| Recently, there have been a lot of environmental | | | | sources of bioethanol are in this grey area. Solar cells, |
| buzzwords floating around. It can be difficult to find a | | | | wind and hydroelectric turbines are all produced and |
| clear definition. I'll explain what the term "carbon | | | | transported using fossil fuels to some extent. The |
| neutral" means, and why it's important. | | | | technology exists to make these things truly carbon |
| You might think that carbon neutral simply means | | | | neutral, but it is hopelessly uneconomic at this time. |
| that something does not release any carbon dioxide | | | | Nuclear power involves the burning of fossil fuels in |
| into the atmosphere. This is true to an extent, | | | | the mining and transport of uranium, the building of |
| however it is too simple a definition. It is possible to | | | | power stations, and the disposal of waste. When |
| release CO2 into the atmosphere and still be carbon | | | | uranium becomes scarce, mining it will consume even |
| neutral, so long it is balanced by a CO2 reduction | | | | more fossil fuels. |
| elsewhere. | | | | Sometimes companies plant trees to offset the CO2 |
| Biofuels are carbon neutral, even though burning | | | | released by burning fossil fuels. This is not truly |
| them releases CO2. How can this be? Well, the | | | | carbon neutral. Fossil carbon is being released into the |
| carbon in the biofuel comes from photosynthesis, | | | | atmosphere, and locking it up in trees is a very short |
| where CO2 is captured from the atmosphere by a | | | | term measure. To be truly carbon neutral, the carbon |
| plant and turned into glucose. The glucose can then | | | | would have to be locked up for millions of years. |
| be turned into more complicated molecules such as | | | | Trees only live for tens or hundreds of years, after |
| sugars, starches, oils and proteins. Sugars and | | | | which they decay or are burned, releasing the carbon |
| starches can easily be converted into bioethanol, | | | | back to the atmosphere. We have no way of |
| while oils can be converted into biodiesel. Carbon is | | | | knowing whether people in the future will be able to |
| removed from the atmosphere, stored in plants for a | | | | keep replanting trees to keep the carbon locked up. |
| few months, then released when the biofuel is | | | | Scientists are trying ways to lock up carbon on a |
| burned. For every gram of CO2 released by burning a | | | | long term basis. This is called sequestration, and most |
| biofuel, there was a gram removed from the | | | | experiments involve pumping carbon compounds such |
| atmosphere by photosynthesis just a few months | | | | as CO2 into old oil wells or coal mines. This would |
| ago. This perfect balance is why biofuels are carbon | | | | genuinely make fossil fuels carbon neutral, but it is |
| neutral. | | | | questionable whether enough carbon could ever be |
| Alternatively, the term carbon neutral can be used to | | | | stored to offset fossil fuel use. |
| describe energy that does not cause the release of | | | | In summary, moving to a genuinely carbon neutral |
| any CO2 at all. For instance, solar cells, wind turbines | | | | society will take time. It may take government tax |
| and hydroelectric turbines generate electricity without | | | | breaks to make biofuels and alternative energy |
| releasing CO2. Nuclear power does not release CO2 | | | | economically viable. People can take steps towards |
| during the generation process either. | | | | being carbon neutral by using biofuels and alternative |
| There is a problem with this, however. Currently, | | | | energy. Where it is impossible to avoid fossil fuels, |
| virtually all forms of carbon neutral energy actually | | | | people can focus on efficiency to reduce their fossil |
| involve the burning of fossil fuels. The crops for | | | | fuel use to a bare minimum, and switch to biofuels |
| biofuels are harvested using machinery that burns | | | | when they become available. This will move them |
| fossil diesel. This is because fossil fuels are a great | | | | closer to the ideal of having no net effect on the |
| deal cheaper than biofuels. Some ways of producing | | | | amount of carbon in the biosphere, in other words, |
| biofuels are controversial because so much fossil fuel | | | | to be carbon neutral. |
| has to be used in the production process. Some | | | | |