Hydrogen Not a Viable Replacement for Natural Gas Due to Safety and Cost
Gas utilities across the country are promoting hydrogen (and renewable natural gas, see the accompanying article) as a viable energy source that will enable them to continue to grow their business in a rapidly decarbonizing world.
Portland-based NW Natural, the region’s largest gas utility, has been particularly vocal in its support for hydrogen. In its first quarter earnings call in early May, for example, CEO David Anderson told analysts: “We’re really focused on RNG and hydrogen. They’re both going to be the solutions for the industry, and I would argue for the greater economy as a whole.”
The Northwest’s other gas utilities are also supportive. For example, Puget Sound Energy (PSE), a joint electric and gas utility based in Bellevue, WA, is pursuing plans to use hydrogen in its natural gas system. It asked Washington regulators in its rate case filing earlier this year to approve $6.3 million in ratepayer funding for three hydrogen blending pilot projects over the coming three years. It also touts both RNG and hydrogen on its website, claiming that “clean, alternative fuels such as renewable natural gas (RNG), synthetic natural gas (SNG), hydrogen and renewable biofuels will play a critical role in the clean energy future.”
For heating homes and buildings, however, research indicates that hydrogen is a poor choice because it is inefficient and costly, and technical and safety challenges abound. A report in March from Energy Innovation, a California-based energy think tank, explains: “The existing body of research suggests blending hydrogen with natural gas for use in buildings or for power generation is highly inefficient and does little to reduce [greenhouse gas] emissions.
There are serious issues with relying heavily on hydrogen to decarbonize our current gas uses. One of the biggest challenges is that the existing natural gas pipeline infrastructure is unable to manage high percentages of hydrogen without raising serious safety issues. Most current estimates indicate that a blend of 20 percent hydrogen is the maximum that can be safely introduced into the gas pipeline system but due to hydrogen’s lower energy density, it will only replace 6-7 percent of natural gas’ energy and thus avoid only 6-7 percent of the greenhouse gas emissions.
Even at those levels, there is uncertainty about the impact on downstream users. Residential appliances likely could operate on a blend of up to 20 percent hydrogen, but other users, particularly existing gas turbines and compressed natural gas vehicles could not, which would limit the amount of possible blending.
When moving above blending levels of 20 percent, large capital expenditures would be required to replace pipelines across a utility’s service territory, and likely pipelines within homes and buildings as well. Such a transition would also require a wholesale transition of existing home appliances to ones designed to use higher percentages of hydrogen. These costs would pose serious financial threats to ratepayers, who would be forced not only to pay for new appliances, but also for the new utility pipeline infrastructure investments. Plus, the higher price associated with hydrogen when compared to electricity makes the effective climate mitigation costs of hydrogen for these uses extremely high.
Hydrogen is also potentially unsafe and highly explosive. Hydrogen is highly flammable, igniting more easily than methane or natural gas. It also burns hotter than methane generating higher levels of nitrogen oxides (NOx). At the power sector level, the elevated NOx emissions could require the inclusion of additional air pollution control equipment, boosting system costs; at the home level, consumers’ exposure to indoor air pollution would increase, heightening the growing health and safety concerns with existing gas-based appliances.
Electric heating for homes and buildings has gained momentum because the appliances are extremely efficient and do not suffer from the built-in losses associated with hydrogen production or the subsequent combustion of that hydrogen in the home. Given this, regulators and policymakers will need to carefully examine the risks and costs associated with hydrogen-based gas utility decarbonization proposals before they are incorporated into future resource plans.