The Guardian questions: thorium, shale gas, off-grid renewables, and much more…

The Guardian newspaper’s Environment Facebook page recently put the following to their readers:

Ask the Global Energy Prize‘s expert panel your toughest energy questions and they’ll be back here on Friday with their answers. What should power our cities, homes and industry in the future — renewable energy, nuclear power, or fossil fuels? How significant will shale gas be? And what role will oil play in our energy future? Just post your energy Qs here. 5 experts will answer the 10 best questions: Harry Fair (US), Tom Blees (US), Thorsteinn Sigfusson (Iceland), Barry Brook (Australia) and Klaus Riedle (Germany).

Below are the six questions put to me (Barry Brook) and Tom Blees — and our answers, of course! The original answers were not hyperlinked, but if you are curious about anything we mention here, try searching for the keywords on this website (e.g. type bravenewclimate.com/?s=thorium in your browser address bar), or on Google (e.g. type  “ammonia site:bravenewclimate.com” in your search box).

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BARRY W. BROOK

Q1. Do you agree that Thorium power is a safe, plentiful, and viable energy source that should be investigated as a matter of urgency?

Yes, thorium power is an attractive prospect for the next generation of nuclear reactors, but then surprisingly enough, so is uranium.

For today’s reactors, it takes about 150 tonnes of natural uranium to fuel a 1 gigawatt (GW) power plant for an entire year (the total energy produced is called a gigawatt year, or GWyr).  One GWe of power (the ‘e’ stands for electrical power rather than ‘t’ for thermal power, or heat) is a huge amount. It’s enough to run 65 million desk lamps (assuming they used 15 W compact fluorescent globes), or more practically, to satisfy today’s electricity demand of a typical UK city of more than half a million people. For comparison, to deliver a GWyr of energy using a coal-fired power station, about 4 million tonnes of coal must be burned (the amount can vary depending on the grade of coal).

Most of the nuclear power stations in use today are called ‘thermal reactors’, or ‘light water reactors’ (LWR). They use ordinary (‘light’) water as a coolant, which take heat away from the reactor core. The water also acts as a ‘moderator’, slowing down subatomic particles called neutrons, which shoot out of the atom’s nucleus when a nuclear chain reaction is underway. These neutrons are responsible for causing unstable heavy atomic nuclei to split apart and release energy. Other reactor designs use heavy water (enriched in ‘heavy hydrogen’: deuterium) or graphite (a form of carbon found in pencils) to moderate the neutrons (the latter is used in the UK’s gas-cooled Magnox reactors, for instance), but the effect is similar. These nuclear power plants need, as fuel, a form (isotope) of uranium that has 143 neutrons in its nucleus, called ²³⁵U (or ‘uranium 235’). Yet natural uranium contains 0.7% ²³⁵U; the other 99.3% is composed of an isotope that has 3 additional neutrons, called ²³⁸U (or ‘uranium 238’). As a result, today’s LWRs are able to extract less than 1% of the atomic energy content of uranium. The rest is discarded, unused, either as spent fuel (‘nuclear waste’) or as depleted tails (the leftovers, composed mostly of ²³⁸U, after the fuel has been ‘enriched’ to raise the concentration of ²³⁵U to 3 – 5%).

However, other sorts of nuclear power plants have been developed called ‘fast spectrum’ reactors (FR) and ‘liquid fluoride thorium reactors’ (LFTR). These are able to not only fission ²³⁵U like LWRs, but also readily ‘breed’ other fissionable isotopes from ²³⁸U or ²³²Th. With repeated recycling, this allows them to unlock virtually all of the energy in nuclear fuel. The amazing upshot is that instead of using 150 tonnes of natural uranium to produce a GWyr of electricity, FRs and LFTRs require only 1 tonne.

The key for both types of reactors – uranium and thorium based — is that the nuclear fuel is repeatedly recycled. For thorium, this is crucial because in order to ‘burn’ nuclear fuel, the ‘fertile’ ²³²Th must be converted, in the reactor, to ‘fissionable’ ²³³U – which is then consumed to generate the power. Given currently estimated reserves of cheap uranium, there is enough already identified to run the planet at a power level of 10,000 GWe for 4,000 years (which takes us well beyond 2050, to the year 6000AD). Then, consider that there is roughly four times more thorium, and we have 20,000 years of energy, give or take a few millennia. And this is before we start looking for lower-grade ores or uranium in sea water.

Finally, it’s worth noting that uranium FR and thorium LFTR type designs take advantage of a range of ‘passive’ safety systems based on natural physical processes, rather than just depending on active engineered systems or operator actions. In the LFTR design, the coolant is a molten fluoride salt, with the thorium and uranium dissolved within it (a liquid fuel). If the reactor starts to overheat, the molten salt expands in volume. This causes fissile particles to move away from each other, just like dots on the surface of a balloon spread apart as it is inflated. This heat-expansion feedback, in turn, causes the nuclear reaction to slow down, and allows the reactor to cool. It’s a self-regulating form of control.

In the Integral Fast Reactor (IFR) design, the fuel is a metal alloy (of uranium, plutonium and other heavier elements), not a ceramic oxide like in today’s reactors. Metals are superb heat conductors, which mean that if the reactor overheats, the fuel rods expand, like railway tracks on a hot day. As with the LFTR, this causes the reaction to passively slow or shut down, and natural convection in the sodium coolant then takes heat away from the core without needing active pumps. These stunning safety features are not just theory – they have been proven in experiments at US National Research Laboratories.

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Q2. Considering ‘energy’ itself is free, enough of it all around us and with cheaper, cleaner, safer, decentralised methods of harnessing it as individuals(going ‘off-grid’) and the growing devastating, global crisis of Fuel Poverty on social-economic conditions:

-Why do you think the energy industry and governments are so keen to continue the current dependency on the infinite extraction of gravely finite fuels, wasteful and polluting means of supplying across great distances from source to customer?

-What are the chances of seeing off-grid autonomous power generation becoming our main energy source? what role could it have in eliminating fuel poverty, climate change and the world economy/markets?

Energy from the sun, which powers all renewable energy sources, is abundant but variable and diffuse. Although solar energy is constantly replenished, the test (and cost) lies in capturing and storing this energy on a large scale. Technically, there are many challenges with economically harnessing renewable energy to provide a reliable power supply. Because solar and wind energy is diffuse, collecting it in large amounts requires wide geographical areas to be exploited and large material inputs for building the installations (concrete, steel, glass and other more exotic materials). For some countries, like Australia, the scale of the installations is not, in itself, a major problem, but it is a severe constraint for small nations with high population density, like the UK. The other issue with capturing industrial-scale amounts of solar and wind energy is that it is variable and intermittent (sometimes delivering a lot of power, sometimes a little, and at other times none at all, meaning that they are not ‘dispatchable’), and it also varies seasonally (this is especially true for rooftop solar energy in winter in countries like the UK).

The most commonly proposed ways to overcome intermittency and unscheduled lulls in local renewable energy generation are: (i) to store energy during productive times and draw on these stores during periods when little or nothing is being generated; (ii) to have a diverse mix of renewable energy systems (including distributed generation – the second part of the question being asked), coordinated by a smart electronic grid management system (so that even if the wind is not blowing in one place, it will be in another, or else the sun will be shining or the waves crashing); and (iii) to have fossil fuel or nuclear power stations on standby, to take up the slack when needed.

The reality is that any of these solutions are uneconomic, and even if we were willing and able to pay for them, the result would be an unacceptably unreliable energy supply system. Energy storage (batteries, chemical conversion to hydrogen or ammonia, pumped hydropower, compressed air), even on a small scale, is currently very expensive, and in order to store the truly massive amounts of energy required to keep a city or country going through long stretches of cloudy winter days (yes, these even occur in the desert) or calm nights with little wind and no sun, we would have to ‘overbuild’ our system many times, to allow for  not only delivering  all of our regular power demand, but also  continuing  to do this whilst  charging up the energy stores when it needs to catch up on those low generation periods. This is the case whether or not the system involves hundreds of very large wind or solar ‘farms’, or millions of rooftop-scale PV panels with grid-connected inverters and on-site lead-acid batteries.

As a result, an overbuilt system of wind and solar would, at times, be delivering five to twenty times our power demand, and at other times, none of it. Modelling of these contingencies has shown that a system which relies on wind and/or solar power, plus large-scale energy storage and a geographically dispersed electricity transmission network to channel power to load centres, would be at least an order of magnitude more expensive than an equivalent nuclear-powered system, and still less reliable.

The answer to the first part of the question is therefore that economic and technical realities currently dictate typical government policies on the use of fossil fuels worldwide. Coal is relatively cheap, gas moderately so, and both are natural forms of stored chemical energy. Society has not yet worked out how to properly price (or implement appropriate penalties) on the damaging externalities these fuels cause to society, so they continue to be sought preferentially. If renewables were cheaper than fossil fuels, or even if they were slightly more expensive but were in the convenient form of stored energy, their uptake would be more likely. Nuclear fission, the other low-carbon, low-impact alternative, has the advantage of using an energy-dense stored fuel, but it carries a social stigma in many countries (centred on ‘radiophobia’) that will be a real challenge to overcome. So currently, fossil fuels win by default.

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Q3. My question is about shale gas. It is a natural form of gas which large reserves have recently been found in Lancashire. However, it emits the same levels of greenhouse gases into the environment. Our move from fossil fuels should be for environmental reasons more than a lack of resource. Do you believe we should continue finding new reserves of fossil fuels and try to attenuate the impacts of the emissions, or do we make a move towards a renewable energy future?

Shale gas, derived from fractured sedimentary rocks, is one of the forms of ‘unconventional’ fossil fuels that exist in large quantities. Other unconventional sources include coal-seam gas, deep water offshore oil, tar sands and oil shale. However, these resources are more difficult and costly to extract than conventional oil and gas, requiring substantial energy and chemical inputs and new technologies. Yet, because of the lower quality source material, the extraction efficiency is worse than conventional supplies and faster production-depletion rates are a typical feature. In addition, we are seeing increasingly large local environmental impacts, greater emissions of greenhouse gases, and more public resistance from people concerned about contaminated water supplies and climate change impacts.

Historically, coal, oil and gas have represented a huge store of energy; the accumulated byproduct of millions of years of sunlight harvesting by ancient forests and marine plankton. Most of the cheap and readily available oil and gas, used for transportation, is concentrated in a few, geographically favoured hotspots, such as the Middle East, Russia and parts of South America; coal is found most abundantly in the US, China, India, Australia, Indonesia, Russia and South Africa.

Yet many credible industry analysts are now suggesting that we’re already close to, or have passed, the point of maximum global oil production – at a figure of around 85 million barrels per day – even after accounting for an increasing future use of shale gas and other unconventional fossil fuels. Others, including the International Energy Agency, suggest that with sufficient investment in exploration and improved extraction methods, we may not hit ‘peak’ oil production for a few decades yet. We’ve tapped less of the available natural gas (methane), used mostly for heating and electricity production, but globally, it too has no more than a few more decades of major production left before supplies start to tighten and prices rise significantly, especially if we ‘dash for gas’ as the oil wells run dry.

Most of the world’s coal is buried so deep that we will never access it – even if we were not concerned with the carbon emissions that result from burning coal, we still might only end up using 10 to 20 percent of the estimated 15 trillion tonnes of coal that has been deposited in the Earth’s crust. Why? Because coal is an energy source, and if you need to use more energy to dig it up than you get back from burning it, well, then there’s no point. It just takes too much energy to access the deepest coal seams. A rough estimate is that globally, there may be two centuries of minable coal left, at today’s level of use (less, if we continue to burn more and more each year). Hence to push to stretch our technology to new types of supplies, to keep our seemingly insatiable thirst for fossil fuels quenched.

The development of an 18^th century technology that could turn the energy of coal into mechanical work – James Watt’s steam engine – heralded the dawn of the Industrial Age. Our use of fossil fuels – coal, oil and natural gas – has subsequently allowed our modern civilisation to flourish. It is now increasingly apparent, however, that our almost total reliance on these forms of ancient stored sunlight to meet our energy needs has some severe drawbacks (climate change, environmental pollution, regional economic disparities and resource wars), and cannot continue much longer. As the oil runs out, we need to replace it if we are to keep our vehicles going. Oil is both a convenient energy carrier, and an energy source (we ‘mine’ it).  In the future, we’ll have to create our new energy carriers, be they chemical batteries or oil-substitutes like methanol or hydrogen. On a grand scale, that’s going to take a lot of extra electrical energy – and this is likely to come from both nuclear and renewable sources. Although both of these low-carbon alternatives to fossil fuels will be important, I suspect nuclear fission will play the larger role.

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TOM BLEES

Q1.  Do you think nuclear fusion, as opposed to fission, will be the biggest energy development in the future, or do you foresee other technologies as a more realistic alternative to the burning of fossil fuels?

Fusion has been a hoped-for panacea for years despite the old joke among physicists: “Fusion power is only 40 years away…and always will be.” The prominent Russian physicist who was the founder of the ongoing ITER project (the international fusion research effort), Dr. Evgeny Velikhov, intended for fusion to be the answer to providing unlimited clean energy to the entire planet. Though still dedicated to that effort, Dr. Velikhov and many others realize that the urgent and ever-increasing energy needs of humanity warrant utilizing fission systems until such time as fusion comes of age. We simply cannot afford to wait for fusion—or any other as-yet-undeveloped promising technology—to come to the rescue.

Many data-driven and peer-reviewed studies have been carried out to determine the feasibility of providing humankind’s energy needs utilizing various mixes of systems, particularly so-called renewable energy sources such as wind and solar. Most tend to agree that nuclear power will have to play a dominant role in replacing fossil fuels. (Massive, economically viable and extremely effective carbon sequestration technologies to allow continued use of coal have yet to be demonstrated and so cannot yet be considered dependable solutions—even without taking into account the carbon footprint of coal mining itself, for which there is not even talk of a remedy.) Breakthroughs could conceivably happen with geothermal technology or other systems, but for now we have to plan on using proven methods. As for wind and solar systems’ ability to provide the bulk of our energy, adherents of such views have yet to convincingly solve the problems of energy storage, economics (especially in regard to the massive redundancy necessary) and, especially, intermittency and extended down times that are inherent shortcomings of such systems.

Many who have reflexively rejected nuclear power systems of any kind in the past have recognized that those technologies evolve like any other, and that modern nuclear power plants show every indication of being safe, effective, economical and reasonably fast to build. We saw this with the first two GE Advanced Boiling Water Reactors built in Japan in the Nineties. Even those first-of-a-kind plants took just 36 and 39 months to build. We’re seeing it again as China builds the first Westinghouse-designed AP-1000 nuclear reactors, a so-called Generation III+ design that uses modular construction techniques and passive safety systems that greatly enhance their economics. (GE-Hitachi will soon be building their own III+ design, the ESBWR, that will have similar characteristics.)

Many of the same countries that are building nuclear power plants today are concurrently working on fast reactor systems—so-called breeder reactors—as the ultimate step beyond even the most advanced water-moderated reactors. These fourth-generation reactors will produce more fuel than they use by converting abundant non-fissile uranium 238 into fissile plutonium, forever removing the threat of fuel shortages, since their utilization of uranium’s potential energy is so efficient that even extracting uranium from seawater would be economically viable to fuel them hundreds of years hence, when our current inventories of fuel could finally be used up. Nuclear power systems utilizing thorium as their primary fuel are also being researched and may very well prove their viability and economics with pilot plants in the near future. Prototypes were already built in the Fifties that prove the principles are sound. A couple decades hence we might well witness molten salt thorium reactors and metal-fueled fast reactors replacing water-moderated reactors entirely.

What makes nuclear power such a compelling candidate for future energy demand is its energy density. This is the same feature that conversely makes wind, solar, wave and tidal power systems so difficult to scale up to the needed extent, for they rely on extremely dilute energy sources. No matter how efficient solar cells become, there’s still only a limited amount of solar radiation that falls on any square meter of the earth, even under optimal conditions. Energy density is what led to the age of fossil fuels, and energy density millions of times greater—as is possible with advanced nuclear power systems—is the key to bringing the fossil fuel era to a close.

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Q2. By what year could the UK decarbonise our electricity supply (i.e. run on 100% renewables)? Would this decarbonisation process be quicker with new nuclear power?

David MacKay, the chief science advisor to Britain’s Department of Energy & Climate Change (DECC), wrote a book prior to his assuming that position called Sustainable Energy – Without The Hot Air. In this book Mackay exhaustively explored the entire range of possible energy mixes available to the UK. Like others who’ve undertaken such challenging projects (though rarely with MacKay’s comprehensiveness), his conclusions could not support the feasibility of 100% renewables being able to power the country.

Germany, being at nearly the same latitude and with similar cloud cover issues, has provided a substantial amount of data to weigh the feasibility of an all-renewable path for the UK. We should be grateful to our German friends for dedicating so much effort (and money) to demonstrating what can be accomplished when a government puts its full effort behind wind and solar power. Rather than rely on glib predictions about these systems’ ability to meet all Britain’s energy needs, we need only look at the German data from the past couple decades to get an idea of the viability of renewables to meet the UK’s energy demands.

That data, alas, is not friendly to those who dream of an all-renewables future. Having committed over 75,000,000,000 Euros to solar subsidies and development, Germany can expect to obtain barely 3% of their electrical needs from the sun, and intermittently at that. Wind power projects are as skittish as they always will be by their very nature, and so have not allowed for the retirement of any fossil-fuel power plants despite the additional and not insubstantial money that’s been poured into them.

If the United Kingdom is to decarbonise its electricity supply, the hard numbers indicate that nuclear power will not only do the job faster but that it will be absolutely necessary. Fortunately, this very week, the nation’s energy policy experts and scientists are being offered an elegant solution to both the plutonium disposition issue and the need for safe, carbon-free and essentially unlimited energy for the future. GE-Hitachi has offered to build the first of its cutting-edge PRISM modular fast reactors in Great Britain. This is the fruit of the most forward-thinking energy R&D project ever undertaken in the USA. It took decades of work from a small army of top-flight scientists and billions of dollars to solve all the thorny issues of nuclear power (safety, proliferation resistance, fuel supply and fabrication, waste, etc.). The PRISM reactor that GE is now offering to the UK is the result of that American effort.

Since the PRISM reactor operates at atmospheric pressure and its modules can be factory produced, once the first one is built to demonstrate its effectiveness (which could likely be accomplished within five years) it would be possible to quickly ramp up production and build as many of these power plants as necessary. Since the UK already has the world’s largest supply of plutonium, that startup fuel could quickly be put to good use providing clean energy for British households and industry.

The UK could certainly completely decarbonize its electricity production well before 2050 using this technology. But the potential goes far beyond just the electricity domain. If sufficient PRISM systems are built to meet peak demand, the fact that they operate just fine at full power 24/7 means that vast amounts of excess energy would be available for other uses, such as heating and the production of liquid fuels, that are now met with fossil fuels. Because the PRISM can be fueled with nuclear waste or depleted uranium, that means that its fuel is essentially free (or even better than free, since people would pay to get rid of it). Since peak demand is roughly three times average electrical demand, that means that Britons would have twice as much excess energy for alternative uses as they require for all their electrical needs.

Decarbonizing must include far more than just the electricity sector. The PRISM system can address the full spectrum of energy needs, and it can do so quickly, safely and economically.

Full disclosure: I have absolutely no financial connection of any kind to General Electric or any other energy company. I do, however, want to repair the damage that the industrialized world has wrought upon the planet, and I firmly believe that the PRISM is the best currently-available technology to do that. It is only because nuclear politics in the USA is so dysfunctional that this opportunity is being proffered to the UK instead of being built within the country of its origin.

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Q3. Why is there so much emphasis on fixing the supply side? To reach our targets we need to “simultaneously” reduce the kgCO2/kWh and reduce the total kWh used. Then the benefits will be multiplied and we’ll have a chance to make a real impact on emissions. Why aren’t government talking more about reducing the total demand for energy? Yes, we can do efficiency but it isn’t enough. We need conservation too. Could it be that reducing demand would go directly against their economic goals?

As a resident of California, I’ve been a beneficiary of the most effective energy efficiency policies in the USA. Per capita electricity demand in this state has remained fairly flat for the last three decades, though that statement must be qualified somewhat since some industries have left the state and so reduced the overall electricity demand. Nevertheless, energy efficiency is something that should always be a goal even if we develop virtually unlimited clean energy supplies, since we would still want to save the capital costs of building unnecessary power plants. By the way, you can read about one of the winners of this year’s Global Energy Prize, a man some call the Grandfather of Energy Efficiency, at this website.

But you are right, efficiency is not enough. It isn’t actually an energy source. Talking about conservation and reducing demand for energy is a luxury only allowed those of us in developed nations with already-high per capita energy use. All too often, purported solutions to climate change are trotted out that ignore the fact that the vast majority of people on this planet live in energy poverty. Even if everyone in the USA and the UK stopped using all energy tomorrow, global energy demand would still rise inexorably, for energy availability is inextricably bound to standard of living. This applies to both personal energy use and to the energy used by industries that contribute to high living standards.

If there is to be any egalitarianism and social justice in the world, those living today in poverty must be afforded the opportunity to raise their standard of living to levels enjoyed today in fully industrialized countries. This will be absolutely impossible without a massive increase in global energy supply, all the more so because the world’s population is expected to increase by another 2-3 billion people by mid-century.

But the raw numbers tell only part of the tale. Consider where the fresh water will come from for all those people, not just their personal water use but all the additional water needed to grow the food for such a tide of humanity. The only place where so much fresh water can come from will be from the sea, necessitating desalination projects on a scale hitherto unimagined. Those desalination projects (and the energy needed to move both the water and the salt to their ultimate destinations) will require staggering amounts of energy.

Hence the focus on fixing the supply side. We must consider the entire planet, not just the fortunate nations in which we might live. While ever-better energy efficiency is certainly something to strive for, the policies and technologies to provide virtually unlimited clean energy for the entire planet must be the focus if we are to leave a better and fairer world to our progeny.