Biogas powerplant

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Environmental science
Environmental technology

Energy conservation
Renewable energy
Remediation
Solid waste treatment
Waste water treatment
Water purification
Waste management

Environmental science
Environmental technology
Energy conservation Renewable energy Remediation Solid waste treatment Waste water treatment Water purification Waste management

A biogas power plant is a system where biogas is used to generate electricity. The gas which is produced via anaerobic digestion is used to drive an electricity generator. By-products of this process are steam and hot water. The hot water can be recycled in a combined heat and power cycle to increase the temperature of the digesters to optimal conditions.

Contents

1 Overview
2 Principle procedure

2.1 Plant engines
2.2 Plant types
2.3 Plant sizes

3 See also
4 External links
5 Education

Overview

Biogas power plants are a combination of anaerobic digestion systems with associated electricity generators such as gas turbines or gas engines. The electricity they produce is classified as renewable or green energy and if sold into the national grid may attract subsidies (such as renewable obligation certificates in the UK).

Feedstock into the biogas power plants must be biodegradable in order to produce methane. Suitable feedstocks include (but are not limited to):

Sewage
Slaughterhouse waste
Food wastes
Farm wastes
Organic component of mixed municipal waste (in mechanical biological treatment)

There are three stages of anaerobic digestion: hydrolysis, acidogenesis, and methanogenesis. These stages can occur in the same digestion tank or can be controlled independently and optimised according to the requirements of the different bacterial processes.

The more complex and efficient a biogas plant the more expensive it will be for the locality. Biogas plants can be simplified to produce gas for villages in countries where organic wastes are available and funds are limited. Alternatively, in more developed countries pressure in the form of legislation and high energy costs is increasing the amount of projects generating renewable energy from waste.

Biogas plants can be found in countries such as India, China, Philippines, Germany, and Turkey.

Advanced processing systems can recover the organic fraction mixed waste streams. These systems are a subgroup of Mechanical Biological Treatment plants. They sort the recyclable elements of the waste and process the organic fraction into a high surface area low solids soup which are then passed into a biogas power plant (anaerobic digester). Advanced systems like this can be found in Israel ([ArrowBio]) and Australia and are being widely considered in Europe to meet the EU Landfill Directive.

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Principle procedure

Biogas production

1 Preparing the biomass
2 Mixing
3 Digester/fermenter (Heating 40-90 °C)

Gas input

4 Raw biogas input 40 °C
5 Liquid gas Separator → condensates
6 Gas dryer (refridge) 4 °C → condensates
7 Gas compressor about 400kPa
8 Gas filter (cleaning of dust particles, less then 5 parts per billion by mass of siloxanes)
9 Gas heating (minimum about 10 °C)

Gas combustion → thermal energy

10 Gas turbine exhaust output 300 to 400 °C
11 Generator → electric energy

Exhaust output → heat exchange

12 HRSG heat recovery steam generation
13 Heat exchanger for hot water

Siloxane might be present in the biogas and must be removed prior to input in the gas engines as it erodes moving parts. Hydrogen sulphide may also be produced in the process if there are high levels of sulphur in the biogas. The exhaust gas must be cleaned up as sulphur dioxide is toxic.

Plant engines

Gas motor engines
Micro–gas turbines
Fuel cells
Boiler

Plant types

Plant type depends on the type of biogas and usage of energy.

CHP combined heat & power or HRSG
CCHP combined cooling heat & power

Plant sizes

Size Power Plant Size
Small 500 W to 5 kW 10 m²
Medium 5 kW to 75 kW 15 to 100 m²
Large 75 kW to 4 MW 1000 m²

The plant can also be segmented, including gas motor, gas turbines.

Education

Sustainability and energy development [Edit]
Energy production	Active solar \| Anaerobic digestion \| Biomass \| Blue energy \| Deep lake water cooling \| Distributed generation \| Electricity generation \| Energy tower \| Fuel cell \| Fusion power \| Geothermal power \| Hydroelectricity \| Mechanical biological treatment \| Ocean thermal energy conversion \| Passive solar \| Seasonal thermal store \| Solar cell \| Solar panel \| Solar pond \| Solar power \| Solar power tower \| Solar thermal energy \| Solar tracker \| Solar updraft tower \| Tidal power \| Trombe wall \| Water turbine \| Wave power \| Wind farm \| Wind power \| Wind turbine
Energy development and use	Energy development > Environmental concerns with electricity generation \| Future energy development \| Inertial fusion power plant \| Hydrogen economy \| Hubbert peak \| Renewable energy \| Hypermodernity \| Technological singularity
Energy and sustainability status	Ecosystem services > Kardashev scale \| TPE \| UN Human Development Index \| Value of Earth \| Appropriate technology \| Infrastructural capital
Sustainability	Autonomous building > Ecoforestry \| Ecological economics \| Earth sheltering \| Development economics \| Environmental design \| Exploitation of natural resources \| Green building \| Green chemistry \| Green gross domestic product \| Natural building \| Permaculture \| Self-sufficiency \| Straw-bale construction \| Sustainability \| Sustainable agriculture \| Sustainable design \| Sustainable development \| Sustainable industries \| Sustainable living \| The Natural Step \| Windcatcher
Sustainability management	Commission on Sustainable Development > Human development theory \| Maldevelopment \| Rio Declaration on Environment and Development \| Rocky Mountain Institute \| Sim Van der Ryn \| Underdevelopment \| World Business Council for Sustainable Development \| World Summit on Sustainable Development \| Precautionary principle \| Intermediate Technology Development Group
Energy and conservation	Energy conservation > Energy-efficient landscaping \| Passive house \| Superinsulation \| Voluntary simplicity \| Ecological footprint \| Ecovillage \| Waste \| Zero energy building
Transportation	Battery electric vehicle > Electric vehicle \| Hydrogen car \| Trolleybus
Communication	Wireless Mesh

Topics related to waste	[http://encycl.opentopia.com/ edit]
Anaerobic digestion \| Compost \| Dustbins \| E-waste \| Waste collection vehicle \| Incineration \| Landfill \| Mechanical biological treatment \| Radioactive waste \| Recycling \| Reuse \| Sewage \| Scrap \| Sewage treatment \| Waste \| Toxic waste \| Waste management \| Waste management topics \| Waste minimisation

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