Replacing fossil fuels with hydrogen and electricity won’t fully eliminate greenhouse gases, study finds

Researchers from the Paul Scherrer Institute (PSI) have analyzed the global regions best suited for cost-effective hydrogen production to support a future hydrogen-based economy. Their findings, published in Nature Communications, reveal that simply replacing fossil fuels with hydrogen and electricity won’t fully eliminate greenhouse gas emissions.

This research is crucial for countries like Switzerland, which aims to achieve climate neutrality by 2050, a goal requiring zero net greenhouse gas emissions to mitigate climate change.

To meet this goal, the electrification of transportation, industry, and households, coupled with a shift to renewable energy sources like hydroelectric, wind, and solar power, is essential. However, electricity alone isn’t always viable due to its energy storage limitations, especially in sectors with high energy demands.

Hydrogen can fill this gap, offering a more suitable alternative for industries such as aviation, agriculture, and steel, which could significantly reduce their climate impact by utilizing hydrogen, sometimes converted into fertilizers or synthetic hydrocarbons.

The research team, led by Tom Terlouw and Christian Bauer from the Laboratory for Energy Systems Analysis at PSI, used geographical and economic data to explore four scenarios for developing a global hydrogen economy. They project that by 2050, hydrogen demand could range between 111 and 614 megatonnes annually, depending on the scenario.

These scenarios range from a continuation of fossil fuel reliance to the adoption of rigorous climate protection measures aligned with the 1.5-degree Celsius target. Currently, global hydrogen production stands at around 90 megatonnes per year.

The study focused on identifying the most suitable locations for hydrogen production, particularly through PEM electrolysis, a process that uses electricity to split water into hydrogen and oxygen. This method, when powered by renewable energy, produces up to 90 percent fewer greenhouse gases than the traditional steam methane reforming method, which relies on fossil fuels.

Economic criteria played a key role in determining the optimal production locations. The researchers evaluated where green electricity from renewable sources could be harnessed most efficiently and where sufficient land is available for large-scale production facilities.

Canada emerged as an ideal location due to its vast open spaces with strong winds, ideal for wind turbines, and its abundant water resources. Although water availability and political stability weren’t the primary focus, they remain important considerations.

Beyond Canada, the central United States, parts of Australia, the Sahara, northern China, and northwestern Europe also showed potential for hydrogen production. These regions offer either ample sunshine for solar energy or strong winds and open spaces for wind turbines and hydrogen factories.

In contrast, industrialized regions like central Europe, including Switzerland and Germany, are less suitable due to limited land for wind turbines and low solar radiation. Other densely populated areas, such as Japan and large coastal regions of the US and China, face higher hydrogen production costs.

Terlouw highlights a discrepancy between regions with high hydrogen demand and those capable of efficient production. Overcoming this gap requires global trade, which in turn demands additional energy and political cooperation. Transporting hydrogen often involves converting it into compounds like ammonia or methanol due to the impracticality of transporting pure hydrogen gas or its liquid form, which requires massive cooling.

The study also addresses the environmental downsides of a hydrogen economy that are often overlooked. Even in a well-functioning hydrogen economy, residual greenhouse gas emissions are inevitable. The study estimates these emissions at nearly one gigaton of CO2 equivalents annually, a fraction of the current 40 gigatonnes but still significant.

This is partly due to hydrogen production and distribution processes, which involve emissions. For example, around 2.5 percent of hydrogen is lost through leaks, indirectly contributing to greenhouse gas formation by promoting the creation of potent gases like methane and ozone.

Moreover, the electrolysis systems themselves produce so-called embodied emissions during the production and transport of required materials, even if the final systems operate on green electricity. Many of these systems are manufactured in countries where fossil fuels dominate energy production. For instance, most solar panels are produced in China, where coal-fired power stations still supply most of the electricity.

To truly achieve climate neutrality, residual emissions must be offset by capturing and removing equivalent amounts of carbon dioxide from the atmosphere. Technologies like direct air capture, which extracts CO2 from the air, or reforestation, where trees absorb carbon from the atmosphere, could serve this purpose.

Terlouw and Bauer also caution about the broader environmental impact of a hydrogen economy. The machines and systems required for hydrogen production rely on materials that are either harmful to the environment or whose production processes are detrimental.

Wind turbines, for example, use permanent magnets made from rare earth metals, often extracted in China under environmentally questionable conditions. PEM electrolysis requires iridium, a scarce metal. The large amounts of land and water needed for hydrogen production could also pose environmental challenges.

Lastly, the researchers raise concerns about social acceptance. Terlouw questions whether people will accept large hydrogen production plants on coastal landscapes. In regions with scarce water, seawater would need to be desalinated before electrolysis, a process that requires additional energy and land.

Bauer acknowledges that these factors weren’t fully considered in the current study, suggesting that future research will delve deeper into these issues. Ultimately, the energy transition’s success depends on socio-political decisions regarding how vigorously to pursue these paths.

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