Net Zero | Sustainability | Renewable Energy

 The Doel nuclear power station in Antwerp, Belgium
Doel nuclear power station in Antwerp (represents 15% of total energy for Belgium)

Zero carbon emissions energy

Wind and solar are renewable energy sources which are zero emission energy sources; however they are also intermittent and variable. Nuclear, is also a *"zero" emission energy source; however nuclear continuously generates energy, representing a reliable energy source with the highest capacity factor of any energy source. Nuclear power is somewhat clean (see the notes about toxic waste generated by nuclear power plants below), and is becoming much safer (see the notes about Gen IV nuclear below). Nuclear energy, though NOT a renewable energy source, represents a much more concentrated source of energy than fossil fuels or renewables (a pound of nuclear fuel holds 1 million times more potential for energy production than a pound of fossil fuels, and fossil fuels have a higher energy density than renewables, so nuclear has the highest energy density of any energy source).

In order to stay on track to meet the goal of net zero emissions by 2050, low carbon sources need to meet the interim goal of generating 75% of global energy by 2030. That implies OVER 70% of the world's energy mix must be renewable and nuclear energy combined by 2030. Nuclear and renewable energy are currently the world's zero carbon emissions sources of energy; other low carbon energy sources will hopefully come online in the next several years to help fill in the gap of these ambitious net zero goals.

Nuclear energy has a significantly higher energy production capacity than other energy sources, especially considering that only a relatively small quantity of the fuel (uranium mostly, thorium for future consideration in Gen III, IV plants) is required for nuclear power plants. A small amount of a fossil fuel, say 1 kg of coal, can only keep a light bulb lit for a few days; while the same quantity of fuel from a nuclear energy source will keep the same bulb lit for well over 100 years. Nuclear does this without any CO2, or most other GHG emissions, from the  power plant.

To be clear, once a nuclear power plant is at the operational stage, carbon dioxide emissions from a nuclear reactor are zero. Greenhouse gas emissions (GHGs) from mining and refining uranium into nuclear fuel, transporting toxic waste from nuclear sites to safely store the waste, and maintenance for nuclear reactors are energy-intensive activities that do produce GHGs. Burning nuclear fuel emits no carbon, and minimal other GHGs; with *GHG emissions on par with wind and solar emitted during the lifecycle of energy generation (so, next to nothing). Therefore, nuclear energy production must be considered as a part of the world energy mix needed to fight anthropogenic climate change. [* Note:: neither nuclear nor renewables are actually completely "zero" GHG emissions, but both are relatively just as close to zero emissions as possible; and close enough to zero to be worthy of being called "clean energy", "zero emission" energy sources].

Summation of the global need for nuclear energy

Wind and solar are intermittent renewable energy sources. Nuclear energy, while not a renewable energy source, is an energy-dense, constantly dischargeable, fuel source; that is also a zero carbon emissions source. Renewable energy and nuclear energy both produce little to no greenhouse gas emissions during the energy production process, and both forms of energy do not contribute significantly to anthropogenic climate change. In order to provide global zero emission energy on a scale to mitigate climate change, both nuclear and renewable energy's contribution to energy production on the planet must increase to a combined energy production level which is significantly more than what coal alone currently provides (over 30% of total global energy production). Advanced nuclear technologies (small modular reactors, Gen IV nuclear, some Gen III - see below) are designed to be much more safe and efficient than current reactors.

Both nuclear and renewable energy are needed in the global energy mix to help fight climate change

In order to cut down on the share of fossil fuels in the world energy mix, a total of 40% of the world's energy mix for renewable and nuclear energies combined is needed to reach significant greenhouse gas emission reduction targets.(as an initial goal on the path towards the target of 100% clean, zero emission global energy generation) Only 25% of the total global energy mix of renewable and nuclear combined is projected in the next 20 years - by 2040. In order for the entire planet to achieve at least 30% GHG reduction by 2030 compared to 2005 levels (a reasonable, yet challenging, significant GHG emissions reduction target for the planet), nuclear energy is going to have to augment truly environmentally-friendly, renewable energy in the effort to dramatically reduce fossil fuel use.

Nuclear reactors provided 10% of the world's total energy sources, on average annually, during the last decade. 13 countries get at least 1/4 of their energy from nuclear, including France (which gets around 3/4 from nuclear), Belgium, Sweden, Switzerland, and Finland. Now is probably as good of time as any in this article to mention a couple major drawbacks (to put it mildly) of nuclear energy; namely the danger- catastrophic disasters due to large-scale accidents like the one at Fukushima, Japan, enrichment of uranium in order to create nuclear weapons, and the difficult, expensive process of securely managing the disposal of nuclear waste. The former major problems mentioned (and less waste generated by the nuclear process) are resolved in the 4th generation (Gen IV) nuclear reactor designs, discussed below.

Current reactors, mostly Gen I & II nuclear plants, along with several operational Gen III plants, rely on water and uranium. Therefore, these nuclear plants still deplete water supplies, create nuclear waste, use a fuel source that can be enriched to convert the material into a bomb, and represent a source of potential danger, as in the Fukushima disaster (although this risk is dramatically minimized in a Gen III plant).

Advanced nuclear reactors

Safer, cheaper, still energy abundant and emissions-free designs that use relatively benign energy sources (thorium or depleted uranium), and much less water for cooling the reactor than previous designs and current operational nuclear plants, are being envisioned in 4th generation nuclear, and are currently available in a few 3rd generation nuclear power plant designs.

Using a small fraction of the water as previous designs, Gen IV nuclear plant designs, are safe, cost-effective, environmentally-friendly, and still offer tremendous potential for energy production. Molten salt reactors using depleted uranium, nuclear waste from other plants, or thorium as complete replacement of uranium, are being planned in Gen IV nuclear plant designs. 4th generation designs (and many 3rd generation plants, both planned and operational) are autonomous, smart plants, with heightened safety measures.

In order to meet increased demand for low-emission, safer, lower up-front capital investment, high-efficiency energy sources, there has also been an increased global interest in light water small modular nuclear reactors (SMRs). Benefits of nuclear SMRs include-

Small modular reactors offer a lower initial capital investment, greater scalability, and siting flexibility for locations unable to accommodate more traditional larger reactors.  They also have the potential for enhanced safety and security compared to earlier designs. Deployment of advanced SMRs can help drive economic growth. From- USDOE Office of Nuclear Energy

Thorium  is being looked at as a fuel source for new nuclear reactors, as it is abundant, much less radioactive than uranium, and creates by-products from burning the fuel source that can be used again in the reactor. There is a higher level of thorium than uranium on the planet. Thorium, as well as depleted uranium, are being designed with relatively lower up-front capital costs. Little manpower is needed to run and maintain future, advanced 4th generation nuclear plants, due to the autonomous computer technology set to be deployed in the plants.

Nuclear reactors designed to run on thorium, and depleted uranium, have a very low chance of being developed into a nuclear weapons, produce less radioactive waste, are abundant fuel sources; and are safer, more cost-efficient in addition to being energy-efficient, and cleaner vis-a-vis energy generation compared to current widely deployed nuclear reactors.

One other good thing about nuclear energy production is that there are low marginal costs, and there are little to no negative externalities with regard to the actual energy production (i.e. little to no GHG emissions). Yucca mountain-type facilities, or equivalent toxic waste disposal locations, are necessary to bury the radioactive waste so people aren't exposed to potentially cancer-causing radiation (except in the cases of burning depleted uranium or thorium as fuel, where this risk is minimized, and less extreme means of disposal for nuclear waste can be employed). Also, with nuclear energy in its current form (not Gen IV nuclear) to hope that there's not a Fukushima-type catastrophe.

The US Energy Information Administration estimated that for new nuclear plants in 2018, capital costs will make up 75% of the levelized cost of energy. The major issues with nuclear plants are: how to safely store nuclear waste, the potential for another Fukushima-type disaster, and/ or nuclear weapons proliferation (at least until 4th gen nuclear is ready to be produced and deployed); and the very high up-front capital cost of building new nuclear plants. Keep in mind, when focused on looking at the downsides of technologies for nuclear energy production, 4th generation nuclear promises to be safe, cost efficient (cost of new nuclear fuel is low), and environmentally-friendly, with a very high energy production capacity given a relatively small quantity of nuclear fuel need for energy production (whenever 4th-gen nuclear gets built). New reactors can run on spent uranium and even thorium. 4th generation nuclear has entirely safe, cost efficient designs. Actually, the levelized cost of energy production from new, advanced nuclear reactors that are already available, deployed, and generating nuclear energy, is looking viable.

Thorium, in particular, is being looked at by developing nations like China and India because of the relatively low cost, increased safety, abundance of the material, and tremendous energy potential of this energy source. The U.S. has huge amounts of thorium, in places like Kentucky and Idaho (as well as depleted uranium); and there are large quantities in countries like India, Australia and Brazil.

The U.S., Europe, and even some of the aforementioned developing countries, also have large stockpiles of depleted uranium, with more being produced every day, which would work in many of the 4th generation designs. 3rd generation nuclear plants are already operating, and some 4th generation plants are projected to be developed and ready for operation by 2025. 4th generation nuclear promises to produce abundant, low-cost energy safely, and with little environmental impact.

For a comprehensive guide on public policy that also increases nuclear energy globally, in order to help fight anthropogenic climate change, please see: Public policy proposal to stabilize greenhouse gas emissions

Please also see:

Renewable energy overview

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  1. Please let us here at Green City Times know what you think in a comment; and we’ll try and answer any questions as well.

    Please also visit our other blog at

    [Dan Braff is the founder of GCT –

    Daniel Braff]

    • Any serious scientist, engineer or economist verifies that nuclear is crucial to reducing GHG in the next three decades. Especially given the weekly introduction of new coal plants in India and China and the enormous base load electrical demand in those countries alone. Waste disposal has been solved and is a political and marketing issue, not a technical issue.

      The crucial question is how nuclear power can be marketed successfully to the developing country elites and serious accounting and engineering work is done to lower the cost of nuclear plants. How can this marketing be achieved ? Movies starting Hollywood stars ? Al Gore standing up for the truth about nuclear ? This is a more important problem than gen 4 vs gen 3 technology – without a reversal of the “china syndrome” and radiation scare tactics, the GHG reduction effort is doomed.

      • Nuclear is essential to maintaining a “baseload” energy source for the grid. Hopefully as SMRs and other advanced nuclear reactors see technological breakthroughs and subsequent mass deployment; it will become more obvious globally, and in context of the Paris Climate Accord, that nuclear is a necessary sustainable energy source to reach net zero by 2050.

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