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CO2 Emissions from Energy


Political disputes about climate change are keeping many people, politicians and companies distracted from focusing on reducing energy-related CO2 emissions.  But many are not distracted and seek assistance reducing their energy-related CO2.  They are sometimes confronted by misleading information about how best to reduce CO2, especially emissions related to their electricity usage. 

This presentation begins with examination of CO2 emissions trends, including trends in various nations and US states, with particular focus on Midwest US states like Ohio, Kentucky and Indiana.  Then it compares CO2 emissions for various fuels.  Finally, it compares state-by-state averages for CO2 per kWh from utility grid-supplied electricity.  Knowing all this helps when assessing customer energies and related CO2 emissions.

CO2 assessments for customers usually begin with calculations to derive:  

  • CO2 per person (relative to people)
  • CO2 per sf (relative to the floor area of buildings and houses)
  • CO2 per mile (relative to vehicles)

Each of these starts by multiplying volumes of each type of consumed conventional energy times the CO2 per unit index for each energy type.  CO2 indices for fuels like natural gas and petroleum are fairly consistent regardless of location, but CO2 indices for grid-supplied electricity vary wildly.  Most customers’ fuel usage happens onsite, so it can be easily and accurately assessed.  However, emissions associated with conventional electricity generation are usually offsite and happens at such large scale that it is unaffected by an individual customer’s smaller-scale usage reductions.  The problems with varying CO2 per kWh and mismatched scales make calculating CO2 reductions from electricity usage reductions more difficult.  And marketing surrounding net-metering of customers’ onsite renewable energy also presents complications. 

Environmentally conscious car-buyers considering electric vehicles sometimes do so because they believe using electricity to power their vehicles results in lower CO2 emissions than petroleum.  This assumption is usually false when the grid’s electric fuels mix includes substantial amounts of coal-fired generation, as in Ohio, Kentucky and Indiana.  And when there is net-metered renewable electricity generation, users often think their conventional energy usage during non-sunny or non-windy times is offset or cancelled by surpluses they sold to the grid during sunny or windy times.  Similarly, electric car owners with net-metered RE systems who charge at night often mistakenly believe their daytime RE surpluses offset or cancel the conventional electricity their cars actually use.  When doing CO2 accounting, all conventional electricity usage must be assessed as accurately and precisely as possible.



John F. Robbins, CEM, CSDP
Design & Energy Consultant, Continuing Education Instructor
Robbins Alternate Energies

John F Robbins has done residential and small commercial structure & envelope design as well as energy consulting since 1983, mostly in Ohio, Indiana and Kentucky but also in 10 other states.  Most of his projects aim for lower energy usage and environmental impacts.  His specialties include passive solar design and off-grid solar design.  Since 2009 Robbins has also created and presented many energy-related continuing education courses in which energy-related principles, codes and savings opportunities are taught to contractors and engineers who usually are not energy practitioners.

Robbins is a long standing board member of the SW Ohio Chapter of Association of Energy Engineers (AEE).  He holds 2 AEE certifications, CEM and CSDP, and has received 6 awards from AEE since 1990 for energy and environmental achievements, including SW Ohio Energy Engineer of the Year in 1994, SW Ohio Environmental Engineer of the Year in 2004, Energy Professional Development in 2009 and Renewable Energy Innovator of the Year in 2012.  John was also co-recipient of the 1998 Ohio Governor's Award for Excellence in Energy Efficiency in the Education Category.

Robbins sells no products, receives no commissions for referrals and has no commercial affiliation with manufacturers and retailers of products and services he uses, recommends, specifies or mentions in his projects and presentations.