Meer dan groene chemie

Transcriptie

1 Meer dan groene chemie Dr. Ir. Rosalie van Zelm Universitair docent Afdeling milieukunde Scheikunde docentendag 4 april

2 Wat gaan we doen? Inleiding van green chemistry naar complete milieu analyse Casus Discussie 2

3 3 First steps towards Green Chemistry 1987: Brundtland Commission on Environment and Development (United Nations) defined sustainable development as:... meeting the needs of the present without compromising the ability of future generations to meet their own needs. Since then: discussion on sustainable development: Two key aspects of sustainable development from a chemicals and energy perspective are: how fast should we use up fossil fuels? and how much waste or pollution can we safely release to the environment? 3

4 4 Green Chemistry 1990s: US Environmental Protection Agency (EPA) coined the phrase Green Chemistry To promote innovative chemical technologies that reduce or eliminate the use or generation of hazardous substances in the design, manufacture and use of chemical products. Since then, Green Chemistry has gradually become recognized as both a culture and a methodology for achieving sustainability The 12 Principles of Green Chemistry were formulated, which can be considered guidelines for improving the sustainable character of chemical production 4

5 5 But How fast should we use up fossil fuels? And how bad is that How much waste or pollution can we safely release to the environment? And what are the environmental consequences 5

6 6 How green is green chemistry? Inleiding This cannot be measured by a single green chemistry principle only This cannot be measured by one aspect in a chemistry process or reaction only Less atoms might end up in by-products, but they could be more toxic A greener reagent might be used, but the whole process could need more energy A biofuel needs a large area of land, leading to a loss of biodiversity, just like CO 2 emissions of fossil fuels Water as a solvent requires a lot of energy to clean up (distillation, heat transfer..) 6

7 Environmental impacts Effectbeoordeling Resources Abiotic resources Biotic resources Land occupation Water depletion Pollution Climate change Ozone depletion Human toxicity Ecotoxicity Acidification Eutrophication Photochemical ozone formation Particulate matter formation Radiation Waste heat Noise 7

8 Environmental life cycle assessment Life-cycle of a product, (chemical) process, service all life-cycle stages from cradle to grave, including transport and energy use Resource extraction Production Consumption/ Use Transport Waste treatment/ disposal 8

9 9 A method to evaluate the greenness of chemistry Inleiding Evaluate the potential environmental impact of a product systematically and quantitatively: Compiling the environmental inputs and outputs Evaluating their potential environmental impacts Ecosystems/ Biodiversity Resources Humans 9

10 Reasons to start an LCA To identify environmental bottle necks in a product or process system e.g. chemical production To compare different products with a same service e.g. fossil fuel vs. biofuel Doel en reikwijdte To compare improvement options for a product or process system or new production processes e.g. chemical production old-fashioned vs catalysis use Identify prospects of novel chemical process e.g. a process not implemented yet e.g. what would de the consequences of upscaling a process

11 11 Applications of LCA results Coca Cola (1969): glass or synthetic/plastic? - plastic was back then more easy to recycle - plastic less energy during transport because of the low weight - Plastic bottles made in own factory - Glass a natural product ( Inleiding Procter and Gamble: what causes the largest environmental burden? - energy- and wateruse of a washing machine Consequence: development of detergents that are able to wash at low temperatures and a consciousness raising campaign for consumers 'tikkieterug'. LCA is used in Europe to draw up recycling- and recovering target figures for packaging garbage 11

12 12 Groene beoordeling (organophosphorus-catalyzed Appel and Wittig reactions)

13 Appel and Wittig reaction Catalytic reaction: - In situ phosphine oxide regeneration - Stoichiometric reducing agent silanes require rather lengthy synthetic preparation 13 Van Kalkeren et al Green Chemistry 15:

14 Wittig reaction The reaction cycle for the catalytic Wittig reaction; the reducing agent is an organosilane and the phosphine compound acts as a catalyst. 14

15 Process trees 15 Van Kalkeren et al Green Chemistry 15:

16 Inventory olefin (1 mol) Yield 95% 1Molecular weight Amount (mol) Amount (kg) theoretical Product output 1 Nature (resources) Technosphere (materials/fuels) Required chemicals ethyl(tpp)acetate substrate toluene (3M) Energy (electricity/heat) Heat Electricity 0.60 MJ 0.10 kwh classic Wittig Emissions (0.2% of raw materials) ethyl(tpp)acetate 0.00 substrate 0.00 toluene (3M) 0.00 To waste/river?: ETPPA (TOC) 0.02 toluene (3M) phosphates (from TPPO) Van Kalkeren et al Green Chemistry 15:

17 Global warming potential (GWP) Characterisation factor GWP CO 2 GWP x RadiativeForcing RadiativeForcing x CO2 CH 4 N 2 O Environmental Mechanism (Heat Trapping) Infrared Radiative Forcing kg CO2 eq. SF 6 17

18 LCA results greenhouse gas emissions 18 Van Kalkeren et al Green Chemistry 15:

19 Conclusions Using PMHS as silane 66% reduction GHG potential LCA helps to determine environmentally preferable option - Type of reaction - Type of catalyst, reagent or solvent LCA important in early chemical methodology development 19 Van Kalkeren et al Green Chemistry 15:

20 20 LCA in de praktijk (biobrandstoffen en zonnecellen)

21 21 LCA van biobrandstoffen EU-beleid: 10% biobrandstoffen in de transport sector in 2020 Klimaat voetafdruk biobrandstoffen? Voorbeeld van biodiesel 21

22 22 Biobrandstoffen Klimaat voetafdruk Vrijmaken landbouwbodem Gebruik landbouwbodem Kunstmest Transport + raffinage Koolzaad-productie Palmboom-plantage Soja-productie 22

23 23 Klimaat voetafdruk (bio)diesel 20 kg CO2-eq/liter verstookte diesel Fossiele diesel Koolzaad Soja - regenwoud Sojasavanne Palm - minerale bodem Palm - veenbodem Initieel C verlies Jaarlijks C verlies Jaarlijkse N2O emissie Fossiele input 23 Reijnders & Huijbregts, 2008a,b. Journal Cleaner Production 16: ,

24 24 Voordelen van biobrandstoffen? Klimaat voetafdruk van biodiesel gelijk of hoger in vergelijking tot fossiele brandstoffen Mogelijkheden 2e generatie biobrandstoffen (lignocellusose), organisch afval, gebruik van marginale landbouwgronden Direct omzetten van zonlicht in (elektrische) energie? 24

25 25 LCA van zonnecellen Type zonnecellen Crystalline Silicon (grootste marktaandeel) Dunne-laag cellen (toenemend marktaandeel) Dunne-laag cellen 1) Amorphous Silicon (a-si based) 2) Cadmium telluride (CdTe) 3) III-V materials (e.g. GaAs) 4) Others (e.g. CIGS and organic) 25

26 26 Proces-stappen a-si/nc-si laminaat production Niet het hele verhaal: Waar komen de materialen en energie vandaan? 26

27 27 a-si/nc-si laminate zonnecellen Milieu effecten Milieu effecten over de hele levenscyclus worden geanalyseerd, bv voor broeikaseffect Energie Terugverdientijd a) Consumptie van energie gedurende de levenscyclus van de zonnecel b) Productie van energie door de zonnecellen 27

28 28 Energie terugverdientijd Type module Energie terugverdientijd in Nederland (jaar) Energie terugverdientijd in Z- Europa (jaar) Helianthos zonnecel Multicrystalline Si Resultaat: Energie terugverdientijd is veel kleiner dan de levensduur van zonnecellen (> 20 jaar). 28 Mohr et al Progress in Photovoltaics 21, (4):

29 29 Klimaat voetafdruk van zonnecellen kg CO2 eq/kwh Standard UCTPE European mix mc Si a Si/nc Si InGaP/GaAs Electricity type Gemiddeld gezin verbruikt 4 tot 5 MWh aan elektriciteit per jaar: van 2,000-2,500 kg CO 2 naar kg CO 2 per huishouden per jaar 29

30 30 Voordelen van zonnecellen? Energie en klimaat voetafdruk van zonnecellen veel lager in vergelijking tot fossiele brandstoffen Energieterugverdientijd van zonnecellen is 2-5 jaar. 30