Introduction

Biogas systems produce a methane-rich gas (called biogas) by anaerobically digesting manure, food-based materials and other organic by-products. Biogas can be used in the production of renewable energy. In the spring for 2008, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) commissioned a report to investigate the quantity, quality and current uses of various food-based materials that could be used as biogas system inputs. The results are reported in the Final Report for the Study of Food-Based Inputs for Biogas Systems in Ontario – May 9, 2008 (referred to in this document as ‘the study’). Copies of the study are available through the authors of this document.

Did You Know...

The food and beverage processing sector in Ontario is a $32.5 billion industry, providing the link between agricultural commodities and the food consumer. As in any industrial sector, the production of food and beverage products results in a number of residuals, byproducts and wastes. The study summarized in this document shows that using food-based inputs in biogas systems can provide new options for waste management for the food and beverage processing sector, while also contributing to Ontario’s renewable energy generation objectives.

Figure 1. The rate of residual production (such as for off-specification vegetables) is company specific, and may vary from facility to facility.

Summary of Food-Based Inputs Study

1. Food-based inputs for biogas systems include:
   
   
   • food processing byproducts
   • off-specification or out-of-date food products
   • 'plate food waste' (from homes, institutions, restaurants), and
   • other similar materials.
     
     
   Based on a number of methodologies used in the study for assessing availability of food-based inputs, there are between 1.2 and 9.8 million wet tonnes per year of suitable food-based inputs that are produced in Ontario. The study estimates that roughly 50 per cent of this material could be available for use in biogas systems (the remaining 50 per cent might have other suitable end uses, or may not be accessible).
   
   
2. Production and residual rates in the food and beverage processing industry are typically proprietary information and not publicized by individual companies. Therefore, biogas developers will need to develop individual relationships with food and beverage processors to determine the actual opportunities from each facility.
   
   
3. The consistency of the supply of materials, reliability of biogas systems as a destination, cost of transportation of materials, and avoided costs normally associated with materials will be key factors affecting a company's decision-making process about where to send materials.
   
   
   • Wastewater and wet residues may readily find their way into biogas systems, while dry residues may have a number of other competitive end uses.
   • Materials such as fruit and vegetable processing byproducts that are only available during harvest season may not be suitable as the primary or sole input for biogas systems because of the resulting biogas system downtime (when those inputs are not available).
   • Residues and waste are typically managed in a "least-cost" fashion, meaning that if biogas systems represent an economical and low-effort management solution, they can be a desirable destination for these types of materials.
     
     
4. The study shows that the bulk of estimated energy available from food and beverage processing materials is from the meat processing, rendering, and grains and oilseeds sectors. Post-consumer plate food wastes also account for a significant share of the estimate of overall energy potential.

Figure 2. Some materials (such as the vegetable byproducts shown) are only seasonally available. This adds complexity to the operation of the biogas systems as the "recipe" changes.

5. If the estimated 50 per cent of available food-based inputs outlined in the study are used in biogas systems, the study predicts the following energy production potential:
   
   
   • Electrical production in a conventional 30 per cent efficient co-generation unit would produce from 53 to 697 gigawatt-hours/year (GWh/yr) of electrical production. This is equivalent to 6.1 to 80 megawatts (MW) of continuous electrical capacity, or 27 to 350 MW of peak power production.
   • Using the 2008 Renewable Energy Standard Offer Program electricity value of 11¢/kWh, the electrical production could result in between $5.8 million to $77 million in electricity sales per year.
   • If the biogas produced was converted to natural gas, between 0.64 to 8.4 million gigajoules per year (GJ/yr) of energy could be captured. Using a conservative estimate for the value of natural gas ($7/GJ) the total value of natural gas replacement from the biogas is between $4.5 million to $59 million per year.
     
     
6. The study focuses only on by-products from food and beverages. However, other materials may also be used in biogas systems:
   
   
   • Manure: a reasonable estimate developed by OMAFRA predicts that 33,000 tonnes/day of manure could be directed to biogas systems under good circumstances, producing approximately 54 MW of continuous electrical power. Thus, the estimates of total energy from manure and from food-based inputs available in Ontario are of approximately the same magnitude.
   • Energy crops: In Germany, when the economics of using energy crops like corn silage became viable, total biogas production quickly doubled from the baseline biogas production level (which had been based on using manure and food-based inputs alone).
     
     
7. The study indicates that tipping fees for receiving food-based inputs can provide additional revenue for biogas system operators.
   
   
   • Using general approximations, the study estimates that approximately $233 million per year in tipping fees could be collected at biogas systems.
   • Alternatively, if competition for inputs drives down tipping fees, sending materials to biogas systems could represent a savings to the food and beverage processing sector of an equivalent amount (i.e. approximately $233 million).
   • While tipping fees will usually be associated with the materials received at biogas facilities, in some cases, high-quality inputs might be purchased for use as inputs at biogas systems. This already occurs with some high-quality materials in Ontario.
     
     

Figure 3. Receiving food-based materials at the biogas system site requires storage facilities suited to the type of material. These dry inputs are stocked in a roofed and walled area near the digester.

Conclusion