T. Gundersen

1. Special Lecture on Energy & Environment Process Process Integration Energy Environment Process, Energy and System • Clean Process Technology (Ch. 28 in R. Smith) • Classes of Waste (Process & Utility) • Environmental Impacts from Energy Usage • Energy/Exergy & Component/System Efficiencies • Actions to mitigate Greenhouse Effects (Energy21) • How can TEP4215 Energy & Process (PI) Contribute Energy & Environment T. Gundersen E&M 01

2. Clean Process Technology – Some Ideas (Ref.: Robin Smith, Chemical & Process Integration, Ch. 28) • Environmental Issues (similar to Heat Integration) are often considered late in the Design Process • The Result is often “End-of-Pipe” Solutions • Clean Process Technology represents an Opposite Approach similar to Process Integration thinking: Minimize Waste at Source−Examples: • Choose Reactions Paths that avoid harmful Chemicals being produced as byproducts • Keep harmful Chemicals “inside the loop” by combining producing and consuming Reactions • Closing Processes as in Pulp & Paper Process, Energy and System Energy & Environment T. Gundersen E&M 02

3. S H U R Sources of Waste from the Process Industry R + S : Process Waste H + U : Utility Waste • Types of Process Waste: • Waste Byproducts, Purge Streams, etc. • Sources of Process Waste: • Reactors (byproducts, used catalysts, etc.) • Separation & Recycle Systems (inadequate recovery and recycle of valuable materials) • Process Operations (start-up, shutdown, product changeover, equipment cleaning, etc.) Process, Energy and System Energy & Environment T. Gundersen E&M 03

4. S H U R Sources of Waste from the Process Industry R + S : Process Waste H + U : Utility Waste Process, Energy and System • Types of Utility Waste: • Gaseous Combustion Products (CO2, SOx, NOx, Particles) • Aqueous Waste from BFW (Boiler FeedWater) Treatment • Waste from Water Systems • Sources of Utility Waste: • Hot Utilities (incl. Cogeneration) • Cold Utilities and Water Systems Energy & Environment T. Gundersen E&M 04

5. S H U R Sources of Waste from the Process Industry R + S : Process Waste H + U : Utility Waste Process, Energy and System • Our Focus in these Lectures: • Environmental Impacts from Energy Consumption • Remember to take a Systems Approach: • Local Emissions vs. Global Emissions • Producing or importing Electricity? Energy & Environment T. Gundersen E&M 05

6. Environmental Impacts from Processes including their Use of Energy • Various Kinds of Waste Material • Heavy Metals • CO and CO2 • NOx and SOx • CH4 , NH3 and other volatile compounds • Particles (“Particulates”) • VOC (Volatile Organic Compounds) • Heat (or Cooling) • Wastewater • Using scarce Freshwater Resources Process, Energy and System Energy & Environment T. Gundersen E&M 06

7. Environmental Design for Atmospheric Emissions (Ref.: Robin Smith, Chemical & Process Integration, Ch. 25) • Urban Smog (Los Angeles, Mexico City, Lima, Shanghai) • Photochemical Reactions • VOCs + NOx + O2O3 (Ozone) + Other Photochemical Pollutants (Aldehydes, Peroxynitrates, etc.) • Acid Rain • Natural Precipitation is slightly acidic with pH around 5-6 • Carbonic acid from dissolved CO2 • Sulfuric acids from natural emissions of SOx and H2S • Human Activity can reduce pH to 2-4 • Mainly caused by emissions of SOx • This is a primarily a local environmental problem • Can be a regional problem (from UK to Norway) Process, Energy and System Energy & Environment T. Gundersen E&M 07

8. Environmental Design for Atmospheric Emissions (Continued) • Ozone Layer Destruction • Lower Levels of the Atmosphere: Ozone is harmful! • Upper Levels: Ozone essential; it absorbs ultraviolet light! • Destruction is due to Oxides of Nitrogen and Halocarbons • The Greenhouse Effect • CO2 , CH4 and H2O present in low conc. in the atmosphere • Reduces emissivity and reflects some of the heat radiated by Earth. • Keeps the Earth warmer −a prerequisite for Life as we know it • This Balance can be disturbed Global Warming • Burning Fossil Fuels (increased emission of CO2) • Large Scale harvest of Forests (reduced absorption of CO2) • The largest Volume of Atmospheric Emissions from Process Plants is due to Combustion Process, Energy and System Energy & Environment T. Gundersen E&M 08

9. Actions that reduce the Environmental Impacts from Energy Consumption • Statement: The most “Green” Energy is the Energy that is not used • Process Integration increases Energy Efficiency and results in Energy (in various forms) not being used • Investment in Equipment may cause use of Fossil Fuel based Energy elsewhere (considering LCA) • More comprehensive List of Actions • Use less Energy (vs. “Standard” of Living) • Increase Energy Efficiency • Increase Process Efficiency • Switch between Fossil Fuels • Switch from Fossil Fuels to Renewables Process, Energy and System Energy & Environment T. Gundersen E&M 09

10. “Energi21” −National Strategy for R&D, Demonstration & Commercialization − Energy in the 21st Century • The Vision of Energi21 • Norway: Europe’s leading Energy and Environment-Conscious Nation −from a National Energy Balance to Green Energy Exports • To realize this Vision: 5 Priority R&D Areas • Efficient Use of Energy (Industry/Transport/Buildings) • Climate-friendly Power • CO2-neutral Heating • An Energy System to meet the Needs of the Future • Desirable Framework Conditions for R&D Process, Energy and System Energy & Environment T. Gundersen E&M 10

11. Energy Consumption (TWh) in Norway by Sector in 2007 (Total: 813.5 PJ) Other Sectors: Private household (20.0%), Community Consumption (13.7%) and Fishing/Agriculture (3.6%) Process, Energy and System 35.1% 37.3% 27.6% T(erra) = 1012 The Course “Energy & Process” makes Sense !! Energy & Environment T. Gundersen E&M 11

12. Energy Consumption (TWh) in Norwegian Industry in 2007 (Total: 80.66 TWh) 29.6% Process, Energy and System 12.0% 17.6% 13.6% Discuss: Primary Application Areas for Process Integration? Energy & Environment T. Gundersen E&M 12

13. Main Focus in TEP 4215: Efficient Use of Energy • Saving Energy means Saving the Environment in one or more Ways (CO2, SOx, NOx, Particulates) • Process Integration provides Methods and Tools to improve Heat Recovery and Heat Integration • The Result is reduced Energy Consumption • With the current Energy Mix this also means reduced Emissions from Fossil Fuels • The Systems Approach in Process Integration can be used also to reduce Waste and other Impacts from the Process Industries Process, Energy and System Energy & Environment T. Gundersen E&M 13

14. What we’ve done in TEP 4215 Process Integration • Heat Recovery between Hot and Cold Streams to reduce Energy Consumption in the form of Hot and Cold Utilities • Heat Integration of Distillation Columns and Evaporators with the “Background Process” • Use of Heat Pumps to “lift” Thermal Energy (Heat) from below to above the Pinch by using Mechanical Energy (Power or Electricity) • Combined Heat and Power (Cogeneration) by using Backpressure Turbines and deliver Heat to the Process or District Heating System while producing Power/Electricity • Process Modifications to improve Scope for Heat Recovery guided by the “Plus/Minus” Principle Process, Energy and System Energy & Environment T. Gundersen E&M 14

15. Tools developed in Process Integration • The Composite Curves • Provides Insight and a Graphical Way to establish Energy Targets • Suggests Process Modifications (+/−Principle) • The Grand Composite Curve • Based on the Heat Cascade −a Transshipment Model • Optimal Mix of Utilities (including Production) • Possible Integration of Reactors • Integration of Distillation Columns and Evaporators • Potential for and Correct Use of Heat Pumps • Combined Heat and Power Considerations Process, Energy and System Energy & Environment T. Gundersen E&M 15

16. A brief Discussion about Efficiencies • Energy vs. Exergy Efficiency • Exergy is defined as the Ability to produce Work • Exergy screens Energy Types w.r.t. Quality • Exergy does not reflect Cost −or better: The Cost of various Energy Forms does not reflect the 2nd Law • Component vs. System Efficiency • “Local” vs. “Global” Considerations • Importing Electricity may improve Plant Efficiency and Emission Figures (inside Battery Limits) • With Process Integration, Systems Thinking and utilizing Synergies, Component Efficiencies become less Important and System Efficiency improves Process, Energy and System Energy & Environment T. Gundersen E&M 16

17. 10% 30% 100% 20% 40% Ref.: Olav Bolland Basic Principle for Combined Cycle Plant Process, Energy and System Energy & Environment T. Gundersen E&M 17

18. Ref.: Olav Bolland Combined Cycle Power Plant Power Production only Heat & Power Production Process, Energy and System Energy & Environment T. Gundersen E&M 18

19. Some Efficiency Calculations • Exergy Content of Heat Q at Temperature T • Ex = Q (1 − T0/T) • T0 is “ambient” temperature (25°C or ≅298 K) • Exergy Content of Fuel • Includes Chemical Exergy −Difficult !! • Often taken to be the Low Heating Value (LHV) • More pragmatic: Pure (100%) Exergy • Exergy Content of Power & Electricity • This is Pure Exergy !! • Calculations on the Blackboard • The Heat Pump “Congregation” • Produce Electricity, “take back” the Heat later !! Process, Energy and System Energy & Environment T. Gundersen E&M 19

20. Indicators for CO2 Emissions • Material Production • tons of CO2/tons of Product • Energy Production • tons of CO2/MWh Electricity • Consider 3 Cases of Power Production • Natural Gas (assume pure CH4) based Combined Cycle Power Plant with an Efficiency of 60% • Same as above but Cogeneration of Heat and Power with a Total Efficiency of 90% • State of the art Coal (assume C/H=1) based Power Plant with an Efficiency of 40% • Calculations on the Blackboard • Fuel Switching can be Powerful Process, Energy and System Energy & Environment T. Gundersen E&M 20