In a country like Australia, you would think solar greenhouses would be a way forward to reduce energy costs and minimise the grower’s carbon footprint, but despite the merits of the technology, there is little interest among commercial growers for large-scale photovoltaic systems. Holding back its uptake is the high cost of solar panels, even though there would be lower running costs over time, and risks of hail and wind turbulence damage. Notwithstanding, many growers incorporate a degree of solar technology to run growing and monitoring systems.
Pioneering solar greenhouses in Australia, is Sundrop Farms (www.sundropfarms.com/), located outside Port Augusta, South Australia. The facility uses a stretch of 70 solar panels to harness the sun’s energy to desalinate seawater for irrigation, and to produce electricity to power the greenhouse and provide energy for heating and cooling. The experimental greenhouse has been in operation since 2010, but few other technical details are known. Using proprietary technology, the operators plan to expand the current operation by 20ha, which they say will be completed in 2014.
Further afield, Dutch installation builder, Van der Hoeven, has commenced the construction of the world’s largest solar greenhouse. Spanning 27 hectares and spread over 12 locations in the South of France, the project is innovative in that integrated into the roofs of the greenhouses will be 80,000 solar panels, which have a capacity to generate 18 MW of electrical power. However, like the Australian project, technical details about the project are sketchy and little is known about the client or investor, who is said to be a leader in the field of solar technology. In this issue, we talk to the greenhouse builder, who gives a broad outline of this project.
There is much about solar greenhouse developments that is surrounded by ‘commercial in confidence’ and licence agreements, reminiscent of the early days of hydroponics development, which was enveloped in secrecy. However, at the end of the day, solar technology to power greenhouses and irrigation systems, and to run cooling and heating systems, is not rocket science. The mechanics of passive and active solar greenhouses are described in Greener Greenhouses by the late Dr Keith Garzoli (available from Casper Publications), the result of years of research and experience by the author in the field of greenhouse construction, design and technology. New developments in solar greenhouses include optical lenses rather than mechanical means of solar tracking, said to generate 15% more electricity over a standard photovoltaic system. As these projects progress, I look forward to new technological developments to reduce grower dependence on fossil fuels, at an affordable price.
In this issue, we again focus on potato tuber production in hydroponics culture. Although potato production is not economically viable as a commercial greenhouse or hydroponic crop, its importance as a food crop should not be underestimated. Next to wheat, rice and maize, it is the most important food crop in the world, the fifth largest produced agricultural crop and the largest produced tuber and root crop. The fact that high yields of tubers can be produced hydroponically, is significant for future food production.
PH&G August 2013 – Issue 134