Henry Sielmann of Summerland BC discusses Canada's nuclear future.
Pairing Renewables with Nuclear Power Generation to meet 2050 GHG Emission Reduction Targets
Over the years several studies have been published comparing GHG reduction potentials by replacing fossil fuel electrical power generation with either nuclear or renewable alternatives. These studies are typically based on existing nuclear reactor technology classified as Gen (Generation) 1, 2, and 3. This article examines why, in the opinion of the author, new Gen 4 reactor technology combined with renewables, is the key to meeting 2050 GHG emission reduction targets.
CAN NUCLEAR POWER GENERATION BECOME AN ACCEPTABLE ALTERNATIVE TO POWER GENERATION BASED ON FOSSIL FUELS?
Classic Gen 1-3 reactor types are all based on enriched Uranium 235 fission technology that has been employed almost unchanged since the 1970s.
While Gen 1 reactors were early research engines, Gen 2s were built for military (primarily submarine and aircraft carrier propulsion) and commercial use (electrical power generation for public utilities).
Gen 3 post-Chernobyl reactors employ similar fission technology, but incorporate walk-away safety features including gravity fed cooling, which requires no operator action should there be a malfunction. These features help guard against melt-downs of the nuclear core which can lead to catastrophic failure of the containment structure and massive release of nuclear materials and radiation (example Chernobyl which was extremely damaging as it was equipped with neither walk-away safety features nor a containment structure).
The political landscape has been hostile to nuclear power generation for decades though the safety record of 100s of reactors around the world is excellent with a very few, well-understood exceptions.
The US currently operates over 100 reactors producing 20% of its electric power with only one notable accident (Three Mile Island).
France has been operating nuclear power plants since the 1970s and now produces over 70% of its electric power using various types of nuclear reactors. There has been only one notable accident in France (classified as a level 4 accident out of 7 levels on the International Nuclear Event Scale) when in 1980 a reactor was damaged by overheated reactor material.1
The Three Mile Island accident (1979) was one of three level 5 events recorded at nuclear power plants. Canada and the UK experienced one level 5 event each, both in the 1950s. The only Level 6 event worldwide was at a Soviet military nuclear waste reprocessing facility (1957) while Chernobyl (1986) and Fukushima (2011) were the only level 7 events.
In addition to reactor safety, the cost of construction and the effects of long-term storage of spent nuclear material and radioactive waste have long been of major concern. Costs have been brought down to a point where nuclear can compete with fossil generation though it is unclear for any of these technologies to what extent published data includes the cost of decommissioning, environmental clean-up and waste disposal/control. Disposition of spent nuclear material and radioactive waste remain an ongoing challenge.
Given these longstanding issues, should we even consider nuclear as an option? Why not just move to 100% renewable power generation such as solar and wind?
Let’s assess what that means.
CAN WE MOVE TO 100% RENEWABLE POWER GENERATION?
Just like fossil power plants burning coal or natural gas, most commercial Gen 2 and 3 nuclear power plants are high capacity (1-4 GW) generators, providing centralized electrical power capable of supporting industrial plants, urban centres, and entire regions.
1 The severity of unplanned nuclear events is measured on a sliding scale of 7 levels (the International Nuclear Event Scale - INES). Like the Richter scale for measuring earthquake severity, each successive level on the INES represents an event of ten times the severity of the level below. That is, an accident of severity 4 on the scale is ten times as severe as an incident of severity 3. Events ranging from 1-3 in severity are named incidents while events of severity 4-7 are named accidents.
Renewable generation on the other hand is typically based on distributed small capacity installations (0.1 MW – 4MW per unit wind turbine or solar panels) though recently many of these are being combined into high-capacity plants.
Capacity is an important consideration when integrating a generating plant into an existing electrical grid. So is variability of power output which is high for solar and wind power plants but low for hydro, fossil and nuclear plants. Low variability is extremely important to service a baseload of residential, commercial and industrial consumers.
This clearly puts a limit on the use of wind and solar in utility power generation.
The demand for electrical power is projected to increase for decades to come. One example is the impact of climate change on residential housing. Rising temperatures and increased expectations of living standards will drive the installation of air conditioners (AC) across the world. China alone has installed 200 million AC units since 2003, consuming an additional 200 GW of power. India’s demand for AC is estimated to be 150 GW by 2030. The worldwide energy demand for AC is projected to grow from 700 GW now to 2,300 GW by 2050, an increase of 1,600 GW.
With the average coal or gas-fired power plant producing 4 GW of electrical power, this increase in demand alone would trigger the construction of 400 new fossil fuel power plants.
Alternatively, 400,000 off-shore wind turbines or 4.5 million ha (45,000 sqkm) of solar plants, an area equivalent to 150 times the size of Okanagan Lake, need to be added to the current generating capacity. One of the largest solar plants under construction is the 1,000,000 panel, 2.4 sqkm PV, 400 MW Puerto Libertad Solar Plant in the Mexican Sonoran Desert. Covering 10 sqkm of desert floor, ten of these installations would be required in perfectly situated high solar yield locations, to replace just one conventional 4 GW fossil fuel plant. In addition enormous energy storage solutions will be required to service a constant baseload.
On the other hand, a fossil or Gen 3 nuclear power plant with a 4 GW capacity can be built and operated on a 60 ha or 0.6 sqkm site. 400 plants with a combined output of 1,600 GW require 24,000 ha or 240 sqkm, two thirds the size of Okanagan Lake.
This calculation alone illustrates the limits to replacing fossil fuel power generation with renewables, or satisfying future energy needs driven by climate change, improved living standards and population growth. This cannot be ignored: nuclear generation has a footprint 0.5% the size of solar or wind generation of a similar output. And while wind generation is increasingly installed offshore on the continental shelf, growth is limited there as well in addition to the challenge of supplying energy to far away onshore customers. Similar concerns exist for hydropower because most naturally suitable sites have already been developed and the unexplored once are frequently located in remote areas. Local opposition to new dams and unsightly high-voltage transmission lines is an ever increasing factor in addition to dwindling water resources due to climate change.
There clearly are growth limitations to renewable generation capacity.
Which poses the question: if we can overcome longstanding concerns regarding the use of nuclear power, should nuclear complement renewables? And if we have to shut down fossil fuel power generation to meet zero-carbon emission targets by 2050, can we afford not to pursue nuclear?
This leads to the next question.
IS THERE A NUCLEAR ALTERNATIVE TO HELP SATISFY FUTURE ENERGY NEEDS?
There is growing evidence that we need to develop scalable, safe and affordable nuclear power generation. This has spawned worldwide research efforts into the development of Gen 4 nuclear reactors.
A few different approaches exist to developing this new power source. For brevity sake let’s focus on the 195 MW Integrated Molten Salt Reactor (IMSR) modules researched by the Canadian company Terrestrial Energy. These reactors operate at near atmospheric pressure which makes them one of the safest Gen 4 designs. Terrestrial Energy’s technology is based on an enriched molten salt solution which serves both as a coolant and a fuel. Heat is extracted through heat exchangers and transferred to the turbine/generator assembly.
The big improvement from classical nuclear reactors is the progression from U235 fission to blended fission and breeding designs.
Gen 1 – Gen 3 reactors burn enriched uranium 235 but extract only about 8% of the available nuclear energy. The rest is not accessible with that technology. France for a long time has employed breeder reactors which can process this depleted uranium and extract additional energy while reducing the volatility of the material for long-term storage.
Gen 4 reactors take this a step further by simultaneously breeding and burning uranium and plutonium, producing and consuming various nuclear materials in the process. Gen 4 reactors are capable of processing a wide variety of spent nuclear fuels, rendering them safer for long-term storage while extracting sufficient energy from existing stock piles to satisfy global power needs for centuries.
Gen 4 reactors can process depleted nuclear material which is widely available as a by-product of nuclear enrichment for the production of weapons grade uranium.
Terrestrial Energy designed its reactors so that they can be built in 195 MW modules using a central manufacturing facility. Once constructed and tested, the reactors are transported to the customer’s site for installation and commissioning. Controlled manufacturing processes and standardized designs significantly reduce engineering and manufacturing cost while improving quality and safety.
There still exist technical challenges regarding the manufacturability, efficiency and safety of the reactor core. Commercial use of Gen 4 nuclear reactors such as Terrestrial Energy’s IMSR is not anticipated until the 2030s. However, once these engineering hurdles have been overcome, nuclear power can be installed at a much faster rate than renewables when measured by GW added/year. This is particularly the case when Gen 4 modular reactors are mass-produced. Whether sufficient new generating capacity can be built to complement renewables and achieve carbon neutrality by 2050 remains to be seen.
COMBINING RENEWABLES AND GEN-4 NUCLER GENERATION
In addition to its large physical footprint perhaps the biggest drawback of solar and wind power generation is its dependence on the weather. In addition to the day/night cycle severely affecting the output of solar panels, the seasons of the year, changing wind currents and precipitation result in highly variable, often unpredictable power output. Various types of energy storage solutions are being assessed in an attempt to flatten these variations. All are expensive to install and operate; many such as lithium-based batteries or water reservoirs may result in significant disruption of the natural environment.
Steady, reliable, high-capacity baseload power generation 24 hrs/day and 365 days/year is necessary to fuel our society. This function is currently performed primarily by a combination of fossil fuel, hydro and nuclear generating capacity. In eliminating all fossil fuel generation by 2050, and considering the limited growth potential of hydro power generation, growing baseload consumption will have to be satisfied by nuclear technology. Solar and wind indisputably have their place and have played an increasing role across the globe. By blending all available technologies and adjusting their mix based on local conditions, we should be confident that our energy needs can be satisfied while also meeting GHG targets.
Canada has recognized the importance of assessing all available options and has renewed its research into nuclear technologies. Canada has a long history of building the respectable CANDU Nuclear Reactors and is one of the founding members of the Gen IV International Forum. A few weeks ago on October 15, 2020, the Canadian Minister of Innovation, Science and Industry Hon. Navdeep Bains, announced a $20 million investment in Terrestrial Energy to accelerate development of the company’s ISMR Power Plant.
“The Government of Canada supports the use of this innovative technology to help deliver cleaner energy sources and build on Canada’s global leadership in SMRs,” said Minister Bains. “By helping to bring these small reactors to market, we are supporting significant environmental and economic benefits, including generating energy with reduced emissions, highly skilled-job creation and Canadian intellectual property development.” “SMRs are a game-changing technology with the potential to play a critical role in fighting climate change, and rebuilding our post COVID-19 economy,” said Hon. Seamus O’Regan, Minister of Natural Resources.
Canada is expecting to issue a nuclear strategy by the end of this year.
Published by Henry Sielmann, Summerland BC on October 27, 2020