Meer dan groene chemie

Transcription

1 Meer dan groene chemie Dr. Ir. Rosalie van Zelm Universitair docent Afdeling milieukunde Scheikunde docentendag 10 april

2 Wat gaan we doen? In discussie over milieu effecten die chemie kan veroorzaken, hoe je deze kan inschatten en hoe je ze kunt verminderen 2

3 Which car is better, with regards to climate change? Let s say you live in the USA, and you want to buy a new car, should you go for: The Zero-emission Nissan Leaf - 100% Electric kwh/mile ~ 0.18 kwh/km Hybrid Electric Vehicle Toyota Prius - Runs on gasoline (50 mpg ~ 21.3 km/l) - Combustion engine and small electric engine - Does not use electricity from the grid 3

4 Which car is better, with regards to climate change? Easy right? One is a zero-emission vehicle, the other uses gasoline Probability that a Nissan LEAF emits less CO 2 than a Toyota Prius 4 Source: Tamayao et al. 2015, Environ. Sci. Technol.,

5 Why isn t there a clear winner? - Internal combustion engine vehicles emit CO 2 during driving - 100% electric vehicles have zero emissions during driving, but: - During electricity generation fossil fuels are burned and these emit CO 2 - Depending on the location the electricity may be more or less green - Ignoring these emissions is a typical example of burden shifting - Further emissions occur during the production phases of both cars For a fair comparison of mitigation options we need to take all these aspects into account! 5

6 6 Other questions arise 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 6

7 7 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..) 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 Doel en reikwijdte 1 0 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 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 10

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 Voedsel productieketen Resources Energy Emissions Waste 12

13 13 ReCiPe Huijbregts et al. 2016

14 Soep van Knorr 14 Milà i Canals et al Int J LCA 16, 50-58

15 15 Vergelijken 2 producten effecten biodiversiteit (NL) 15

16 Voetafdruk levensmiddelen 16

17 Klimaat voetafdruk door verbouw tomaten locatie en jaar belangrijk? 17 Lam, van Zelm et al Environ Sci Technol

18 Verbouw tomaten in Iran Irrigatiesysteem 18 Pishgar-Komleh et al J Clean Prod

19 Irrigatie en kunstmest vs Organisch Mais Sojabonen Kg soil lost per kg crop produced 19 Van Zelm et al Ecosys Serv

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 Proces-stappen 26 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