Features Alternative Fuels Energy
New options with Energy Planning with Inside View – June 2015

Juned 2015 – This month we carry on the theme looking at alternative energy options, now considering potential “free” energy opportunities.

Heat, Electricity and CO2 from garbage! VE Clean Energy Inc. is Village Farms International’s recently acquired cogeneration facility that was formerly known as Maxim Power Inc.

The technicalities of taking methane from a landfill site to generate electricity for the grid and heat for a business are not new. What is new is bringing this in-house from a previously separate business.

Also, relatively new is the potential for scrubbing the gasses to provide clean CO2 for the greenhouses. “Clean” meaning both “clean” enough from contaminants so as not to be phytotoxic and being environmentally “clean.” This makes the carbon footprint of a large-scale model greenhouse producer even more attractive.

Wind energy: The success of wind energy depends on site climate conditions, as an average wind speed of about 10 m.p.h. is required for sufficient electricity generation. Coastal or mountainous areas are therefore good candidates for such systems.

Compared to large (often obtrusive, noisy) 30-metre wind turbine towers, smaller (often more efficient) vertical wind turbines suitable for individual greenhouse businesses are now available.

Solar energy: Solar photovoltaic (solar p.v.) panels typically operate at about 20 per cent conversion efficiency at maximum light intensity. Some experimental cells have operated at up to 40 per cent1.

But solar p.v. panels do not transmit light, so installation on a greenhouse is not feasible. Until now. The “revolutionary solar PV greenhouse incorporating Polysolar’s unique transparent photovoltaic glass” provides another option. Although small, (2.4 m x 3.5 m), this domestic greenhouse is generating 600 kWh/year of renewable electricity.”3 Similar commercial applications are being developed.

Solar energy for heating water is already applied in many commercial greenhouses, particularly where long, sunny days are guaranteed.

Free light energy? Diffuse glass has been around for a few years. While more expensive than conventional glass, diffuse glass distributes sunlight evenly through the greenhouse space (meaning no shadow!). Hence, more light to leaves that are usually in shade increases the conversion of sunlight to biomass.

Better solution – scrounge! “Ambient energy scavenging, (energy- or power-harvesting), is the process of obtaining usable energy from natural and human-made sources that surround us in the everyday environment.”4

One example is piezoelectric (PE) generators, created with crystals that give off a charge under pressure, being tested under roadways … “to obtain usable energy from traffic and activity above them.” An Israeli company estimates that such devices under a half-mile of a busy highway could generate enough electricity to power 250 homes.4

Other energy scavenging options include: ambient-radiation sources, thermo-electrics, magnetic induction and even blood sugar, tree-based sources and atmospheric pressure changes. Human power sources might include biomechanical and perhaps pedal power.5

The best solution – use less energy: The most sustainable long-term solution is to use less – in other words, the concept of “zero energy.”

“Dutch horticulture consumes, produces and stores energy. This means the sector is of great importance for the future of (horticultural) energy supply,” so says André Faaij, professor of energy at the University of Wageningen.”6

Greenhouse clustering, “energy scavenging” and “zero-energy” are perhaps topics worthy of future research and development.

1. Both and Manning, (2008) Rutgers University.
2. http://www.houwelings.com/files-2/sustainability.php.
3. http://www.solarpvgreenhouse.com/.
4. http://whatis.techtarget.com/definition/ambient-energy-scavenging.
5. Wikipedia.com
6. HortiDaily.com April 21, 2015.

Gary Jones is co-chair of Horticulture at Kwantlen Polytechnic University, Langley, B.C. He serves on several industry committees and welcomes comments at Gary.Jones@kpu.ca.