Table Of ContentGREENHOUSE GAS BALANCES OF
BIOENERGY SYSTEMS
GREENHOUSE
GAS BALANCES
OF BIOENERGY
SYSTEMS
Edited by
Patricia Thornley
Paul Adams
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Contributors
Paul Adams University of Bath, Bath, United Suzanne Milner University of Southampton,
Kingdom Southampton, United Kingdom
Tony Bridgwater Aston University, Birming- Sophie Parsons University of Bath, Bath,
ham, United Kingdom United Kingdom
Laura Craggs University of Manchester, Mirjam Röder The University of Manchester,
Manchester, United Kingdom Manchester, United Kingdom
Lorenzo Di Lucia Imperial College London, Andrew Ross University of Leeds, Leeds,
London, United Kingdom United Kingdom
Julia Drewer NERC Centre for Ecology & Ian Shield Rothamsted Research, Harpenden,
Hydrology, Penicuik, United Kingdom United Kingdom
Paul Gilbert University of Manchester, Raphael Slade Imperial College London,
Manchester, United Kingdom London, United Kingdom
Zoe M. Harris Imperial College London, Caroline M. Taylor EarthShift Global, Kittery,
London, United Kingdom ME, United States
David Howard NERC Centre for Ecology & Gail Taylor University of Southampton,
Hydrology, Lancaster, United Kingdom Southampton, United Kingdom
Amanda Lea-Langton University of Manches- Patricia Thornley University of Manchester,
ter, Manchester, United Kingdom Manchester, United Kingdom
Marcelle C. McManus University of Bath, Ian Watson University of Glasgow, Glasgow,
Bath, United Kingdom United Kingdom
Niall McNamara NERC Centre for Ecology & Carly Whittaker Rothamsted Research,
Hydrology, Lancaster, United Kingdom Harpenden, United Kingdom
ix
C H A P T E R
1
Sustainable Greenhouse Gas
Reductions From Bioenergy
Systems—Climate Change:
A Bioenergy Driver and Constraint
Laura Craggs, Paul Gilbert
University of Manchester, Manchester, United Kingdom
1.1 INTRODUCTION
In response to the increasing evidence of human impact on the climate, the International
Panel on Climate Change (IPCC) was created in 1988 with the intention of stabilising global
greenhouse gas (GHG) emissions in the atmosphere [1]. Even with the increased attention
on GHG emissions and climate change over the last 30 years, anthropogenic GHG emissions
continue to increase and in 2010 they stood at 49 GtCO per year [1]. The observed impact of
2
climate change can be seen through occurrences of extreme weather, with melting ice caps in
the arctic, rising sea levels, severe flooding, and increased rain levels [2].
Climate change theory states that an increased abundance of GHGs in the atmosphere
traps reflections of solar radiation from the earth’s surface, keeping this radiation within the
earth’s atmosphere and causing a warming effect [3]. The major anthropogenic GHGs are
carbon dioxide (CO ), nitrous oxides (NO ), and methane (CH ), with CO accounting for
2 x 4 2
60% of the observed global warming [1,4]. The balancing movement of carbon between the
atmosphere and land storage is an important component of climate change. Large volumes
of carbon are frequently exchanged between the land and the atmosphere, through biolog-
ical, chemical, geological, and physical processes, highlighting the importance of balance,
as atmospheric CO will only be stable when these processes are in equilibrium [5]. Certain
2
human activities can alter this equilibrium, for example, deforestation, which reduces the
carbon stored on land, and burning fossil fuels, which increases the carbon released into the
atmosphere [6].
1
Greenhouse Gas Balances of Bioenergy Systems © 2018 Elsevier Inc. All rights reserved.
https://doi.org/10.1016/B978-0-08-101036-5.00001-X
2 1. CLIMATE CHANGE: A BIOENERGY DRIVER CONSTRAINT
Although burning fossil fuels has smaller net GHG emissions than most natural carbon ex-
changes, the key difference is the absence of any counteracting storage of CO ; meaning this
2
is a one-way movement and all fossil fuel burning contributes to carbon in the atmosphere
[5]. Seventy-eight percent of the increase in GHG emissions between 1970 and 2010 were from
fossil fuel combustion and industrial processes, highlighting the important role humans play
in the climate change process [1]. This chapter provides an understanding behind the urgency
for reducing greenhouse gas emissions and the potential role of bioenergy in avoiding the
very real threat of an increased global temperature.
1.2 SCALE OF THE GLOBAL CHALLENGE
Since 1971, cumulative emissions from burning fossil fuels have increased from 13,995 mil-
lion tonnes to 32,189 million tonnes of CO in 2013 [7]. This trend is projected to continue into
2
the future, due to increasing populations and economic development of countries such as
China and India creating an increased energy demand [1]. A continued growth of CO emis-
2
sions will lead to long-term and irreversible impacts on the climate to the detriment of the en-
vironment and human health. With no mitigating actions against these increasing emissions,
the temperature increase compared to pre-industrial levels is expected to be 4°C by 2100 [2].
In a 4°C warmer future, sea levels will rise dangerously, cities will be sub-merged, food
security will be at risk from reduced crop productivity, and society will experience extreme
weather patterns, including forest fires, violent storms, and devastating droughts [2,8]. In
a 2°C warmer world, these risks are still apparent but with less severe and life-threatening
impacts [9]. Evidence suggests that society’s previous emissions are so significant that a 1.5°C
temperature increase from pre-industrial levels can no longer be avoided. This means that ur-
gent and dramatic action must be taken to ensure that we keep the global temperature below
the dangerous levels of 2°C [2].
1.3 CLIMATE POLICY OBJECTIVES
Following building evidence and increasing concern around the effects of climate change,
a global commitment has been made through the highly anticipated Paris agreements (COP
21), to keep global temperature increases ‘well below 2°C’ and to explore the potential for
1.5°C [10]. COP 21 also led to an agreement that, from 2020, richer countries will spend
money helping lower income countries either mitigate climate change or try to adapt to the
impacts of rising temperatures, such as rising sea levels [9]. This is a key change from previ-
ous agreements, as historically commitments have been made only by developed countries.
This commitment also highlights the fact that climate change can no longer be fully avoided
and measures must be taken to mitigate the inevitable impacts.
Following the Paris agreement to limit global warming, the 195 countries of the United
Nations Framework Committee on Climate Change (UNFCCC) laid out their most ambi-
tious targets through Intended Nationally Determined Contributions (INDC’s), which are
declarations of their best efforts on emissions reduction [11]. There is concern among scien-
tists that the INDC’s as set out will not provide the emissions reductions necessary to keep
1.4 THE ROLE OF THE ENERGY SECTOR 3
warming below 2°C [9,11]. Moving forward, countries need to set ambitious emissions re-
duction targets and effective policy frameworks in order to meet global goals and avoid the
consequences of a 2°C global temperature increase.
There are multiple ways in which emissions reductions can be achieved, which essen-
tially fit into two categories; reducing emissions of carbon to the atmosphere and increasing
the carbon stored on land [10]. Methods of increasing carbon sinks include afforestation
and improving forest management. Reducing emissions involves decarbonising energy
generation by moving to renewable sources, reducing energy demand, and reducing fossil
fuel use in other industries, such as construction or transport [1]. Ambitions to tackle cli-
mate change are global, but each country declares their contribution to meeting these goals
through their INDCs.
In addition to INDCs, there are global mechanisms to encourage emissions reductions. The
Emissions Trading scheme under the Kyoto Protocol is a market-based approach to mitigat-
ing emissions; the largest of these schemes is the EU Emissions Trading Scheme, which sets
a cap on total emissions and allows companies to trade allowances for emissions between
businesses [12]. Another policy mechanism is REDD+, first created in 2007 and later mod-
ified; REDD+ intends to maximise carbon sinks on land through minimising deforestation
and degradation of forest land, although implementation of REDD+ in developing countries
is currently relatively slow [13]. The purpose of these mechanisms is to address the issues of
climate change from a range of perspectives to provide a suite of measures that span multiple
sectors and nations.
1.4 THE ROLE OF THE ENERGY SECTOR
Almost 70% of GHG emissions from human activity are related to energy production, and
with energy demand projected to increase in the future, the energy sector is a key area of
interest [14]. However, provisional numbers suggest that 35 billion tonnes of CO were emit-
2
ted in 2015, which is relatively consistent with emissions in the previous 2 years, suggest-
ing that CO emissions are beginning to plateau [7]. This stabilisation of CO emissions has
2 2
happened alongside economic growth, and therefore, has an important implication that our
decarbonisation does not have to require the slowing down of economic development [7].
This potential stabilisation could be attributed to improved energy efficiency or an increase
in energy generation from renewable sources; however, in 2013, the three major types of en-
ergy generation in total global primary energy supply were still oil (31%), coal (29%), and gas
(21.4%) [15]. If society is to reach net zero CO emissions between 2050 and 2100, it will need
2
to rapidly increase the uptake of renewable energy, so that all generation from fossil fuels is
replaced with a renewable alternative.
Renewable energy has great potential for reducing CO emissions, but there are chal-
2
lenges associated with large-scale development of renewables. The potential for renewables
is limited by land and technical constraints and energy is usually required to convert renew-
able energy potential into usable energy. These energy requirements can make renewable en-
ergy more costly and reduce the available useful energy [16], but it is clear from the science
that emissions from fossil fuel use need to be eliminated, so these challenges should be an
area of priority.
4 1. CLIMATE CHANGE: A BIOENERGY DRIVER CONSTRAINT
1.5 GLOBAL RENEWABLE ENERGY TARGETS
From mid-2015, 164 countries had at least one type of renewable energy target, com-
pared to 43 countries in 2005, highlighting the significant development over these 10 years
[17]. These ‘targets’ can range from declarations and plans, to legally binding targets for
the uptake of renewable energy [17]. Fig. 1.1 shows the total EU target for renewable
energy generation is 20%, but there are significant targets also being set in developing
countries: Nicaragua, for example, is aiming to get more than 90% of their energy from
renewable sources by 2020 [18].
India and China are among the major GHG emitters globally and, in 2013, they had a joint
contribution of 35% to global GHG emissions [19]. India is now the fourth largest user of en-
ergy in the world, and although renewable energy currently only accounts for only 12.5% of
total installed capacity, a number of policies have been implemented to promote renewable
energy [20]. China has also committed to a target of 15% of primary energy consumption
from renewables by 2020 and a medium target of 30% by 2030 [19].
1.6 RENEWABLE ENERGY TARGETS FOR EUROPE
The current target for renewable energy generation in the EU is 20% of the total energy
generation by 2020, apportioned across EU countries. The share of the target for each coun-
try is based on a standard increase from the amount of renewable energy produced in 2005
and also takes into account the wealth of each country, so wealthier countries take on a more
challenging target [21].
Share of renewable energy in gross final energy consumption (%)
80
70
60
50
40
30
20
10
0
U (28 countries) Belgium Bulgaria Czech Republic Denmark Germany Estonia Ireland Greece Spain France Croatia Italy Cyprus Latvia Lithuania Luxembourg Hungary Malta Netherlands Austria Poland Portugal Romania Slovenia Slovakia Finland Sweden United Kingdom Norway
E
2013 Target
FIG. 1.1 Graph comparing the 2013 share of renewable energy for each EU member state to the 2020 target.
Data from http://ec.europa.eu/eurostat/data/database; http://ec.europa.eu/eurostat/statistics-explained/index.php/Renewable_
energy_statistics.
1.7 BIOENERGY 5
Fig. 1.1 shows that the EU is making good progress towards the 2020 targets, with 15%
of all energy generation now from renewable sources, but it needs to look into the future in
order to avoid a 2°C temperature increase. Beyond 2020, the EU must look to dramatically in-
crease the proportion of renewables in energy generation, from 20% to 100%, in order to meet
the goals of the Paris agreement. In Europe, bioenergy provides almost two-thirds of total
renewable energy generation, with the remainder from hydropower, wind, solar, geothermal,
and tidal energy [22].
1.7 BIOENERGY
The definition of ‘biomass’ is any plant-based organic matter and bioenergy is the energy
derived from this organic matter. The underlying principle behind using biomass fuels is that
the CO released in combustion is the same amount which is absorbed from the atmosphere
2
as the plant grows, thus theoretically it is carbon-neutral, provided the biomass is regrown
and does not drive wider change in land use [23]. The balance of CO from uptake and com-
2
bustion is discussed in more detail in subsequent chapters.
Bioenergy is energy created from the combustion of biomass and has always been an im-
portant source of fuel, widely used for heating before the industrial revolution and still used
in developing countries today [24]. Bioenergy is currently thought to provide over 10% of
energy globally, with nearly two thirds of this used in developing countries compared to
developed countries, where there is a stronger reliance on fossil fuels [4,25]. Outside of the
traditional use of bioenergy in developing countries, more modern uses of bioenergy in de-
veloped countries have also increased, as a requirement for countries to move to renewable
energy has led to a significant increase in bioenergy use [26]. In order to move towards a fully
decarbonised energy sector, renewable energy technologies must be deployed on a larger
scale and must be competitive with fossil fuel generation. To be a realistic competitor to gen-
eration from fossil fuels, more modern applications of bioenergy are required to harness the
energy from biomass in a cost-effective and efficient way.
Bioenergy is the most widely applied renewable energy source available and is currently
the only technology available for transport fuels [27]. As we strive towards zero GHG emis-
sions in this century, it is likely that we will see a dramatic increase in the uptake of bioenergy
to displace carbon-intensive energy generation. Future levels of bioenergy use are expected
to increase significantly, with predicted deployment levels in 2050 of between 100 and 300 EJ,
made up of both traditional wood fuel use and modern uses of biomass [28].
As of September 2016, there are 104 policy support mechanisms for bioenergy globally,
across 56 different countries [29]. These policy mechanisms include laws and plans for the
uptake of renewable energy generally, increasing renewable fuels used in transport and bio-
energy for heating and electricity. Across Europe, there are clear plans for the deployment
of bioenergy as a renewable energy source, but across the globe, countries are planning in-
creased bioenergy use, including an intention in the United States for an annual consumption
of 36 billion gallons of biofuels each year by 2022 [30]. Other countries also have strong poten-
tial for bioenergy use, such as Brazil, where biomass currently produces 9.7% of all electricity
generation [31]. The intended use of bioenergy for different types of energy within Europe
can be seen in Fig. 1.2.
