SHABIHA NUR KHATOON, OP
Hydrogen has the potential to replace electricity as an energy carrier and emerge as an alternative to gasoline. However, humanity is still many light years away from developing the technology required to minimise dependence on conventional, but fast depleting, sources of energy
Scientists predict that in the future hydrogen will join electricity as an important energy carrier, since it can be made safely from renewable energy sources and is virtually non-polluting. It will also be used as a fuel for ‘zero-emission’ vehicles, to heat homes and offices, to produce electricity, and to fuel aircraft.
Hydrogen has great potential to reduce reliance on imported energy sources such as oil. Before hydrogen can play a bigger role and become a widely used alternative to gasoline, many new facilities and systems, however, need to be built.
Professor B C Tripathy of the School of Life Sciences at Jawaharlal Nehru University says: “Hydrogen is the simplest element in existence. It is also one of the most abundant elements in the earth’s crust. As a gas, it is not found naturally on Earth and must be manufactured. This is because hydrogen gas is lighter than air and rises into the atmosphere as a result. Natural hydrogen is always associated with other elements in compound form such as water, coal and petroleum.”
“Hydrogen has the highest energy content of any common fuel by weight. However, it also has the lowest energy content by volume. It is the lightest element, a gas at normal temperature and pressure,” Tripathy adds.
Hydrogen is considered to be a secondary source of energy, commonly referred to as an energy carrier. Energy carriers are used to move, store and deliver energy in a form that can be easily used. Electricity is a well-known example of an energy carrier.
As an important energy carrier in the future, hydrogen has a number of advantages. For example, a large volume of hydrogen can be easily stored in a number of different ways. Hydrogen is also a high efficiency, low polluting fuel that can be used for transportation, heating, and power generation in places where it is difficult to use electricity. In some instances, it is cheaper to ship hydrogen by pipeline than sending electricity over long distances by wire.
Hydrogen can be converted into usable energy through fuel cells or by combustion in turbines and engines. Fuel cells now in development will not only provide a new way to produce power, but will also significantly improve energy conversion efficiency, especially in transportation applications.
Hydrogen is a versatile energy carrier that can be used to power nearly every end-use energy need. The fuel cell—energy conversion devices that can efficiently convert and use the power of hydrogen have a key role in making this happen. Stationary fuel cells can be used for backup power, power for remote locations, distributed power generation, and cogeneration (in which excess heat released during electricity generation is used for other applications). Fuel cells can power almost any portable application that uses batteries, from hand-held devices to portable generators. Fuel cells can also provide primary and auxiliary power for transportation, including personal vehicles, trucks, buses, and marine vessels.
Fuel cells directly convert the chemical energy in hydrogen into electricity and heat. Inside a fuel cell, hydrogen electrochemically combines with oxygen from the air to create electricity, with pure water and potentially useful heat as the only byproducts.
Hydrogen-powered fuel cells are not only pollution-free but also have two to three times more efficiency than traditional internal combustion technologies. A conventional combustion-based power plant typically generates electricity at efficiencies of 33 to 35 per cent, while fuel cell systems can generate electricity at efficiencies of up to 60 per cent – and even higher with cogeneration. In normal driving, the gasoline engine in a conventional car is less than 20 per cent efficient in converting the chemical energy in gasoline into power that moves the vehicle.
Hydrogen fuel cell vehicles, which use electric motors, are much more energy efficient and use up to 60 per cent of the fuel’s energy. This corresponds to a reduction of more than 50 per cent in fuel consumption compared to a conventional vehicle with a gasoline internal combustion engine. In addition, fuel cells operate quietly, have fewer moving parts, and are well suited to a variety of applications.
Scientist Dr Chitta Ranjan Mishra says: “Many see hydrogen as a clean fuel of the future, because its only byproduct is water. The world has a voracious appetite for energy and hydrogen is likely to be the future energy source. A hydrogen molecule in the presence of oxygen can be converted into water with release of heat and work.”
The scientist explains the different challenges involved in the process. “There are several technical challenges to the commercialisation and widespread use of hydrogen as an energy carrier,” he says. “The great promise of hydrogen in providing clean, safe, reliable, and abundant energy has prompted both government and industry to make significant investments in research, development, and demonstration activities needed to bring hydrogen and fuel cell technologies to the commercial market.”
The technological barriers are:
- Reducing the cost of hydrogen. The cost of hydrogen, which includes the cost of production and delivery, must be competitive with conventional fuels (on a cost-per-mile basis).
- Improving hydrogen storage technology. The low volumetric energy density of hydrogen makes storage a challenge. No current hydrogen storage technology enables a hydrogen fuel cell vehicle to travel the desired 300 miles or more per fill while meeting vehicular packaging, cost, and performance requirements.
- Reducing fuel cell cost and improving durability. The cost of fuel cell power systems must be reduced and durability must be improved for fuel cells to compete with conventional technologies.
COST FACTOR
The greatest technical challenge to hydrogen production, however, is cost reduction. Hydrogen is produced, stored, delivered, and used today, but not in ways appropriate or at costs low enough for widespread use in transportation. Distributed production from natural gas offers a cost-effective near-term option. Given the limited supply of natural gas, however, it is not a sustainable long-term pathway. A diverse portfolio of low cost and efficient hydrogen production technologies with great potential is emerging. Ongoing research seeks to reduce the capital cost of equipment and increase distribution efficiency so that hydrogen can be cost-competitive with conventional fuels and technologies in the range of $2.00 – $3.00 per gasoline gallon equivalent (untaxed).
“The estimated cost of centrally-produced, delivered hydrogen using currently available technologies is considerably higher than that of conventional fuels,” says Mishra. “The investment risk to develop a hydrogen delivery infrastructure is currently too great, given technology status and current hydrogen demand. Government and industry partners are gathering data and analysing the options and trade-offs of hydrogen production and delivery infrastructure to help lower costs.”
STORAGE TECHNOLOGY
Delivery and vehicle storage systems require advanced technologies to compensate for the low volumetric energy density of hydrogen. Current hydrogen storage of Ford Motor Company systems for vehicles is inadequate to meet customer expectations for a driving range greater than 300 miles per fill without intrusion into cargo or passenger space. Moreover, durability of the storage system over the expected life of the vehicle must also be verified and validated. To meet these challenges, scientists and engineers in government, industry, academia, and at national laboratories are researching a wide variety of storage systems, with particular emphasis on materials-based technologies.
FUEL CELLS
Cost and durability are the major challenges to commercialisation of fuel cells, although these cells are being demonstrated on a limited scale. Some portable and stationary fuel cells are now available for critical needs applications such as backup power, and a small number of fuel cell vehicles are on the road as part of “technology validation” projects. To be considered ready for mainstream consumers, however, fuel cell systems must be cost-competitive and perform as well or better than traditional power technologies over the life of the system. That means fuel cells for transportation must prove 5,000 hours durability, or the equivalent of 150,000 miles, and cost approximately $30/kW.
Stationary fuel cells have slightly different customer requirements, with targets for 40,000 hours durability and $400-750/kW to compete with comparable, traditional power generation technologies.
TECHNOLOGY ADOPTION
Using hydrogen as a mainstream energy carrier requires codes and standards specific to hydrogen, as well as a sustained public education effort focused on specific target audiences.
- Safety and code officials must be familiar with hydrogen technologies to facilitate permitting processes and emergency responders must know how to handle potential incidents.
- State and local government officials must understand near-term realities of hydrogen technology to make sound decisions about current opportunities and lay the foundation for long-term change.
- Local communities will embrace the opportunity to host hydrogen demonstration and validation projects if they are familiar with hydrogen and understand the facts about hydrogen safety. Early adopters and potential end users must understand their options for choosing hydrogen and fuel cell technologies as an alternative to traditional power systems.
- Government, industry, and academia also need a steady stream of educated students who will comprise the next generation workforce of hydrogen and fuel cell researchers, engineers, scientists, and technicians.
- Today’s students are tomorrow’s hydrogen fuel cell users. Introducing students to hydrogen fuel cells in the classroom facilitates long-term market acceptance and engages children in the study of science and technology. This will facilitate early adoption and market transformation and ensure long-term market success.
BENEFITS OUTWEIGH COSTS
Expanding the use of hydrogen as an energy carrier requires a fundamental change in the way we produce, deliver, store, and use energy —putting it all together is the ultimate challenge. To achieve the goal of commercially-viable hydrogen and fuel cell systems, research and development efforts are focused on the most promising technologies, and demonstrations are validating fully integrated systems operating in real world conditions. While there are barriers to overcome, the benefits outweigh the costs. Developing and expanding the use of hydrogen, along with other domestic energy resources and energy-efficient technologies, will ensure that the world moves towards affordable supply of clean energy to maintain economic growth.
