Renewable Energy Sources Lecture Notes PDF

Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 12: Overview of Renewable Energy Sources Bradley J McPherson P.Eng Depar...

Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 12: Overview of Renewable Energy Sources Bradley J McPherson P.Eng Department of Chemical Engineering University of New Brunswick Department of Renewable Energy Sources Chemical Engineering By definition, renewable energy sources rely on the energy contained in the natural environment rather than the consumption of a finite resource; thus, they are an effectively infinite resource. Renewables typically contain the following traits: – Ubiquity of the energy source; – Low power density meaning that the rate of energy extraction from the renewable resource is slow (small Joules per second per unit area – W/m2); – Intermittent nature of the energy fluxes. Department of Renewable Energy Sources Chemical Engineering Ultimately, all “renewable” energy sources are derived from the sun, with the exception of tidal and geothermal: – The Sun radiates energy to the earth (solar); – The Sun creates thermal gradients in the atmosphere creating areas of high/low pressure (wind); – The Sun is the original source of energy that produced the fossil fuels (photosynthesis); Where as: – Geothermal energy is the heat released from the radioactive elements in the Earth’s crust and emanating from the core; – Tidal energy is dependent on the gravitational pull of the Moon. Department of Chemical Engineering The renewable energy sources receiving most attention include: – Hydro power; Conventional hydroelectric dams; Tidal barrages & turbines; Wave power; Pumped Storage* – Wind power Onshore vs Offshore; – Solar power; Photovoltic cells; Collectors; – Geothermal; – Biomass & hydrogen; Fuel cells Department of Chemical Engineering Each of these technologies fit into the overall generation scheme that we’ve seen over the duration of this course: methane Geothermal Energy Electrochemical Solar Energy Solar Energy collectors Photovoltic Panels Biomass Heat Engine Fuel Cells Water Mechanical Generator Electrical Turbine Energy Energy Wind Turbine Transmission & Distribution Department of Chemical Engineering Typical power densities of different renewable technologies: Source Area Heat (W/m2) Work (W/m2) Solar Collector 150 20 Photovoltaic Cells 30 Hydroelectric Drainage basin 0.01 Wind Turbine 40 Geothermal Field 0.1 0.02 Biomass Field 0.5 0.1 Ocean Tidal Tidal pond 1 Ocean Wave Frontal area 10000 *compare to a fossil or nuclear plant where we typically achieve > 100 kW/m2 Department of 2010 Installed Capacity Cost Chemical Engineering Typical installed costs for each technology (remember … installed costs of ≤ $100/MWhr or $1000/kWe is the target) Department of 2007 ----→ 2016 Chemical Engineering Department of 2009 vs 2019 Chemical Engineering Department of 2022 Costing Chemical Engineering Department of Hydro Power Chemical Engineering The potential energy extracted from water as it changes elevation … Department of Mactaquac Dam - Fredericton Chemical Engineering Department of Hoover Dam - Nevada Chemical Engineering Department of Dam Level (320/370m) Chemical Engineering Department of Three Gorges - China Chemical Engineering Department of Tidal Power Chemical Engineering Tidal Barrage … Department of Annapolis Royal – Nova Scotia Chemical Engineering Department of Tidal Concerns Chemical Engineering "There's still a giant killing machine sitting on the sea floor of the Bay of Fundy with absolutely no environmental monitoring at this point," Colin Sproul , vice-president with the Bay of Fundy Inshore Fishermen's Association http://www.openhyrdo.com/images Department of Nova Scotia In-stream Tidal Turbine Chemical Engineering Department of Wave Power Chemical Engineering Department of Chemical Engineering Pelamis Department of Wind Chemical Engineering North Cape - PEI Department of Solar - PV Chemical Engineering Solten project - Spain Department of Solar - collectors Chemical Engineering Heliostats reflect the suns energy to a central point … Department of Geothermal Chemical Engineering Department of Chemical Engineering Department of Biomass Chemical Engineering Landfill gas collection … Department of Hydrogen Chemical Engineering Steam Methane Reforming Water electrolysis Department of Fuel Cells Chemical Engineering Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 13: Wind Power Mr. Bradley J. McPherson P. Eng. Department of Chemical Engineering University of New Brunswick Department of Chemical Engineering As we’ve seen, the source of surface wind’s are due to the differences in solar radiation that reaches the Earth. More of the Sun’s energy is accepted near the equator than near the poles leading to heating of the land and air. This gives rise to density gradients in the atmosphere … the hotter air rises and is replaced with cooler air. This convective process is what we call wind. Department of Chemical Engineering The rotation of the Earth creates bi-directional air flow from what would otherwise be a North-South bias to wind direction. Local heating/cooling effects create much more complicated local wind patterns. Department of Chemical Engineering Mechanical energy extracted from wind turbines has been used for a long time for pumping water, grinding wheat & grain and for industrial milling operations. The first such wind turbines were vertical axis orientation and were used in Persia (~500 – 900 AD)... This is a 19-century American knock-off. http://www.telosnet.com/wind/early.html - Part 1: Early History Through 1875 Department of Chemical Engineering Horizontal axis wind turbines began to appear in Europe in the late 12th to early 13th centuries. They were primarily “cloth sails” but evolution over several hundred years showed the engineering know-how developing. Key features of a turbine blade as known today and perfected in the “sails” of early European mills include: – Camber along the leading edge; – Blade spar at the ¼ point between leading edge and trailing edge; – Centre of gravity at the same ¼ point; – Non-linear twist of the blade from root to tip. Department of Chemical Engineering Department of Chemical Engineering Small scale metal-bladed wind turbines were extensively used in the American mid-west for pumping water for agricultural purposes … Department of Chemical Engineering Modern wind turbines are used exclusively for electricity production and are of the horizontal axis configuration … The major components of a modern wind turbine include: – Rotor; – Hub; – Gearbox; – Generator; – Control unit; – Tower. Department of Chemical Engineering Low speed shaft rotor Gearbox Controller Anemometer blades Wind vane Generator Yaw drive Yaw motor Nacell Department of Side View of a Wind Turbine Chemical Engineering Wind Turbine Aerodynamics and Flow Control | IntechOpen Department of Chemical Engineering How is kinetic energy in the wind extracted as mechanical energy in the rotation of the turbine blades? We’ll start by looking at the energy equation … z1g + 21 V12 + h1 + win + qin = z2g + 21 V22 + h2 + wout + qout In a wind turbine z1=z2, h1≈h2, qin=qout=0 and win=0, thus we have kinetic energy conversion to work: V12 - V22 wout = J/kg 2 Department of Chemical Engineering The power generated in the wind turbine is the work extracted from the change in kinetic energy of the wind upstream and downstream multiplied by the mass flow of air through the blades …. P = mair DKE The mass flow of air is proportional to the area available for KE extraction (blade diameter) and the velocity and density of the air going through it … mair = rair Ablade Vair Department of Chemical Engineering Here, we see that the area available for energy extraction is the area encompassed by the length of the blades. R A = p R2 Vu Vd The power, thus is a function of blade sweep … Vt æ Vu2 - Vd2 ö P = rair AVt ç ÷ è 2 ø Department of Chemical Engineering If we estimate the actual blade wind speed (V t) as the average between the upstream and downstream velocities we get … æ Vu + Vd ö æ Vu2 - Vd2 ö P = rair A ç ÷ç ÷ è 2 øè 2 ø Expanding and factoring out the known velocity V u … rair AVu3 P= 4 ( 1+ VR - VR2 - VR3 ) Where VR = Vd/Vu … the ratio of downstream to upstream velocity. Department of Chemical Engineering Some simple calculus shows that the optimum VR, or the ratio of the downstream air velocity to the upstream air velocity, that will maximize the power produced is 1/3rd Inserting this optimum ratio gives: rair AVu3 Pmax = 0.593 2 Or a maximum of 59% of the total kinetic energy can be converted to work output. Department of Chemical Engineering The power coefficient, or theoretical wind turbine efficiency is given as: Pactual Cp = 1 2 r AVu3 And this has a maximum of 0.593 (as seen above). Actual power coefficients are dependent on the ratio of the blade-tip speed to the upstream wind velocity. Department of Chemical Engineering We see that actual power coefficients are well less than the theoretical 59% maximum … Department of Chemical Engineering Power output of a wind turbine depends on wind speed, so ideal locations are where sustained wind speeds are high. The wind velocity increases with altitude, thus ideal wind farm locations are high altitudes, mountainous regions or next to large bodies of water. Also, since wind speed will change continuously, the turbines are designed to maximize the Cp by appropriate gearing (maintains more or less constant generator RPMs) and by regulation of the pitch of the blades. Department of Chemical Engineering Wind turbines are designed for variable wind speeds but obviously there will be a minimum and a maximum where no power can be efficiently or safely produced … Because of variability of wind speed, wind turbines have capacity factors of 20-30% … remember capacity factor is the actual power produced over the total amount that could have been produced if operating continuously at maximum output. Department of Mixing it all together Chemical Engineering Department of No matter what, wind speed rules Chemical Engineering  Theoretical Power using diameter Department of Chemical Engineering Theoretical power in moving air - or wind - can be calculated P = 1/2 ρ A v3 = 1/8 ρ π d2 v3 (1) where P = power (W) d = Turbine diameter (m) ρ = density of air (kg/m3) (usually 1.23 kg/m3) v = wind velocity (m/s) A = blade area perpendicular to the wind (m 2) π = 3.14.... Department of Actual Power (Efficiency) Chemical Engineering Actual Available Power Actual available wind power can be calculated Pa = Cp ρ A v3 2 = Cp ρ π d2 v3 where the A term = 1/4 π d2 (2) 8 Where: Cp = efficiency of the turbine (in general less than 0.45 - or 45%) Department of Example # 1 Chemical Engineering Example - Wind Power The actual available power from a wind turbine with diameter 1 m, capacity factor 0.2 (20%) - with wind velocity 10 m/s - can be calculated as Pa = Cp [ρ π d2 v3] 8 Pa = (0.2) [1.2 kg/m3) π (1 m)2 (10 m/s)3] 8 = 94.2 W » 1 W = 1 J/s = 1 kg*m2/s3 Department of Example # 2 Chemical Engineering Example - Wind Power The actual available power from a wind turbine with blade radius of 10 m, capacity factor 0.2 (20%) - with wind velocity 10 m/s - can be calculated as Pa = Cp [ρ π r2 v3] 2 Pa = (0.2)[1.2 kg/m3) π (10 m)2 (10 m/s)3] 2 = 37.68 kW » 1 W = 1 J/s = 1 kg*m2/s3 Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering We see that at 50 – 80 metres there are several suitable locations for potential wind farms … offshore would be ideal, however costs of installation, maintenance, cabling etc currently make it uneconomical. Prince Edward Island has proven an ideal location for wind farming … New Brunswick is following suit … Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Miscou Island … Department of Chemical Engineering Cape Tormentine … Department of Chemical Engineering The government of PEI committed to an installation of 500 MWe of wind power by 2013 … although their peak load requirements are only ~ 240 MWe. PROBLEM In 2007, 18% of PEI’s electricity production was from installed wind capacity … note the oil & nuclear are primarily imported from NB. 2007 Department of Chemical Engineering There are currently eight main wind-farm installations on the island: – North Cape/Norway: 16 0.66-MW turbines (50 m hub height) 4 3-MW turbines (90 m hub height) – East Point: 10 3-MW turbines (90 m hub height) – West Point: 55 2-MW turbines (70 m hub height) Total installed capacity of 204 MW … Wind Energy in Prince Edward Island | Government Department of PEI 2008-2013 Chemical Engineering Department of PEI Wind Energy 2021 Chemical Engineering Department of November 19, 2024 Chemical Engineering  Department of Chemical Engineering North Cape West Point East Poin Department of Chemical Engineering  Current PEI Installed Department of Chemical Engineering Wind Generation Department of North Cape Wind Farm Chemical Engineering asdf Department of Chemical Engineering Department of West Point (near O’Leary) Chemical Engineering Department of East Point Chemical Engineering Department of Chemical Engineering Environmental Effects of wind power: – Visual impact; – Potential threat to birds, bats; – noise (~40 db @ 350 m); – Land use: Although the footprint of an individual wind turbine is small, they must be spaced at least 5-10 blade diameters apart to avoid interference. For a turbine with a 90 m blade sweep that’s about 4 turbines per km2 … at 3 MW per turbine this gives ~ 12 MW/km2 Department of Chemical Engineering Note: this is quite high – typical power density is 5 to 10 MW per km2 … And remember that the maximum capacity factor is ~1/3 … so in reality you’re extracting 1.5 – 3 MW/km2 So, land usage for 500 MW installed capacity on PEI will require ~ 166 – 330 km2 in prime wind generation locations.  Department of Chemical Engineering Scaled from bar below and represents ~ 60 km2 Show’s PEI’s maximum capacity is 480 km2 - @ 3 MW/km2 PEI could max out at ~ 1.4 GW of wind production At 33% capacity that’s just shy of 500 MWe Department of Chemical Engineering Overall world prospects … Department of Chemical Engineering Department of Overall world wind forecast Chemical Engineering … Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 14: Conventional Hydro Power Bradley J McPherson P.Eng. Department of Chemical Engineering University of New Brunswick Department of Chemical Engineering Man has been harnessing the mechanical energy available from flowing water for millennia. Mills located near suitable waterfalls were traditionally used to grind flour, saw logs etc. However, it has been only the past century, since the industrial revolution and electrification, that significant amounts of work have been achievable due to the mechanical-to-electrical energy transformation. Department of Chemical Engineering All hydropower stations rely on the potential energy stored in the water due to its relative position, or elevation, above its point of discharge. Remembering the energy equation … z1g + 21 V12 + h1 + win + qin = z2g + 21 V22 + h2 + wout + qout And assuming V1≈V2, h1≈h2, qin≈qout and win=0, we have: z1g = z2g + wout Department of Chemical Engineering Rearranging … ( ) wout = z1 - z2 g [m×m/s2 ´ kg/kg Þ J/kg] This describes the ideal work output from the potential energy stored in a given elevation. If we take into account the fluid (water) that is experiencing this elevation change (H) and its total flow rate (Q) we have the ideal power output of a given hydropower source: wout = rgHQ kg / m3 ´ m / s2 ´ m ´ m3 / s Þ J / s Þ W Department of Chemical Engineering There are two primary ways that the potential energy in the water may be extracted, these are: – Impulse turbines; – Reaction turbines. Department of Chemical Engineering Impulse turbines: – the full pressure-loss (potential energy conversion) is converted to kinetic energy by ejection through a nozzel. – The kinetic energy of the fluid is then extracted as flow through buckets or vanes, which are independent. – Typically suitable for very high pressure heads (> 1000 ft – mountain installations); – The Pelton wheel is a typical example … Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Reaction turbines: – Unlike the impulse turbine, the majority of the pressure loss (potential energy conversion) in a reaction turbine occurs in the completely submerged, rotating blades (runners); – To increase the efficiency of energy transfer, stationary guide vanes are used to give the fluid the proper tangential velocity on the target runners. Department of Chemical Engineering Francis turbine. Department of Chemical Engineering Department of Chemical Engineering Department of Shaft to generator Chemical Engineering Kaplan Turbine: Typically have variable pitch blades Hydraulically actuated gates Department of Chemical Engineering Typical efficiencies of potential-to-mechanical energy transfer … Thus, actual power output is a function of the turbine internal efficiency … wactual h= wideal wactual = hrgHQ Department of Chemical Engineering Kaplan turbines typically used for large installations with high flow rates; Pelton wheels used with high head; Francis turbines are the in between compromise. Department of Chemical Engineering Details of a hydroelectric power station … Department of Mactaquac Chemical Engineering powerhouse Spill gates (Sluice gates) 6 Kaplan turbines/generators 660 MWe Earth (clay) dam Department of Chemical Engineering Hydroelectric stations will typically be one of two types: – High head (storage) – have very large head ponds that can change level and follow load (Hoover, Churchill Falls, Three Gorges etc …) – Run-of-the-river – only use the daily and seasonal water flows (Niagra, Mactaquac etc …) Department of Chemical Engineering Environmental Effects: – Once installed, conventional hydro is “free” energy Capital investment is large; Depending on location vast amounts of land are flooded to create the “head pond” – Displacement of local population & wildlife (as many as 1.2 Million ordered out for the Three Gorges project in China) – Changing of aquatic ecosystems, fish, plants etc … SJ river used to be significant for Atlantic salmon … – Erosion of upstream & downstream river banks – Silt deposits Department of Chemical Engineering Some of the world’s larges hydro turbine installations … China Three Gorges Corporation ©2002 All rights reserved Department of Chemical Engineering These figures are per penstock/turbine installed … Three Gorges consists of 26 independent turbine/generators each running at ~ 710 MWe output … This means the total flow of the Yangtze river is around: Wout 26 ´ 710x106 W(kgm/s2m/s) = 3 )( )( )( Q= = 26240 m /s ( hrgH 0.90 996kg/m 9.81m/s 80m 3 2 ) Or about 1000000 L/s in EACH turbine! Department of Muskrat Falls Hydro Project Chemical Engineering Department of Muskrat Falls Hydro Project Chemical Engineering https://muskratfalls.nalcorenergy.com Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 14a: Non-Conventional Water Power Mr. Bradley J. McPherson P. Eng. Department of Chemical Engineering University of New Brunswick Department of Tidal Power Chemical Engineering Tides are caused by the gravitational pull of the moon and occur on a predictable schedule. Mid-ocean tides are typically ~ 0.5 – 1.0 metres however in restricted passages (Bay of Fundy) they can reach as high as 16 metres. “Spring” tides are typically the highest and occur when the Moon’s position is along the Earth’s equator. “Neap tides” are typically much smaller … although always predictable and occur on the monthly cycle. Department of Chemical Engineering Department of Chemical Engineering The predictability of the tides makes energy extraction attractive, particularly in regions where tides are of considerable height (BoF) … Department of Chemical Engineering Three basic types of tidal generator have been proposed and/or tested: – Tidal barrages/basins; Several operating in the world – Annapolis Royal included. – Tidal fences (more-or-less hypothetical …); – Tidal turbines. Essentially underwater “wind” turbines. – Several in operation and proposed – Eg. East River in NYC (see verdantpower.com) Department of Chemical Engineering For a tidal basin, average power output can be approximated by: rgAH2 Pavg = 2T Where: A – tidal basin area H – tidal height T – time between tides (~12.5 hours) Department of Chemical Engineering Looking at the BoF: The potential is there for: Pavg = rgAH 2 = ( 998kg/m ) ( 9.81m/s ) ( 240x10 m ) ( 5.5m) 3 2 6 2 2 = 789.8x106 W 2T ( 2 12.5hr x 3600 s/hr ) Or about 790 MW of renewable energy, if it could all be harnessed, transmitted and maintained... That’s about 1 Pt. Lepreau generating station. Department of Chemical Engineering Tidal Fences Department of Tidal turbines Chemical Engineering OpenHydro – Bay of Fundy (2 MW) Verdant power installed in East River NYC (~ 0.36 MW) and in the St. Laurence at Cornwall, Ontario (potential for ~15 MW) Marine Current Turbines Horizontal Axis Propeller Department of Chemical Engineering Open Hydro news clip … – Installed originally in 2009.. Tore itself apart in about 3 days! – First tidal turbine connected to N. American electrical grid, Nov. 22, 2016.  Department of Chemical Engineering Verdant 60-80 kW turbines Turbine blades – 5 m diameter Gear box generator Nose cone Department of Chemical Engineering RITE Project (East River) Phases: – Phase 1 (2002 – 2006): Prototype Testing – Phase 2 (2006 – 2008): Demonstration – Phase 3 (2009 – 2012): MW-Scale Build-Out – Verdant Power | Projects Phase 2 Demonstration Completed – Verdant Power recently achieved a major milestone by successfully completing the RITE Project’s Phase 2 Demonstration, which began in 2006 with the installation of the company’s first full-scale (5m diameter rotor ~ 60 kW) Free Flow System turbine into the East River. – Over this two-year period, Verdant Power operated six full-scale turbines in array at the RITE Project, successfully demonstrating the Free Flow System as an efficient source of renewable energy with the following outcomes: – Excellent hydrodynamic, mechanical and electrical performance; – Grid-connected power with no power quality problems; – Fully bidirectional operation – passive yawing with high efficiency on both ebb and flood tides; – Automatic control and continuous, unattended operation; – No fouling or damage from debris; – 70 megawatt hours of energy delivered to two end users; – 9,000 turbine-hours of operation. The RITE Project demonstration system stands as the world’s first grid-connected array of tidal turbines. Department of Chemical Engineering Drawbacks of tidal power: – Dilute energy source … many turbines or large tidal basins required for significant electricity production. – Blocks navigation pathways. – Potential to alter local ecosystem; – No power produced at low or high tide (although, at least this is predictable!) – Cost (still high per MWhr produced … a bit higher than wind turbines) Department of Wave Power Chemical Engineering Several schemes have been proposed to extract the enormous amount of energy available from surface waves. Waves have both kinetic energy, due to their relative velocities (c), and potential energy due to their amplitude (H). Wave velocity (c) Department of Chemical Engineering The energy contained in a wave can be estimated by: Ewave = 0.125rgH2 Its potential power, per unit length is: rgH2 gl P= W/m 16 2p Department of Chemical Engineering Oscillating Water Columns – Air column contains a Wells turbine – spins the same direction independent of air flow. – Can generate up to 1 MW per installation. Department of Chemical Engineering Archimedes Wave Swing – Fully submerged – Air column has buoyancy that causes it to oscillate due to wave amplitude – Floater connected to linear generator (moving a magnet through a coil) – 9.5 m diameter, 33 m high ~ 2 MW … Department of Chemical Engineering Pelamis Wave Energy Converter – The Pelamis Wave Energy Converter is a semi-submerged, articulated structure composed of cylindrical sections linked by hinged joints. The wave-induced motion of these joints is resisted by hydraulic rams, which pump high-pressure fluid through hydraulic motors via smoothing accumulators. The hydraulic motors drive electrical generators to produce electricity. Power from all the joints is fed down a single umbilical cable to a junction on the sea bed. Several devices can be connected together and linked to shore through a single seabed cable. – 180m long and 4m in diameter - 4 power conversion modules per machine. – Each machine is rated at 750kW. – Machines will, on average, produce 25-40% of the full rated output over the course of a year. Department of Pelamis Chemical Engineering Department of Chemical Engineering Ocean Thermal Energy Converter (OTEC) – Due to the variation in temperature as the ocean depth increases, there is considerable potential to drive thermodynamic cycles on this temperature difference. – In the tropics, surface temperatures are >20oC while can be nearly freezing at 1000 metres below the surface. – Potential to use a Rankine cycle with ammonia … Department of Chemical Engineering Department of Chemical Engineering Design concept for a 100 MWe OTEC power plant … 15 kWe prototype plant constructed in Hawaii originally ran but was disbanded … In 2015 a 105 kWe plant was grid connected for power & desalinated water. Department of Chemical Engineering Thermodynamic cycle (Anderson Cycle): Department of Chemical Engineering Thermodynamic properties Department of Chemical Engineering Calculate: Ans: 145 MW Ans: 4.5% Ans: 120 MW Ans: 0.8% Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 15: Solar Power Bradley J. McPherson P. Eng. Department of Chemical Engineering University of New Brunswick Department of Solar Chemical Engineering With the exceptions of nuclear, tidal and geothermal energy sources, all the energy we use is derived from the Sun. The average solar irradiance on the Earth’s surface amounts to 164 W/m2 and drives the wind, photosynthesis process, and can be used directly for energy production. Unfortunately, the Sun doesn’t always shine (for ~12 hrs per day we receive no insolation – night time) but accounting for the ~ 8 hours per day in an ideal location this can be as high as 600 W/m2. Department of Chemical Engineering In an article in the Scientific American (January 2008 – A Solar Grand Plan) it was estimated that the US could supply ~ 69% of its electricity needs by 2050 from solar energy. This would require a vast area in the American South-West (~ 50,000 sq miles) that would be populated with photovoltaic and solar concentrator power plants. Would require $420 BILLION ($600B in 2024) dollars in subsidies between 2011 and 2050 to make the scheme cost- competitive … Department of Chemical Engineering Department of Chemical Engineering Solar energy can be harnessed through: – Active solar collectors; Flat plat collectors heat a pumped fluid; – Passive solar collectors; Building design to maximize heat inventory (southern exposures for example) – Photovoltaic cells. Direct conversion of light photons to electric current through the photoelectric effect. Active/passive solar have been extensively used for water and space heating. Department of Chemical Engineering Active solar collectors: – Rely on the radiation of the Sun to heat a fluid (air, water or antifreeze Warmed air fluid) on a flat-plate insulating space collector. – Power received dependent upon: P = es AT4 fluid  = 5.67x10-8 W/m2K4 Department of Chemical Engineering Department of Chemical Engineering These flat-plate collector systems aren’t good for much else but water/space heating on a small scale. In order to generate the energy densities required for electricity production, concentrating collectors are required. In effect, this can be accomplished through many flat- plate collectors all reflecting onto a central location Department of Innovation ☺ Chemical Engineering Department of Chemical Engineering The “power tower” arrangement … Department of Chemical Engineering Department of Chemical Engineering Mirrors or flat-plate concentrators can be improved upon by using the focusing power of a parabolic (or spherical) trough. Point of focus Department of Parabolic Trough Chemical Engineering Department of Photovoltaic Cells Chemical Engineering Photovoltaic cells: – The photoelectric effect (fully described by Albert Einstein, Nobel Prize 1921) dislodges a valence electron from an atom when light (photons) of suitable energy are incident on the material. – A photovoltaic cell relies on the n- & p-type semiconductivity of a doped silicon crystal to transport the photoelectrically generated electrons. Department of Chemical Engineering Silicon has a valence of 4 and in a perfect crystal, all four electrons are covalently bonded to another Si atom and is a pure insulating material. By doping the pure crystal with an atom of higher valence (for example arsenic, antimony or phosphorus which have a valence of 5) a single electron is left that can freely conduct … effectively producing an excess negative charge – this is an n-type semiconductor. By doping the pure crystal with an atom with lower valence (for example boron, aluminum or indium which have a valence of 3) a positive vacancy is left that can freely accept an electron… effectively producing an excess positive charge – this is a p-type semiconductor. Department of Doped Silicon crystals Chemical Engineering Department of Chemical Engineering By placing an n-type and p-type semiconductor in intimate contact, electrons will freely diffuse across the n-p junction creating a capacitance or an electric field. A photovoltaic cell is produced when the n- & p-type semiconductors are connected to an external load. Incident light liberates photo-electrons in the n-type semiconductor, which are then free to jump to the p-type semiconductor … Department of Chemical Engineering Department of Chemical Engineering Current – voltage characteristics for typical monocrystalline PV cells … Department of Chemical Engineering 90,000 solar modules with rated capacity of 25 MWe. Produces ~ 42000 MWhr electricity per year giving an average of 4.8 MWe output or 19.2% capacity factor. One of Spain’s multiple PV power stations … Department of Chemical Engineering PV power output in Spain: Department of Chemical Engineering Department of Chemical Engineering Department of By 2014 …… $/Wp Chemical Engineering Department of 2015-2025 Cost Reduction Chemical Engineering Department of Path to cheap solar Chemical Engineering Department of Chemical Engineering Environmental Impacts: – Visual impact; – Land use; – CO2 emission from 0.99999 pure silicon wafers: Estimated as ~ 50 g CO2 emmitted per kWhr electricity placed on the grid. SiO +C ® Si +CO 2 2 Every mole of Si creates one mole of CO2 i.e. 1 gram Si produces 1.6 grams of CO2 … 90000 module farm from previous slide with panel 1x1.5m and 0.1mm thin film Si = 51.98 tonnes CO2 emitted! Department of Chemical Engineering Key is to increase conversion above the current ~ 20% plateau through multi-junction, thin-film technology: Department of Chemical Engineering Department of g/CO2 Production & Use Chemical Engineering Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 16: Biomass Technologies Mr. Bradley J. McPherson P. Eng. Department of Chemical Engineering University of New Brunswick Department of Chemical Engineering Biomass refers to organic materials that have energy stored as carbohydrates, produced from photosynthesis. energy + 6CO2 + H2O ® 6O2 +C6H12O6  Department of The Carbon Cycle Chemical Engineering Biomass and animals respire CO2 and H2O back into the atmosphere in the “carbon cycle”. Injection of carbon from underground reserves of hydrocarbons adds additional carbon to the environment (see lecture on climate change). Other carbon emissions seen as “carbon neutral” Department of Biomass Sources Chemical Engineering Biomass sources for energy production include: – Forests Stem wood Milling wastes Urban wastes – Agriculture Food crops & residues Energy crops Algae – Garbage (landfill gas) – Raw Sewage – Animal Waste Manure Scraps from butchering – Industrial Waste Wood residues (sawdust, chips) Mill sludge Department of Biomass Energy Processes Chemical Engineering Energy may be extracted from biomass sources in a number of ways: – Direct combustion; – Co-firing with conventional fossil fuels; – Thermal conversion processes: Gasification: syngas (H2 & CO) production by reaction with steam and oxygen at high temperatures. Pyrolysis: high temperature process in absence of oxygen. Leaves pure carbon (charcoal) as product. Note that some processes such as hydrothermal liquefaction may simulate geologic-production of hydrocarbon gases and liquid products. Torrefaction: moderate heat is applies to evolve moisture and oxygen from the biomass. Product is high in carbon and hydrogen (much like coal). Chemical conversion: production of biofuels … methane, ethanol, biodiesel … Department of Chemical Conversion Chemical Engineering Ethanol production: – Fermented from corn, wheat, rice, sugar beets, sugar cane or other starchy foods. – Primarily used as a blending agent in conventional gasoline (10% – 85% ethanol depending upon engine design). Department of Chemical Engineering Biodiesel production: – Relies upon transesterfication of vegetable oils or waste cooking oils. – Can be used as direct replacement or as a blend for / with conventional diesel fuel. Department of Chemical Engineering Typical flow diagram for biodiesel production: Department of Chemical Engineering Biofuels from Algae and micro-organisms: – Algae can be used to produce organic oils in a photo- bioreactor. Department of Algae Raceway Chemical Engineering Department of Keys to Algal Development Chemical Engineering Crop protection What about our harsh weather swings? Water and nutrient management Feeding wastewater and agricultural runoff. Ecosystem design Where can I discharge final effluent to? Light optimization Temperature management Seasonal succession. Would we be able to grow year round? Department of Bio-Gas Chemical Engineering Anaerobic digestion can produce biogas (CH4, CO2 & H2O), which is used for direct firing in a power plant or for upgrading to synthetic fuels: Department of Landfill Gas Systems Chemical Engineering Significant amounts of biogas are produced from the anaerobic digestion of garbage in municipal landfills. Properly designed landfill sites can easily capture the biogas produced: Department of Chemical Engineering Fredericton Region Solid Waste Commission installed landfill gas management system in 2005/06. Following was the installation of 2.1 MWe combustion engines for connection to the NBPower grid system.  Combined Heat and Power Department of Chemical Engineering Systems Lots of use of biomass for district heating and electricity production in Sweden … Estimate 90 Tractor Trailer Loads of Biomass needed to run Belledune Generating Station / day. Torrification / Pyrolysis of material an option. Waste heat for industrial applications Department of Chemical Engineering CHE 5313 / 6313: Energy and the Environment Lecture 17: Geothermal Energy Bradley J. McPherson P. Eng. Department of Chemical Engineering University of New Brunswick Thanks to: David Addison (Thermal Chemistry Ltd) Simon Addison (Mighty River Power) Ian Richardson (Mighty River Power) Department of Geothermal Chemical Engineering The heat in the interior of the Earth is a vast supply of energy, however it is mostly inaccessible. The inner core of the Earth is a solid mass while the outer core is molten at around 4000oC which extends to about half the radius. The mantle is covered with a solid crust of rock with a thickness between 8 – 40 km. Department of Chemical Engineering In the Earth’s crust there is an outward flow of heat from the interior of ~ 50 mW/m2 –this is really small heat flow and needs to be amplified. The heat flux is accompanied by a temperature gradient of ~ 30 K per km so by drilling deep down into the crust (~ 2 – 10 km depending upon location) we can achieve temperatures of 200-300oC Department of Chemical Engineering Suitable locations for geothermal power exploitation are typically near tectonic plates and active volcanic regions. The Pacific “Ring of Fire” is a prime example … Department of Worldwide Geothermal Electricity Chemical Engineering Global capacity ~ 0.2 to 0.5% (depending on what data for total global generation is used). Current global geothermal capacity 2013 Geothermal Power: International Market Overview ~12,000 MWe Figure 1: Global Installed Capacity (MW) of Operating Geothermal Power Plants 14,860 14,000 13,402 12,000 11,765 10,000 8,000 6,000 4,000 2,000 - 2024 Global Installed Capacity PCA of Plants Under Construction Note: PCA (Planned Capacity Additions), Pilot plants and geothermal plants built in the first half of the 20th century and then decommissioned are not included. Source: Author  Geothermal – what is it? Department of Chemical Engineering Enhanced Geothermal System Hot Sedimentary Volcanic Geothermal (EGS) Aquifer (HSA) Technologically challenging Utilises conventional Utilises conventional Represents 0% global technologies technologies installed capacity Represents 4% global Represents 96% global Significant long-term potential installed capacity installed capacity Department of How does Geothermal work? Chemical Engineering Nearly all geothermal power plants require deep wells be drilled. Steam is extracted from the well … either through natural subterranean hydro reservoirs, or more often by pumping of water down an injection well, picking up heat from the geothermal reservoir and using pressure differential and bouyancy to collect the steam produced in a production well. Most geothermal reservoirs require “geothermal stimulation” to ensure adequate water flow between injection and production wells … i.e. Hydraulic Fracturing. Department of Hydraulic Fracturing Chemical Engineering Geothermal Stimulation or Hydraulic Fracturing (“fracking”) is the process whereby the geothermal rock is drilled and shattered by injecting fluid into the well at pressures higher than the rock’s yield strength, typically 30 – 75 MPa. The fracking fluid is typically > 99.9% water and sand particles (silica, SiO2 < 100 m), with small concentrations of additives to help lower fluid friction and prevent deposits in the well casings. The sand particles help keep the fractured rocks open to allow fluid to flow after the pressure is relieved from the fracking process.  Department of Types of Geothermal Power Plants Chemical Engineering Dry / superheated Steam directly to turbines Hot reservoir > 300oC Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Department of Chemical Engineering Double Flash Geothermal Plant – Kawerau, NZ Department of Chemical Engineering Department of Chemical Engineering Flash unit Moisture Separators Department of Environmental Effects Chemical Engineering Emissions from plant operation: – Off gases from geothermal reservoirs include: H2 S SO2 CO2 NOx Radon – although the middle three at much reduce levels versus conventional fossil plants. Department of Process / Environmetnal Issues Chemical Engineering Water/steam emanating from the geothermal production wells contain considerable amounts of salts, heavy metals and potential hydrocarbons from nearby natural gas, coal or oil reserves. – Huge issue if plant operation is on direct cycle, heavy metals, salts and silica (SiO2) may carry over and deposit on turbine blades … bad for production efficiency and safe operation. – Flash separators act to concentrate impurities leading to concentrated brine solutions … bad for power plant materials (corrosion – Chlorides are bad!) – Typically re-injected into reservoir but may leak / spill and contaminate groundwater. Department of Environmental Effects Chemical Engineering Induced seismicity – potential for creation of small earthquakes due to the “geothermal stimulation”, water injection and steam extraction processes. Heat draw: – Most reservoirs in N. California are removing heat at a faster rate than they can be replenished effectively cooling the geothermal reservoir. – NON-RENEWABLE when operated in this fashion. Future of Geothermal: – Deep underground reservoirs (10 km ??) required to alleviate dissipation problem;