Combining coal and renewables

Transcription

1 Combining coal and renewables Dr Stephen Mills IEA Clean Coal Centre, London International Power Summit, Munich, February 2014

2 Introduction and content Introduction and background Reasons for coupling coal use with REs Growing level of renewables and their impacts (with particular emphasis on biomass and wind) Gasification and co-gasification Hybrid energy-producing schemes Summary

3 Global energy demand and supply By 2040, world population of ~9 billion Global energy demand 30% higher than now Coal will still be used widely biggest use now is for electricity generation (42% of world s electricity) provides >30% of global primary energy global coal consumption has increased for 12 successive years 250, , , ,000 50,000 Largest individual proven national coal reserves (Mt) 0 production has soared in some non-oecd countries

4 Global increase in renewable energy Wind: latest additions of ~45 GW/y global wind capacity now >280 GW around 70 countries have >10 MW of capacity ten biggest players = 87% of total capacity includes China, the USA, India, Germany, UK, Canada Biomass: can take many forms uptake for energy production increasing in many countries often environmental and economic considerations frequently supported by incentives EU 27 gross energy consumption Mtoe

5 Why the growth in renewable energies? depletion of energy resources diversification of sources possible climate change linked to the use of fossil fuels Perceived advantages of VREs capital costs high, but operating costs may be low fuel costs may be negligible or even zero no pollutant emissions from day-to-day operation similarly, no direct CO 2 emissions

6 Intermittent renewable energies Solar power USA Wind power - UK

7 The rise of intermittent renewables the use of such technologies will increase further - particularly wind and solar power increasingly, they will form part of networks or grids that also include thermal plants (coal and gas) because they operate in a different manner, their variable output can have a number of impacts on thermal plants

8 Impacts on other power plants When input from renewables is high, thermal stations may be expected to operate at part load or cycle Hard coal Lignite Natural gas

9 Combining coal and renewables Biomass, wind, solar, etc. - why bother? - what are the incentives?

10 Energy production using combinations of coal and renewables Forest residues Biomass thinning operations logging fire prevention downstream processing Wind power mmm Energy crops Various ways to combine the use of coal, biomass and intermittent renewables have been proposed

11 Advantages and disadvantages of biomass use Pros: use unwanted wastes minimises landfill reduce fossil fuel use extend life of fossil fuel reserves reduce conventional emissions reduce CO 2 Cons: can be expensive to harvest and produce may tie up land and other resources seasonal limitations some residues retained in situ for ecological reasons low CV - may need large amounts physical properties grinding, pulverising chemical properties (alkalis, chlorine)

12 The World s forests Where and how much? (1000 ha) Africa 675,000 Asia 593,000 Europe 1,005,000 Americas 1,570,000 Total >4,000,000 Top five most forested countries: Russian Federation > Brazil > Canada > USA > China

13 Logging operations

14 Gasification versatile and well proven for power generation, chemicals, fuels, and fertilisers virtually any carbon-based material can be gasified coal most widely used; but also some biomass different gasifiers - many variants available: entrained flow fluidised bed fixed bed systems

15 Coal and biomass gasifiers Typical biomass gasifiers much smaller than coal Coal Biomass ,000 t/d t/d Air- or oxygenblown Mainly air-blown Great Plains, USA JY biomass gasifier, China

16 Coal/biomass co-gasification Advantages Coal Biomass Co-gasification High energy content May be low cost waste or residue Large coal gasifiers economies of scale - high efficiency, better economics Widely available Lower emissions Allows biomass access to wellestablished processes Large reserves High availability in some countries Smooths out seasonal biomass availability Less prone to price fluctuations Reduces impacts of variations in biomass properties Usually costs less than Reduces coal plant emissions; possibly biomass credits for the use of renewable fuel Well proven in largescale processes Some biomass catalyses coal reactions; synergetic effects observed Disadvantages Production-related impacts Lower energy content Storing, feeding, blending arrangements may be more complex Conventional pollutant Variable properties emissions CO 2 emissions Harvesting, transport and pre-treatment costs Seasonal availability Tar, alkali issues

17 Co-gasification projects IGCC power plants Plant Capacity (MWe) Gasifier Biomass used Buggenum, Netherlands ELCOGAS, Spain 284 Shell Dried sewage sludge, chicken litter, sawdust 335 Krupps- Olive wastes, almond shells, waste wood, Koppers vineyard wastes, MBM PRENFLO Polk plant, USA 250 GE Bahia grass, eucalyptus Chemicals production Berrenrath, Methanol HTW fluidised MSW, dried sewage sludge, loaded cokes Germany bed Schwarze Pumpe, Methanol Combination of BGL, FDV, Demolition wood, sewage sludge, plastics, MSW Germany GSP Sasol, S. Africa Various Sasol-Lurgi Bark, wood pulp/bark ZAK + PKE, Poland 300 MWe + MeOH, chemicals na na

18 The Willem Alexander IGCC plant, The Netherlands Dried sewage sludge Sawdust Chicken litter

19 Combined gasification and renewable energy concepts Organisation Technologies proposed NREL, USA Gasification/ co-gasification + electrolysis (wind) NETL, USA Coal gasification + electrolysis (wind) CRL Energy, New Zealand Leighty Foundn, USA Univ. Lund, Sweden Elsam/DONG Denmark Lausanne, Switzerland Coal/biomass co-gasification + electrolysis (wind) Coal/bio. co-gasification + electrolysis (wind) Biomass (wood) gasifier + electrolysis (wind) Biomass gasification + electrolysis (wind, solar) Wood gasification + electrolysis China Various: Gasification + electrolysis (wind) Status Various studies under way. Concepts include: combining wind power and biomass gasification combining biomass gasification and electrolysis combining coal and biomass co-gasification Several gasification-based hybrid systems being examined Systems to produce SNG, electricity and biodiesel t/d plant proposed. Unconverted coal from gasifier fed to oxy-combustor Syngas could be used to produce low-carbon FT chemicals, synfuels Oxygen from electrolysis fed to gasifier Hydrogen - enrich product gas, stored, transport fuel, fuel cells Oxygen from electrolysis fed to gasifier Oxygen from electrolysis fed to gasifier Various co-generation concepts to produce power, heat, transport fuels examined. Hydrogen added to syngas. Oxygen for biomass gasification Several processes examined for SNG production Oxygen from electrolysis fed to gasifier. Hydrogen fed to syngas. Mainly for SNG, methanol, ethylene glycol production

20 Water electrolysis Electrolysis is a means for separating water into gaseous hydrogen and oxygen Only inputs are feed water and low voltage direct current

21 Hydrogen and oxygen production by water electrolysis Several different types of electrolyser are available commercially: proton exchange or polymer electrolyte membrane (PEM) electrolysers alkaline electrolysers solid oxide electrolysers electrolyser efficiencies between 56 and 73%, but RD&D is improving this; electricity supply from any source but to be viable, must be low cost; despite intermittent output, wind currently the lowest-cost renewable. Several factors determine the cost of hydrogen and oxygen: capital cost of the electrolysis plant its overall efficiency the cost of the electricity input

22 Large scale electrolysis Examples of commercial scale electrolysis facilities NEL Hydrogen Technologies Lurgi electrolyser

23 E.ON Power-to-Gas (P2G) project Electrolysers Natural gas grid hydrogen oxygen

24 Possible uses for gases produced Syngas Fuel cells Transport fuel Gas turbines Hydrogen Oxygen Industrial applications Coal/biomass gasifier Oxyfuel combustion

25 Hybrid systems incorporating renewables Examples of studies based on coal, biomass, coal + biomass USA Denmark Sweden New Zealand China Switzerland Germany Several studies of hybrid systems for SNG, electricity, transport fuels. Includes gasification and electrolysis, and coal/biomass co-gasification with CCS REtrol Vision (REnewable energy + petrol) - cogeneration + transport fuels. Biomass gasification, electricity from renewables, water electrolysis, + CO 2 from post-combustion capture Biomass gasification + wind power. Oxygen from electrolysis fed to gasifier CRL Energy coal/biomass co-gasification + wind energy for electrolysis. Oxygen fed to gasifier; hydrogen to enrich syngas. Production of FT liquids and other products Various studies combining coal gasification + renewables. Wind energy for electrolysis. Oxygen fed to gasifier. Hydrogen used to enrich syngas. Syngas used for methanol production Biomass gasification + electrolysis. Oxygen fed to gasifer. Hydrogen used to enrich SNG then fed into natural gas grid RWE Power-to-gas project (Niederaussem) will couple wind electricity, Siemens PEM electrolyser, CO 2 from power plant flue gas, to produce SNG

26 APS demonstration plant, New Mexico, USA H 2 and O 2 from windpowered electrolysis H 2 to gasify >3000 t/d of coal produces SNG, fed to grid or power plant unconverted coal fed to oxygen combustor to generate 41 MWe 90% CO 2 capture from power production - fed to an algae farm for biodiesel production

27 Summary 1 Growing global population and rapidly rising energy demand Incentives to develop novel energy-producing systems many schemes proposed, but fossil fuels will remain vital - combine these with renewables such as biomass and wind each individual power source has its own pros and cons - but combining these may overcome many shortcomings to be a runner, systems need to be practical, economically viable, and environmentally benign

28 Summary 2 Gasification Coal/biomass co-gasfn. Gasification + renewables combinations both coal and biomass gasified individually many technology variants available for each can provide advantages; overcome some problems can be environmentally and economically beneficial possibilities for producing a range of different products (SNG, chemicals, transport fuels) a number of routes being pursued examined some of the more promising concepts being developed particular emphasis on co-gasification coupled with windpowered electrolysis (H 2, O 2 ) many projects still at early stage in their development some propose to incorporate CCS Co-gasification + renewables Some further advanced - some parts well established (co-gas) other parts being trialled (commercial demo of H 2 production from wind, and advanced electrolysers). If economics can be made to work, several concepts that combine coal, biomass and intermittent renewables look promising.

29 Thank you for your attention Dr Stephen Mills IEA Clean Coal Centre, London