Introduction

Whole Systems Approach to Ecological Design

Appropriate Technology: Water

Organic Agriculture and Local Food

Appropriate Technology: Energy

Green Building & Retrofitting
4. Appropriate Technology: Energy
Energy Roadmap Energy Generating Technologies Efficient Energy Use Technologies Sustainable Transport

Biofuels

Biofuels are produced from various crops and have their origin in agriculture or aquaculture.  As a result, the basic materials have fixed current carbon, which is then released when burned or used in a vehicle.  Carbon is used as part of the biofuel production process for fertilizer, farm machinery, transportation and also for distillation in ethanol from sugar cane.  As a result there are different ratios for biofuels of energy in and energy out.

Four biofuels are considered in this section:

  • Biodiesel from rape seed
  • Ethanol from sugar cane
  • Ethanol from corn
  • Ethanol from cellulose (trees, etc)

Fossil Fuels/Biofuels Comparisons

These fuels are compared to their fossil equivalents in terms of emissions, farmland area for production, energy in/out ratio and retail price.  The last factor was current at the beginning of 2008 and prices, especially for fossil fuels have risen substantially since then.

Cellulosic ethanol is still in the research laboratory.  The production process involves fermentation.  The other biofuels are in the market.

  • Biodiesel (from Rape Seed) has quite good numbers with emissions 68% less than fossil fuel and energy balance of 2.5:1
  • Cellulosic Ethanol has great promise.  Emissions are 91% less than fossil fuel & energy balance could be as high as 36:1.  Main current problem is production cost.
  • Cane ethanol is also adequate with emissions 56% less than fossil fuel and energy balance of 8:1
  • Corn Ethanol only saves 22% of emissions compared with fossil fuel and energy balance is low at 1.3:

Litres of biofuels per hectare of land

  • Biodiesel is not land efficient.  However there are substantial crops of rape seed (canola) grown in northern Europe.  In Brasil, the oil of choice is often sunflower oil.
  • Cellulosic and cane ethanol is quite efficient in the use of land.  However the waste from the sugar cane plants is burned in the distillation process for cane ethanol.  Permaculture would encourage this waste to be returned to the land for the good health of the soil.  Current practice, which provides a good energy in/out ratio, also leads to land degradation.
  • Corn ethanol is moderate in land efficiency.

The numbers for the charts shown above are contained in the following table:

  1. Energy In/Out is a ratio of energy for production compared with energy in fuel, with fossil fuel = 1.
  2. Emissions are for production & use.
  3. Retail Price is relevant to the country of production and is for January 2008.
  4. Cellulosic Ethanol is in development & the energy balance In/Out is predicted to lie between 2 & 36.
  5. Energy Equiv. is € per litre for same energy as fossil fuel.

The Jatropha plant is grown in Africa, South America and Asia.  It is a good source of biodiesel and the leaves can be used to grow silk worm.

The photographs aside show the pressing of canola oil (rape seed oil) at two different scales.  The smaller machine is suitable for many ecovillage applications.

 

In the jatropha plant seed are 37% oil

 

Pressing of canola oil