sustainable energy and fuel options for future aviation · sustainable energy and fuel options for...

Sustainable energy and fuel options for future aviation

Arne Roth

Future Technologies and Ecology of Aviation

Alle Rechte bei / All rights with Bauhaus Luftfahrt

Contents

Alternative fuels & aviation: Key drivers & challenges

Background: What is jet fuel?

Synthetic jet fuel: Review of selected pathways

Alternatives beyond biomass

Conclusions and outlook

Elements of a Greenhouse Gas Neutral Society, Berlin, Oct 10-11, 2013 Seite 2


Contents








Alternative fuels: Key drivers & challenges

Supply security for aviation fuels

Growing mobility demand

Reduction of greenhouse gas

emissions


Today:

85 Mio. barrels per day

10

20

30

40

50

60

70

80

90

100

110

120

130 Exhaustion of oil reserves following:

• IHS (2005)

• EIA (2005)

• Exxonmobil (2005)

• CERA (2005)

• IEA (Alternative, 2005)

• LAHERRERE (2005)

• BP (2005)

• OPEC (2004)

• TOTAL (2005)

• KOPPELAAER (2005)

• ASPO (ver 5.0926, 2005)

Data: IPCC, 2007

- 360

14,4

14,2

14,0

13,8

13,6

13,4

13,2

13,0

- 340

- 320

- 300

- 280

- 260

1850

2000

1860

1870

1880

1890

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

14,6

Global average temperatur in ºC

CO2– content in atmosphere in ppm


Alternative fuels: Key drivers & challenges

Efficiency gains through

aircraft technology & innovation

Efficiency gains through

infrastructure and operations

Economic measures

Sustainable fuels: will be a key

component


2005 2010 2020 2030 2040 2050

50

100

150

200

CO2 Index(2005 = 100)

Emissions, should theindustry not invest innew technology

Carbon-neutralgrowth by 2020

Halving ofemissionsby 2050

(schematic)

Savings through technology, infrastructure and operations

Savings from additional technologies and sustainable fuels

Savings made in other sectors through carbon trading

Source: IATA, 2010


Contents








What is jet fuel?


ca. 80% alkanes („saturates“)

n-alkanes (n-paraffines)

iso-alkanes (iso-paraffines)

cycloalkanes (naphthenes)

ca. 18% aromatics

complex(!) mixture of hydrocarbons


How can jet fuel be produced?

Traditionally from petroleum

Already a crude mixture of hydrocarbons

Availability?

Ecobalance?

Alternatives will have to be synthesized (i.e. synthetic)

In principle, hydrocarbons can be synthesized from any carbon-based

feedstock!



Contents








Selected feedstocks and processes


coal

natural gas / biogas plastic waste

(ligno)cellulosic material

triglycerides (fat and oil)

sugar / starch

CtL (gasification, FT)

GtL (reforming, FT) WtL (gasification, FT)

BtL (gasification, FT)

AtJ (fermentation, oligom.)

PRJ (pyrolysis, hydropr.)

Hydrothermal conversion

CRJ (chemical conversion)

FRJ (fermentative conversion)

AtJ (fermentation, oligom.)

CRJ (chemical conversion)

FRJ (fermentative conversion)

HEFA (hydroprocessing)


Assessment of synthetic fuel options

Various options!

But which make sense?

Suitability

Drop-in capability?

Scalability

Economics

Technical scalability

Feedstock availability

Sustainability

Ecology (e.g. GHG balance)

Socio-economics

Near-term: drop-in mandatory

min. 8% aromatics

European Advanced Biofuels Flightpath

Initiative: 2 Mt biojet fuel in 2020

Less than 1% of global jet fuel demand

More than 3 Mha (rapeseed) required!

Mandatory, especially w.r.t. long-term

implementation

Complex w.r.t standards and evaluation



Biogenic feedstock: Risks and drawbacks

Primary problem:

Low overall efficiency

Photosynthesis

Energy efficiency of about 1% (upper

limit for C3 plants: 4.5%)

Multi-step conversion of biomass

required

Secondary problem:

High input required

Energy, water, land, nutrients, etc.

Suitability

No principle problem

Scalability

High production costs

Restricted land/feedstock availability

Sustainability

Food vs. fuel

LUC and land grabbing

Emissions (GHG, toxicants,

eutrophication)



Contents








Beyond biomass: General considerations

What we are doing:

E-carrier + O2 CO2 + H2O + energy

Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

carbohydrates

Combustion

2„CH2“ + 3O2 → 2CO2 + 2H2O + energy

hydrocarbons



Beyond biomass: General considerations

What we are doing:


What we want to do:


In nature: Photosynthesis

Sunlight (energy)

Water (electrons)

And in the laboratory?



Solar Fuels

Solar-driven thermochemical

splitting of H2O and CO2

H2O + energy → H2 + ½ O2

CO2 + energy → CO + ½ O2

Synthesis gas

Fischer-Tropsch synthesis

CO + 2H2 → „CH2“ + H2O

Refinement of hydrocarbon (CnHm)

product mixture yields SPK jet fuel

„Reverse combustion“


Chueh, W. C. et al, Science 2012, 330 , 1797-1801


Electrochemical pathways

Utilization of electric energy for

re-energizing carbon

Electrolysis of H2O


CO2 + H2 → CO + H2O

Electrolysis of H2O and CO2


CO2 + energy → CO + ½ O2

FT synthesis → CnHm product

Ecologic value depends on

electricity production



Nature as blueprint: artificial photosynthesis

Photo-catalytic approach


antenna/reaction center

oxidation catalyst reduction catalyst

H2O

2H+ + ½ O2

e- e-

synthetic reaction center

H+ (or) CO2

H2 (or) red. carbon


Electrofuels

CO2 assimilation through

utilization of electric energy by

non-photosynthetic, autotrophic

microbes

Novel technology!

low TRL

Efficiency?

Technically viable? Extensive genetic

engineering required!

Scalable?

Economics?


fuel

fuel

CO2, H2O

e- H2

H+

e-

CO2, H2O

Direct electrosynthetic

pathway Indirect lithotrophic

pathway

A. S. Hawkins et al., Current Opinion in Biotechnology 2013, doi 10.1016/j.copbio.2013.02.017 (in press) D. R. Lovly et al., Current Opinion in Biotechnology 2013, doi 10.1016/j.copbio.2013.02.012 (in press)


Dropping the „drop-in“ requirement?

Critical issues of „drop-in“ capable alternatives

Complex mixtures of complex organic molecules

Multi-step synthesis required

Disadvantageous w.r.t. overall efficiency, costs, GHG emissions etc.

Long-term option: „Non-drop-in“ alternatives

Disruptive technologies!

Examples:

Liquid carbon-based gases (e.g., CH4)

Hydrogen (H2)

Combustion

Fuel cell (electric flying)



Electromobility in aviation?

Exergy (useable energy):

The energy density is insufficient as

feasibility assessment criterion







Ragone metrics:

Exergy and power densities are the key

indicators for electric aircraft feasibility

in the comparison of alternative power

sources


References:

[1] A. Sizmann, Fuelling the Climate 2010, Hamburg, 18.07.2010

[2] H. Kuhn et al., CEAS, Venice, 24.10.2011

[3] H. Kuhn et al., ICAS, Brisbane, 2012 (accepted)






Ragone metrics:

Exergy and power densities are the key

indicators for electric aircraft feasibility

in the comparison of alternative power

sources

Hybridization:

energy storage devices each inadequate

may be an enabling energy system in

combination


References:

[1] A. Sizmann, Fuelling the Climate 2010, Hamburg, 18.07.2010

[2] H. Kuhn et al., CEAS, Venice, 24.10.2011

[3] H. Kuhn et al., ICAS, Brisbane, 2012 (accepted)

0.1

1.0

10.0

0.01 10.0 1.0 0.1 Relative Exergy Density

Rel

ativ

e P

ower

Den

sity

Combination (tbd)

Subsystem 1

Subsystem 2


Contents









Alternative (i.e., synthetic) jet fuel:Various pathways existent or

conceivable

From long-term perspective: No alternative yet developed to fully meet all

of the main criteria suitability, scalability and sustainability

Critical issue of „drop-in“ solutions: Complex product, requiring complex

and costly production procedures

Good reasons to

continue and increase efforts toward development of novel renewable alternatives, e.g.,

pathways beyond biofuels

seriously pursue R&D on „non-drop-in“ options for long-term application


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