Sooner or later the world is going to have to make the switch away from fossil fuels, says Keith Guy. In this week's Green Room, he explains what needs to be done to make the vision of a global hydrogen economy a reality.
An increasing global population, rising standards of living and more industrial production mean the amount of energy the world consumes could rise by 50-60% over the next 25 years.
Today, the biggest forms of energy are fossil fuels - oil, gas, coal. But that is set to change in the future for at least two reasons:
- "easy" oil and gas sources are declining
- emissions of greenhouse gases related to fossil fuels are rising to unacceptable levels
But what are the alternatives and can they ever become a reality?
Hydrogen is already providing a growing alternative energy source for transportation in several countries, including the US and Japan.
In a bold move, Iceland has set itself the challenge of becoming the world's first hydrogen economy, with the aim of the fuel supporting all its energy needs by 2050.
This means the total elimination of fossil fuels and should result in cutting the country's greenhouse emissions by up to 50%.
However, one could argue that Iceland's natural energy resources, its waterfalls and hot springs, give it an unnatural advantage over less well-endowed countries.
Making the switch
So what progress can other countries hope to achieve and what do they need to make the hydrogen economy a reality?
Let's start with a look at what advances the world is currently making.
The most obvious step that we are beginning to see is the introduction and take-up of fuel-cell powered vehicles.
Although there may be an intermediate stage with onboard gasoline reformers, these cars offer immediate benefits - they are about twice as efficient as current fossil fuel transport and can significantly reduce air pollution in cities.
Since the first hydrogen filling station was set up in 2000 in Dearborn, US, we have seen a steadily growing number opening up to meet the increased demand, especially in the US, Japan, Germany and Iceland.
Many buses in Iceland are already converted to use hydrogen and are refuelled by a filling station on the outskirts of its capital, Reykjavik. There are also plans to convert the country's entire fishing fleet.
Breaking down barriers
Unfortunately, whilst moves towards an increased use of hydrogen are starting to gather speed, as things stand this growth is restricted by a number of constraints at the political, commercial, technical and social levels.
Safety concerns are still widespread, with the spectre of the Hindenburg accident still in the minds of many.
The public perception of the dangers around hydrogen's transportation and distribution need to be addressed if we're to see widespread use in the future.
At a practical level, there are real issues in terms of how we store and transport hydrogen. Hydrogen is a very light gas making it far more difficult to work with than gasoline.
From an economic point of view, the costs of switching over to hydrogen-based technologies are high. In the US for example, the investment required to convert existing gasoline stations to provide hydrogen to vehicle drivers will run into billions of dollars.
While fuel cells may be getting cheaper, they are still more expensive than conventional engines.
The cost of producing the actual hydrogen itself is high, although the good news is that economies of scale do exist.
As the supply increases, the costs will start to come down. It is expected that the same will apply to the associated costs of storage, transport and vehicle design.
What we'll also need to see is a move from natural gas-based hydrogen, which is being used during the market development phase, to industrial-level hydrogen production using renewable resources on an economic basis.
This will require further development, both in the public and private sector, if we're to see any significant progress.
There is a real political need for a common worldwide approach if we are to see the transition to a hydrogen economy.
National and international government organisations must get behind the technology and provide the support for research, and ultimately the commercialisation of hydrogen, if we are to succeed in developing a viable and green alternative to fossil fuels.
The hydrogen economy is developing but more must be done if we're to see real progress in the medium to long term; only then will it cease to be a theory and become a reality.
Professor Keith Guy is a Chem Envoy for the Institution of Chemical Engineers (IChemE)
The Green Room is a series of opinion pieces on environmental topics running weekly on the BBC News website