| Hydrogen is often cited as the solution to | | | | Net Energy |
| global energy problems and the perfect energy | | | | |
| carrier for a sustainable society due to | | | | It takes energy to make energy. We use energy |
| its’ non polluting nature and | | | | to find and pump oil but, luckily for |
| suitability to store and transport energy | | | | industrial society, oil has huge net energy |
| generated from renewable sources. This essay | | | | and we can usually obtain more than 200 times |
| examines the practicalities of a | | | | the amount of energy from oil than is |
| hydrogen-based energy system and its’ | | | | required for its’ extraction. Oil has |
| ability to provide a sustainable future. | | | | the highest net energy return of any fuel; |
| | | | gas, coal, wind and solar all have |
| Many people including Romano Prodi, president | | | | dramatically less. Hydrogen has negative net |
| of the European Commission, President Bush | | | | energy meaning it takes more energy to |
| and numerous "deep greens" including Amory | | | | produce it than it contains, this highlights |
| Lovins, author of Natural Capitalism advocate | | | | the first problem of a hydrogen society. |
| the "hydrogen economy" as the future of world | | | | |
| energy supply. The justification seems well | | | | Counting Calories |
| founded; a renewable energy plant generates | | | | |
| electricity sporadically, hydrogen can be | | | | Although it is the most abundant element in |
| produced by the electrolysis of water, | | | | the universe hydrogen is not very easy to |
| storing energy in the form of hydrogen | | | | obtain. Ironically, petrol is the most |
| negates the need for large and inefficient | | | | concentrated form of hydrogen available for |
| batteries (and associated pollution) and fuel | | | | human consumption containing more hydrogen by |
| cells (fig. 2) can turn hydrogen back into | | | | volume than pure hydrogen itself, since the |
| useful electrical energy (using oxygen from | | | | structure of the atoms in hydrocarbons use |
| the atmosphere) as and when required, the | | | | less space. Hydrogen also has a very low |
| only by-product being steam or water. | | | | calorific value (a gallon of petrol has |
| | | | 115,000 btus, a gallon of liquid hydrogen has |
| The associated benefits include the | | | | only 30,000 btus) so it takes about 4 times |
| elimination of exhaust pollution (sulphur | | | | the volume of hydrogen (compared with petrol) |
| dioxide, carbon monoxide, carbon dioxide and | | | | to travel the same distance, requiring larger |
| other particulates associated with the | | | | and heavier fuel tanks (compressing or |
| combustion of fossil fuels) particularly in | | | | liquifying hydrogen uses more energy) which |
| cities, the associated reduction in global | | | | require additional energy to transport. This |
| warming and the ability to generate power | | | | low calorific value dictates increased |
| locally promoting the development of a | | | | volumes (or high pressures) throughout the |
| decentralised energy system. It is even | | | | entire hydrogen system. |
| suggested that ultimately a hydrogen economy | | | | |
| would help avoid global economic downturn due | | | | Hydrogen manufacture |
| to unmanageable increase in peak demand and | | | | |
| the limited supply and increasing costs of | | | | There are several ways to obtain hydrogen; by |
| fossil fuels. | | | | electrolysis of water, by splitting water |
| | | | using light, by collecting and reforming gas |
| Don’t believe the hype | | | | from biomass, by reforming natural gas or any |
| | | | other fossil fuel. Each of these processes is |
| It’s easy to be convinced by stories | | | | extremely energy intensive and always results |
| we want to believe. Ergo magazines claims | | | | in hydrogen with a negative net energy, |
| hydrogen ‘is the one’. Jeremy | | | | electrolysis (the cleanest and most |
| Rifkin, head of the Foundation on Economic | | | | appropriate process for obtaining hydrogen |
| Trends claims the hydrogen economy will be | | | | from wind and solar power) is the most energy |
| ‘the next great economic | | | | intensive of them all – roughly 75% |
| revolution’ James Burges thinks it | | | | efficient and costs roughly four times as |
| ‘may be our only option for | | | | much as reformation. The simplest, cheapest |
| survival’; hydrogen is the answer. | | | | and most efficient process is the reformation |
| However, critical analysis of the properties | | | | of natural gas, an established industry, yet |
| of hydrogen and the necessary steps in a | | | | this is still only 85% efficient. It is |
| hydrogen society reveal a far less optimistic | | | | therefore less polluting and resource |
| picture. | | | | intensive to simply burn natural gas. |
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