Energy use efficiency

Energy is one of the fastest growing costs for cotton growers, with electricity and diesel accounting for a significant proportion of total farm input costs.

Growers have already experienced significant price rises in electricity costs - with costs, adjusted for annual use, increasing by approximately 350 percent since the year 2000 (while cumulative inflation has only been in the order of 45 to 50 percent over that period).

Energy use efficiency:

Energy use efficiency describes the total amount of energy used on farm (in the form of electricity, diesel, or other sources) compared to the amount of production. If energy consumed can be reduced, while production is maintained or increased, energy use efficiency is improved. This may be one of the fastest and easiest ways to improve profitability and will also reduce greenhouse gas (GHG) emissions. 

Water use efficiency for water required in-crop is the key driver of energy use efficiency because it reduces the total amount of water that is required to be pumped. 

Pump efficiency and engine efficiency are the next most important factors in total farm energy use efficiency. 

Energy consumption:

Irrigation pumping is the major energy consumer in cotton production. Irrigation typically accounts for 45 percent of all energy that is directly used on farm for river irrigation, and up to 75 percent for bore irrigation, with diesel use in tractors and machinery the next largest consumers of energy on farm. 

Greenhouse gas emissions:

As well as being a major cost, diesel and electricity are also significant contributors to GHG emissions. So maximising energy efficiency can not only help your bottom line, but also help support the industry's push for sustainability. 

Other sources of GHG emissions in cotton production are from biologically generated soil emissions and from indirect energy use, related to the energy consumed by production processes used to create farm inputs such as fertiliser (particularly nitrogen) and chemicals. 

Energy saving practices: 

• Significant efficiency gains can be made by optimising pump performance to reduce diesel consumption. Improved pump efficiency can also lead to increased water flow rates. More timely irrigation and improved crop yield can result from assessment of in-field irrigation performances completed as part of this process.
• Moving from conventional tillage to minimum tillage can create savings of around 10 percent of fuel use on farm.
• Ensuring equipment is well maintained and operating efficiently is particularly important for high energy use operations such as picking.

Alternative energy sources:

• LPG Gas: injected into diesel engines improves diesel combustion and creates a slightly cheaper energy source than pure diesel. There are many suppliers with ‘off the shelf’ injection systems that will suit most motors. Importantly, this is only the case for electronically injected diesel engines. LPG injection increases costs for mechanically injected engines. LPG electronic injection systems release lower emissions than diesel. 
• Electricity: has the highest emissions of any energy source and is similar in cost to diesel.
• Biodiesel: invoiced as either B5 or B20 receive the Commonwealth Government fuel rebate on the full amount of the fuel. Other blends receive a rebate only on the diesel portion of the mix.
• Biofuels: made from waste energy sources such as tallow (animal fat), and are economically viable as they are cheaper to produce than diesel (and commercially available from suppliers in Brisbane). Biofuels have a slightly lower combustion efficiency than diesel due to differences in calorific value and viscosity, therefore these fuels need to be around 2 percent cheaper than diesel to reach real price parity. The cotton industry has the capacity to be self-sufficient in energy supplied through cotton seed oil.  Unfortunately at $300 per tonne of seed, cotton seed biodiesel is priced at around $2.50 per litre, which is cost prohibitive. 
• Coal Seam Gas (CSG): technically an alternative energy option, however a survey of growers found high levels of resistance to CSG due to environmental concerns. It was rated as ‘not an option’ by 61 percent of those surveyed.
• Solar PV: an option to offset workshop and domestic electricity demand, but is a less feasible energy source for pumping large volumes of water, with the exception of irrigation bores with access to earthen storages. 
• Wind Power: considered unviable in cotton growing areas due to the low reliability of wind and high generation costs.
• Hydro power: Like wind power, the reliability of water is too low in cotton growing regions to make effective use of the high capital investment required for hydro power.

• Perform a pump test to identify how efficiently your pumps are operating and determine the correct duty point (Installing an hour metre on a pump is a low cost strategy that can provide valuable information on how to prioritise pump improvements).
• Record farm energy usage by application/enterprise.
• Explore ways to reduce energy use by focusing on high energy input areas. Investigate opportunities to reduce energy inputs by changing practices or doing the same operation more efficiently
• Maintain machinery and equipment and ensure modifications do not affect their efficiency.
• Consider the impact on energy use efficiency when making changes to farm management or investing in new equipment or infrastructure.

For more best practice information on energy use efficiency, visit the myBMP Energy and Input Efficiency module.