Using Methane Gas to Produce Electricity and Thermal Energy

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Joel Barker
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1 Using Methane Gas to Produce Electricity and Thermal Energy Presented by: Stephen J. Chippas, PE Regional Chief Executive Robert W. Hunt Company American Public Power Association Engineering & Operations Technical Conference 2006 Sacramento, California April 11,

2 1 Why Use Methane Gas to Produce Power? 8 Cost to generate electricity using conventional fuels is increasing Spiraling natural gas costs Rising environmental control costs for coal and fuel oil 8 As cost of electricity rises, the cost of doing business also increases Ability to compete with suppliers in other parts of the country is reduced Lower margins reduce operating profits 8 Costs must eventually be passed on to the customer Higher rents Higher water and sewer fees Energy surcharges - energy fee when staying in hotels 2

3 1 Solutions for Your Customers 8 Ride It Out 8 Reduce power consumption Lower lighting levels Turn thermostat up/down Energy efficient appliances & devices 8 Install Temporary Power Generation Diesel power generation 8 Move 3

4 1 Solutions You Can Use 8 Control Fuel Costs Purchase futures contracts for fuel 8 Encourage Energy Efficiency Incentive programs 8 Find Way to Lower Your Costs Increase operational efficiency Generate energy using lower cost fuels Implement distributed generation technologies to reduce system loads 4

5 2 What Is Distributed Generation? 8 Generation of energy away from a large centralized power station 8 Normally located in close physical proximity to the load being served 8 May or may not be connected to the grid 8 Can utilize traditional or renewable sources of energy 5

6 2 Why Distributed Generation? 8 Decreases or eliminates reliance on the electrical grid 8 Increases reliability and power quality 8 Can result in substantial cost savings 8 Increases the opportunities for cogeneration 8 Lower environmental impact 6

7 2 Distributed Generation Opportunities 8 Generate electricity at a lower cost Free fuel 8 Increase reliability and power quality 8 Reduced emissions compared to a central plant 8 Built-in backup when drawing power from the grid 8 Cogeneration 7

8 2 Sources of Free Fuel 8 Free fuel ability to generate electricity using a zero cost source of fuel 8 Primary source of free fuel will be biogas Municipal Wastewater Treatment Plant Industrial Waste Treatment Facilities Landfills Agricultural Digesters 8 Other free fuels include Solar energy Water 8

9 3 Free Fuel Technologies 8 Technologies include: Microturbines Stirling Engines Internal Combustions Engines Combustion Turbines Hydroelectric Geothermal Solar Cells Wind Turbines 9

3 Microturbines 8 Very small combustion turbines sized between 30 kw and 100 kw 8 Can combine with multiple units to create larger generating capacity 8 Operate on a variety of fuels including

10 3 Microturbines 8 Very small combustion turbines sized between 30 kw and 100 kw 8 Can combine with multiple units to create larger generating capacity 8 Operate on a variety of fuels including natural gas, methane, propane and diesel 8 Excellent emissions profile (<9 ppm NOx) 8 Several manufacturers in the United States and overseas Capstone Microturbine Ingersoll-Rand Elliott Bowman Power Turbec 10

11 3 Key Microturbine Considerations 8 Can operate on low BTU fuel typically associated with biogas Range of Btu / scf 8 Very low emissions profile usually does not require extensive permitting 8 Gas pressure at turbine usually must be over 55 psig Normally requires a compressor to boost gas pressure from the digester 11

12 3 Lean Burn Engines 8 Reciprocating engines sized from 100 kw to 6 MW 8 Range of fuels similar to microturbines 8 Emissions profile greatly improved over the traditional diesel generator 8 Many manufacturers Waukesha Wartsila Cummins Caterpillar 12

3 Stirling Engines 8 External Combustion Engine that operates on the Stirling cycle 8 Current versions produce 65 kw each Can be combined to provide a larger generation capacity 8 Can operation on

13 3 Stirling Engines 8 External Combustion Engine that operates on the Stirling cycle 8 Current versions produce 65 kw each Can be combined to provide a larger generation capacity 8 Can operation on very low BTU fuel Range goes as low as 200 Btu / scf May not need a gas conditioning system 8 System only requires gas pressure of 2 psig; can usually be obtained using a small blower 8 Only current manufacturer of commercial sized engines is STM Power 13

14 3 Fuel Cells 8 Outputs of 1W to 3 MW 8 Primary fuel is natural gas 8 Limited use of biogas 8 Generate electricity using a chemical reaction 8 Almost zero emissions 8 High capital cost ($ / kw) 8 Major manufacturers Fuel Cell Energy GE Microgen / Plug Power UTC Fuel Cell 14

15 4 Gas Filtration System 8 Due to the nature of digester or landfill gas it is usually necessary to install a gas filtration and treatment system upstream of the generation equipment Moisture Particulate Hydrogen sulfide Organic compounds Siloxanes 15

16 4 Siloxanes 8 Nearly all digester and landfill gas contains one or more species of siloxanes Chemical used extensively in industrial products such as lubricants and in personal care products like cosmetics, hair spray and deodorants Siloxanes make their way into municipal wastewater and ultimately into the methane liberated in municipal digesters Discarded cosmetics and cosmetic containers introduce siloxanes into the solid refuse that decomposes in landfills, producing methane that is contaminated. 16

4 Siloxanes 8 The combustion of methane containing siloxanes causes damage that can be quite severe in generator engines Deposits of solid silica (silicon dioxide) on the engine internals can

17 4 Siloxanes 8 The combustion of methane containing siloxanes causes damage that can be quite severe in generator engines Deposits of solid silica (silicon dioxide) on the engine internals can increase maintenance requirements by a factor of 5 or 10 times Systems designed to run 20,000 to 40,000 hours between teardowns, some engines are requiring rebuilds in as short as 14,000 hours, and in severe cases, after only 2,000 to 4,000 hours. 17

18 4 Gas Filtration System 8 Gas filtration system will be designed to remove the moisture and contaminants from the gas so that the digester gas is almost the same quality as natural gas Hydrogen sulfide removal system» Iron sponge» Wood chips Moisture removal system» Refrigerated dryer» Coalescing filter Siloxane removal system» Activated carbon system» Applied Filter Technology Blower or Compressor to maintain necessary gas pressure 18

19 5 Combined Heat and Power 8 Uses the excess heat from combustion process 8 Overall thermal efficiencies in the mid-80% range 8 Heat can be used to: Raise temperature of digesters Drive absorption chillers for AC Heat water Drying of products 19

5 Combined Heat and Power 8 Use of excess heat can decrease overall project payback by making more efficient use of the energy 8 Heating digester sludge can increase

20 5 Combined Heat and Power 8 Use of excess heat can decrease overall project payback by making more efficient use of the energy 8 Heating digester sludge can increase temperature of the digester More efficient digestion process More gas 8 Double effect absorption chiller/heater can provide air conditioning Laboratories Administrative offices 20

21 6 Incentives for Distributed Generation 8 Many incentives are available for the installation of distributed generation systems 8 Federal Tax Credits Renewable fuels including biogas Photovoltaic 8 Private / Public partnerships are available which allow public agencies to take advantage of tax credits 21

7 Real Life Applications 8 San Elijo Joint Powers Authority, Cardiff by

water treatment plant digester gas and heat recovery Gas that was being

22 7 Real Life Applications 8 San Elijo Joint Powers Authority, Cardiff by the Sea, California Three (3) Capstone 30 kw units running on waste water treatment plant digester gas and heat recovery Gas that was being flared is now used to generate power as well as heat for the digesters Cost to generate is $0.005/kWh; cost to purchase power from the grid is $0.18/kWh Total project cost of $275,000 with a payback of less than one year 22

Real Life Applications 8 Lopez Canyon in San Fernando Valley World s largest array of biogas microturbines: 50 units 1.5 MW capacity 200 kw consumed onsite Up to 1.

23 Real Life Applications 8 Lopez Canyon in San Fernando Valley World s largest array of biogas microturbines: 50 units 1.5 MW capacity 200 kw consumed onsite Up to 1.3 MW is exported into the LADWP utility grid 8 Running since August A project of Los Angeles Department of Water & Power and the South Coast Air Quality Management District 23

24 8 Distributed Generation Summary 8 Distributed generation can be a source of reduced electricity cost, increased availability and lower emissions 8 There are many technologies available to take advantage of distributed generation opportunities 8 No cookie cutter solutions need to design and engineer the right system 8 Key to success is to match the right technology for your application 24

Microturbine Applications and Issues

Microturbine Applications and Issues Presented to the Mid-Atlantic Distributed Energy Resources Workshop Presented by Kevin Duggan Capstone Turbine Corporation February 21, 2002 Lessons from the field