David
Lindenmayer, Australian
National University and Brendan
Mackey, Griffith
University
The Australian government
has agreed to invest almost $53
million in a north Tasmanian company that will upgrade
its coal-fired kiln to burn wood “waste” and used tyres
for cement
manufacturing.
The Federal Minister for Climate
Change, Chris Bowen, says
this initiative will help decarbonise the Australian
economy.
However, the science is clear: burning
forest biomass, or so-called forest “waste” – which
could include dead trees, understorey vegetation and fallen
logs – generates large amounts of carbon
emissions. It will likely also accelerate poor forest
health.
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The empirical evidence shows burning
forest biomass to make concrete is poor climate policy, poor
environmental and forest policy, and a poor use of taxpayer
funds.
Why is this happening?
In line
with climate change treaty commitments under the Paris
Agreement, governments worldwide are working to
decarbonise their economies in an attempt to limit global
warming.
This includes finding alternative sources
of clean energy to using fossil fuel. This is especially
important for carbon-intensive, high-polluting industries,
such as concrete production. While about 56%
of concrete emissions come from processing clinker (the
base material for cement), 39% come from using fossil fuel
to generate heat, and 14% from electricity.
Unfortunately, forest biomass is increasingly
being promoted as an energy source to replace fossil fuels,
for example in the United
Kingdom and Europe. Most forest biomass used to generate
energy will likely be
trees. And what is often referred to as “waste” is
actually a critical part of the structure and composition of
natural forests. For example, understorey vegetation and
logs provide habitat for a wide range of animal species.
They play an essential role in nutrient cycling, such as
storing substantial amounts
of carbon.
Whilst forest biomass is technically a
renewable resource, as trees can be regrown after logging,
it is not a source of clean energy.
This is because about half of tree biomass is carbon
(assuming a moisture content of 45%). Therefore, burning a
tonne of wood generates roughly a tonne of carbon dioxide
emissions. Importantly, up to 30% of carbon dioxide
emissions are still in the atmosphere after 1,000
years.
The time lag between release and
absorption
Critically, there is a highly
significant lag time, of decades to centuries, between
carbon being instantaneously released from burning forest
biomass and when it is removed from the
atmosphere. These removals occur either by plant growth
or through carbon making its way to the bottom of the
ocean.
The lag time between burning forest
biomass and tree regrowth is important because the increase
in atmospheric carbon dioxide concentrations causes even
more climate change. This is one of the key reasons why
widespread burning of forest biomass in some European
countries threatens their
ability to meet Paris Agreement greenhouse gas reduction
targets.
Furthermore, forest biomass has a far
lower calorific content relative to coal. This means large
quantities of forest material has to be burned to generate
an equivalent amount of energy. This high demand for wood
for biomass energy can contribute significantly to poor forest
health.
Notably, Australia, along with many
other governments, has
committed to ending deforestation and degradation by
2030. This recognises the importance of forest carbon
sequestration and storage in meeting climate
targets and achieving the Paris Agreement
goals.
Not an isolated example
The
Tasmanian plan, that would see Cement Australia burn forest
“waste” to generate energy, is far from an isolated
case. There are well-developed plans for Verdant Earth
Industries to reopen the former coal-fired Redbank Power
Station in the Hunter Valley, in New South Wales, and
generate energy by burning hundreds of thousands of tonnes
of “wood
waste” annually.
Much of this “waste”
will likely be trees from forest and woodland
regrowth, which are fundamental to the integrity of
those ecosystems. This regrowth also provides habitat for a
vast array of species, including a range of threatened
species.
Biomass burning is frequently
supported by native forest logging advocates because of
structural issues in the industry. These issues include
attempts to extract some financial return from an industry
that is largely unprofitable. The native forest sector
produces primarily low-value, high-volume commodities such
as [woodchips and paper pulp], whereas plantation forest
sector dominates high-value
sawn wood products.
Similarly, state government
forestry agencies have been unable to get
market certification for wood products such as woodchips and
pulpwood from bodies such as the Forest Stewardship Council.
This is partly because the areas logged to produce wood
products are often are home to a diverse range
of plants and animals that may be threatened by
logging.
Decarbonisation matters
We
fully acknowledge the efforts being made to explore how
emissions-intensive industries can be decarbonised, such as
reducing the clinker
content in cement.
However, Australian
governments must stop using taxpayer money to subsidise
projects that entail large-scale burning of forest and
woodland biomass for industrial energy.
Alternative
forms of energy, including concentrated
solar power, will be important in this regard. Unlike
forest biomass burning, these are both renewable and clean
sources of energy.
A response was
sought from Cement Australia.
David
Lindenmayer, Distinguished Professor of Ecology, Fenner
School of Environment and Society, Australian
National University and Brendan
Mackey, Director, Griffith Climate Action Beacon, Griffith
University
This article is
republished from The
Conversation under a Creative Commons license. Read the
original
article.
