Putting Eggs in More than One Basket

By Maurice Carter, Sustainable Newton President

When we think about climate change, fossil fuels, and carbon footprints, the first culprits most of us think about are the vehicles we drive.  And those emissions are a big deal.  That's why you're seeing so much activity around electric cars and trucks.

But globally, according to Project Drawdown, 25% of the world's greenhouse gas emissions come from electricity generation.  So, to achieve zero-emission transportation, we must also transform how we generate power to charge those vehicles, light/heat/cool our homes, and run our factories.  In Georgia, ~66% of our electricity is still generated by plants burning fossil fuels (coal, oil, and natural gas) that create those emissions.  The remainder comes from nuclear (26%) and renewables (9% -- primarily hydro and solar).

Renewable energy -- primarily wind and solar -- gets most of the press.  But there's really more to it.  Cost overruns and schedule delays with the additional reactors at Plant Vogtle reflect how difficult it is to scale quickly with nuclear.  But, until battery storage can be deployed at massive scale, the intermittent generation characteristics of wind and solar mean we need other options.   In fact, Project Drawdown has identified, analyzed, and quantified 32 different climate solutions in the Electricity Sector as part of our overall carbon reduction plan.  Understanding them all can get pretty mind-boggling!

University researchers and public policy experts in our state have banded together though Drawdown Georgia to narrow our climate focus to just 20 solutions with the greatest practical impact in Georgia over the coming decade (by 2030).  And five of those are in the Electricity Sector.  The sun shines brightly most days in Georgia, which is why both Rooftop Solar and Large-Scale (Utility) Solar are among the list of five.  On the other hand, our hilly terrain makes on-shore wind farms non-viable here.

The other three Electricity Sector solutions prioritized by Drawdown Georgia are less familiar to most of us:

• Cogeneration is an industrial solution where plants that use heat in their production processes capture it to create steam and generate electricity.
• Demand Response includes an array of methods to encourage or force the shift of electricity consumption to off-peak hours, which reduces the amount of electricity that has to be generated at peak times.
• Landfill Methane involves installing equipment to capture methane emitted by decomposing material in landfills and burning it to generate electricity.

From a carbon reduction perspective, solar and wind are easy to understand -- since the electricity they generate is 100% emissions-free.  With Cogeneration and Landfill Methane (and sometimes Demand Response), critics note carbon-based fuels are still being burned, and greenhouse gases are emitted.  But, in each case, emissions are already occurring due to existing processes (ie, manufacturing or solid waste decomposition), so using those processes to also generate electricity avoids the emissions that would have been generated elsewhere to satisfy electricity demand.  And the new processes are generally substantially more efficient.  So the net effect is less total emissions.

I recently spent time learning about Cogeneration through conversations with a local industry interested in using Combined Heat and Power (CHP -- a form of Cogeneration) to reduce greenhouse gas emissions from their manufacturing process.  Those conversations included a meeting with a leading CHP expert, Marilyn Brown, at Georgia Tech’s School of Public Policy, who recently published extensive research on the current state and future potential for CHP in Georgia.  Dr. Brown is also a member of the core research team for Drawdown Georgia.

When I first heard about the project being considered locally and learned it would use natural gas, I was skeptical about the carbon reduction benefits.  But, since Cogeneration/CHP is a priority solution in the Drawdown Georgia framework, I was also open-minded and curious.

Both the US Department of Energy (DOE) and the US Environmental Protection Agency (EPA) promote CHP as an energy efficiency measure and a way to lower greenhouse gas emissions/reduce environmental impacts.  On its website, the EPA provides an easy to follow explanation of the benefits from CHP, and the DOE offers technical assistance for installations through its Better Buildings program. 

In the future, CHP can potentially be fueled by an emissions-free energy source like hydrogen.  But today most systems burn either natural gas or bio-mass left over from the industrial process.  Still, even with a fossil fuel energy source, the graphic below from the EPA shows how a CHP system results in lower carbon emissions than a traditional scenario where natural gas is burned separately to power both steam boilers and electricity generation at a power plant somewhere else.

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Reduced emissions are achieved through several factors:

• Accomplishing multiple tasks (industrial heating and electricity generation) with the same process.
• Using high-efficiency boilers in that process.
• Avoiding the roughly 4.5% of electricity lost during transmission and distribution from the central power plant to the facility where it is used.

In her paper, Georgia Tech's Dr. Brown writes "There is an enormous opportunity for CHP to save industries money and make them more competitive, while at the same time reducing air pollution, creating jobs and enhancing public health."

Also from her team's research:

If Georgia added CHP systems to the 9,374 sites that are suitable for cogeneration, it could reduce carbon emissions in Georgia by 13%. Bringing CHP to just 34 of Georgia’s industrial plants, each with 25 megawatts of electricity capacity, could reduce greenhouse gas emissions by 2%. The study authors, using modeling tools they developed, note that this “achievable” level of CHP adoption could add 2,000 jobs to the state; full deployment could support 13,000 new jobs. 

So, while solar has a sunny future in Georgia, less familiar solutions like Cogeneration, Landfill Methane, and Demand Response are an equally important part of the climate solution mix.  We know from science how crucial it is to reach net-zero emissions by 2050.  We have a lot of eggs to carry and will need every basket we can find.