power generation in the uk: carbon source or carbon sink? · 2016. 5. 27. · 1. co-firing with ccs...

Power generation in the UK: Carbon Source or Carbon Sink?

Niall Mac Dowella,b

a. Centre for Process Systems Engineering b. Centre for Environmental Policy

Imperial College London [email protected] @Niallmacdowell

UKCCSRC Direct Air Capture/Negative Emissions Workshop Imperial College London

18th March 2014

mailto:[email protected]

Outline

• What is BECCS? • Why should we do BECCS? • How do we do BECCS? • Pitfalls of BECCS? • Outlook for BECCS

N. Mac Dowell, Imperial College 2014

Outline

• What is BECCS? – The TESBIC project

• Some key findings of TESBIC – BECCS Technologies

• Why should we do BECCS? • How do we do BECCS? • Pitfalls of BECCS? • Outlook on BECCS


What is BECCS? • Using biomass (with/without co-firing of fossil fuels) in

conjunction with CCS leading to net negative emissions – Acronym first used by Fisher, B.S., et al. (2007) in B. Metz et al.

(Eds.), IPCC 4th Assessment Report • BECCS offers the potential to achieve long‐term reductions

in GHG emissions necessary to stabilise atmospheric CO2 concentrations, and could be applied to a wide range of biomass‐related technologies

• Compared to CCS, BECCS appears to have a much lower profile than CCS – BECCS has been observed to increase public acceptance of CCS – BECCS can add important flexibility to GHG mitigation toolbox


What is BECCS?


The TESBIC project


Some key findings of TESBIC


Some key findings of TESBIC

1. Co-firing with CCS - Costly - Moderately

negative - Large scale only

2. Dedicated biomass with conventional CCS - Costly - Suitable for

small scale 3. Dedicated biomass

with advanced CCS - High efficiency - Suitable for

small scale N. Mac Dowell, Imperial College 2014

BECCS Technologies 1 Moderately negative, possibly nearer term

– Coal-biomass systems • Co-firing: post-combustion capture and oxy-combustion • Co-gasification

2 More negative, more development needed? – Gas-biomass combustion systems – Gas-biomass gasification systems – Gas-biomass looping combustion

3 Highly negative, near term or development needed – Dedicated biomass (combustion, gasification, looping)

4 Very highly negative, long term, development needed – Biomass combustion with CaO looping and ocean liming


Technology 4: Biomass combustion with CaO looping and ocean liming


Outline

• What is BECCS? • Why should we do BECCS?

– What is the role of BECCS in cutting CO2 emissions?

– What is the mitigation potential in the UK? • How do we do BECCS? • Potential BECCS pitfalls • Outlook on BECCS


Why should we do BECCS? System State of Stored

Carbon Description Published Cost Estimates

Afforestation & Reforestation

Biomass and soil organic carbon

Restoring cleared forests and planting new forests on suitable land

$20-100/tCO2

Wetland Restoration

Biomass and soil organic carbon

Restoring damaged, carbon-dense wetlands such as peatlands and mangrove forests.

On the order of $10-100/tCO2 in some cases

Agricultural Soil Sequestration

Soil organic carbon

Adopting a range of practices on arable and grazing lands that enhance soil carbon levels, including reduced tillage and new cropping patterns.

$0-100/tCO2, and can be cost negative

BECCS Pressurised CO2 in geological storage

Capturing CO2 from biomass-fuelled power plants or industries and storing it in geological reservoirs.

$60-120/tCO2, but perhaps as little as $25/tCO2 in niches such as bioethanol production

Direct Air Capture (DAC)

Pressurised CO2 in geological storage

Capturing CO2 directly from the air using chemical sorbents and storing it in geological reservoirs.

Widely varying, from $30-1000/tCO2, depending on system and assumptions

Enhanced Silicate

Weathering

Dissolved bicarbonate and carbonate in groundwater or oceans

Spreading finely ground silicate mineral powder on land or ocean to accelerate natural reaction with atmospheric CO2

$20-130/tCO2 assuming complete reaction

Ocean Liming Dissolved bicarbonate and carbonate in oceans

Adding lime or other metal oxides / hydroxides to the ocean to convert dissolved CO2 to bicarbonate and drive drawdown from the atmosphere.

$70-160/tCO2

Adapted from Lomax, G. et al, Energy Policy, 2014, In Press N. Mac Dowell, Imperial College 2014

Why should we do BECCS? • Potential to offer deep reductions in atmospheric CO2

concentrations – Current emission reduction technology may not be

adequate – Many future emission scenarios require negative emissions

• Appears practicable and relatively cost-effective – Cheaper than CCS on transport – Cheaper than DAC

• Could be applied to a wide range of technologies • Offers the potential for carbon-offsetting

– Address “hard to reach” areas


BECCS and Energy Systems Mitigation


Growth in total power generation by region

• Increased electrification is a critical element of decarbonisation • Note OECD EU/US outpaced by China (2014 - 2030s) and India (2040 – 2050s)


Summary of power generation mix scenarios (low fossil fuel prices)

• Total generation in LMS is 117 EJ and 147 EJ in LCS • Each of the LCS scenarios represents a world with an average carbon intensity of 94

gCO2/kWhr • BECCS plays an important role in all scenarios N. Mac Dowell, Imperial College 2014

What is the CO2 mitigation potential of BECCS in the UK?

• UK’s negative emission potential in the range 21.3 – 82.4 MtCO2/yr • Indigenous biomass potentially small – import is necessary • AVOID / Workstream 2 / Deliverable 1 / Report 18 [ AV/WS2/D1/18 ]

Negative Emissions Curve (MtCO2/yr) for the UK ramp up of BECCS between 2020 to 2030 assuming linear increase in biomass production and full utilisation.

Negative Emissions (MtCO2/yr)


How much biomass is there?

0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5

Ener

gy c

rop

pote

ntia

l (EJ

)

Land area assumed for energy crops (Gha)

Bauen04

Beringer11

Cannell02

de Vries07

Field08

Fischer01

Hall93

Johansson93

Hoogwijk05

Hookwijk03

Lysen08

Moreira06

Sims06

Smeets07

WEA2000

WGBU09

Wolf03

5odt.ha-1

10odt.ha-1

15odt.ha-1

Globalarable area

Globalpasture area

Slade et al., EES, 2011 N. Mac Dowell, Imperial College 2014

Economics v emissions

-100

-500

-1000

50 100 150 200

kgCO2/MWh

LCOE £/MWh

1

2

3

4


Outline

• What is BECCS? • Why should we do BECCS? • How do we do BECCS?

– A UK case study using MINLP • Pitfalls of BECCS? • Outlook on BECCS


Mac Dowell et al, Energy & Environ. Sci, 2010

Decarbonised electricity generation – a multi-scale problem

Mac Dowell et al., CACE., 2010 Mac Dowell et al., Int. J. GHG. Con., 2013 Mac Dowell et al., Int. J. GHG. Con., 2013

Mac Dowell et al., Ind. Eng. Chem. Res., 2010 Mac Dowell et al., J. Phys. Chem. B, 2011 Rodriguez et al., Mol. Phys., 2012

Mac Dowell et al., CACE., 2011 Akgul et al., Int. J. GHG. Con., 2014

Mac Dowell et al., Int. J. GHG. Con., 2014


BECCS Network: Problem Statement

3,870MW

31

26 27 28 29 30

24 23 22 21

32 33 34

19 18 20 17

13 14 15

9 10 11

6 7 8

3 4 5

1 2

25

16

12

Co-firing plants

2,008MW

2,000 MWe

1,972MW

1,960MW

1,940MW 1,925MW 750MW

1,955MW

1,006MW

Given • Biomass availability and

cost • Fuel and CO2 cost • Energy demand

Determine • Which plants • % Co-firing • % CO2 capture

Meta process model y = yb + A(x – xb)

Input Samples

Outputs; Meta-Modelgeneration

u yMeta-model

Case studies (WP2),Public domain data/models

• 10 Power plants • Capacity = 19 GW • Demand = 9 GW

Akul et al., Int. J. GHG. Con., 2014 N. Mac Dowell, Imperial College 2014

What is the whole-system objective function?

∑∑∈ ∈

=Pp Gg

pgp EICCRFTAC

∑∑∈ ∈

+Ri Gg

igig PUSCα

∑∑∑∈ ∈ ∈

+Ri Gg Pp

ipgiip DfUPC γα

∑∈

+Gg

gelecg PUGC .,α

∑∈

+Gg

gfossilgg mUFOC ,ϕα

∑∈

+Gg

ggelec CIPUCARC .,α

∑∑∈ ∈

+Ri Gg

igg PALDUTC*α

Total pellet production plant capital cost

Total biomass supply cost

Total pellet production cost

Total non-fuel power generation cost

Total fossil fuel cost

Total carbon cost

Total raw material transportation cost

Economic objective function

∑∈

=Gg

ggelec CIPTAE .,α

Environmental objective function

Total annual CO2 emissions

Akul et al., Int. J. GHG. Con., 2013 (Sub)

Biomass + SRF cost

Power plant cost

CO2 cost

Supply chain cost

Environmental cost


What is the fuel composition? • This is important as the

fuel energy density and moisture content are key contributors to overall system cost, efficiency and carbon intensity

• The biogenic MSW is assumed to have the same composition as “standard” biomass

Parameter Bituminous coal

Biomass

GCV (MJ kg-1) 24.6 18.7

Moisture 12.0 7.0 C 59.6 43.5 H 3.8 4.5 N 1.5 0.2 O 5.5 42.6 S 1.8 0.01 Cl 0.2 0.01

• Coal: standard bituminous coal, UK BCURA coal bank

• Biomass fuel specification from Orchid Environmental N. Mac Dowell, Imperial College 2014

What are the cost scenarios?

• We use coal and CO2 price projections from UK Department of Energy and Climate Change

• Notable for rather conservative coal prices and generally optimistic CO2 prices

• Is this realistic?

Low carbon price scenario

Central carbon price scenario

High carbon price scenario

CO2 (£/t) Coal (£/t)



2012 13 80 22 84 28 89 2020 14 52 25 71 31 98 2050 100 52 200 71 300 100


What does the UK look like in 2020?


…and in 2050?


What are the trade-offs in cost? (Low Carbon price)

Akul et al., Int. J. GHG. Con., 2014

Coal gen. only

Coal gen. + CCS

Co-firing of biomass pellets with coal+CCS

Co-firing of biomass and SRF pellets with coal+CCS


What are the trade-offs in cost? (Central Carbon price)


Is there a route to cost BECCS reduction?

• BECCS with co-firing and amine scrubbing is clearly a costly option – Recall TESBIC project!

• In particular, there is a non-monotonic relationship between the costs associated with “low carbon” and “carbon negative”

• One route to cost reduction: – an increase in biomass availability, either through

import or land use change: – Slade et al, Energy and Environmental Science, 2011


What is the effect of increased biomass availability?

Akul et al., Int. J. GHG. Con., 2013 (Sub)

£82/MWh £73/MWh

-31MT CO2/yr

-27MT CO2/yr


What is the effect of increased biomass availability?

• Increased biomass availability can reduce BECCS costs

• Improved land yield? • Land use change:

– Must be aware of competition for arable land for food – CO2 emissions associated with land use change must be

accounted for – these can be difficult to quantify • Importing biomass is an important option

– Recall AVOID project


BECCS Network: Conclusions • Using existing generation assets, proven technology

and indigenous biomass, its possible to remove 27 – 31 MtCO2/yr from the atmosphere

• This is equivalent to 23 - 26% of the UK’s ground transport emissions in 2012 – https://www.gov.uk/government/uploads/system/uploads/att

achment_data/file/193414/280313_ghg_national_statistics_release_2012_provisional.pdf

• The MINLP framework we have developed provides a useful platform with which to investigate the potential of other BECCS technologies – For example, BIGCC + CCS and so forth


https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/193414/280313_ghg_national_statistics_release_2012_provisional.pdf



Outline

• What is BECCS? • Why should we do BECCS? • How do we do BECCS? • Pitfalls of BECCS?

– Carbon accounting? – Horsemeat in the supply chain?

• Outlook on BECCS


Pitfalls of BECCS – Carbon accounting? • International climate reporting guidelines, as they currently

apply to industrialised countries (Annex I Parties), only make passing reference to CCS – Accounting guidelines relating to Kyoto Protocol make no mention

of it at all. – The Clean Development Mechanism (CDM), does not currently

allow for CCS projects • Revised carbon reporting guidelines were developed by IPCC

in 2006 – Specifically refer to CCS and provide guidance to ensure that its

reported fairly in national GHG inventories – Make no distinction between CCS on fossil or biomass – They explicitly account for negative emissions

• Revised IPCC guidelines have not yet been adopted by Annex I parties, but are envisaged to become binding by 2015 – The UK will need to provide clear and unambiguous incentives for

negative emissions technology Data from: Working paper of the IEA: “Combining Bioenergy with CCS: Reporting and Accounting for Negative Emissions under UNFCCC and the Kyoto Protocol


Pitfalls of BECCS - Horsemeat in the supply chain? • If biomass is produced from unsustainable sources

– Its use may contribute to environmental degradation in a number of different ways

• Carbon emissions • Land use change • Water depletion • Loss of biodiversity

– Its damaging effects may outweigh the benefits of negative CO2 emissions

• Current accounting for biomass-related impacts under the Kyoto Protocol may not be comprehensive – Annex I Parties are required to report such emissions under LULUCF

• LULUF: Land use, land-use change and forestry – Parties are able to opt into or out of accounting for certain LULUCF

activities • Raises the possibility of the GHG benefits of BECCS counting towards Kyoto

Protocol GHG commitments, but the dis-benefits of using unsustainable biomass in BECCS being ignored

Data from: Working paper of the IEA: “Combining Bioenergy with CCS: Reporting and Accounting for Negative Emissions under UNFCCC and the Kyoto Protocol


Pitfalls of BECCS - Horsemeat in the supply chain? • Further risk: an Annex I Party establishing a

BECCS project that is fuelled by biomass from a developing country – Any assessment of biomass sustainability could

realistically not be made from GHG reporting – could lead to a situation where the Annex I Party

benefits from negative emissions against its Kyoto Protocol commitments, but even greater positive emissions go unreported in the country where the biomass was sourced

• The question of biomass sustainability in the context of the Kyoto Protocol should be urgently addressed

Data from: Working paper of the IEA: “Combining Bioenergy with CCS: Reporting and Accounting for Negative Emissions under UNFCCC and the Kyoto Protocol


Outline

• What is BECCS? • Why should we do BECCS? • How do we do BECCS? • Pitfalls of BECCS? • Outlook on BECCS


Outlook on BECCS • BECCS is a highly promising option for the near-term,

cost-effective removal of CO2 from the atmosphere – Significantly less costly than DAC

• BECCS is more costly than conventional CCS, but less costly than attempting decarbonisation of disperse sources, e.g., transport – Important carbon offsetting potential – Significant scope for disruptive technologies to make a

difference • Ocean liming?

• Some important regulatory gaps remain – Carbon accounting – Incentivising negative emissions from power stations (in the

UK) N. Mac Dowell, Imperial College 2014

power generation in the uk: carbon source or carbon sink? · 2016. 5. 27. · 1. co-firing with ccs...

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