There is a lot of bad news about the climate lately. The melting of
Greenland is accelerating; July of 2019 was the hottest month on record; and
CO2 emissions continue to grow, having reached 37 billion tonnes in 2018.
But amid all this bad news is a glimmer of hope: Over the past few years, a
suite of negative-emissions technologies, or NETs, have been developed
and they continue to improve. NETs are systems that remove CO2 directly from the
atmosphere and store it in long-term sinks — most often, underground geological
formations — where the carbon will stay for millennia. NETs differ from more
conventional carbon capture and
storage
(CCS) systems because NETs pull CO2 directly from the atmosphere, whereas
CCS draws CO2 from fossil fuel exhaust. In other words, while CCS can lead to
carbon-neutral processes, NETs can lead to true carbon negativity. Think of NETs
as CCS version 2.0.
Major corporations, especially those with carbon-intensive businesses, have
taken notice of the future-altering potential of NETs — and they’re signaling as
much with their investment dollars. Chevron was among the firms that
invested $68 million earlier this year in Carbon
Engineering — a startup employing one type of
negative-emissions technology; and BP put £3.5 million in the bioenergy-based
firm C-Capture. Global
Thermostat, another NET startup, announced an
agreement to share technology with ExxonMobil.
Why would major oil and gas companies be taking stakes in companies that can
help achieve negative emissions? Perhaps they believe the demand for oil will
drop in the coming decades and they are looking to invest in a post-oil world.
Or maybe they are banking on the possibility that the development of NETs will
relieve the necessity to transition away from carbon (for the sake of humanity,
let’s hope policymakers don’t see this as an option). Whichever way, companies
across industries should pay attention to these canaries in the coal mine — and
start learning about, and investing in, negative-emissions technologies.
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But is all the hype surrounding NETs deserved? Well, they are the only method
for truly removing CO2 emissions from the atmosphere. While we cannot mitigate
all 37 billion tonnes of current CO2 emissions via NETs, we could capture and
store a sizable fraction of those emissions. The fact is, employing this
technology is our only realistic chance for staying below 2°C of warming. Every
plausible emissions scenario that ends with less than 2°C of warming by 2100 —
that is, all of the scenarios consistent with the 2015 Paris agreement —
includes storing 5 to 10 billion tonnes of net negative emissions per year
starting around 2050 to 2060; the only way to achieve those negative emissions
is with NETs.
Not only might all of this help us stave off environmental catastrophe, it also
presents a tremendous business opportunity — which is why smart investors are
paying close attention. Due to the passage of the federal “45Q” tax
credits
in 2018, each tonne of CO2 placed in geological storage by a US company earns a
tax credit of $50. Given that at least 5 to 10 billion tonnes of annual NETs
will be needed by mid-century, the NET industry is expected to generate
$250-500 billion annually by the 2050s. Standing between the present and this
carbon-negative future are two interrelated obstacles: public policy and
technological development.
First, public policy: The 45Q tax credit, while a remarkably progressive policy,
isn’t perfect. The credit only applies to the first 12 years of facility
operations, and $50 per tonne is a bit low for current NET costs. This is
because 45Q was not designed for NETs but for more conventional CCS from power
plant and industrial exhaust. In these systems, a modest price of carbon and an
expiration prevision might make sense, but NETs will always require significant
energy and financial subsidies and a 12-year sunset provision is a major
weakness. Likewise, a $50 per tonne tax credit might be appropriate for CCS,
but not for NETs. As of 2018, one of the industry leaders, Carbon Engineering,
estimated its system costs at about $92 per tonne — far lower than cost
estimates a few years ago, but still well above the $50 per tonne target.
Second, technology: NET technology is evolving rapidly as new systems are
developed, but more R&D is needed. NET systems can be divided into three major
categories depending on how they actually capture CO2. Perhaps the most obvious
solution uses plants to capture CO2 via photosynthesis, then uses some method –
like combustion, gasification or pyrolysis – to create a storage product from
the plant biomass. These biological systems come with the advantage that they
are based on relatively well-known technology, but their disadvantage is that
plants require lots of water and land that could be used for other things — such
as
biodiversity
or
agriculture.
A second NET system that has received a lot of attention in recent years is
Direct Air Carbon Capture and Storage (DACCS) systems, which look like a
huge assemblage of fans that pass air over a chemical that reacts and binds with
CO2 in the air. This system scrubs CO2 from the air, but it is energy intensive
because of the heat needed to regenerate the chemical catalyst. In fact, if we
wanted to remove all 37 billion tonnes of CO2 emitted in 2018 by DACCS, it would
require on the order of 50 percent of the energy used in 2018.
Finally, enhanced weathering is a process in which rocks that would naturally
bind CO2 are pulverized to expose a larger surface area of the rock to air. The
rock could then be spread on land where it would remove CO2. The catch here is
that you need a lot of rock. A lot. Terrestrial enhanced weathering would
require between 1 and 5 kg of pulverized rock applied per m2 per year over 20 to
69 million km2 of tropical soils. For comparison, South America is slightly
under 20 million km2, and 69 million km2 is roughly the combined area of
Africa and Asia. Thus, each year we would need to cover one or more
continents with 2 to 10 pounds of rock over each and every square meter.
NETs still have kinks to work out, and policies supporting the technologies need
to do a better job of it. Still, corporate leaders who ignore the rapidly
emerging space will be missing out on a massive opportunity. Not only could NETs
become a crucial key to avoiding climate catastrophe, they could transform some
of our biggest industries in the meantime.
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Brian Snyder, Ph.D. is an Assistant Professor in the Department of Environmental Sciences at Louisiana State University.
Published Oct 23, 2019 8am EDT / 5am PDT / 1pm BST / 2pm CEST