Many fossil fuel companies and utilities are suggesting using hydrogen as a clean alternative to natural gas in getting to a net zero carbon future. But Hydrogen is impractical, unsafe, expensive and unnecessary for most energy needs. Here are some facts about hydrogen, its production and its uses (good and bad).
What is Hydrogen?
Hydrogen is an energy carrier, allowing the transport of energy in a usable form from one place to another. Although it is the most common element in the universe, on earth, hydrogen is attached to other molecules, like oxygen in water and carbon in methane (the main ingredient in natural gas). Hydrogen can be separated from these elements and used as a source of energy or fuel. It has the highest energy content of any common fuel by weight (about three times more than gasoline), but it has the lowest energy content by volume (about four times less than gasoline).
It takes more energy to produce hydrogen (by separating it from other elements in molecules) than hydrogen provides when it is converted to useful energy. However, hydrogen is useful as an energy source/fuel because it has a high energy content per unit of weight, which is why it is used as a rocket fuel and in fuel cells to produce electricity on some spacecraft. Hydrogen is not widely used as a fuel now, but it has the potential for greater use in the future.
Producing Hydrogen – 3 basic types:
- Gray hydrogen: 99% of current hydrogen production is produced by separating methane into hydrogen and carbon dioxide via “steam methane reformation,” typically powered by fossil fuels. In addition to the carbon dioxide released in the reformation process, the fracked gas used in this process leaks significant amounts of methane, a powerful greenhouse gas over 80 times more potent than carbon dioxide.
- Blue hydrogen: This is the same as gray, except some of the waste carbon dioxide is captured and sequestered or utilized (Carbon Capture and Storage, CCS, or Carbon Capture and Reuse CCRU). But sequestering carbon still carries unknowns, and today most captured carbon dioxide gets used to force yet more gas or oil out of the ground, making another climate-damaging industry more profitable. And like gray hydrogen, methane leakage from wells, compressors, and pipelines contributes untenable climate pollution.
- Green hydrogen: Is produced by separating water into hydrogen and oxygen using electrolysis powered by renewable energy and then used as a fuel or industrial feedstock. Green hydrogen can be important in helping to decarbonize sectors where renewable energy isn’t applicable, like steel production, shipping and chemical manufacturing. But green hydrogen requires lots of energy and water to produce and emits NOx if it is combusted for fuel. If used in a fuel cell, hydrogen is not burned and does not release harmful emissions. Green hydrogen is expensive and scarce and likely cannot offer economically viable and scalable solutions to meet GHG reduction goals for the buildings sector and has limited economic potential in the power sector.
Hydrogen Uses – Key Points
- It is always more efficient to directly electrify with renewable sources than to convert renewable energy to hydrogen and then use it as an energy source.
- Green hydrogen, from electrolysis of water, could be used to limit greenhouse gas emissions from hard-to-decarbonize sectors like steelmaking, shipping and chemicals manufacturing. But using it as a substitute for natural gas to heat buildings, or even to fuel power plants, could waste precious time and money that would be better directed to more realistic and cost-effective options to reduce carbon.
- Today, almost all hydrogen is produced using methane gas and increases climate-warming emissions.
- Arguments against blending hydrogen:
- Blending hydrogen with natural gas for use in buildings or for power generation is highly inefficient and does little to reduce GHG emissions.
- Natural gas pipelines can only handle low hydrogen blends (≤20%) before imposing safety risks, and such blends max out on reducing GHG emissions by a mere 6 to 7 percent.
- Hydrogen has low blending thresholds for use in consumer appliances designed to burn natural gas, and even these low levels pose higher safety and human health risks.
- Electric appliances utilize clean electricity far more efficiently than their hydrogen-burning counterparts, thus requiring less renewable energy generation capacity.
- The difference in chemical properties between hydrogen and methane presents major challenges and safety risks throughout the existing natural gas infrastructure system.
- Concerns about carbon capture and storage (CCS):
- CCS is not economically viable without substantial public support and has not been demonstrated at scale.
- In practice, the average capture rate is 55-72%, much lower than 90% projections.
- Economics improves if CO2 is used for oil recovery- but this defeats the purpose of GHG reduction.
- CCS is only possible in limited geologic storage areas.
- Methane continues to cause upstream GHG emissions from leaks even if CO2 is stored.
- Today, green hydrogen is 3 times more costly than grey or blue hydrogen to produce ($6-12/Kg on average) and may remain high without large subsidies and other policy supports. (See more on costs.)
- Hydrogen projects should be assessed on their merits and in the context of available alternatives to avoid increased rate-payer costs and unnecessary health and safety risks for limited GHG emission reductions.
Selected and additional resources