Grass To Gas Anaerobic Digestion Q&A

This page lists questions and answers from the C-Change GrassToGas project’s PA Extension newsletter.  To be added to the newsletter mailing list, contact GrassToGas@psu.edu.

1. Question: Is switchgrass a good feedstock for biogas digesters?

Answer: Not usually. Anaerobic digestion involves microscopic organisms that eat energy-rich components such as sugars. Lignocellulosic biomass, such as switchgrass, contains sugars, but is structured in a way that specifically prevents easy access to its energy-rich components. Because of the limited accessibility to the energy-rich …

Anaerobic Digestion and Biogas

 

Farm Energy IQ logo

This Biogas module provides reasonable expectations for investing in on-farm bio-digesters to convert animal waste to process heat and/or electricity. Learn how to calculate the number of animals needed to build a cost effective system.

Link to all of the Northeast Farm Energy IQ Curriculum, developed by Extension specialists from Penn State, Rutgers and University of Vermont.

This is part of the On Farm Energy Production Curriculum Series: 

Bioenergy Feedstock Production | Biodiesel and SVO | Biogas | Wood

Farm Energy Anaerobic Digestion and Biogas


Contents:barn

Articles and Fact Sheets


Processing Biomass Into Biogas


Tables Of Contents

Anaerobic Digestion of Animal Manures: Understanding the Basic Processes

Anaerobic Digesters and Biogas Safety

When manure is anaerobically digested, the biogas produced is primarily composed of methane and carbon dioxide, with lesser amounts of hydrogen sulfide, ammonia, and other gases. Each of these gases has safety issues. Overall, biogas risks include explosion, asphyxiation, disease, and hydrogen sulfide poisoning.

Image: US Municipal Supply Company.

Extreme caution is necessary when working with biogas. Adequate ventilation, appropriate precautions, good work practices, engineering controls, and adequate personal protective equipment will minimize the dangers associated with biogas. Wherever possible, …

Biogas Utilization and Cleanup

Introduction

Biogas generated from anaerobic digestion processes is a clean and environmentally friendly renewable fuel. But it is important to clean, or upgrade, biogas before using it to increase its heating value and to make it useable in some gas appliances such as engines and boilers.

Biogas Utilization

While most large farms use their biogas for heat and power, it is worthwhile to consider all the options before deciding which path to take, including direct sale of biogas to an …

Environmental Benefits of Anaerobic Digestion

The manure handling system of any farm is made up of many different components, each with a different function and purpose. An anaerobic digester, although only one component of the system, can greatly improve the environmental performance and efficiency of the overall system. The main effect of anaerobic digestion is conversion of organic matter to biogas. This conversion has many potentially beneficial environmental and management side effects.

Odor reduction

By removing organic matter, the digester reduces the organic matter-loading and …

Types of Anaerobic Digesters


Table Of Contents
Passive Systems
Low Rate Systems
High Rate Systems
Contributors To This Article

All anaerobic digesters perform the same basic function. They hold manure in the absence of oxygen and maintain the proper conditions for methane forming microorganisms to grow. There is a wide variety of anaerobic digesters, each performing this basic function in a subtly different way. Seven of the most common digesters are described in this article. Construction and material handling techniques can vary greatly within …

Feedstocks for Biogas

  Find videos on feedstocks at the Farm Energy Media archive.

  Find images of feedstocks at the Farm Energy Media archive.

Anaerobic digestion of manure and other feedstocks produces biogas which can be burner to make energy on farms. Learn how to evaluate a feedstock and which ones to exclude for biogas production.

Anaerobic Digester in Charlotte, VT.  Photo: Caragh Fitzgerald, University of Maine.

Contents

Introduction to Biogas and Anaerobic Digestion

Harnessing energy from livestock waste.

Intro | Feedstocks | Processing | Utilization

On-farm biogas production has long been a topic of interest for farmers, with historical records of biogas production going back several hundreds of years. In modern livestock production systems, for example, the benefits of producing biogas are significant and include:

  • provision of supplemental renewable energy
  • odor reduction
  • reduction of emissions of greenhouse gases
  • pathogen control
  • waste biostabilization
  • nutrients are preserved and transformed into plant-available forms

The economics of …