Renewable gases : What are the challenges? François CAGNON CEDEC Gas DAY, February 18, 2013

Transcription

1 Renewable gases : What are the challenges? François CAGNON CEDEC Gas DAY, February 18, 2013

2 RENEWABLE GASES: Definitions Biogas is the raw product of the biological process of anaerobic fermentation. Typically biogas consists of 35-65% methane. Biomethane is biogas that has been upgraded to resemble natural gas It consists of 95-97% methane. Bio syngas is the product of the thermal process of gasifying the biomass. It consists of a mixture of mainly hydrogen (H 2 ), carbon monoxide (CO), carbon dioxide (CO 2 ), water vapour (H 2 O) and methane (CH 4 ). Bio-SNG (Bio-Synthetic Natural Gas) is bio syngas to which methanation is applied. The methane content which can be obtained by this process is at least 95%.

3 Processes of renewable gas production Direct use in Energy production Direct use in Industry / filling stations Reforming, upgrading Bio-Hydrogen Biomass or biodegradable fraction of waste Gasification Anaerobic digestion Bio syngas Biogas (raw gas) Methanation, upgrading Upgrading Biomethane (Bio-SNG) Biomethane Renewable gas to the natural gas network

4 Methanisation/gasification: different maturities + seaweed 4 Anaerobic digestion and gasification are complementary processes for the production of green gas (different resources and maturity)

5 Growing supplies, growing renewable energy G Microalgae On site production and CO 2 recycling Maturity R&D 2G Gasification/methanation Lignocelulosiqc Biomass (Woody, ) Pilot scale Anaerobic digestion Organic waste (municipal, industrial ) Biomethane energy vector potential Available 5

6 Anaerobic digestion Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen. The process can either be thermophilic digestion in which sludge is fermented in tanks at a temperature of 55 C or mesophilic, at a temperature of 30 to 40 C. The methane generation is a key advantage of the anaerobic process. The key disadvantage is the long time required for the process (up to 30 days) and the high capital cost. Biogas CHP Heat Electricity End-users End-users Dedicated biogas grid End-users Manure and energy crops from farms Digester Cleaning and upgrading Digestate as fertilizer End-users Natural gas grid End-users

7 Thermal way of producing biomethane Dry biomass (water content between 20 and 40 %) composed essentially of ligno-cellulosic material Thermo-chemical oxidation at elevated temperatures (above 700 C). Methanation is a catalytic process, which principally consists in transforming CO (and CO 2 ) and H 2 into methane: fixed beds: high pressure; easier to operate; already been used on fossil fuels. fluidized beds: not yet been commercially developed but they allow a better valorization of the heat flows and are less sensitive to pollutants. 7

8 Micro algae Biomethane INDUSTRIAL INPUTS industrial, municipal, C RESIDUAL HEAT recycling HARVESTING TECHNOLOGY 2011, technology : open ponds Global energy yield 1-5% MAIN PRODUCTS Results from pilot scale plant CO 2 NOx - SOx Surface needed Nutrients BIOREMEDIATION A large unknown potential with 2M species estimated on Earth GREEN PRODUCTS PRODUCTION

9 European regulation frame Renewable Energy Directive (2009/28/EC): Connexion costs transparent and non-discriminatory Integration of biomethane easier thanks to grid extension if necessary Publication by grid operators of the technical rules and connexion tariffs Gas Directive (2009/73/EC) invites States members to: Adopt measures for an increasing use of biogas Guarantee the access to natural gas grids for biogas (with respect of technical and safety rules) For the regulation authority: promote the integration of renewable gases in distribution and transport grids No European standards at that time: Technical specification at national levels 9

10 Biomethane is usually injected into the distribution grid Grids pressures usually below 16 bar (some cases 40 or 70 bar). Most units quite small installations: flows under Nm 3 /h, or even 500 Nm 3 /h. In Germany and in the Netherlands some bigger installations can be found. 10

11 Sites injecting biomethane into the gas grids 11 Germany is leading in feed-in capacity (with more than Nm 3 /h)

12 Biomethane injection in natural gas grid: Quality issues Upgrading to biomethane Full interchangeability with natural gas No impact on network or end use Biomethane properties have to comply with natural gas specifications Producer cleans the biogas (CO2 and impurities removal) Grid operator may have to adapt the biogas (GCV adjustment, odorisation) Control of biomethane properties VERY important Once biomethane is in the grid it is in the customers house Out of spec gas or gas with odd impurities may lead to safety issues CEN PC 408: Work ongoing on biomethane specification (M 475) Recommendation: Grid operators keep a watchful eye on gas composition

13 Biomethane injection in natural gas grid: Capacity issue 13

14 Recompressing to transmission network: Solution? Biomethane in distribution grids is "Wet" : Water content about mg/m 3 : Transmission needs mg/m 3 High CO 2, O 2 content: Transmission may need <2.5% (CO 2 ) <10 ppm O 2 Odorised : Transmission sometimes doesn't want odorant (?!) At low pressure And recompression shall not "empty" the distribution grid! Thus compression costs may be small when compared to "cleaning" costs. Other solutions (storage, flaring, ) may be more economical even in environmental terms! 14

15 Biomethane injection in natural gas grid: Grid Design issue Not the other way round 15

16 Biomethane injection in natural gas grid: Custody transfer issue Volume measurement: Similar to natural gas Energy content measurement Gas analysis and Calculation with ISO 6976, AGA 8, Properties measurement (GCV, water content, etc) Same technologies as natural gas available Cost issues High investment for control laboratory Needs minimum production for profitability 16

17 Mixing biogas in natural gas grid No or partial upgrading of the biogas Not within natural gas specifications Blending with natural gas Resulting mixture within specifications Biogas flow rate: Function of natural gas quality and flow rate Specifications are controlled in the grid Close collaboration between producer and grid operator necessary Biogas Natural gas Mixture within specifications 17

18 Biogas used in dedicated grid No or partial upgrading of the biogas Potential impact on infrastructure and end use Need to customise network and end use Usually isolated grid Balance between supply and demand needed

19 Utilisation Direct use of raw biogas Num ber of Biogas Digester : M il. Units B iogas production : B il. m 3 Home production and use Fast growing in India and China Efficient but safety issues (H 2 S, CO) R E MO V A B L E MA N H O L E C O V E R S E A L E D WI T H C L A Y L O O S E C O V E R I N L E T G A S O U T L E T G A S Ave.500mm MA X 1000mm S L U R R Y D I S P L A C E ME N T T A N K O U T L E T P I P E

20 Utilisation On site use of partially purified biogas Local use for electricity and heat production Treatment is necessary for equipment protection Biogas Desulfurizer Dehumidifier system Siloxane Remover

21 Thank you for your attention. 21