Climate science may not require us to stop burning fossil fuels, but everything else does

To stop climate change, do we have to stop using fossil fuels? Hasn’t this already been decided? Surprisingly, no. And it has become one of the most contentious issues in climate policy debates, globally and in many countries, as observed at the last United Nations COP, where the meeting leader claimed that “science” does not require us to stop burning fossil fuels.

This claim is based on the fact that companies can trap CO₂ and bury it permanently underground. They can do this either by preventing their CO₂ emissions from entering the atmosphere (via carbon capture and storage, CCS) or by removing the emitted CO₂ from the atmosphere (via carbon dioxide removal, CDR). Because we have CCS and CDR, fossil energy producers argue that climate science does not require ending fossil fuels; society can achieve net-zero emissions by either capturing fossil CO₂ emissions at the source or balancing them with negative emissions elsewhere. This would avoid what they portray as a costly and challenging transition to renewable energy.

In fact, fossil fuel defenders are right about climate science: it is in theory possible to achieve net-zero energy systems while continuing to burn fossil fuels. In this opinion piece, we explain why, in practice, we shouldn’t, and unpack some of the hidden reasons behind the fossil industry’s enthusiasm for CDR and CCS.

Fossil fuels have no role to play in the net-zero energy system

When CCS first emerged, it promised to be a game-changing technology to keep coal and natural gas as key sources of electricity. At the same time, Klaus Lackner, the father of direct air capture, a CDR technology, famously compared CDR to a giant toilet for global emissions, claiming that “rewarding people for going to the bathroom less would be nonsensical”. Massively scaling CCS and CDR would thus save us from an unnecessary and painful phase-out of fossil energy.

The phase-out of fossil fuels in the energy system has indeed long been considered painful due to their lower cost and greater flexibility. Today, these claims don’t hold up. Because of their remarkable growth over the last 20 years – over 80% of global power system investments, approaching 100% in Europe, is in renewables – renewables have become less expensive than coal, oil, and natural gas, across the entire energy system and taking into account the associated investments like electricity storage. The price disparity becomes even greater if we factor in the additional costs of CCS and CDR to make fossil energy climate-compatible. CCS and CDR have not only high costs, but also negative environmental impacts, and the uncertainties around their scale-up can jeopardize our chances to meet ambitious climate targets. In almost all energy applications, new renewables are the cheaper and safer option, and their growing market share is already dampening the effects of price volatility in fossil energy markets.

The majority of people who will benefit from continuing to use fossil fuels are the people selling them, and they are remarkably few. Take natural gas, which the United Nations resolution lists as a “low carbon fuel” despite only modest emissions reductions compared to oil. Natural gas production is dominated by just five countries – the United States, Russia, Iran, China, and Qatar – three of which have economies that largely depend on natural gas exports, resulting in a disproportionate amount of geopolitical power. Renewable energy resources, by contrast, are abundant and spread across the globe. They create jobs in every country where they are developed and are not limited in supply by cartels seeking to maximize their profit margins.

These same high profit margins of the fossil industry are however the very reason why renewable energy needs government leadership. Today, many renewable energy sources are cheaper than their fossil counterparts, but relative costs are not the only things that determine which energy system gets built. Investors themselves will not kill off fossil energy. Switching to renewable energy requires vast amounts of new infrastructure, and while it is cost-effective, building it has become an uphill battle. The key success factor for getting the needed permits quickly – our climate targets demand speed – is widespread public buy-in. Leaving fossil energy on the table reduces buy-in for renewables by allowing opponents of renewable energy projects to argue that we don’t need them.

Paradoxically, fossil fuel energy can sneak into a net-zero emissions world by hiding inside two Trojan horses: hydrogen and direct air carbon capture and storage (DACCS). Hydrogen is needed to decarbonize many industries, such as steel and plastics production. While so-called “green” hydrogen can be manufactured from water and renewable energy and thus be inherently zero carbon, its production demands completely new infrastructure investments. So-called “blue” hydrogen is more readily available, as it can be produced from existing natural gas sources. In theory, it is close to CO₂ neutral, if it uses CCS to remove the process CO₂. In practice, it falls wide of the mark, because of the leaks in the natural gas production chain. Indeed, recent analysis suggests that blue hydrogen can be more harmful to the climate than the fossil fuels it replaces.

DACCS is a novel CDR technology that will likely play an important role in achieving net-negative emissions in the second half of the century, since nature-based solutions, like planting trees or burning biomass and capturing the previously absorbed CO₂ have limited scalability and numerous socio-insitutional challenges. The most recent IPCC scenarios foresee CDR removing up to 20 billion tons of CO₂ from the air each year, about 1/3 of present yearly greenhouse gas emissions. DACCS is expected to contribute up to half of the long-term CDR capacity. Some companies claim that DACCS “belongs in every company’s net zero plans” and urge to “locking in access to offsets now, as demand is likely to outpace supply going forward”.

Currently, two companies dominate the small DACCS market: Climeworks and Carbon Engineering. Both companies manufacture machines that absorb CO₂ from the air using chemical films and release it into a closed container when heated. While the Climeworks technology can use low-temperature heat from renewables, the Carbon Engineering chemistry requires heat at 900°C, which currently relies on burning natural gas, with CCS offsetting most of the resulting emissions.

If the two technologies were deployed at scale, they both would require a massive amount of energy, but from different sources with different implications. Deploying the Climeworks technology to its full future potential scale (20 GtCO2) would require a square of desert land equivalent to more than half of the surface of Switzerland in solar energy. Doing the same with the Carbon Engineering technology would require more than three trillion cubic meters of natural gas annually, which nearly rivals current global consumption. Using fossil-powered DACCS to offset continued fossil fuel use in the conventional energy sector, at even a small fraction of its current level, could alone cause global demand for natural gas to grow.

The impacts from this are two-fold: firstly, the growth of natural gas demand would reinforce societal lock-ins and block the growth of renewables; and secondly, the same countries and firms that have profited from emitting CO₂ will use their market leverage to earn huge profits from removing it. These benefits did not go unnoticed: Occidental Petroleum, which already claimed in 2019 that DACCS would enable “carbon-negative oil”, acquired Carbon Engineering in 2023 and stated that DACCS “gives our industry a licence to continue to operate for the 60, 70, 80 years that it’s going to be very much needed”.

So what should we do?

Continuing to use fossil energy in a net-zero world requires secondary investments in CCS and CDR, and these additional investments will always cost someone money. Hence, there will always be an incentive to delay or avoid such secondary investments. If mitigation comes at such an additional cost, and everyone has an incentive to pass that cost on to someone else (for example to future generations), the chances of missing our climate targets and of the environment spinning out of control are far higher. Relying on the additional costs of CCS and CDR to keep fossil fuels in the energy system is a risky gamble, especially if the only winners are the few fossil fuel producers. We thus believe that any economically and socially viable pathway to net-zero emissions must have an emphasis on “zero”. Zero means no fossil energy in the system.

Unfortunately, this is far from reality and politics. In Switzerland, the revision of the Glacier Initiative, passed by referendum in June 2023, omits the requirement to phase out fossil fuels, leaving the option for CCS and DACCS to offset continued fossil energy use open. The United Nations resolution from last December puts investments into CCS, which go together with investments into new fossil energy, on an equal footing with investments into energy that aim to be actually zero carbon. But the two are anything but equal in terms of their outcome to people. Governments that serve their people need to recognize this and do more: protecting the climate while promoting prosperity means ending all new investments in fossil energy.