Integrating Waste Management Systems to Provide Renewable Household Heating by Means of Biomass Digestion
From Drexel Smart House
Contents |
Project Information
ENGR 103, Freshman Design Project
Dr Adam Fontecchio, Section 035, Team 7
Team Members
- Evan Richter Undeclared Engineering ejr42@drexel.edu
- Amey Khanolkar Mechanical Engineering ark69@drexel.edu
- Deepesh Rana Electrical Engineering dr425@drexel.edu
- Kevin McHugh Architectural Engineering ktm36@drexel.edu
- Jonathan Davis Business & Engineering jad329@drexel.edu
Abstract
The concept of biogas production from the digestion of biomass has traditionally been used in agricultural farmlands. Large quantities of agricultural wastes such as crop residue, livestock and poultry excreta, sewage etc. are fermented by anaerobic bacteria to evolve biogas, which in turn is used as a fuel. This project aims to introduce the concept of biogas digestion to the household-setting and thus meet domestic-heating demands. With the estimated 200 million tons of municipal organic-waste being produced in the USA per year [1] for which efficient disposal is a problem, anaerobic digestion is a highly promising technology for converting biomass waste into large quantities of methane, which maybe directly used as a fuel. This project also aims to develop a highly cost-effective and renewable solution to household-heating systems.
The generation and disposal of organic waste without adequate treatment result in significant environmental pollution. Besides health concerns for the people in the vicinity of disposal sites, degradation of waste leads to uncontrolled release of greenhouse gases (GHGs) into the atmosphere. Conventional means, like aeration, is energy intensive, expensive and also generates a significant quantity of biological sludge. In this context, anaerobic digestion offers potential energy savings and is a more stable process for medium and high strength organic effluents. Waste-to-Energy (WTE) plants, based on anaerobic digestion of biomass, are highly efficient in harnessing the untapped renewable energy potential of organic waste by converting the biodegradable fraction of the waste into high calorific gases.
Problem Statement
Conventionally, homes are heated by fossil fuels supplied by an energy company, which can be both costly and contribute to net greenhouse gas emissions. Obtaining energy that can be used as heat from biomass at home has the potential to reduce energy bills and net greenhouse gas emissions, which may meet the environmental and economical demand of the Drexel Smart House.
Introduction
The human race has made tremendous advancements in science and technology in the past few decades and as a result, our lives have been made more simplistic in every sphere. However, today, we are faced with a grave new problem, the energy crisis, which if unresolved will certainly have dire consequences for civilization in the not too distant future.
By the year 2000, the U.S. gross energy consumption alone is projected to be 163.4 quadrillion (1015) Btu, more than a two-fold increase as compared to the 1974 U.S. consumption [2].At present, 94% of our total energy consumption is based upon conventional fossil fuels, i.e., coal, petroleum, and natural gas. [3]. The supplies of natural gas and petroleum are rapidly approaching depletion, and many of our coal deposits, although abundant, are environmentally unacceptable because of the related air pollution problems. Other forms of energy such as nuclear power and solar energy are still being explored and making these sources commercially-viable will take some time to translate. Exotic forms of energy such as wind and geothermal steam are expected to have relatively little impact on our energy needs in the near future [4].
The bio-conversion of municipal and domestic wastes to clean forms of usable fuel is one alternative energy source that is showing great promise in replacing or at least in part replacing diminishing conventional fuels. In practical terms, biomass is a renewable resource that is capable of supplying non-polluting safe fuels. Traditionally, biomass has been used to satisfy energy demands. For many years the Europeans, for example, have practiced one form of bio-conversion by the generation of steam from waste combustion [3]. In developing agrarian countries like India, organic wastes from farmlands such as crop residue, poultry and livestock excreta have been fed into biomass digesters to obtain bio-gas. In India, cow dung is usually dried into ‘cakes’ and is burned as a cooking fuel. Today, a world-wide effort is being initiated into research and development of processes that can commercially use wastes, agricultural products, and marine life as forms of energy. To be practical, the energy or fuel produced must be storable, or transportable, environmentally acceptable and within certain economic constraints. This project explores the promising prospect of using household organic wastes to satisfy the heating requirements of a house by the installation of a biomass digester to facilitate the process. It primarily focuses on the Drexel Smart House, but model of waste-management to energy integration can be applied to any average household.
Objective
For our freshman engineering design project, we have decided to propose a feasible solution to generate biogas for Drexel’s Smart House, which can be used to heat the home. Biogas generation technology is relatively simple, but it is mostly used in agriculture, rather than residential. We hope to be able to design an anaerobic digester and as a system that could supply the organic waste from the kitchen, as well a system that could supply it with sewage from the house
We would like to design a pipeline that can supply the gas to a natural gas heater in the HVAC room in the basement since natural gas is primarily composed of methane, and would likely to burn in a similar manner. Being able to store the biogas when it’s not being used much during the summer would be desirable, but safety of stored flammable gas is an important concern. The digester will probably be enclosed by a greenhouse, which will keep it warm enough for the bacteria to function at the proper temperature during winter months. Figure 1 is a simple drawing of what we expect the digester to look like.
