LAS203-FINAL Notes PDF

LAS203-FINAL Notes: *Calculations: -​ Power = the rate at which energy is transferred → Power = Energy/Time -​ 1 kWh = 10^3 * (60 * 60) = 3.6 * 10^6 J -​ E=P*t -​ Formula to estimate an appliance’s energy use: -​ Wattage * hours used per day / 1000 = daily ki...

LAS203-FINAL Notes: *Calculations: -​ Power = the rate at which energy is transferred → Power = Energy/Time -​ 1 kWh = 10^3 * (60 * 60) = 3.6 * 10^6 J -​ E=P*t -​ Formula to estimate an appliance’s energy use: -​ Wattage * hours used per day / 1000 = daily kilowatt-hour (kWh) consumption -​ Multiply by the number of days you use a particular appliance during the year for the annual energy consumption -​ 1kW = 1,000 watts → why we divide by 1,000 -​ You can calculate the annual cost to run an appliance by multiplying the kWh per year by your local utility’s rate per kWh consumed (e.g., $0.4/kWh) -​ Energy intensity (I in kWh/$) = primary energy consumption per capita per year (kWh) / GDP per capita ($) *Unit 4: climate change and energy policy → climate change and the cedars of Lebanon -​ After centuries of human depredation, the cedars of Lebanon face perhaps their most dangerous threat: climate change could wipe out most of the country’s remaining cedar forests by the end of the century → rising temperatures push their natural habitat higher up the mountains where colder winters are essential for their reproduction -​ In areas like the Barouk forest within the Shouf Biosphere Reserve, the cedars have almost no higher ground left, indicating a looming risk if warming continues as projected -​ The Tannourine Cedars Forest Nature Reserve, Lebanon's densest cedar forest, faces additional challenges from a climate-change-induced pest, the cedar web-spinning sawfly (Cephalcia tannourinensis) -​ Rain and snow days have drastically decreased, shortening the snow cover period that previously helped manage the pest population by slowing down the sawfly's life cycle → Lecture 10: CO2 and other GHG emissions -​ [CO2] measurements: -​ Today, we measure CO2 directly in the atmosphere using sensors and other instrumentation technology → the Mauna Loa Observatory (MLO) in Hawaii has been continuously recording atmospheric CO2 since the 1950s, providing one of the longest and most reliable datasets on global CO2 concentrations -​ Ice core sampling: for historical CO2 data extending back hundreds of thousands of years, scientists analyze ice cores: -​ Ice cores contain air bubbles trapped at the time the ice was formed, offering snapshots of ancient atmospheric compositions  -​ These cores can be as deep as 3 kilometers, representing layers formed up to 800,000 years ago -​ By chemically dating ice core layers, researchers can determine the age of specific depths +​ by counting the annual layers preserved in glacial ice, we can date these atmospheric samples, providing a record of how CO2 changed over time in the past +​ the ice cores also give us a temperature record → by studying the ratios of stable isotopes of oxygen that make up the glacial ice, we can estimate the temperature (in the region of the ice) at the time the snow fell (the compression of snow forms glacial ice as it gets buried to greater and greater depths) -​ Revelle and Charles Keeling began monitoring atmospheric CO2 levels at Mauna Loa Observatory in Hawaii, chosen for its high elevation and remote location, minimizing industrial influence -​ This CO2 record, now one of the most iconic scientific plots, revealed the impact of human activity on the global carbon cycle, capturing worldwide attention -​ CO2 concentrations crossed 400 ppm for the first time in millions of years, reaching a yearly average of 412 ppm in 2018 → today, we are 419.44 ppm = it is always increasing, which is alarming → the data also gives a local maximum & minimum → in winter, we have a local maximum & in summer, a local minimum = in winter, we don’t have a lot of vegetation/plants to take CO2 out of the atmosphere & in summer, we have lots of them that take out CO2 from the atmosphere -​ Global CO2 atmospheric concentration: -​ The large growth in global CO2 emissions has had a significant impact on the concentrations of CO2 in Earth’s atmosphere -​ If we look at atmospheric concentrations over the past 2000 years, we see that levels were fairly stable at 270 to 285 parts per million (ppm) until the 18th century -​ Since the Industrial Revolution, global CO2 concentrations have been increasing rapidly -​ If we look even longer-term (greater than 800,000 years into the past) we see that today’s concentrations are the highest they’ve been -​ The cycles of peaks and troughs in CO2 concentrations track the cycles of ice ages (low CO2) and warmer interglacials (higher CO2) -​ Concentrations in the atmosphere will continue to rise unless emissions are significantly reduced due to CO2’s long atmospheric residence time -​ CO2 remains in the atmosphere for varied durations → some is removed within 5 years, but absorption by vegetation, soils, and the deep ocean can take hundreds to thousands of years -​ To slow and eventually halt temperature rise, we need to stabilize CO2 and greenhouse gas concentrations, but there is a lag between stabilizing these concentrations and the subsequent stabilization of global temperatures → CO2 concentration changes that historically took centuries or millennia have now occurred within a few decades, challenging ecosystems and species’ ability to adapt -​ The world’s largest per capita CO2 emitters are the major oil-producing countries -​ Most are in the Middle East: in 2017, Qatar had the highest emissions at 49 tonnes (t) per person, followed by Trinidad and Tobago (30t); Kuwait (25t); United Arab Emirates (25t); Brunei (24t); Bahrain (23t) and Saudi Arabia (19t) -​ China, USA, and EU-28 (today, EU-27 w/o the UK) emit the most CO2 → to reach our climate goal of limiting average temperature rise to 2 degrees, the world needs to urgently reduce emissions = one common argument is that those countries which are contributing most to the problem today should take on the greatest responsibility in tackling it -​ USA, Russia, and China have the highest cumulative CO2 emissions = the total sum of CO2 emissions produced from fossil fuels and cement since 1750, measured in tonnes -​ Up until 1950, more than half of historical CO2 emissions were emitted by Europe -​ Over the century that followed, industrialization in the USA rapidly increased its contribution -​ It’s only over the past 50 years that growth in South America, Asia, and Africa has increased these regions’ share of the total contribution -​ Other GHG = CO2 is not the only greenhouse gas that is driving global climate change -​ There are a number of others, such as methane, nitrous oxide, and trace gases such as the group of “F-gases”, which have contributed a significant amount of warming to date  -​ Greenhouse gases are measured in “carbon dioxide-equivalents” (CO2e) -​ Today, we collectively emit around 50 billion tonnes of CO2e each year -​ CO2 equivalents (CO2e): a metric used to express the warming impact of different greenhouse gases in terms of the equivalent amount of CO2 -​ CO2e helps standardize greenhouse gas measurements, enabling comparisons of gases with varying warming effects -​ Global Warming Potential (GWP): each greenhouse gas is assigned a GWP over a 100-year timeframe, representing its warming impact relative to CO2 → EXAMPLE: methane (CH4), with a GWP of 28, means one tonne of CH4 is equivalent to 28 tonnes of CO2 in warming effect over 100 years *e.g., 10kg of CO2 & 1kg of CH4 → CO2e = (10*1)+(1*28) = 38kg CO2e -​ By converting each greenhouse gas to its CO2e, total emissions can be summed up to provide a single, comparable measure -​ As is the case with CO2 emissions, China is the world’s largest emitter of greenhouse gases today (> 10 billion tonnes) -​ It emits around twice as much as the United States, which is the second-largest emitter, followed by India, Indonesia and Russia -​ Per capita greenhouse gas emissions: measured in tonnes per person per year -​ Many of the world’s smaller countries are the largest per capita emitters → these countries, such as Guyana, Brunei, Botswana, the United Arab Emirates, and Kuwait tend to be large oil and/or gas producers (> 15 tonnes) -​ Of the major emitters, we see large differences in per capita emissions: in the US, the average person emits more than 18 tonnes; in China, it's less than half, at 8 tonnes; and in India, emissions are much smaller at around 2.5 tonnes -​ Electricity and heat production are the largest contributors to global emissions -​ This is followed by transport, manufacturing, and construction (largely cement and similar materials), and agriculture -​ If we look at the United States, for example, transport is a much larger contributor -​ In Brazil, the majority of emissions come from agriculture and land use change -​ BUT land use change and forestry TAKES CO2 AWAY from the atmosphere → does not emit -​ Food production contributes around 26% of global greenhouse gas (GHG) emissions -​ The food system, including production, processing, and distribution, significantly impacts emissions but lacks widespread technological solutions to reduce its footprint effectively -​ Methane: → comes from several primary sources: -​ Agriculture: -​ Livestock: ruminant animals like cattle, goats, and sheep produce methane through enteric fermentation during digestion  -​ Rice cultivation: waterlogged paddy fields create an ideal environment for microbes to produce methane through methanogenesis -​ Biomass burning: incomplete combustion of woodlands, savanna, and agricultural waste generates methane -​ Waste: organic waste in landfills decomposes and produces methane as a byproduct -​ Fossil fuel production: methane can be released during oil and gas extraction, often referred to as fugitive emissions -​ Considered a short-lived greenhouse gas, with an average lifetime of around 12 years in the atmosphere → unlike carbon dioxide, which can persist for centuries or longer -​ This short atmospheric lifetime means that reducing methane emissions can result in a rapid decrease in its atmospheric concentration, offering an effective way to mitigate some of the impacts of climate change within a decadal timeframe -​ Atmospheric methane is measured in parts per billion (ppb) -​ The largest contributors to methane emissions are USA, Russia, and China, with more than 1 billion tonnes emitted over 100 years -​ Nitrous oxide (N2O): -​ Primarily produced by agricultural activities, particularly through the use of nitrogen fertilizers -​ It is created by microbes in soils, but when nitrogen fertilizers (synthetic or organic, like animal manure) are applied, the increased nitrogen availability leads to higher production of nitrous oxide -​ Not all of the nitrogen from fertilizers is absorbed by crops, contributing to this emission -​ Nitrous oxide is 265 times more potent as a greenhouse gas than carbon dioxide (CO2) over a 100-year period -​ The average lifetime of nitrous oxide in the atmosphere is approximately 121 years → while this is much shorter than CO2 (which can persist for centuries or millennia), it is longer than methane, which stays in the atmosphere for about 12 years -​ Nitrous oxide concentrations are measured in parts per billion (ppb) -​ Much like methane, concentrations increased significantly throughout the 20th century, and particularly sharply in the second half → this coincides with the rise of the use of nitrogenous fertilizers (agriculture is the largest source of N2O) and large increases in global food production -​ China, India, USA and Southern USA lead in N2O emissions, with more than 1 billion tonnes emitted over a 100-year period -​ The countries with the highest per capita methane emissions are Mongolia, Australia, Cameroon, and Central African Republic → Lecture 11: climate change -​ The climates of the world and some of the major climate types differ in terms of characteristic precipitation and temperature conditions -​ We live in the Mediterranean climate -​ In order for our climate not to change, the planet needs to emit back 100% of the radiation it receives -​ Some heat is being trapped in the atmosphere = reason why the climate is changing -​ Human emissions of greenhouse gases (especially CO2) are the primary driver of climate change -​ This link between global temperatures and greenhouse gas concentrations has been consistent throughout Earth's history -​ Over the last few decades, global temperatures have risen sharply by approximately 0.7 degrees compared to the 1961-1990 baseline -​ Back in 1850, temperatures were about 0.4 degrees colder than the 1961-1990 baseline -​ Overall, this results in an average global temperature rise of 1.1 degrees -​ A changing climate has a range of potential ecological, physical, and health impacts, including extreme weather events (such as floods, droughts, storms, and heatwaves); sea-level rise; altered crop growth; and disrupted water systems -​ Global warming is not uniform across the world; temperature changes vary significantly by region -​ Environmental, ecological, and human effects of global warming: -​ Changes in river flow: -​ With a continuation of global warming, melting of glacial ice and reductions in snow cover are anticipated to accelerate throughout the twenty-first century -​ This is also projected to reduce water availability and hydropower potential, and change the seasonality of flows in regions supplied by meltwater from major mountain ranges -​ Overconsumption  -​ Agricultural lands taking water from the sea and building channels for irrigation -​ Less rain in some areas -​ Rise in sea level: -​ Thermal expansion of water as it warms -​ Melting ice sheets on land adds water to the oceans -​ Current rate of rise: approximately 23 cm per century since the last ice age -​ Future projections: -​ Global warming could double the rate of sea level rise -​ Predictions vary from 20 cm to 2 meters by the end of this century -​ Most likely rise is 20-40 cm -​ About 50 million people face flooding each year due to storm surges -​ As the sea level rises and populations grow, more people will be vulnerable to coastal flooding -​ Island nations and coastal areas are particularly threatened, with risks of coastal erosion and increased damage to structures from waves -​ Change of mass of US glaciers -​ Change in mass of ice sheets -​ Changes in biological diversity: -​ Global warming's effects on biodiversity are uncertain due to the complexity of organisms and their responses to warming, nutrient availability, predator-prey relationships, and habitat competition -​ Black guillemots: -​ A decline in abundance has been observed in black guillemots, linked to warming temperatures since the 1990s -​ The receding sea ice has increased the distance between feeding grounds and nesting sites, now up to 250 km (previously under 30 km) -​ Loss of food sources has affected the birds' ability to feed their chicks, reducing their survival rate -​ The fate of the guillemots depends on springtime weather → too warm: the species may disappear; too cold: insufficient snow-free days for breeding, leading to their potential disappearance -​ Wildfires: -​ Increasing heat, changing rain and snow patterns, shifts in plant communities, and other climate-related changes have vastly increased the likelihood that fires will start more often and burn more intensely and widely than they have in the past -​ Can also be caused by human error as the weather is very dry → easy to start a fire and spread it -​ Glaciers and sea ice:  -​ A major concern is whether global warming will lead to a great decline in the volume of water stored as ice, especially because the melting of glacial ice raises the mean sea level -​ Global emissions have not yet peaked: -​ To stabilize (or even reduce) concentrations of CO2 in the atmosphere, the world needs to reach net-zero emissions -​ This requires large and fast reductions in emissions -​ At a time when global emissions need to be falling, they are in fact still rising -​ Those that have access to energy produce greenhouse gas emissions that are too high → the richer the country, the more CO2 per capita emissions we have as people can afford energy/heating/luxury cars… -​ Some countries have scaled up nuclear power and renewables and are doing much better than the global average -​ In France, 92% of electricity comes from low-carbon sources, in Sweden, it is 99% → Lecture 12: energy policies -​ Paris Agreement: -​ The Paris Agreement is a legally binding international treaty on climate change -​ It was adopted by 196 Parties at COP21 in Paris, on 12 December 2015, and entered into force on 4 November 2016 -​ The Agreement sets long-term goals to guide all nations: -​ Substantially reduce global greenhouse gas emissions to limit the global temperature increase in this century to 2 degrees while pursuing efforts to limit the increase even further to 1.5 degrees -​ Review countries’ commitments every five years → submit an updated national climate action plan (Nationally Determined Contribution, or NDC, which will be available for all countries to check) +​ track progress towards their commitments under the Agreement through a robust transparency and accountability system -​ Provide financing to developing countries to mitigate climate change, strengthen resilience, and enhance abilities to adapt to climate impacts -​ Today, 191 Parties (190 countries plus the European Union) have joined the Paris Agreement -​ The operational details for the practical implementation of the Paris Agreement were agreed on at the UN Climate Change Conference (COP24) in Katowice, Poland, in December 2018, in what is colloquially called the Paris Rulebook -​ The agreement recognizes the role of non-Party stakeholders in addressing climate change, including cities, other subnational authorities, civil society, the private sector, and others -​ Whilst current climate policies fall well short of what’s needed to keep temperatures below 1.5 degrees or 2 degrees, countries have set more ambitious targets to reach net-zero emissions -​ The inclusion criteria may vary from country to country → some countries may include international aviation and shipping in their net-zero commitment, while others do not -​ Reducing emissions: -​ Improving efficiency (using less energy to produce a given output; and using less land, fertilizer, and other inputs for food production, and reducing food waste) -​ Transitioning to low-carbon alternatives -​ How can we decarbonize our energy systems? -​ Shift towards low-carbon electricity (reduce carbon intensity → carbon per unit energy):  -​ Renewables & nuclear energy -​ Shift from coal to gas (which emits less CO2 per unit energy) as an interim step -​ Shift sectors such as transport, toward electricity: -​ Some energy sectors are harder to decarbonize → for example transport THEREFORE we need to shift these forms towards electricity where we have viable low-carbon technologies -​ Develop low-cost low-carbon energy and battery technologies -​ Improve energy efficiency: energy per unit GDP -​ The 2024 UN Climate Change Conference (UNFCCC COP 29) will convene from 11 to 22 November 2024 in Baku, Azerbaijan -​ Should the government regulate the energy sector? → 2 SIDES: -​ If we are to meet our climate goals, government intervention is crucial to support the development and commercialization of new technologies while actively creating markets that value the qualities we want to see in an advanced energy system: zero carbon emissions, energy reliability, and resilience -​ The free market should regulate it: no need for government intervention and regulation → once a renewable technology becomes cheap and competitive, it will automatically replace fossil fuel *Unit 5: energy in transportation -​ There was a time when diesel was cheaper than gasoline SO taxi drivers moved to it BUT today they are approximately the same price -​ Plug-in hybrid car: electric but also runs on gasoline → when the battery runs out, it moves to gasoline -​ Pure hybrid: when the car moves, the rotation of the wheel charges the battery  -​ Hydrogen fuel cell: operates on hydrogen → emits 0 carbon emissions; emits H2O instead of CO2 into the atmosphere → if bought from methane = harmful BUT can be produced from water (electrolysis); harmless if bought from renewable energies -​ Electric car: emits 0 carbon emissions -​ 2017: Toyota used to produce the most cars -​ Tesla asked BYD to produce their batteries BUT then BYD started their own venture into the automotive industry -​ VW is in trouble globally because they cannot compete in the Chinese market -​ Norway is leading globally in the transition to 0 carbon emission cars by using battery-electric cars -​ Around 10 years ago, 85% of cars were running on fossil fuels (diesel or petrol) -​ Today, plug-in hybrid and battery-electric cars are increasing in use (more than 60% usage in Norway) → Norway is leading globally in the transition to 0 carbon emission cars by using battery-electric cars (25% of new cars are battery-electric) -​ Countries have put a target date to stop selling gasoline/diesel cars (phase-out of fossil fuel vehicles) → Norway = 2025; Iceland, Ireland, Slovenia, Netherlands = 2030; Denmark = 2035… -​ Carbon intensity: grams of CO2 emitted per km traveled → Switzerland, Germany, Luxembourg… have some of the highest carbon intensity values as they can afford luxury cars that emits lots of CO2 into the atmosphere + mountainous countries (emits more CO2 than driving on flat land) -​ Fuel economy: L per 100 km traveled → aviation & rail industry: -​ Global aviation (including domestic and international; passenger and freight) accounts for 1.9% of greenhouse gas emissions (which includes all greenhouse gases, not only CO2) and 2.5% of CO2 emissions → 2018: aviation industry emitted 1.04 billion tonnes of CO2 into the atmosphere -​ Most emissions come from passenger flights: in 2018, they accounted for 81% of aviation’s emissions; the remaining 19% came from freight, the transport of goods -​ 60% of emissions from passenger flights come from international travel; the other 40% come from domestic (in-country) flights -​ When we break passenger flight emissions down by travel distance, we get a (surprisingly) equal three-way split in emissions between short-haul (less than 1,500 kilometers); medium-haul (1,500 to 4,000 km); long-haul (greater than 4,000 km) journeys -​ Also divided in terms of income: high-income countries (16% of population); upper-middle income countries (35% of population); low income countries (9% of population)  → East-Asia (Japan & China) + France have some of the most developed railways → truck (with trailer) is the most energy-intensive mode of transport: with a value of 3.75 kWh/passenger-kilometer, it consumes significantly more energy per passenger compared to other modes, likely due to the low passenger capacity of trucks → towards zero-carbon transport: → today, CO2 is mainly emitted by passenger cars BUT the projection of 2070 shows that it is expected to completely decarbonize 2-3 wheelers (expected to run on electricity by 2040) BUT aviation, shipping, and medium-to-heavy trucks are the hardest to switch to electricity -​ Expected growth in transport demand (International Energy Agency = IEA projections): -​ Transport demand (passenger-kilometers) will double by 2070 due to: -​ Rising global population -​ Increasing incomes and affordability of transport modes (cars, trains, flights) -​ Car ownership is projected to increase by 60% -​ Passenger and freight aviation demand is expected to triple -​ Technological innovations to reduce emissions: -​ Electric vehicles (EVs): a promising solution for reducing emissions from passenger vehicles as electricity shifts to lower-carbon sources -​ Hydrogen technologies: can help decarbonize specific transport sub-sectors -​ Sustainable development scenario (reflected in the IEA’s Energy Technology Perspective report): -​ Aims for net-zero CO2 emissions in global energy by 2070 -​ Timeline for decarbonization in transport sub-sectors: -​ Motorcycles: phased out by 2040 -​ Rail: decarbonized by 2050 -​ Small trucks: emissions eliminated by 2060 -​ Cars and buses: phased out in regions like the EU, US, China, and Japan by 2040, with global emissions nearing elimination by 2070  -​ Challenges in hard-to-decarbonize sub-sectors: -​ Long-distance road freight (large trucks), aviation, and shipping face significant hurdles: -​ Hydrogen and battery-electric solutions are limited by range, power, size, and weight constraints -​ These sectors will likely remain major contributors to transport emissions -​ Residual emissions and negative emission solutions: -​ Despite projected emissions reductions by three-quarters, transport could remain the largest energy-related emissions contributor by 2070 -​ Net-zero for the energy sector will require: -​ Offsetting transport emissions with negative emissions technologies like carbon capture and storage from bioenergy or direct air capture. -​ Car companies are concerned with reverse engineering (reproduction of another manufacturer's product following detailed examination of its construction or composition) → HYDROGEN FUEL CELLS are difficult to get your hands on -​ 5 years ago, the driving range of electric cars was very low BUT today, they have high driving ranges → disadvantages of electric cars: battery made of lithium (rare Earth element; extracting it emits lots of CO2; efficiency decreases over time), charging time, charging it from the grid (if charging at night) *Unit 6: nuclear energy → Lecture 14: -​ The 4 fundamental forces of nature: -​ Electromagnetism: interaction that occurs between particles with electric charge → 2 positive charges repel & 2 opposite charges attract -​ Weak interaction: responsible for radioactive decay -​ Strong interaction: reason for which protons and neutrons do not repel + causes nuclear energy -​ Gravitation → in our DAILY LIVES, we interact with gravity & electromagnetism → X^A (up) & Z (down) with A = number of protons + neutrons (nucleons); Z = number of protons -​ Nuclear energy is the energy in the nucleus, or core, of an atom → can be used to create electricity, but it must first be RELEASED FROM THE ATOM -​ The nucleus contains protons and neutrons, held together by the strong force (the strong force becomes ineffective at distances greater than 3 femtometers (fm) → 1 fm = 10^-15 km) -​ Nuclear energy can be produced in two ways: fission, when nuclei of atoms split into several parts, or fusion, when nuclei fuse together -​ The nuclear energy harnessed around the world today to produce electricity is through NUCLEAR FISSION, while technology to generate electricity from fusion is at the R&D phase 1.​ Fission: a nucleus much heavier than iron splits into two lighter ones → the binding energy per nucleon of the fragments is greater than that of the original nucleus, so energy is released → it has problems: nuclear waste + enrichment of 235^U 2.​ Fusion occurs when nuclei much lighter than iron join to form a heavier one → the increased binding energy per nucleon results in energy release → elements with the same Z BUT a different A = ISOTOPES 1.​ Nuclear fission is a reaction where the nucleus of an atom splits into two or more smaller nuclei, while releasing energy -​ For instance, when hit by a neutron, the nucleus of an atom of uranium-235 splits into a barium nucleus and a krypton nucleus and two or three neutrons → these extra neutrons will hit other surrounding uranium-235 atoms, which will also split and generate additional neutrons in a multiplying effect, thus generating a chain reaction in a fraction of a second -​ Each time the reaction occurs, there is a release of energy in the form of heat and radiation → the heat can be converted into electricity in a nuclear power plant, similarly to how heat from fossil fuels such as coal, gas and oil is used to generate electricity  2.​ Nuclear fusion is the process by which two light atomic nuclei combine to form a single heavier one while releasing massive amounts of energy -​ Fusion reactions take place in a state of matter called plasma, hot, charged gas made of positive ions and free-moving electrons that has unique properties distinct from solids, liquids and gases -​ The sun, along with other stars, is powered by a reaction called nuclear fusion → if this could be replicated on Earth, it could provide virtually limitless clean, safe, and affordable energy to meet the world’s energy demand -​ Nuclear fusion research: conducted in over 50 countries, with fusion reactions successfully achieved in experiments → challenge: net fusion power gain has not yet been demonstrated -​ Achieving star-like fusion on Earth depends on global partnerships and resource mobilization -​ Inside nuclear power plants, nuclear reactors and their equipment contain and control the chain reactions, most commonly fuelled by uranium-235, to produce heat through fission -​ The heat warms the reactor’s cooling agent, typically water, to produce steam -​ The steam is then channelled to spin turbines, activating an electric generator to create low-carbon electricity → pressurized water reactors are the most used in the world → mining, enrichment, and disposal of uranium:  -​ Because nuclear fuel can be used to create nuclear weapons as well as nuclear reactors, only nations that are part of the Nuclear Non-Proliferation Treaty (NPT) are allowed to import uranium or plutonium, another nuclear fuel → the treaty promotes the peaceful use of nuclear fuel, as well as limiting the spread of nuclear weapons -​ A typical nuclear reactor uses about 200 tons of uranium every year -​ Complex processes allow some uranium and plutonium to be re-enriched or recycled → this reduces the amount of mining, extracting, and processing that needs to be done -​ Uranium is a metal that can be found in rocks all over the world → has several naturally occurring isotopes, which are forms of an element differing in mass and physical properties but with the same chemical properties -​ 2 PRIMORDIAL ISOTOPES: uranium-238 and uranium-235 → uranium-238 makes up the majority of the uranium in the world BUT cannot produce a fission chain reaction, while uranium-235 can be used to produce energy by fission BUT constitutes less than 1% of the world’s uranium -​ To make natural uranium more likely to undergo fission, it is necessary to increase the amount of uranium-235 in a given sample through a process called URANIUM ENRICHMENT* → once the uranium is enriched, it can be used effectively as nuclear fuel in power plants for three to five years, after which it is still radioactive and has to be disposed of following stringent guidelines to protect people and the environment -​ Used fuel, also referred to as spent fuel, can also be recycled into other types of fuel for use as new fuel in special nuclear power plants *To use U-235 as an energy source, companies mine and enrich the ore: 1.​ After the ore is mined, it is mixed with groundwater to dissolve uranium oxides 2.​ The oxide is filtered and dried and is known as YELLOW CAKE 3.​ Enrichment requires the uranium be in gaseous form, so it is converted to uranium hexafluoride 4.​ Enriched uranium is turned into uranium oxide and pressed into pellets for use as fuel rods  -​ Nuclear fuel cycle: an industrial process involving various steps to produce electricity from uranium in nuclear power reactors → the cycle starts with the mining of uranium and ends with the disposal of nuclear waste → facts on nuclear energy: -​ Nuclear fuel is extremely dense → it’s about 1 million times greater than that of other traditional energy sources and because of this, the amount of used nuclear fuel is not as big as you might think -​ All of the used nuclear fuel produced by the U.S. nuclear energy industry over the last 60 years could fit on a football field at a depth of less than 10 yards -​ That waste can also be reprocessed and recycled, although the United States does not currently do this → however, some advanced reactors designs being developed could operate on used fuel -​ Byproducts of nuclear energy: -​ Radioactive material contains unstable atomic nuclei, which release energy -​ Can cause burns, cancers, blood diseases, and bone decay -​ Long-lasting waste remains hazardous for thousands of years -​ Radioactive waste: -​ Includes protective clothing, tools, and materials exposed to radioactive dust -​ Requires strict government regulation for safe disposal to prevent contamination -​ Used fuel storage: -​ Removed nuclear fuel from the reactor remains highly radioactive -​ Uranium pellets stored in pools to cool and isolate radioactivity -​ Some nuclear plants use dry storage tanks above ground -​ Controversies over storage sites: -​ Proposed nuclear waste facility at Yucca Mountain, Nevada sparked environmental concerns -​ Protesters feared leakage into the water supply and local environment -​ Plans for Yucca Mountain facility were halted in 2009, despite decades of investigation -​ Big DISADVANTAGE: nuclear waste → the operation of nuclear power plants produces waste with varying levels of radioactivity -​ Low level waste: -​ Includes items that have become contaminated with radioactive material -​ This is typically contaminated protective clothing and shoe covers, wiping rags, mops, filters, reactor water treatment residues -​ Also includes medical tubes, injection needles, lab animal carcasses and tissues -​ Can be stored on site until quantities are sufficient to send to a low level waste disposal site in appropriate containers where it is buried  -​ Burial sites must be far from ground or surface water (or lined with an impermeable layer to prevent contamination via leaks) and in seismically stable areas -​ High level waste: -​ Spent (used) reactor fuel that can no longer create electricity because fission has slowed but is still thermally hot and highly radioactive, emitting beta and gamma radiation -​ MUST BE STORED ON-SITE in specially designed pools made of reinforced concrete with 40 feet of water or in dry casks → activity & half-life: -​ The activity (symbol R) is simply the absolute value of the decay rate -​ The SI unit of activity is the Becquerel (Bq), with 1 Bq = 1 decay/s -​ An older unit often still used is the Curie (Ci), defined as the activity of naturally occurring radium = ~37 billion decays/s → N = number of nuclei at a time t; No = number of nuclei at a time t = 0; lambda = radioactive constant -​ Half-life (t1/2) is defined as the time for half the nuclei in a radioactive sample to decay → nuclear energy trends: -​ Transition to low-carbon energy: shift from fossil fuels to renewable energy (hydropower, wind, solar) and nuclear power -​ Environmental benefits of nuclear energy: -​ Low CO2 emissions per unit of energy -​ Significantly less air pollution compared to fossil fuels -​ Diverging global approaches: -​ Some countries are expanding nuclear energy supply -​ Others are decommissioning nuclear plants -​ How much of our energy comes from nuclear power? How is its role changing over time? We look at levels and changes in nuclear energy generation across the world, and its safety record in comparison to other sources of energy -​ Nuclear energy, alongside hydropower, is one of our oldest low-carbon energy technologies -​ Nuclear power generation has been around since the 1960s, but saw massive growth globally in the 1970s, 80s and 90s → global nuclear generation has changed over the past half-century -​ Following fast growth during the 1970s to 1990s, global generation has slowed significantly -​ We see a sharp dip in nuclear output following the Fukushima tsunami in Japan in 2011, as countries took plants offline due to safety concerns -​ We also see that in recent years, production has once again increased -​ The U.S is leading in terms of nuclear power generation, with more than 800 TWh produced in 2020, compared to China having produced ~380 TWh -​ The global trend in nuclear energy generation masks the large differences in what role it plays at the country level -​ Some countries get no energy at all from nuclear, or are aiming to eliminate it completely, whilst others get the majority of their power from it → the amount of nuclear energy generated by country  -​ France, the USA, China, Russia and Canada all produce relatively large amounts of nuclear power -​ Regarding PER CAPITA ENERGY CONSUMPTION FROM NUCLEAR, France, Sweden, the USA, Russia and Canada are all leading with 2,500 to more than 7,500 kWh of nuclear energy used -​ Regarding the share of PRIMARY ENERGY from nuclear: -​ France is leading with more than 30% of primary energy coming from nuclear -​ In 2019, just over 4% of global primary energy came from nuclear power -​ Electricity forms only one component of energy consumption -​ Since transport and heating tend to be harder to decarbonize, they are more reliant on oil and gas, nuclear and renewables tend to have a higher share in the electricity mix vs. the total energy mix → the share of electricity that comes from nuclear sources -​ Globally, around 10% of our electricity comes from nuclear BUT some countries rely on it heavily: it provides more than 70% of electricity in France, and more than 40% in Sweden → safety: -​ Historical context: -​ Fossil fuels powered the Industrial Revolution, driving productivity, wealth, and improved living conditions -​ Energy access is crucial for development, as recognized by the UN -​ Negative consequences of fossil fuels: 1.​ Air pollution: -​ Responsible for 5 million premature deaths annually -​ Fossil fuels and biomass burning are the main contributors -​ Eliminating fossil fuels could prevent 3-4 million deaths per year  2.​ Accidents: occur during mining, extraction, transport, and power plant construction 3.​ Greenhouse gas emissions: fossil fuels account for 87% of global CO2 emissions (2018), driving climate change -​ Comparison of energy sources: -​ Fossil fuels are the dirtiest and most dangerous energy source -​ Nuclear and modern renewables are much safer and cleaner → the PRIORITY is to move away from fossil fuels, whether transitioning to nuclear or renewable energy -​ Fossil fuels are significantly more dangerous than nuclear energy and renewables -​ Nuclear energy death rate: -​ Includes major incidents*: -​ Chernobyl (1986): ~4,000 deaths (WHO estimate) -​ Fukushima (2011): 1 worker death, 573 stress-related deaths from evacuation -​ Occupational deaths from mining and milling -​ Death reduction with nuclear energy (vs. fossil fuels): -​ 99.8% fewer deaths than brown coal -​ 99.7% fewer than coal -​ 99.6% fewer than oil -​ 97.5% fewer than gas -​ Renewables (wind, solar, hydropower) are even safer than nuclear energy SO both nuclear energy and renewables are far safer alternatives to fossil fuels -​ Deaths per TWh of energy produced: 1.​ Fossil fuels: -​ Coal: 25 deaths per year -​ Oil: 18 deaths per year -​ Gas: 3 deaths per year. 2.​ Nuclear energy: -​ 0.07 deaths per year -​ Equivalent to one death every 14 years 3.​ Renewables (Deaths per year): -​ Wind: 0 (one death every 29 years) -​ Hydropower: 0 (one death every 42 years) -​ Solar: 0 (one death every 53 years) -​ *It’s reported that in the days which followed the Chernobyl disasters, residents in surrounding areas were UNINFORMED of the radioactive material in the air around them -​ In fact, it took at least 3 DAYS for the Soviet Union to admit an accident had taken place, and did so after radioactive sensors at a Swedish plant were triggered from dispersing radionuclides -​ It’s estimated that the delayed reaction from the Soviet government and poor precautionary steps taken (people continued to drink locally-produced, contaminated milk, for example) led to thousands of thyroid cancer cases in exposed children -​ In the case of Fukushima, the Japanese government responded quickly to the crisis with evacuation efforts extending rapidly from a 3 km, to 10 km, to 20 km radius whilst the incident at the site continued to unfold -​ In comparison, the response in the former Soviet Union was one of denial and secrecy *THE INCIDENT: -​ A massive earthquake off the coast of Japan caused a tidal wave that broke down the seawall surrounding the power plant -​ The earthquake and tsunami cut off supply of electricity to the plants cooling systems -​ The fuel overheated and caused explosions -​ There were releases of radiation into the environment -​ People were evacuated and many were exposed to radiation -​ Three Mile Island: -​ The worst nuclear accident in the United States -​ No deaths or injuries were directly linked to the accident -​ The Three Mile Island nuclear power plant, near Harrisburg, Pennsylvania, is capable of generating 892 net MW of electricity → enough to power more than 800,000 homes and businesses -​ In 1979, part of the Three Mile Island facility suffered a meltdown and was never reopened -​ What is NUCLEAR RADIATION: -​ Radiation is energy moving through space in the form of waves and particles -​ It is emitted by unstable isotopes -​ It can be ionizing or non-ionizing -​ Ionizing radiation can knock electrons from an atom, creating ions -​ Alpha and beta particles + gamma rays are emitted from ionizing radioactive materials -​ Types of ionization radiation:  -​ Beta particles (electrons/positrons): -​ Small but can be stopped by aluminum metal -​ They can travel several meters but deposit less energy than alpha particles -​ Because they create ions, ionizing radiation can cause chemical changes in living cells, possibly leading to cancer -​ Gamma rays: -​ Waves of energy without mass or charge -​ They travel the farthest but can be stopped by lead, water or concrete -​ Alpha particles: -​ Not very penetrating but can damage very delicate tissue -​ They deposit the most energy -​ However, a piece of paper or your skin can stop them -​ Exposure to radiation: -​ The unit used to measure ionizing radiation in the U.S is the millirem (mrem) -​ The international unit is the millisievert (mSv) → both measure the risk that the radiation will cause damage to a person -​ We use the curie (Ci) or becquerel (Bq) to measure the amount of radioactivity in a substance -​ We use the rad or gray (Gy) to talk about the energy in radiation actually absorbed by a person -​ SAFEST sources of energy: hydropower & solar (lowest death rates) -​ CLEANEST sources of energy: nuclear energy (lowest greenhouse gas emissions) → public opinion: -​ Public opinion on nuclear energy tends to be very negative -​ Many people still remember the two major nuclear disasters in history: Chernobyl and Fukushima -​ Share of the public who oppose the nuclear energy as a means of electricity production in 2011, following the Fukushima disaster = 62% -​ Even though nuclear energy is safer, cleaner, and more efficient than coal, oil, and natural gas, it continues to be abandoned in the United States -​ Pop culture has played a large role in the way nuclear energy and weapons are perceived to the general public → nuclear energy pros & cons: -​ PROS: -​ Generates electricity without creating air pollutants such as CO2 (which increases heating of the atmosphere- climate change), SO2 (which dissolves in rain water to create acid rain) -​ Fewer chronic health risks than those associated with coal (such as asthma)  -​ Generates more power than coal by weight so less needs to be mined (less habitat destruction) → less land use overall -​ Electricity can be produced day or night and can be increased to meet demand -​ CONS: -​ Generates radioactive waste that must be stored with care until it decays which can take a very long time -​ Causes thermal pollution of surface water which can result in fish kills or lower biodiversity -​ Very dangerous if an accident or sabotage occurs because the radiation is linked to various forms of cancer -​ Expensive to build nuclear power plants and decommission -​ Mining and processing of uranium ore produces radioactive mine tailings and habitat disruption *Unit 7: renewable energy → Lecture 15: -​ Since the Industrial Revolution, most countries' energy mixes have been dominated by fossil fuels -​ Fossil fuels contribute significantly to global climate change and human health issues → cause local air pollution, leading to at least 5 million premature deaths annually -​ ¾ of global greenhouse gas emissions come from burning fossil fuels for energy -​ To reduce CO₂ emissions and air pollution, a rapid shift to LOW-CARBON ENERGY SOURCES is essential → nuclear (BUT it is finite & emits radioactive waves) and renewables -​ Renewable energy will be crucial for decarbonizing energy systems in the coming decades -​ How much of an impact has the growth of renewable technologies had on our energy systems?  → in 2019, around 11% of global primary energy came from renewable technologies *PRIMARY ENERGY represents the sum of electricity, transport, and heating -​ Worldwide, hydropower was dominating the renewable energy sector, with more than 4,000 TWh generated in 2020, followed by wind, solar, and a small amount of other renewables -​ In China, more than 1,250 TWh of renewable energy was generated by hydropower -​ In Lebanon, it generated more than 1.2 TWh of renewable energy from hydropower in 2003 & 2013, but in 2020, it fell to ~0.3 TWh -​ In the U.S, ~340 TWh of renewable energy was generated by wind, followed by hydropower, solar, and other renewables → Canada, Brazil, DRC, Angola, Namibia, Norway, Nepal, Bhutan, Afghanistan, N. Korea, and New Zealand… are dominating in the production of electricity from renewables -​ Since transport and heating tend to be harder to decarbonize (they are more reliant on oil and gas), renewables tend to have a higher share in the ELECTRICITY mix versus the total energy mix -​ Globally, around ¼ of our electricity comes from renewables → Lecture 16: hydropower -​ People have a long history of using the force of water flowing in streams and rivers to produce mechanical energy -​ Hydropower, or hydroelectric power is one of the oldest and largest sources of renewable energy, which uses the natural flow of moving water to generate electricity -​ WATER CYCLE: → the energy driving the water cycle comes from RADIANT ENERGY released by the SUN that heats the water and causes it to evaporate -​ A continuous process that involves the movement of water between the Earth's surface, atmosphere, and underground 1.​ Evaporation: liquid water, primarily from oceans, lakes, and rivers, changes into water vapor and rises into the atmosphere 2.​ Condensation: as water vapor rises, it cools and condenses into tiny water droplets, forming clouds 3.​ Precipitation: when water droplets in clouds become heavy enough, they fall to the Earth's surface as precipitation, such as rain, snow, sleet, or hail 4.​ Surface runoff: precipitation that falls on land can flow over the surface as runoff, eventually reaching rivers, lakes, and oceans → converting potential energy to kinetic energy 5.​ Infiltration: some precipitation seeps into the ground, replenishing groundwater supplies 6.​ Groundwater storage: water stored underground in aquifers can be released slowly over time, contributing to springs and streams 7.​ Groundwater discharge: groundwater can discharge into rivers, lakes, and oceans, or it can be pumped out for human use -​ Humans have harnessed the power of moving water for over 2,000 years -​ Early references to water mills appear in Greek, Roman, and Chinese texts, describing vertical waterwheels in rivers and streams -​ Traditional waterwheels were used to grind grains by turning millstones -​ Waterwheels were used in the Middle East until the end of the Ottoman era (mid-20th century) -​ Historical examples still exist in Hama, Syria, where waterwheels scooped water from the Orontes (Asi) River to fill aqueducts for distribution -​ 1882: first commercial-scale hydroelectric plant goes into operation in Appleton, Wisconsin -​ 1935: Hoover Dam, the world's largest hydroelectric power plant, is built -​ HYDROELECTRIC POWER: electricity generated by water turbines that convert energy from falling or fast-flowing water into mechanical energy -​ Process: -​ Water at high elevation flows through pipes or tunnels (penstocks) -​ The falling water rotates turbines, driving generators that produce electricity -​ Advantages: -​ Continually renewable energy source -​ Produces no pollution -​ Countries heavily reliant on hydroelectricity: Norway, Sweden, Canada, Brazil, and Switzerland → benefit from industrialized areas near mountainous regions with heavy rainfall -​ In a hydropower plant: -​ A hydraulic turbine converts the energy of flowing water into mechanical energy -​ A hydroelectric generator transforms mechanical energy into electricity -​ The generator operates based on Faraday's principles: moving a magnet past a conductor (e.g., coils of copper wire) induces an electric current to flow through the wire -​ Mini-hydro hydropower systems, designed for individual homes, farms, or small industries, may be more common in the future → MICRO-HYDROPWER SYSTEMS: have power output of less than 100 kW -​ Many locations have potential for producing small-scale electrical power, either through small dams or by placing turbines in the free-flowing waters of a river → particularly true in mountainous areas, where energy from stream water is often available → GLOBAL hydropower consumption in 2019 reached more than 4,000 TWh -​ Asia Pacific is the region with the most hydropower generation in 2019, reaching ~1,800 TWh -​ Hydroelectric power is one of the oldest and largest sources of low-carbon energy -​ It has been used for over a century and remains a major renewable energy source -​ Excluding traditional biomass, hydroelectric power accounts for over 60% of renewable energy generation -​ BUT the scale of hydroelectric power generation varies significantly across the world → China generates > 1,250 TWh; Canada, USA, and Brazil generate ~500 TWh; Russia & India generate ~250 TWh -​ The LARGEST power plant of any kind in the world is the Three Gorges Dam in China and with an installed capacity of 22,500 GW -​ Canada, Norway, Sweden, Austria, and Switzerland have the highest per capita energy consumption from hydropower (> 25,000 kWh) +​ Peru, Ecuador, Colombia, Venezuela, Brazil have the highest share of primary energy from hydropower (> 25%) -​ In 2019, around 7% of global energy came from hydropower -​ In 2019, around 16% of global electricity came from hydropower → e.g, Alaska, DRC, Angola… dominating with 80-100% electricity production from hydropower → hydropower in Lebanon: -​ Ideal for hydropower: lots of rivers, mountains, snow… BUT no policies to take care of rivers as they are dried up for agricultural purposes, polluted, etc. -​ Hydropower is SEASONAL: → the high water period extends from January to May and the maximum average flows occur primarily in March and April -​ In 2019, less than 2% of electricity was produced from hydropower, compared to 7% in 2013 & > 10% in 2003 → has extremely old equipment that needs an upgrade -​ Hydropower is as crucial as wind and solar energy, with a higher capacity factor and lower economic costs -​ Challenges: -​ Existing hydropower plants require significant rehabilitation and upgrades to operate at full capacity -​ New hydropower sites, both with and without storage (dams), remain untapped -​ Potential benefits: -​ Increased share of renewable energy -​ Enhanced energy security for Lebanon → hydropower environmental impact: -​ Fish populations: -​ Fish migration to spawning grounds (upstream) or the ocean (downstream) can be obstructed by impoundment dams -​ Solutions for upstream migration: fish ladders, elevators, or trucking fish upstream -​ Solutions for downstream migration: diverting fish from turbine intakes using screens, racks, underwater lights, or sounds; ensuring minimum spill flows past the turbine -​ Quality and flow of water: -​ Hydropower plants can reduce dissolved oxygen levels, harming riparian habitats (vegetations such as water-loving plants) -​ Addressed using aeration techniques to oxygenate water -​ Maintaining minimum water flows downstream is essential for riparian habitat survival -​ Ecosystems of rivers and streams -​ Drought: during droughts, water availability decreases, leading to reduced electricity generation from hydropower plants -​ Impact on local environment and land use: -​ New hydropower facilities can disrupt local ecosystems and compete with other land uses that may be more highly valued than electricity generation -​ Humans, plants, and animals may lose their natural habitats due to the construction and operation of these facilities -​ Preservation concerns: -​ Local cultures and historical sites may be impinged upon → some older hydropower facilities may have historic value, so renovations of these facilities must also be sensitive to such preservation concerns and impacts on plant and animal life