they have had to add lignite-burning plants. Further, wind and solar require inordinate amounts of materials. Meeting the global energy demand by renewables would require more than doubling the global production of basic commodities such as copper, steel, cement, and rare-earth metals with enormous environmental degradation from mining. Just replacing one coal power plant with wind and solar along with a modest amount of battery storage would require half the global production of lithium in 2018!

Nuclear power can produce vast quantities of carbon-free energy. It has resulted in the fewest fatalities per unit of energy delivered than any other system, including wind and solar. It also has the smallest environmental footprint. Our unfounded fear of radiation, reinforced by decades of fearmongering, has prevented us from building any new plants in the U.S. for decades and has exacerbated the climate challenge.

Given the urgency to reduce carbon emissions, it is foolish to shut down working nuclear power plants. Instead, we should support their continued operation, and promote building and exporting new walk-away safe nuclear power plants. I have written and spoken on this subject extensively and welcome you to read more about it in book, A Cubic Mile of Oil,” or on earlier posts on this blog. Additionally, you may want to look at, “A Bright Future” by Joshua Goldstein and Steffan Qvist.

Ripudaman Malhotra

Friday, September 20, 2019

Replacing coal with wind and solar power

I am often reminded by my friends that renewable power like wind and solar are making tremendous strides—their deployment is rising exponentially, and costs are coming down. As a result, my friends claim, greenhouse gas emissions in the US are declining. They note that renewable sources are a cheaper alternative than coal power in many parts of the world. We should therefore close down the coal plants and replace them with wind and solar farms. For backup these installations should use batteries, whose costs, I am told, are also plummeting. Indeed, Mr. Bloomberg has pledged $500 million to hasten such a transition.

I wish I could share their positive outlook. Deployment of renewable power technologies has been increasing, but even after twenty years of this exponential growth, in 2018 they provided a mere 3% of global energy, while fossil fuels accounted for over 80%. Wind and solar simply do not scale. Here’s a graphic from the BP Statistical Review of World Energy, 2019. It shows the global primary energy consumption various sources in MTOE, metric tons of oil equivalent. Yes, you can see the increase in renewables, but the even larger increases in consumption of fossil fuels has led to emission of ever-increasing amounts of carbon dioxide.

There has indeed been a decline in the CO2 emissions in the US electricity sector. This decline, though, is largely a result of switching from coal to natural gas, and not due to the rise renewables. Wind and solar contributed only a small fraction. Here are the data from the US Department of Energy’s Energy Information Administration that illustrate the point.

The falling price of wind and solar power that the proponents point too does not reflect their true costs.  Policies such as Renewable Portfolio Standards, subsidies, and alternate revenue streams such as curtailment allowances hide the costs. Wind and solar installations must come with the disclaimer, “Batteries Not Included.” If one includes the cost of storage and other systems for managing their intermittency, the cost of wind and solar would be considerably higher.

Consider closing a 1-GW coal power plant, say the Bruce Mansfield in Pennsylvania, and replacing it with renewables. First, to get the same number of GWh of electricity over a year, you will have to install about 3 GW of wind or solar facilities to account for their reduced capacity factors. Installation costs are often reported in $/W, and so for starters we have allow for the higher installed capacity to get the same amount energy.

Next, you will also have to provide some storage to cover for days that wind might not blow or the clouds obscure the sun. Currently, natural gas plants are used to provide backup power because natural gas in cheap—thanks to fracking—and they can ramp up quickly. But natural gas is a fossil fuel, and we do not want that; instead we want to put in batteries for backup. If we choose to provide storage for just 100 hours, a tad over four days; that would mean installing battery storage capacity of 100 GWh. How much lithium would that require? According to Tahil, theoretically you could store 1 kWh of energy from 73 g Li in lithium ion batteries. Note that g/kWh are the same as Tons/GWh. Thus, theoretically, you would need 73 Tons for storing 1 GWh of electrical energy.

In practice, the amount required is often 3 to 4 times higher because of several factors: discharge rate, irreversible losses, reaction kinetics, etc. Tahil discusses these issues in the paper and concludes by suggesting a requirement of 320 g Li per kWh of storage. In other words, shutting down just a 1-GW coal plant and replacing it with renewables and providing only 100 hours of storage would require 32,000 Tons of lithium. To put that amount in perspective, note that in 2018 the global production of lithium was 62,000 Tons.

In other words, about half the world’s lithium supply would go for backing up renewables to replace one coal plant!  Sure, we could expand the production of lithium, but how soon could we scale it up to get millions of tons per year to replace all the coal power? We do not have the luxury of time. As Greta Thunberg and children all over the world implore us, we must take action to combat climate change. Let's do right by them and not make the problem worse than it already is.

Time to get real and embrace nuclear power!

Monday, August 12, 2019

Links to some of recent videos

I confess I have not been very active in posting blogs lately. But please do not take that as a sign of waning interest in the subject. I have kept up giving lectures and appearing on Michael Killen’s TV show to talk about global energy and the necessity for the world to move towards nuclear power. In addition, my talks at the Thorium Energy Alliance conferences in 2016 and 2018 are also available on YouTube. Here are links to some of these videos:

1.     Michael and I discuss the assessments of the impact of climate change described in recent reports released by the IPCC and a collection of 15 US agencies. (December 2018).
2.     Alex Cannara and I talk with guest host Jonathan Kleid whether renewables alone can prevent climate and economic disaster. (January 2019): 
3.     Michael and I talk about the Green New Deal and its ability to combat climate change. (April 2019):
4.     My talk at the Thorium Energy Alliance Conference # 7, in Palo Alto where I introduce the notion of a cubic mile of oil and discusses the moral imperative for increasing total global energy supply equivalent to several cubic miles of oil. :
5.     My talk at the Thorium Energy Alliance Conference # 8 on replacing the cubic miles of oil that we use and what will be needed in the future with nuclear power.