Turning Down the Heat

In my last article, I talked about rising temperatures, and how the unprecedented surge is linked to greenhouse gasses—mostly carbon dioxide (CO2)—in the atmosphere. I mentioned that even if we stopped all the things that produce CO2 today, the climate would continue to warm for decades, due to those emissions lingering. So, if we could stop (unlikely, if not impossible), it would still take time for things to stabilize. We have time. Right?

Wrong. According to Oxford’s Net Zero initiative and the University of Oxford, scientific consensus says that if we are to limit global warming to 2.7 °F (1.5°C) and prevent the worst climate damages related to rising temperatures, global net human-caused CO2 emissions need to fall by about 45% by 2030, and reach net zero by 2050. (This refers to the deadlines for CO2 alone. Those for other greenhouse gasses are later, but they do push temperatures higher.)

2030. That’s just over six years away. And we’re not talking about just the cessation of CO2 emissions anymore. Even if we could achieve that, it’s too late for simple cessation to make enough of a difference. We’re talking about reaching a net zero CO2 point, which means that the greenhouse gases going into the atmosphere are balanced by those being taken out of it. That is a whole different game. But if we can manage to reach this balance, global warming would stop—as long asthe changes are permanent.

Why the 1.5/2.7° target? What difference can half a degree really make? The World Meteorological Organization has reported that if we allow global temperatures to exceed that limit, climate changes will reach a critical point beyond which there may be no return. At 2°, they predict “frequent and intense heat waves, droughts, heavy precipitation, an additional 10-centimeter rise in sea level, destruction of ecosystems,” and other irreversible changes.

Can we do it? That remains to be seen, but according to the World Resources Institute, we are not on track to reach that goal. In order to avoid the Big Bad that awaits us if we fail, we’d better try hard, and go big.

“Big” Efforts so far

There are a handful of ways countries are working toward the net-zero goal. Most of these are too technical to address in a single newsletter or blog post and, frankly, the whole thing is way over my head. Here’s what I found in my limited research. 

The most popular method, Carbon Capture, Usage, and Storage (CCUS) is the one on which many countries are pinning their hopes. It’s said to be the most cost-effective option for decarbonization of industries on which we rely (iron, steel, chemicals, etc.), and is virtually the only tech option for cutting emissions in the cement industry, which produces nearly 7% of global emissions. There are a growing number of CCUS projects around the world, with three main methods of capturing the culprit gas: post-combustion, which separates CO2 from flue gas emissions; pre-combustion, which removes the CO2 from fossil fuels before combustion is completed; and oxy-fuel combustion, which combines highly concentrated oxygen with fuel (usually coal or natural gas) into a stream of CO2 inside a combustor. 

Another method is Biomass Carbon Removal and Storage (BiCRS), which uses biomass from plants or algae to remove CO2 from the air, and then store it for long periods of time in the form of biochar, bio-oil, and vault storage. Bioenergy carbon capture and storage (BECCS), which converts biomass to heat, electricity, or liquid/gas fuels, and the emissions from the conversion are captured and stored in geological formations. BECCS could even be used to convert biomass to hydrogen, which could result in a carbon-negative fuel. 

Direct air capture is a method in which the technology extracts CO2 from the atmosphere. Unlike carbon capture methods mentioned above, which must be carried out at the site of the emissions, DAC can be done at any location. It is, however, the most expensive method of capture.

Once the CO2 is “captured,” or separated from its source (whether emissions, blended fuels, or air), it’s transmitted via pipeline, ship, rail or road tanker, then stored via one of several potential forms: 1) injection into deep geological formations (1 km or more down); 2) permanently stored in depleted oil and gas reservoirs, coalbeds, or deep saline aquifers; or 3) carbon mineralization, where the captured CO2 is injected into suitable rock types where it forms a solid carbonate, a permanent storage option. Some minerals do this naturally, without our help. The problem is that it takes a long, long, LONG time—hundreds or thousands of years. Scientists are working to find ways to speed up the process, but as yet isn’t cost-effective or scalable.

The ”U” in CCUS, however, is tricky. Once the CO2 is captured, it can be reused as a power source (see entry on NET Power’s 50 M@ clean energy plant here). Plants fitted with carbon capture, use, and storage tech can capture around 90% of the CO2 present in gas exhausted from plant operations and use the carbon dioxide captured to create low-carbon electricity, which is then used to power operations. Another use of captured CO2 is enhanced oil recovery (EOR), which has been used for decades to help increase oil extraction from reservoirs. 

However, most reuse of captured CO2 to produce commercial products or services—EOR is only one example—provides little or no reduction of emissions, nor does it return a net climate benefit, and may even be detrimental once all factors are considered. Also, each of the capture methods have their own down sides. For instance, biochar is made by slowly burning biomass at high temperatures with no oxygen. The resulting charcoal-like substance could even be used as soil fertilizer. If stored, it would retain the CO2 inside it for hundreds or even thousands of years. But despite its potential benefit, it’s only useful and carbon-neutral if the biomass used is biowaste (corn husks, nut shells, those bits of biomass we usually discard). And if you count the environmental cost of transporting the raw biomass to biochar facilities, the numbers are not in our favor.

CCS, or carbon capture and storage, is basically the same as CCUS, only without “usage” options. The CO2 is simply captured, transported, and stored. But even that isn’t without its problems. Both CCS and CCUS are expensive (between $300 billion and $50 trillion over the next 20 years), adding to the production costs in industries wherever it is used by an average of 10%. There are other drawbacks to CCS, like the uncertainty in geologic storage capacities and sustainable injection rates. In addition, CO2 leakage from storage sites could lead to environmental damages, and the reversal of intended savings. Strong regulations are currently in place, but more are needed.

These processes also have detractors. Some claim the CCS projects are basically scams intended to “greenwash” their industries which, otherwise, carry on with business-as-usual attitudes. Others claim that too few of these projects ever reached operation or, if they did, remain operational. One even quoted a recipient of funds ($141 million) from the Department of Energy as admitting in 2020 that the actual technology to capture stack emissions doesn’t exist, and that the possibility of creating it is at least “10 years out.” In addition, managing CO2 produces its own emissions, up to 24% higher than fossil-fuel-derived gasoline.

So what other options are available to us?

Land-Based Carbon Sinks – woodlands, wetlands, agricultural lands, and soil all pull CO2 from the air. Afforestation (planting trees where there weren’t any before) and reforestation (planting trees in deforested areas) add to this carbon sink effort. Earth’s forests absorb about 7.6 billion metric tons annually (1/3 of annual global emissions). Improved agricultural land management can also aid the overall uptake. Making choices that help to stop deforestation, restore cleared areas, and enable fire-damaged woods to regrow would be a huge step forward; damage to the world’s woodlands has caused around 8 billion metric tons of CO2 trapped in trees to be released.

But remember, projections say we have only 6 more years before the first target date and only 26 years until the Big Deadline. Planting trees is always a great thing. But most trees planted tomorrow will still be immature in 2050. Still, better to have 25-year-old trees than no trees.

Blue Carbon – Similar to land-based carbon sinks, blue carbon projects take place in coastal and ocean ecosystems like tidal marshes, mangrove forests, seagrass meadows, etc. The ocean itself absorbs carbon dioxide, almost 1/3 of all global emissions). The absorbed CO2 builds up in the coastal sediments and soils, so protecting our coastal habitats and wetland regions is another way to naturally sequester carbon dioxide.  Even the algae inside coral absorbs the gas and turns it into food. And reefs around the world are important to the blue carbon portion of this equation, not because reefs themselves are “net absorbers” of CO2—they aren’t—but because they are so closely associated with seagrass beds and mangrove forests. Their presence “buffers” the shoreline against storms and waves; without them, the coastal sinks may be lost, and the carbon they stored would be re-released into the environment. That’s one of many reasons why reseeding coral reefs is so important.

Blue sinks aren’t quite as lengthy a project as growing trees. Bleached coral reefs can take 9-12 years to recover, even without help— if there are no further damaging events.

There’s no way humans are going to fully cease carbon emissions. That’s just a fact. The best thing we can do while the larger mitigation efforts are underway is to reduce our own carbon emissions in every way we can, like alternative forms of transportation, green housing, sustainable energy, and so on. Read back issues of this newsletter/blog post for ideas on what you can do or check online. New ideas are surfacing every day for ways individuals and families can lighten the load and, while each effort alone is too small to make a difference, combined we can add to the larger efforts. We’re all going to have to contribute if we’re going to make that 2050 deadline.


Timely Advances in Carbon Capture, Utilisation, and Storage

All the Ways to Remove Carbon Emissions From the Air

4 Ways Carbon Capture Can Help Fight Climate Change

What is carbon capture, usage and storage (CCUS) and what role can it play in tackling climate change?

What is Blue Carbon?

Carbon Capture: Billions of Federal Dollars Poured Into Failure

Carbon Removal Strategies: A Broad Overview

6 Ways to Remove Carbon Pollution from the Atmosphere

Explained: Why is the 1.5 Degree Celsius Target Critical?

What does “Net-Zero Emissions” Mean? 8 Common Questions, Answered

Direct Air Capture

Study Warns Against Hyping Carbon-Fixing Biochar

What is BECCS?


Desert tree photo courtesy of Pixabay

Biomass photo courtesy of Pixabay

Forest Photo by Arın  Turkay

Mangrove Swamp Photo by Ray Bilcliff

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