What’s the problem?
If Britain is to become a Zero Carbon economy we have to replace our current reliance on fossil fuels for energy with non-carbon or low carbon alternatives. An important part of the solution is to power-down – reduce our use of fossil fuels and to power up -– create sustainable sources of power that do not emit Greenhouse Gas Emissions. The Centre for Alternative Technology in Machynlleth has developed a comprehensive plan. This includes a major shift to supplying our energy needs by electricity powered by a combination of wind, wave, solar and hydro-power. These renewable sources of power will replace our dependence on fossil fuels for electricity. However, this still won’t be enough to provide all our energy requirements.
Business, industry and transport need fuels with high energy densities by weight and by volume that are easily stored and transported. The problem is how do we produce synthetic liquid fuel and synthetic gas or biogas without emitting Greenhouse gases?
The proposed solution
Biomass from energy crops can be used to make fuels with identical or similar characteristics to fossil fuels. Unfortunately, there is simply not enough land in the UK to provide energy to satisfy all our energy demands. Nevertheless, biomass can help because it provides storable energy, and can provide gaseous and liquid fuels through various chemical processes. Energy on demand can help the grid meet predictable changes in load and complement variable sources of power like wind and solar. In the near-term, substituting biomass for fossil fuels can prevent carbon stocks in the atmosphere from rising.
Photosynthesis is an energy conversion and storage process: solar energy is captured and stored as carbohydrates in biomass. These plants can be harvested to produce heat, create steam for electricity production, or be processed into oil or gas. Energy and synthetic fuels produced in these ways are carbon neutral. It works like this: Grow plants and sequester carbon. Process and burn biomass. Emit carbon. Repeat. It is a continuous, neutral exchange. This means that over the long-term there is no net increase of Greenhouse Gas emissions in the atmosphere. The plants capture carbon as they grow which is released as they are processed – they are carbon neutral.
We have been producing biofuels for some time from crops that could be eaten: wheat, corn, sugar crops and vegetable oil. These first generation biofuels could also be used to feed a growing global population. The second-generation of biofuels are produced from sustainably grown ‘woody’ plant material that can be grown on ’marginal’ land not suited to food production. Non-food grasses can be harvested for 15 years before replanting and require fewer inputs of water and labour compared to first generation biofuels. These can be grown on land that is currently used to grow grass for livestock. Waste products from wood and agricultural processing are also valuable biomass -– discarded stalks, husks, leaves and so on from crops grown for food or animal feed. The implications for farming is clear – we have to change how we farm and reduce the amount of land used for grazing livestock.
NB biomass is a bridge to reach a clean energy future, not the destination itself.