LED Lights – Status, Cost/Benefit and Pro’s and Cons

I have been receiving several inquiries recently on supplemental lighting for greenhouse production. The most common question is “Should I install LED lights to support growing?”
I have found one report to be the most complete and current on this topic and wanted to share it here.

Economic Analysis of Greenhouse Lighting: Light Emitting Diodes vs. High Intensity Discharge Fixtures by Jacob A. Nelson and Bruce Bugbee. Published: June 6, 2014. DOI: 10.1371/journal.pone.0099010. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099010. Erik Runkle at Michigan State University also summarizes some of this work in Greenhouse Product News here.

There are some industry responses to this including this one from Inda-Grow. And a recent USDA report is somewhat contradictory in its findings here.

There is a also a nice summary by Robert Morrow in Hort Science (HortScience December 2008 vol. 43 no. 7 1947-1950) available here.

Nelson and Bugbee conclude;

The most efficient HPS and LED fixtures have equal efficiencies, but the initial capital cost per photon delivered from LED fixtures is five to ten times higher than HPS fixtures. The high capital cost means that the five-year cost of LED fixtures is more than double that of HPS fixtures. If widely spaced benches are a necessary part of a production system, LED fixtures can provide precision delivery of photons and our data indicate that they can be a more cost effective option for supplemental greenhouse lighting.

Manufacturers are working to improve all types of lighting technologies and the cost per photon will likely continue to decrease as new technologies, reduced prices, and improved reliability become available.

My take-away from all of this; LED’s have a higher initial cost, can have lower recurring costs, can be more effective for specific physiological benefit, and can support certain production layouts.  But the cost/benefit does not seem to pencil out quite yet.

Oilseed Economics Update 2014

Yesterday we held our annual Oilseed Producer’s Meeting.  At this meeting, I presented an economic overview of oilseeds in Vermont.  Ina nutshell, Vermont has an installed on-farm biodiesel capacity of 600,000 gal/yr (5 sites) with a normalized initial cost of $1/gal of capacity (better than national average). Fuel can be produced for an average cost of $2.13/gal, and meal can be produced at an average cost of $340/ton.  The greenhouse gas emissions associated with this model are 60-100% better than US avg oilseed production (net sink) while the average energy return on energy invested (EROEI) is 4 to 1 (i.e. 4 gallons produced for every gallon used in production.  The model is on-farm production for on-farm use; i.e. cost avoidance.

This study made use of the Vermont Oilseed Cost and Profit Calculator, a tool we have developed over the years to collect all the enterprise costs associated with an on-farm oilseed operation that may turn the crop into meal, oil, and/or biodiesel.  It helps growers and others interested in the topic arrive at specific product costs and compare those costs to market prices.  We also have summarized three different likely oilseed enterprise scenarios in e report titled Vermont On-Farm Oilseed Enterprises: Production Capacity and Breakeven Economics. This work has had strong support from the Vermont Bioenergy Initiative of the Vermont Sustainable Jobs Fund and has been accomplished in close cooperation with the UVM Extension Northwest Crops and Soils Program.

Energy and Waste in the Food System

Although estimates vary, we invest about 14 calories of fossil fuel-based energy and 15-20 calories of energy in general into every 1 calorie of food produced.  And (here’s the kicker) 30-50% of the food produced never makes it to a digestive track.  So those energy input numbers are actually low by any true measure of efficiency and productivity.

Calorie for Calorie

A recent report from the USDA ERS sums it up this way, “use of energy along the food chain for food purchases by or for U.S. households increased between 1997 and 2002 at more than six times the rate of increase in total domestic energy use. … The use of more energy-intensive technologies throughout the U.S. food system accounted for half of this increase, with the remainder attributed to population growth and higher real (inflation-adjusted) per capita food expenditures.”

Here is a similar idea, displayed in a slightly different way by the University of Michigan Center for Sustainable Systems (this uses units of millions of pounds, not energy).

US Food System - flows in million pounds

And it isn’t all about energy efficiency and renewable energy and boring engineering BTU, calorie and bean counting (although I do like counting beans).  The food wasted post-harvest is a real loss that we can do something about. (NOTE: The report linked above where I take the 30-50% waste figure from was done by a UK engineering trade organization, IMECHE).

Some of the loss occurs in storage, and I think we all can agree that we can do better with our storage practices. Regardless of whether you are root cellaring, using a CoolBot(TM) or a commercial walk-in cooler, the principles remain the same. Some loss occurs in transport and distribution which speaks to the benefit of the broader food system considerations espoused by UVM’s Food Systems Spire and the Vermont Farm to Plate Initiative. Some, of course, occurs in the kitchen or in consumer storage and suggests we have some work to do with consumers as well.

As one grower recently said to me, “By the time we put food in our farm cooler, 99% of our cost is sunk into that product. We gotta pay attention to what goes on in there and make sure we get paid for it.