Carbon dioxide options for commercial greenhouses

Effect on temperatures

Schematic showing the effect on extreme temperatures when (a) the mean temperature increases, (b) the variance increases, and (c) when both the mean and variance increase for a normal distribution of temperature.

Starfish Associate Ian Gesch has been selected as the lead article for the current edition of Practical Hydroponics & Greenhouses.

The changing landscape of fossil fuels presents increasing business risks for Australian domestic industrial and commercial energy consumers. Rising costs and uncertain supply of natural gas and the existing high price of Liquid Petroleum Gas (LPG) represent a significant portion of this risk. Adding complexity to this changing landscape is mounting international pressure on Australian policy makers to replace fossil-fuelled energy with renewable alternatives. Horticulturists use natural gas and LPG for greenhouse environment management and as a result are left exposed to an uncertain future.

The use of protected cropping practices is a form of climate change adaptation. However, these practices need continued modification to prepare for a changing climate, particularly in response to rising temperatures and increasing fuel costs. Modification of protected cropping practices to accommodate climate change has the potential to create opportunities for strengthening the business viability of horticulture and augmenting food security for domestic consumption and export.

Horticulturists have options for reducing reliance on fossil fuels and adapting to climate change. Most of these options, however, have low or no appeal due to relative cost (such as heat pumps and wind power), complexity (generating syngas from industrial or agricultural processes) or physical footprint (such as solar energy collection). Industrial symbioses (using waste CO2 from industrial processes) also have low applicability due to the continued placement of greenhouses in regional areas as opposed to locating them adjacent to sources of waste heat and carbon dioxide.

Those remaining options for adapting further to climate change require an innovative approach to testing and integration and include:

  • Using the combustion of natural gas and LPG not only as a source of CO2 but to also power absorption refrigeration plant. This would not only provide continued supply of CO2 for enrichment but allow longer exposure times without the need for venting greenhouses.
  • Cleaning the CO2 emitted from the flue of existing coal and biomass furnaces and using this for enrichment. This solution has the potential to make the combustion of expensive natural gas and LPG a secondary source of CO2 for enrichment.
  • Locate new greenhouses adjacent to sources of waste heat and CO2.
  • Perform an assessment of the total volume of CO2 consumed by commercial greenhouses (existing and potential) in Australia in order to inform climate change policy development and recognise horticulture as a legitimate consumer of CO2.
  • Develop tools and methods that simplify the calculation of the true cost of CO2 enrichment so that the efficiency of this practice can be improved.

Climate change will require a response from all commerce and industry. Horticulturists have the choice to either wait for the risks or prepare for the opportunities.

Read the full article ~ Sustainable energy: Carbon dioxide options for commercial greenhouses | Practical Hydroponics & Greenhouses

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