conversion of co2 to fuel and back using high temperature ... · pdf...

1 29 Sept 2016

Christopher Graves <[email protected]>

Closing the Carbon Cycle: Fuels from Air conference

at Arizona State University, Sept. 28-30, 2016

Conversion of CO2 to fuel and back using high temperature electrochemical cells and solar/wind power

2 29 Sept 2016

CO2-to-fuels: renewable transportation fuels

C. Graves, S.D. Ebbesen, M. Mogensen, K.S. Lackner, Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy, Renewable and Sustainable Energy Reviews. 15 (2011) 1–23. doi:10.1016/j.rser.2010.07.014.

Two sources of CO2 – point sources or the atmosphere

Closed-loop

3 29 Sept 2016

Denmark’s need for energy storage

Expected wind power supply compared with gross electricity consumption in Denmark in 2020 and 2050. The wind power supply data from 2012, obtained from energinet.dk, is simply scaled up so the total for the year comprises 50% and 100% of the total consumption. The electricity consumption is assumed constant; the consumption data from 2012 is used without re-scaling.

Storing excess renewable electricity

CO2 + H2O + electricity hydrocarbons

Electrolysis – on the Danish agenda!

transportation fuel

natural gas network (back to electricity)

4 29 Sept 2016

CO2/power-to-fuels via electrolytic hydrogen production

Ingredients needed:

• Low cost electricity

• High efficiency system

• Low cost electrolysis, CO2 capture, system capital cost

5 29 Sept 2016

Cost drivers for power-to-fuels

OPEX CAPEX

Electricity cost Efficiency Here Stack efficiency System losses Theis O&M

Electrolyzer Resistance Anne Lifetime Anne, Theis, Here Capacity factor Here CO2 capture device Yesterday Balance of system Here

Latest levelized cost of installed solar PV: 2.99 ₵/kWh (Dubai, May ‘16) and 2.91 ₵/kWh (Chile, Aug ‘16)

solarlove

cleantechnica

6 29 Sept 2016

Electrolyzer efficiency and rates (why solid oxide cells?)

C. Graves, S.D. Ebbesen, M. Mogensen, K.S. Lackner, Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy, Renewable and Sustainable Energy Reviews. 15 (2011) 1–23. doi:10.1016/j.rser.2010.07.014.

7 29 Sept 2016

Solid oxide cells: Commercialization

• Mainly SOFC so far for combined heat & power, and recently mobile, applications

– Competes with established gas turbines & engines, but higher efficiency + smaller scale vs turbines

• SOEC for H2/CO production using excess renewable electricity

– H2 production competes with established alkaline electrolyzers, but with higher efficiency

– CO production for on-site specialty-gas supply – HTAS initial niche market

– Small markets at the moment, huge growth expected

Bloom Energy Servers (SOFC) 100s of MW installed since 2010

at Apple, AT&T, Bank of America, Coca-Cola, eBay, Google, Ikea, Kellogg, Target, Wal-Mart…

Nissan announced EV with SOFC range-extender that runs on bio-ethanol (June 2016)

8 29 Sept 2016

Stack mass production – factory economies of scale

D. Villareal PhD thesis, 2016 Well suited to achieving very low cost by automated mass

production like in the electronics and automotive industries (and electronics-like energy technology like solar PV and batteries)

9 29 Sept 2016

Cost drivers for power-to-fuels

OPEX CAPEX



D. Villareal PhD thesis, 2016

10 29 Sept 2016

Balance of system cost and size (handling gas and heat flows)


• Literature studies estimate the SOC stack cost at 10-20% of the total installed CAPEX depending on system design

• Heat exchangers, power electronics, installation are each estimated to cost equal to double that amount

11 29 Sept 2016

Reconsidering large chemical plants mass produced systems

12 29 Sept 2016

Power-to-methanol plants

Carbon Recycling International (CRI) alkaline H2O electrolysis + CO2+H2 to methanol

SOEC methanol plant design (Haldor Topsoe)

J.B. Hansen, N. Christiansen, J.U. Nielsen, Production of Sustainable Fuels by Means of Solid Oxide Electrolysis, in: ECS Transactions 35(1), Montreal, QC, Canada, 2011: pp. 2941–2948. doi:10.1149/1.3570293

Currently operational Proposed, conventional chemical plant

13 29 Sept 2016

Power-to-methanol device

S.H. Jensen, X. Sun, S.D. Ebbesen, R. Knibbe, M. Mogensen, Hydrogen and synthetic fuel production using pressurized solid oxide electrolysis cells, International Journal of Hydrogen Energy. 35 (2010) 9544–9549. doi:10.1016/j.ijhydene.2010.06.065.

Proposed: integrated, self-contained, mass-produced, everything at 50 bar

System scale Efficiency CAPEX Installation cost

CRI operating plant Large ~50% High High

HTAS plant design Large 80% High High

Proposed Small 80%+ Low Low

14 29 Sept 2016

Power-to-fuel devices

Commercialized MicroCHP / micro power generation

Let’s aim for Micro power-to-fuel production

Bloom boxes

15 29 Sept 2016

Lowering the system cost

• Mass production

• Integration

• Reversible operation

OPEX CAPEX



16 29 Sept 2016

Reversible operation of solid oxide cells

(H2O not shown)

Conversion of CO2 to fuel and back using high temperature electrochemical cells and solar/wind power

17 29 Sept 2016

Reversible operation of solid oxide cells

Fuel cell mode

fuels electricity

Electrolysis mode

electricity fuels

current density (A/cm2)

C. Graves, S.D. Ebbesen, M. Mogensen, Co-electrolysis of CO2 and H2O in solid oxide cells: Performance and durability, Solid State Ionics. 192 (2011) 398–403. doi:10.1016/j.ssi.2010.06.014.

Perform almost equally well in both modes

18 29 Sept 2016

Reversible operation yields longer cell lifetime

Constant electrolysis vs charge-discharge cycles

C. Graves, S.D. Ebbesen, S.H. Jensen, S.B. Simonsen, M.B. Mogensen, Eliminating degradation in solid oxide electrochemical cells by reversible operation, Nature Materials. 14 (2015) 239–244. doi:10.1038/nmat4165.

Highly enhanced stability!

19 29 Sept 2016

Two scenarios for reversible operation

Controlled directly by time-series data:

1. Electricity supply/demand – energy balancing driven

– 100% wind for a Danish island

– Power-to-methanol(-to-power)

2. Spot market prices of electricity and natural gas – price driven

– Power-to-methane (buy electricity, sell gas)

– Natural gas-to-power (buy gas, sell electricity)

Capacity factor increase by market expansion

20 29 Sept 2016

100% wind power for a Danish island

Existing wind power supply scaled up to meet total energy demand (electricity + fuel)

(and heat demand met as byproduct because all energy conversion losses are in the form of heat)

electricity, 2.3

electric heat, 1.6

heat (district),

4.9

solar heat, 0.03 biomass

heat, 0.32

oil heat, 2.39

diesel transport,

6.95

gasoline transport,

1.85

Minus ~4 MWavg diesel for ferries (shown here but not included in balancing) C. Graves, J.V.T Høgh, M. Chen,

et al (in preparation)

21 29 Sept 2016

Long-term load-balancing stack test

Actual stack data

Energy balancing simulation

8-cell stack

800 °C

C. Graves, J.V.T Høgh, M. Chen, et al (in preparation)

22 29 Sept 2016

Wind Solar


23 29 Sept 2016

Meth-anol

synth.

Fuel cell mode

Anode recycling

H2O(g)

+CO2 (+H2+CO)

CH3OH

Meth-anator CH4

O2

H2O(l)

heat

O2

CO2 (+H2+CO)

O2 H2O

SOC stack

electricity

HX fluid

1

2

3

4

heat

HX fluid

Recycle

Co-electrolysis

H2O(g)

+CO2 (+H2+CO)

CH3OH

Meth-anator CH4

O2 H2O(l)

O2

CO2 (+H2+CO)

O2 H2O

SOC stack

electricity

1

2

3

4

Electrolysis mode

Meth-anol

synth. heat

DME synth.

System runs independently.

DME synth.

Recycle

800 °C

<1.4V, <1 A/cm2

800 °C

>0.8V, <0.5 A/cm2

In SOC stack:

CH4+1.5H2O+0.5CO2+Q3.5H2+1.5CO2

H2+CO2 +QshiftH2O+CO

H2+½O2 H2O+E+Q

In SOC stack:

CO2+2H2O+ECO+2H2 (+1.5O2)

H2+CO2 H2O+CO

(4H2+CO2CH4+2H2O+Q at suitable T and P)

System runs independently. Air

capture System runs independently.

Air capture

System runs independently.

The reforming composition for the first reaction is just an example and not the real one.


24 29 Sept 2016

Electricity price driven

Energikoncept 2035 scenario, energinet.dk

From Norway

Peaking generation (SOFC)

Storage (SOEC)

Spot market prices, 2008, energinet.dk

Operate electrolysis mode

Operate fuel-cell mode

Reversible operation in the Danish scenario

25 29 Sept 2016

Reversible operation controlled by electricity & gas spot prices


Electrolysis mode switch

26 29 Sept 2016

Electrolysis mode growing each year as wind supply grows


Mode of operation per year Profits from each mode per year

• Near term: price volatility due growing variable wind is good for reversible systems (short periods of electrolysis high profits)

• With predicted 2050 time-seies data (100% wind electricity supply), profits by playing this game are much higher, even though the reversible system may erode the volatility and make per hour profit from electrolysis lower

27 29 Sept 2016

If we will turn around and convert it right back to electricity, need not be convenient, portable, high energy density and plug into existing infrastructure – need not be liquid hydrocarbon storage.

Overall fuel production cost (after mass production scale-up)

C. Graves, S.D. Ebbesen, M. Mogensen, K.S. Lackner, Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy, Renewable and Sustainable Energy Reviews. 15 (2011) 1–23.

100% capacity factor 20% capacity factor

28 29 Sept 2016

Conclusions

• High temperature electrochemical cells offer a higher efficiency CO2/power-to-fuels system

• Lower cost expected by mass produced integrated device

• Lower cost by reversible operation: – longer lifetime

– Increased capacity factor (dual markets) with only minimal system cost increase to add fuel-cell mode

• Low cost solar/wind power has arrived – Grid surplus in spot markets

– Standalone solar PV < 3 ₵/kWh

Now we need to get the power-to-fuel technology ready!

29 29 Sept 2016

Acknowledgements

Diego Villarreal PhD project with

Klaus Lackner

Ming Chen

Jón S.G. Mýrdal

Peter V. Hendriksen

Jens Høgh

Karsten Agersted

and other colleagues at DTU Energy

Funding: projects:

“Solid Oxide Electrolysis for Grid Balancing” (2013-1-12013)

“Towards Solid Oxide Electrolysis Plants in 2020” (2015-1-12276)

“Solid Oxide Fuel Cells for the Renew-able Energy Transition” (2014-1-12231)

conversion of co2 to fuel and back using high temperature ... · pdf...

Documents