Climate change issues related to cogeneration are examined, with a focus on carbon dioxide emissions and how to address them. The allocation of carbon dioxide emissions for cogeneration is highly contentious, in part because of the importance of mitigating them to address and also because proposed methods are often viewed as unsound and inconsistent, difficult of use because of their complexity, and lacking in widespread acceptability. After detailing carbon dioxide emissions from cogeneration, allocation methods for these emissions are described. This includes descriptions of selected methods for allocating carbon dioxide emissions for cogeneration, basic considerations in allocating such emissions, and a comparison of exergy and energy-based methods for allocating such emissions. The authors contend that exergy methods provide the underpinnings of logical and practical allocation methods for carbon dioxide emissions, unlike other such allocation methods. A comprehensive case study is presented that compares carbon dioxide emissions allocations for cogeneration and independent plants and explains how to use this information for determining and trading carbon dioxide emissions credits. The latter includes discussions of carbon dioxide emissions credits for trading purposes from switching to cogeneration from equivalent independent plants, carbon dioxide emissions credits when an electricity user switches to cogeneration, carbon dioxide emissions credits when a heat user switches to cogeneration, and carbon dioxide emissions credits for other cases. The importance of the material in this chapter is noteworthy because it can permit the environmental benefits of cogeneration to be better understood and exploited - by allocating carbon dioxide emissions more appropriately among the electrical and thermal products of cogeneration. These benefits can improve cogeneration design and utilization, and enhance related decision-making by companies and policy-making by governments. In addition, exergy-based carbon dioxide emissions allocations provide a sensible, meaningful fair way to establish schemes for emissions trading.

Chapter Contents:

• Overview
• 10.1 Introduction
• 10.2 Carbon dioxide emissions from cogeneration
• 10.3 Allocation methods for carbon dioxide emissions from cogeneration
• 10.3.1 Simplified selected methods for allocating carbon dioxide emissions for cogeneration
• 10.3.2 Basic considerations in allocating carbon dioxide emissions for cogeneration
• 10.3.3 Exergy vs. energy in allocating cogeneration CO2 emissions
• 10.4 Case study: comparing CO2 emissions allocations for cogeneration and independent plants and use for determining and trading CO2 emissions credits
• 10.4.1 Recap of case study 3 of section 9.6: comparison of waste allocations for a cogeneration system and equivalent independent plants
• 10.4.2 Carbon dioxide allocation results
• 10.4.3 CO2 emissions credits for trading purposes from switching to cogeneration from equivalent independent plants
• 10.4.3.1 CO2 emissions credits when an electricity user switches to cogeneration
• 10.4.3.2 CO2 emissions credits when a heat user switches to cogeneration
• 10.4.3.3 CO2 emissions credits for other cases
• 10.5 Closure

Inspec keywords: exergy; environmental economics; cogeneration; climate mitigation

Other keywords: thermal product; exergy-based carbon dioxide emission allocation; carbon dioxide emissions credit trading; emission allocation method; cogeneration design; policy-making; climate change; decision-making enhancement

Subjects: Pollution detection and control; Thermal power stations and plants