Scholarly article on topic 'Global Potential for Biomethane Production with Carbon Capture, Transport and Storage up to 2050'

Global Potential for Biomethane Production with Carbon Capture, Transport and Storage up to 2050 Academic research paper on "Environmental biotechnology"

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{Biomethane-CCS / "Carbon capture and storage" / Biogas / "Gas upgrading" / "CO2 removal" / "Technical potential"}

Abstract of research paper on Environmental biotechnology, author of scientific article — Joris Koornneef, Pieter van Breevoort, Paul Noothout, Chris Hendriks, uchien Luning, et al.

Abstract Biomass in combination with carbon capture and storage (CCS) is one of few options that make a reduction of global CO2 concentration in the atmosphere possible. This option is likely to be required to meet climate targets. This study shows the global potential for combining bio-energy conversion with CCS (BE-CCS) up to 2050. The assessment focuses on two BE-CCS routes for the production of biomethane, based on gasification and anaerobic digestion. Routes for the production of power and liquid fuels have been addressed in an earlier study by IEAGHG. For the two routes the technical and economic potential was analysed. The results show that deployment of the global technical potential can result in negative greenhouse gas emissions (GHG) up to 3.5 Gt CO2-eq. on an annual basis in 2050. Including avoided emissions by replacing natural gas, the annual greenhouse gas emission savings could add up to almost 8 Gt of CO2-eq in 2050. The economic potential reaches up to 0.8 Gt of negative GHG emissions when assuming a CO2 price of 50 €/tonne.

Academic research paper on topic "Global Potential for Biomethane Production with Carbon Capture, Transport and Storage up to 2050"

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Energy Procedia 37 (2013) 6043- 6052

GHGT-11

Global potential for biomethane production with carbon capture, transport and storage up to 2050

Joris Koornneefa*, Pieter van Breevoorta, Paul Noothouta, Chris Hendriksa, Luchien Luninga, Ameena Campsb

aEcofys bv, P.O. Box 8408, 3503 RK Utrecht, The Netherlands bIEA Greenhouse Gas R&D Programme, The Orchard Business Centre, Stoke Orchard, Cheltenham, GL52 7RZ, United Kingdom

Abstract

Biomass in combination with carbon capture and storage (CCS) is one of few options that make a reduction of global CO2 concentration in the atmosphere possible. This option is likely to be required to meet climate targets. This study shows the global potential for combining bio-energy conversion with CCS (BE-CCS) up to 2050. The assessment focuses on two BE-CCS routes for the production of biomethane, based on gasification and anaerobic digestion. Routes for the production of power and liquid fuels have been addressed in an earlier study by IEAGHG. For the two routes the technical and economic potential was analysed. The results show that deployment of the global technical potential can result in negative greenhouse gas emissions (GHG) up to 3.5 Gt CO2-eq. on an annual basis in 2050. Including avoided emissions by replacing natural gas, the annual greenhouse gas emission savings could add up to almost 8 Gt of CO2-eq in 2050. The economic potential reaches up to 0.8 Gt of negative GHG emissions when assuming a CO2 price of 50 €/tonne.

© 2013 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of GHGT

"Keywords: biomethane-CCS, Carbon capture and storage, biogas, gas upgrading, CO2 removal, technical potential"

* Corresponding author. Tel.: +31-30-662-3396; fax: +31-30-662-3301. E-mail address: j.koornneef@ecofys.com.

1876-6102 © 2013 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of GHGT doi: 10.1016/j.egypro.2013.06.533

Nomenclature

BE-CCS Bio-energy conversion combined with Carbon Capture and Storage

Biogas Gas produced from the anaerobic digestion of biogenic feedstock. The gas contains mainly methane and carbon dioxide.

Biomethane Gas produced by upgrading biogas or by Synthetic Natural Gas production. The gas contains mainly methane and the quality is sufficient to inject into a natural gas grid.

BioSNG Synthetic Natural Gas (SNG) produced through biomass gasification followed by the methanation and purification. The gas contains mainly methane and the quality is sufficient to inject into a natural gas grid.

CCS Carbon Capture and Storage

MSW Municipal Solid Waste

Product gas Gas produced through biomass gasification at moderate temperature levels. Product gas consists mainly of hydrogen, carbon monoxide, methane, CxHy and impurities (e.g. tar).

1 EJ exaJoule = 1018 Joule; ~ 24 Mtoe

1 Gt Gigatonne = 109 tonne = 1015 gram

1. Introduction

Carbon capture and storage (CCS) is often associated with fossil energy conversion, but can also be combined with bio-energy conversion (abbreviated BE-CCS or bio-CCS). Short-cycle carbon is then harvested and stored deep underground. Effectively, this suggests that carbon dioxide is removed from the atmosphere, leading potentially to negative greenhouse gas (GHG) emissions. This brings BE-CCS into a select group of technologies that make an actual reduction of global CO2 concentration in the atmosphere possible. In fact, several mitigation scenarios show that biomass, in combination with CCS, is likely to be required to meet low atmospheric concentration of CO2 [1-4].

BE-CCS technologies may play a considerable role in a low-carbon energy supply. It is thus of eminent interest to create a good understanding of global and regional potential of this option and how that potential may be deployed.

In 2011, the IEA GHG R&D programme published a report on the global potential of six technology routes that combine bio-energy conversion with CCS [5, 6]. The study considered four electricity production routes and two routes for biodiesel and bio-ethanol production. In this paper we address two additional technology routes combining the production of biomethane with the capture and storage of the co-produced carbon dioxide.

Biomethane can be produced through several routes. Gasification combined with methanation, and upgraded biogas produced by anaerobic digestion seem to be promising technologies that can be combined with CCS. In these routes the removal of CO2 is already an inherent part of the processes to meet natural gas grid specifications.

The aim of this study is to provide an understanding and of the global potential - up to 2050 - for BE-CCS technologies producing biomethane. We make a distinction between the technical potential and the economic potential. Next to the quantitative estimates of these potentials, presented in the form of global supply curves, this study identifies barriers to the deployment of biomethane production combined with CCS. We also present recommendations to solve possible obstacles and enhance drivers to stimulate the deployment of biomethane-CCS technologies.

2. Approach

We assess two concepts to convert biomass into biomethane: gasification (followed by methanation) and anaerobic digestion (followed by gas upgrading). For both technology routes we assess the global technical and economic potential. The technical potential is determined either by restriction in sustainable1 biomass supply or by limitations in CO2 storage potential. We combine existing studies on regional biomass potentials (in EJ/yr primary energy) and regional CO2 storage potentials (in Gt CO2). The net energy conversion efficiency (including the energy use for CCS) and the carbon removal efficiency of the BE-CCS route then determine the technical potential for biomass CCS in terms of primary energy, final energy and net (negative) GHG emissions. It should be noted that we do not use an economic optimisation, but calculate the maximum potential as if all biomass is allocated to one specific BE-CCS route; the potential of both routes can therefore not be summed.

In Fig. 1, we show the steps that are discussed in more detail in the sections below. It includes the assessment of biomass supply potential, performance of conversion and CO2 removal technologies, and CO2 transport and storage options.

To determine the economic potential we first assess the cost of producing biomethane for both with and without CCS and compare it with the competing natural gas price, including a CO2 premium. The cost assessment include biomass supply cost, energy conversion cost, CCS cost and a CO2 price. Fig. 2 presents the results in the form of supply curves for both routes in 2030 and 2050. It shows the maximum potential of biomethane that can be produced at a certain cost level. The economic potential is subsequently determined as the biomethane potential that can be produced at lower cost than the reference natural gas price.

Biomass supply chain

Biomass production

Pre-treatment

CCS chain

Energy

Transport

Conversion

CO2 Capture

CO2 Transport

CO2 Storage

Forestry residues

Energy crops

Agricultural _ residues

(Torrefied) pellets

Sewage

sludge

Animal

manure

Ship, truck _ train etc

> Digestion —

CO2 removal

compression

Pipeline Hydrocarbon

> Aquifers

> Coal seams

Fig. 1 Chain elements in the BE-CCS routes (in green). Per chain element the options assessed are indicated (in yellow). Note: municipal solid waste (MSW), sewage sludge and animal manure are only applied in the digestion route (dashed lines) and do not require pre-treatment in the form of densification or torrefaction. Forestry residues are only applied in the gasification route.

^ Throughout this paper, we only consider the sustainable biomass supply potential. When we refer to the 'Technical potential', sustainability criteria are already taken into account. Although we do not take into account all sustainability criteria that are currently being discussed, we consider the applied set appropriate enough to estimate the sustainable production of biomethane with CCS.

2.1. Sustainable biomass supply potential & cost

The types of feedstock we take into account differ per conversion technology, see Table 1. Energy crops, forestry residues and agricultural residues are feedstock types that are appropriate for the gasification route. For digestion we consider biogenic component of municipal solid waste (MSW), and animal manure and sewage sludge (MSS) as appropriate feedstock. Digestion technology typically requires wet feedstock.

Table 1. Overview of the applied biomass types and their primary energy potentials per conversion route: gasification or digestion.

Feedstock Primary energy potential (EJ/y)

Gasification Digestion

2030 2050 2030 2050

Energy crops (EC) 39 65 27 45

Agricultural residues (AR) 23 42 16 29

Forestry residues (FR) 11 19 Excluded

Municipal solid waste (MSW) Excluded 5 11

Manure and sewage sludge (MSS) 7 14

Total 73 126 56 99

The estimates are based on work reported in [5], by [7] and own estimates. See more detailed information in [8].

For the gasification route the cost of biomass production, pre-treatment and transport for energy crops, forestry residues and agricultural residues are taken from IEA GHG [5]. For the biomass production we developed cost-supply curves on a regional level. The cost-supply curves for biomass supply are constructed using four cost categories, as presented in Table 2.

Table 2 Cost and price of biomass and the potential of energy crops, agricultural residues and forestry residues

Unit Cost category biomass potential

Cost element per category I II III IV

Biomass production cost €/GJprimary 0.8 1.7 3.3 41.5

Ratio price/cost - 4 3 2.5 1.2

Price of biomass €/GJprimary 3.3 5.0 8.3 49.8

Price incl. densification and transport €/GJprimary 4.7 6.3 9.6 51.2

Price of biomass pellets at factory gate €/GJpellets 5.2 7.0 10.7 56.9

Cumulative biomass potential I II III IV

Global potential EC, AR and FR in 2030 ET L-'J primary 4 24 40 73

Global potential EC, AR and FR in 2050 ET L-'J primary 8 42 68 126

EC = energy crops, AR = agricultural residues, FR = forestry residues

All cost and potential estimates are based on [5]

In the digestion route we take the regional cost-supply curves for energy crops and agricultural residues albeit with different cost assumptions regarding the pre-treatment and transport cost. Because anaerobic digestion requires wet biomass, no extensive pre-treatment of the biomass is required for this technology. We assume the transport costs (expressed in €/GJ) for energy crops and agricultural residues which are not pre-treated to be three times higher than the costs for transport of dried and densified biomass, mainly due to the lower energy density. For MSW, sewage sludge and animal manure we assume a conservative zero feedstock cost as these biomass sources are considered 'waste'.

2.2. Conversion technologies

In this study, we assessed the promising gasification technologies FICFB (Fast Internally Circulating Fluidised Bed) and MILENA. Both technologies are in the demonstration phase. The expectation is that the technology could be developed towards commercial-scale demonstration plant and finally be available as full-scale commercial plants of 500 MW in the coming decades [11].

The digestion route is in certain configurations already a commercially available technology and used as such. Biogas production through anaerobic digestion technology is considered a mature technology for the treatment of slurries and other feedstock with low dry matter content [9], but can also be used for feedstock with higher dry matter content. It is not suitable for feedstock with high lignin content, i.e. woody biomass. The cost of wet biomass transport limits the capacity of digesters considerably. Digester production capacity ranges up to 15 MW of gas produced, but are typically much smaller. A trend in scaling-up digestion conversion technologies is not foreseen.

Table 3 presents technical performance and total investment costs for the production of biomethane, including CO2 removal.

Table 3 Overview of performance and cost of biomethane production technologies with CO2 removal

Technologies Capacity Conversion Carbon Specific investment | Annual O&M

with CO2 capture efficiency removal

efficiency

Total Capture Total Capture

w/cap w/cap

MWfinal % % €/kWfinal €/kWfinal

Gasification 2030 250 68% 36% 1140 40 108 10

Gasification 2050 500 70% 38% 1132 32 108 10

AD - EC and AR 2030 10 60% 27% 1053 103 98 13

AD - EC and AR 2050 15 60% 29% 1043 93 97 12

AD - MSW 2030 10 60% 27% 1753 103 193 13

AD - MSW 2050 15 60% 29% 1743 93 192 12

AD - Sewage/Manure 2030 10 40% 27% 1285 135 103 18

AD- Sewage/Manure 2050 15 40% 29% 1272 122 103 18

AD = anaerobic digestion; EC = energy crops; AR = agricultural residues; MSW = municipal solid waste

Cost estimates are based on [10-21]. Note that the reported CO2 capture costs only refer to the purification and compression step of the CO2 stream as the removal of CO2 is already an integral process step in the biomethane production process.

2.3. CO2 capture during gas upgrading

Both the gasification and the digestion of biomass produce combustible gases, respectively 'producer gas' and 'biogas'. Depending on the feedstock and conversion technology these intermediate product gases may contain methane, carbon dioxide, water, hydrogen sulphide, nitrogen, oxygen, ammonia, tars and particles. Producer gas or biogas thus needs to be upgraded to improve the gas quality before it can be injected in a natural gas grid.

The upgrading process serves two goals: increasing the concentration of methane and removing CO2 and other components [22]. Depending on the upgrading technology (see also [23]), the separated CO2 stream needs to be cleaned before it can be compressed, transported and stored.

There is already 20 years of experience in upgrading biogas and several upgrading technologies are commercially available. The choice for an upgrading technology (and thus CO2 removal) depends on different factors, such as the costs, the composition and characteristics (e.g. temperature, pressure) of the gas flow that has to be treated, the required purity of the CO2 stream and the capacity (i.e. total gas flow).

2.4. CO2 transport and storage

We assume that CO2 will be transported by pipelines. CO2 transport by pipeline is considered a mature technology and is in most cases the most economic option. The global cost range for CO2 transport is estimated to be between the 1 and 30 €/tonne [5]. The default value assumed here is 5 €/tonne.

For CO2 storage we assume the costs to range from 1 to 13 € per tonne. We assume a default value of 5 € per tonne. For the CO2 storage potential we have used estimates reported in [5], which gives storage estimates for 7 world regions. These storage estimates reflect the storage capacity for three types of geological reservoirs:

• Depleted hydrocarbon fields

• Aquifers

• Unmineable coal seams

2.5. Natural gas and CO2 price

We use natural gas price estimates from the World Energy Outlook (WEO) 2010. We consider both high and low natural gas prices. The 'high' price is based on the WEO Current Policies Scenario and the 'low' prices are from the WEO 450 ppm scenario. The WEO does not provide consistent price estimates for 2050. We therefore assume equal gas price references for 2050. Natural gas prices range between 6.7 and 11.4 €/GJ. Including a CO2 price premium, at a price of 50 € per tonne, the natural gas price reference ranges between 9.5 and 14.2 €/GJ. In the 'high' price scenario we assume 14.2 €/GJ as upper price level. The 'low' natural gas price scenario uses 9.5 € per GJ.

2.6. Calculating the net greenhouse gas balance

The net greenhouse gas balance is calculated taking into account the uptake of CO2 by the biomass during its growth, direct emissions from converting the biomass into energy carriers or during end-use, indirect emissions and the amount of (biogenic) CO2 stored. Distribution losses of the gas network are not taken into account.

The direct emission factor is assumed to be equal for all biomass resources and is set at 100 kg CO2/GJ [24]. An equal amount of CO2 is assumed to be taken up by the biomass during its growth. We also include greenhouse gas emissions emitted in the biomass supply chain ranging between 0 and 4.1 kg CO2/GJ. We have included GHG emissions that can be allocated to the use of electricity for the compression of CO2. For animal waste, sewage sludge and MSW we have excluded GHG emissions in the supply chain as these are here allocated to waste treatment and not to the production of the biomethane.

3. Results

Table 4 and Fig. 3 summarise the most eminent results of this assessment from a global perspective. More detailed results on a regional level are presented in [8]. The results show the largest technical potential is found for the gasification route. In this route 79 EJ of biomethane can be produced in 2050. This will lead to the removal of 3.5 Gt of CO2 from the atmosphere. On top of that, substitution of 79 EJ of natural gas with biomethane will result in an additional CO2 emission reduction of 4.4 Gt of CO2. This implies that in total almost 8 Gt CO2 eq can be reduced through this route*. This provides a significant reduction potential compared to the global energy-related CO2 emissions which was reported at 30.6 Gt CO2 in 2010 [25].

Table 4 Global technical and economic potential per BE-CCS route for the years 2030 and 2050

Technology route Year Technical potential Economic potential

Primary energy Final energy CO2 stored GHG balance (CO2 eq) Final energy GHG balance (CO2 eq)

EJ/yr EJ/yr Gt/yr Gt/yr EJ/yr Gt/yr

Gasification

EC, AR & FR 2030 73.1 44.8 2.4 -1.8 2.7 -0.1

EC, AR & FR 2050 125.6 79.1 4.3 -3.5 4.8 -0.2

Anaerobic digestion

EC and AR 2030 43.3 26.0 1.2 -1.1 1.4 -0.1

EC and AR 2050 74.7 44.8 2.1 -2.1 2.4 -0.1

MSW 2030 5.1 3.1 0.1 -0.1 3.1 -0.1

MSW 2050 10.6 6.4 0.3 -0.3 6.4 -0.3

Sewage/ Manure 2030 7.4 3.0 0.2 -0.2 3.0 -0.2

Sewage/ Manure 2050 13.8 5.5 0.4 -0.4 5.5 -0.4

Total 2030 55.9 32 1.5 -1.4 7.4 -0.4

Total 2050 99.1 56.7 2.8 -2.7 14.3 -0.8

EC =energy crops, AR = agricultural residues, FR = forestry residues, MSW = municipal solid waste

Upper estimate of the economic potential is reported and is determined by comparing the biomethane-CCS production cost with the highest natural gas price reference and CO2 price of 50 €/tonne.

The total technical potential for the digestion based route in 2050 is 57 EJ of biomethane. This potential is lower compared to that for the gasification route as a smaller fraction of the biomass potential for energy crops and residues (forestry and agriculture) can be used as this technology is less suitable for the conversion of lignocellulosic biomass. The potential of the most suitable feedstock for digestion, being municipal solid waste, animal manure and sewage sludge, is relatively small. The potential of these sources sums up to almost 12 EJ (-0.7 Gt CO2eq) of biomethane in the year 2050.

* Note that 1 Gt of negative emissions is not the same as 1 Gt of emission reductions. Generally speaking, the emission reduction potential of BE-CCS options is equal to the amount of negative emissions plus the emissions of the technology or fuel it replaces, in this case natural gas. Throughout this paper we will indicate negative emissions, not avoided or reduced emissions, unless otherwise indicated.

The economic potential for biomethane depends on the CO2 price and the natural gas price, which may vary per global region/country. As can be seen in Fig. 2, at a natural gas price of 9.5 €/GJ and CO2 price of 50 €/tonne only sewage/manure offer an economic potential, which is 5.5 EJ (-0.4 Gt CO2-eq.) in 2050. When natural gas price rises to 14.2 €/GJ the economic potential is increased to 14 EJ (-0.8 Gt CO2-eq.): 6.4 EJ (-0.3 Gt CO2-eq.) due to MSW and 2.4 EJ (-0.1 Gt CO2-eq.) due to digestion of energy crops and agricultural residues. For gasification there is no economic potential with a gas price of 9.5 €/GJ, but with a higher natural gas price this potential grows to 4.8 EJ (-0.2 Gt CO2-eq.) in 2050.

We have also calculated the economic potential for gasification and anaerobic digestion under lower and higher CO2 prices (resp. 20 and 100 €/tonne). The economic potential shrinks to almost zero with a CO2 price of 20 €/tonne with only a potential remaining for the digestion of municipal solid waste and sewage sludge. Under a CO2 price of 100 €/tonne the potential increases to 43 EJ for the gasification route and to 37 EJ for the digestion route in 2050. For almost all combinations of feedstock (energy crops, agricultural residues and forestry residues) and conversion technology there is thus only an economic potential at high natural gas prices (>14 €/GJ) combined with CO2 prices of at least 20 €/tonne.

S 30 ><

S> 01 c 0

.'1- 1

atfd—■—-1-----------------------------------------

— Gasification 2050 ---Gasification 2030

— — -natural gas price high

20 30 40 50

Final energy Potential (EJ/yr)

-AD -EC and AR 2050 -AD -MSW 2050

■ AD -EC and AR 2030 -natural gas price low

---AD-MSW 2030

AD - Sewage/Manure 2050 - —- AD - Sewage/Manure 2030

Fig. 2 Global supply curve for two biomethane-CCS technology routes (anaerobic digestion and gasification) and natural gas reference price for the year 2030 and 2050 with a CO2 price of 50 €/tonne. This figure shows the total production cost on the y-axis which increases with higher biomass prices; the associated production potential (in EJ/yr) is shown on the x-axis. AD = anaerobic digestion, EC = energy crops, AR = agricultural residues, FR = forestry residues, MSW = municipal solid waste

4. Barriers and drivers for the deployment of biomethane with CCS

Drivers for the deployment of biomethane are (EU) targets for biofuels, policies aimed at increasing security of supply (e.g. by reducing the import dependency of fossil fuels including natural gas), and the presence of existing natural gas transport and distribution infrastructure.

Barriers typical for the deployment of digestion-CCS are high biomass transport costs which limit the plant size. The small size of digesters generally results in higher cost for connecting to the CO2 and natural gas infrastructure. Nevertheless, anaerobic digestion-CCS of MSW, sewage sludge and animal manure might become a promising niche application that offer the opportunity to simultaneously process waste, reduce carbon emissions and produce valuable biomethane. Further it is important for the digestion-CCS route to look for possible valuable reuse of captured CO2 to enhance business case for smaller systems with CO2 capture (e.g. CO2 use in industry and in the horticulture).

The gasification-CCS route fits best with a large-scale infrastructure for the transport of biomass, natural gas and CO2; that is, a more centralised production of biomethane combined with CCS.

The high proven resources of natural gas and development of new extraction technologies for instance for unconventional gas production may have a suppressing effect on the (global and regional) natural gas price. Also the increased trade capabilities for natural gas - e.g. in the form of increasing number of LNG terminals and long distance gas pipelines will likely have a suppressing price effect on a global level. As biomethane competes with natural gas, a lower natural gas price has a negative impact on the economic potential of biomethane and with it on the potential of biomethane with CCS.

5. Conclusions and Recommendations

Biomethane production in combination with carbon capture and storage has the technical potential to remove up to 3.5 Gt of greenhouse gas emissions from the atmosphere in 2050. One of the interesting features of biomethane production for grid injection is that the separation of CO2 is already an intrinsic step in the biomethane production process. This means that the incremental costs of adding CCS are potentially low and suggests that there is an economic potential for this option. The economic potential for biomethane combined with CCS is most likely restricted to those areas that have sufficient high natural gas and CO2 prices, and have favourable infrastructural conditions. On a regional scale, it can be concluded that small-scale biomethane production with CCS based on digestion is thus most likely restricted to niche market applications; large-scale gasification based production of biomethane with CCS could have potential where large scale infrastructure is already in place - or could easily be adapted - for the transport of biomass, natural gas and CO2.

A logical next step in understanding the potential of technology routes that combine biomethane production with CCS is to assess more location specific, i.e. on the level of a country or local area, where conditions are favourable for biomethane-CCS. The combination of elements like presence of suitable industry, infrastructure and biomass import facilities, and technical knowledge may provide synergies for economical production of biomethane combined with CO2 capture and reuse or storage. A focus could be on regions which preferably meet the (most of the) following conditions: demand for CO2 (industry, horticulture) or starting CCS infrastructure, (dense) natural gas infrastructure, high (local) availability of biomass and/or high natural gas import, high natural gas prices and a well-functioning carbon market.

Acknowledgements

This research is funded by the International Energy Agency's Greenhouse Gas R&D Programme.

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