Can Hydrogen Be Used As Renewable Energy?

Renewable energy comes from natural sources or processes that are constantly replenished. Some examples of renewable energy sources are sunlight, wind, water, plants, and geothermal heat. There is growing interest in hydrogen as a clean, sustainable energy source because hydrogen can be produced from renewable resources and when used in fuel cells, only produces water and no carbon emissions.

Hydrogen has potential as an energy carrier that can store, move, and deliver energy produced from renewable sources. Since renewable energy sources like wind and solar are weather-dependent and intermittent, hydrogen provides a way to store the energy so it can be used when needed. Hydrogen can also enable renewable energy to be transported over long distances. Using hydrogen in fuel cell vehicles and other applications may provide society with an alternative to fossil fuels that reduces greenhouse gas emissions and enhances energy security.

How Hydrogen Can Be Produced

Hydrogen gas is abundant but not available as a gas on Earth. Hydrogen gas must be extracted from compounds that contain it. There are several ways to produce hydrogen (U.S. Department of Energy, n.d.). The most common methods are electrolysis and steam methane reforming.

Electrolysis uses electricity to split water into hydrogen and oxygen. This method can produce high-purity hydrogen. However, a large amount of electricity is required. The cost and environmental impact depend on the electricity source (U.S. Energy Information Administration, 2023).

Steam methane reforming is the most common method of hydrogen production in the United States today (U.S. Energy Information Administration, 2023). This involves reaction of natural gas with high-temperature steam. Steam methane reforming accounts for nearly all hydrogen produced in the United States (U.S. Department of Energy, n.d.).

Coal gasification is another method that uses high temperatures and steam to produce hydrogen from coal. This method generates carbon dioxide as a byproduct. Cost and availability of coal are key factors for this method of hydrogen production (U.S. Department of Energy, n.d.).

Advantages of Hydrogen

Hydrogen has several key advantages that make it an attractive option as a renewable energy source. First and foremost, hydrogen is a clean burning fuel that produces no greenhouse gas emissions when used. The only byproduct from hydrogen fuel cells is water vapor. This makes hydrogen an ideal fuel to help reduce carbon emissions and mitigate climate change (Source).

Secondly, hydrogen’s versatility allows it to be used for a variety of applications including electricity generation, transportation fuel, and heating. Hydrogen can power fuel cell vehicles, replace natural gas for heating, and can be used in fuel cells to produce electricity. This flexibility makes hydrogen useful across sectors of the economy (Source).

Finally, hydrogen has a high energy density by weight, meaning it provides more energy per unit of weight than other fuels. This makes it lightweight and compact for mobile applications like fuel cell vehicles. The high energy density also results in good storage capacity in tanks and potential for long driving ranges for hydrogen vehicles.

Challenges of Hydrogen

While hydrogen has potential as a renewable energy source, there are several key challenges that need to be addressed:

Hydrogen storage and transportation is difficult and expensive. According to the IEEE, “Need for additional onsite compressors. High complexity of the reforming process” (https://smartgrid.ieee.org/bulletins/february-2021/green-hydrogen-challenges-for-commercialization). Hydrogen has a very low density compared to other fuels, so it requires compression or liquification for storage and transportation, which consumes additional energy.

Production costs for green hydrogen are currently high. As noted by 100%RE, “High hydrogen production, storage, and transportation costs” are a key challenge (https://100re-map.net/en/green-hydrogen-market-potentials-and-challenges/). The processes to produce hydrogen from renewable electricity are still expensive compared to fossil fuel-based hydrogen production.

More technological advances and infrastructure build-out are needed to bring down costs and improve efficiency across the hydrogen supply chain.

Hydrogen Infrastructure

The development of hydrogen infrastructure to support fuel cell electric vehicles is still in the early stages, but has been expanding in recent years. According to the U.S. Department of Energy’s Alternative Fuels Data Center, as of 2023, there are 59 open retail hydrogen stations in the U.S., with 43 of those in California (https://afdc.energy.gov/fuels/hydrogen_infrastructure.html). Countries like Japan, Germany, and South Korea also have growing numbers of hydrogen stations. However, infrastructure remains limited compared to the thousands of gasoline stations that exist today.

Most existing hydrogen stations use delivered hydrogen from industrial gas suppliers, stored onsite in tanks. Building out more extensive hydrogen pipelines from production locations is seen as key for expansion. Currently there are over 1,600 miles of low-pressure hydrogen pipelines in the U.S., mainly supplying refineries and chemical plants. High-pressure hydrogen pipelines are rarer, though some demonstration projects exist in Europe and the U.S. (https://www.sciencedirect.com/science/article/abs/pii/S0360319922046973).

To enable larger scale transport and storage, companies are also exploring methods like liquefied hydrogen and conversion of hydrogen to ammonia. However infrastructure build-out remains a major challenge and barrier to wider hydrogen adoption according to the International Energy Agency. Significant investments, likely aided by government support, will be needed to scale up hydrogen storage tanks, pipelines, transportation methods, and refueling stations.

Hydrogen Storage

Hydrogen has a low volumetric energy density, which presents challenges for storage. Two main methods for storing hydrogen include physical storage in high-pressure tanks or as a cryogenic liquid, and materials-based storage using chemical carriers like metal hydrides and carbon materials. Physical storage involves compressing gaseous hydrogen in tanks up to 700 bar pressure or liquefying it at extremely cold temperatures around -253°C. While mature and commercially available, physical storage consumes additional energy for compression and refrigeration.

Materials-based storage has the potential for higher volumetric and gravimetric density compared to physical means. Metal hydrides like magnesium and aluminum hydride can reversibly absorb significant amounts of hydrogen. However, refueling rates are slow and they require high temperatures for desorption. Carbon materials like nanotubes, graphene, and porous carbons can adsorb hydrogen rapidly under ambient temperatures, though their weight percent storage capacity remains low. Ongoing research aims to develop novel materials and hybrid systems to provide safe, affordable and efficient hydrogen storage.

Hydrogen Transportation

Transporting hydrogen from production facilities to end-users presents some unique challenges. The most common methods for moving hydrogen include truck, rail, barge, and pipelines.

For truck transport, hydrogen is compressed and loaded into tube trailers. These trailers can carry gaseous hydrogen at pressures up to 500 bar. Trucks offer flexibility for small volume deliveries, but they have limited capacity compared to other modes.

Rail tank cars provide a higher capacity option for hydrogen transport. These specialized tank cars are pressurized up to 200 bar. Rail transport is more efficient than trucking for long hauls, but transferring to trucks is still needed for final delivery.

Barges equipped with compressed gas containers are another mass transit option. Barge transport is economical for large quantities of hydrogen over water routes. Most barges carry the hydrogen in liquid form because of its higher density.

Liquid hydrogen requires cryogenic temperatures below -253°C. This allows larger volumes to be transported but requires specialized equipment. Insulated tanker trucks and railcars maintain the liquid state during transport. Liquefaction also enables ocean transport of hydrogen via tanker ships.

Pipelines provide the most efficient way to move large, continuous volumes of hydrogen. Existing natural gas pipelines can sometimes be retrofitted for hydrogen use. Dedicated hydrogen pipelines are also being developed to connect major production and demand centers.

Hydrogen Safety

Using hydrogen as an energy source comes with some safety concerns that need to be addressed. Hydrogen has fire and explosion risks that are different from other fuels. It is colorless, odorless, lighter than air, and burns with an invisible flame. Hydrogen can ignite more easily than other fuels and burns faster. A hydrogen leak can quickly lead to a fire or explosion if an ignition source is present.

Materials compatibility is another issue. Hydrogen can make some metals like steel brittle and prone to cracking over time. This can cause hydrogen equipment and storage tanks to fail. Special design considerations are needed. Hydrogen can also leak through materials like rubber and plastic more easily than other gases.

Gas detectors and other leak detection methods are important when working with hydrogen. Since hydrogen is odorless and burns with an invisible flame, detecting a leak before it ignites is critical. Hydrogen sensors can alert people to a leak before it becomes a safety hazard. Proper ventilation, storage, and handling procedures are also necessary.

Overall, hydrogen has unique properties that require safety considerations related to fire/explosion risks, materials compatibility, and leak detection. With the right materials, design, detectors, and procedures, hydrogen systems can be operated safely.

Examples of Hydrogen Use

Some of the largest scale uses of hydrogen today are taking place in pilot projects around the world. For example, hydrogen fuel cell vehicles like the Toyota Mirai are being tested in markets like California and Japan (Source). Companies like Amazon are also testing hydrogen fuel cell forklifts in their warehouses to improve efficiency and reduce emissions (Source).

Another major application is power generation. Hydrogen can be used to store energy and provide electricity when renewable sources like solar and wind are not available. Utilities in Europe have implemented demonstration projects using hydrogen for grid balancing and stability. Overall, hydrogen offers unique capabilities that make it well-suited for transportation, electricity production, and energy storage across industries.

Future Outlook

The future of hydrogen as an energy source depends on several key factors like cost, government policy and public perception. To become viable as a renewable energy source, the costs of producing, transporting and storing hydrogen need to come down substantially. Many experts predict that as technology improves and scales up, costs could fall enough to make hydrogen cost-competitive with fossil fuels in the next 10-20 years. But this will likely require strong government support through policies like carbon pricing, subsidies and incentives for hydrogen infrastructure and transport. As costs decline and visibility increases, public acceptance of hydrogen will also need to grow. People will need to feel comfortable with hydrogen as a safe, sustainable energy option for it to gain widespread adoption. Overall the long-term outlook for hydrogen is positive, but realizing its full potential will hinge on continued innovation to reduce costs as well as smart government policy and public education.