A Hidden Renewable Source

Waste Heat from Industrial Process being Promoted

Bill Opalka | May 19, 2011



A “hidden resource” for clean power generation is being promoted in Congress and throughout the states, one that its supporters point out is being wasted without anyone noticing. The waste heat from industrial processes now has an advocacy group and a fledgling effort to get it recognized where financial players would notice -- in the tax code.

Supporters want equal treatment with other renewable resources and are waiting for the right moment to reintroduce legislation that would grant federal tax incentives to it.

An organization has even sprouted up with the catchy name of Heat is Power to draw attention to the resource.

“There really isn’t a market for waste heat and it’s really a lack of knowledge by policymakers, the public and others interested in clean energy,” said Kelsey Walker, director of government relations for TAS Energy.

The idea is to generate electricity from what is normally considered industrial pollution, heat that used in paper-making, oil and gas refining and other processes, and using that to generate steam and produce power. In short, a smokestack industry uses a waste product that is vented into the atmosphere to create an additional business to become a clean power producer.

The technique is distinguished from combined heat and power, which has been around for decades and uses heat from a municipal or institutional system to create steam and generate electricity.

The group wants to compare itself to the wind farmer catching the breezes and making the electricity with the ability to use what is available on-site.
To catch on, the resource needs some policy help, with either the state renewable portfolio standards crediting it as clean energy or through the tax code.

“The way our rules are written is quite prescriptive,” Walker said. ”If you’re wind you’re renewable. If you’re solar, you’re renewable.”

Now, Heat is Power wants to go to the states to be added to the list. A handful already includes waste heat.

At the federal level, getting the tax code amended would attract investors in much the same way other renewable have used it.

Last year, a U.S. House bill with bipartisan support was introduced to recognize the resources as renewable. The group is seeking a 30 percent investment tax credit and/or a 2.1 cents-per-kilowatt hour production tax credit, just like wind, solar and geothermal power generators receive.

“We’ve been working to get a significant group of Republicans on board before we introduce it again,” Walker said.

 "What we’re saying is that you might have the best renewable energy in the country because it’s base load,” Walker said, pointing out that the areas in the South and Midwest, thought to be renewable resource-poor, might be prime candidates.

The majority of the projects would be 10 megawatts or less.

TAS has developed a technology, its organic rankine cycle process that uses lower temperature resources that is being applied in the geothermal power industry. It can operate at 195 degrees, instead of the 900 degrees that are optimal for traditional steam turbines.

In the meantime, a few projects will be developed as the industry tries to get governments to add the technology to the clean energy list.

Bill Opalka is editor of RenewablesBiz Daily

Related Topics


Conversion of Waste Heat from Vehicles


The use of thermoelectric materials has enormous potential in capturing waste heat from automobiles, trucks and busses and converting it into electricity. For example, there are 137 million passenger vehicles in the United States. That electricity could be used to power vehicle subsystems. Thus, fuel consumption would be reduced. Less fuel usage would lead to lower exhaust emissions and an environmental benefit. Although the U.S. Department of Energy is supporting thermoelectric R&D, what is being done to scale up this technology to accommodate the retrofit of 137 million passenger vehicles, as well as several million new vehicles each year? Please see my blog post for an array of energy issues.

Dr. Jeffrey Everson;  www.jheversonconsulting.com





A Hidden Renewable Resource - Positive Cash Flow


Thanks Bill, for an incisive article, and thanks to “Poor Thermodynamics” for a provocative rebuttal, and thanks to Erik Swenson for a “right-on-the-money” follow-up comment. With folks like you around I can’t understand why these problems are still with us, waiting to be solved!


Here is another comment I would like to make. In all the discussions on recycled energy or waste heat recovery I have rarely seen a mention of the positive cash flow that is usually generated. If it is an in-fence project then the cash flow will probably be concealed as a bookkeeping exercise and pass unnoticed, but in the case of independent power producers (IPP) this could be a true positive income, providing they had a market into which to place the excess power generated.


Yet here are all these threatened coal-fired plants, and now possibly nuke projects, facing closure due to the dark clouds of mandated GHG mitigation measures, often at impossibly high costs, looming on the horizon. So the question must now be asked,  would the same scenario, but minus the GHG issues, have provoked the same reaction? Unless, of course, generators are responding to some other agenda.


Recycled energy, waste heat recovery, or whatever one wants to call it, can be used to offset the high cost of GHG mitigation thus shielding rate payers, at least to some degree.

Unfortunately there are many obstacles, mostly political, standing in the way of this becoming reality. We must collectively do all we can to eliminate them.


But, this is just my humble opinion and I could be way off the mark.


Alan E. Belcher.


Poor Thermodynamics is The Challenge

Poor Thermodynamics, yes. In fact, dreadful thermodynamics!  But that is precisely where the challenge is.


If we change any of the terms of the argument then the result will also change.  So, replacing the Rankine cycle energy conversion system with a radically new ultra low temperature Brayton cycle system then, what was proven to be impossible for the Rankine cycle does become possible for this new approach.


The question is then a matter of, “What are the numbers for this radically new system?”. It develops into a “show me” situation, thrown open for scientists and engineers to examine and test; the very basis of the scientific method of proof. And a very welcome aspect of engineering is that author and author’s work are mostly independent of each other.


If the equations pan out and stand up to mathematical proof, then the outcome  – reduction to practicality – has little to do with the author other than acknowledgement of that authorship. Beyond this, the author could be a genius or a moron, saint, wife-beater, a success, or whatever, all of which should in no way qualify what the equations he or she created, state and prove.


Once we move into the philosophical field then the author does indeed become critical to the outcome of the discussion. A clear “It is not what is said, but who says it” situation.


In closing, I would respectfully suggest that we all keep the door ajar. We simply do not know what lies ahead; let’s go and find out!


Alan E. Belcher.


Hidden Renewable Source


Thanks for calling attention to the potential for greater use of waste heat.  The concept you describe is not new.  Indeed, it was clearly identified in the Public Utility Regulatory Policies Act of 1978 , as amended ("PURPA"), and the Federal Energy Regulatory Commission's ("FERC")  implementing regulations as "bottoming-cycle cogeneration"  (18 C.F.R. 292.202(e)).

The poor thermodyanics referred to by the "Poor Thermodynamics" commenter ("PT") is certainly a valid point that needs to be given due consideration.  In fact, the FERC originally gave bottoming-cycle facilty operators a huge break by allowing such facilities to qualify for PURPA benefits without having to meet an efficiency test.    (Subsequently, FERC added a limited efficiency requirement of 45 percent with respect to any natural gas or oil used for supplementary firiting.)  

The low amount of value that can be readily extracted from waste heat is precisely why it is so commonly thrown away.  Specifically, good design dictates that when the capital/operating cost of installing and using equipment  exceeds the fuel savings cost of recovering the additional energy, the energy should be treated as waste.  Consequently, the cost of fuel and the costs imposed on those who create emissions by burnnig fuel, figure greatly into the equation. 

However, it is not always the case that the value of the waste heat is too low to make it worth recovering.  In fact, as you point out, uses that bring net value are often over looked.  In determining the potential  value, your readers should not misread the comments by PT to suggest that using the waste heat ends up throwing away (in PT's hypothetical) 80% of the fuel energy burned to produce the beneficially captured heat, as if a new fuel source were being used to supply the energy for the heat recovery process.  The heat recovery process is using "trash" heat from the original process.  In that sense, it throws away nothing, but instead claws back energy that would otherwise have been rejected from the first process.  This is truly free fuel, even if the equipment to capture it is not.

So, the question becomes is there a process that can cost effectively make use of the free waste heat that the designer/owner of the plant throwing away the heat overlooked/discounted.  That can often be the case because processes that can cost effectively use the waste heat are often associated with businesses that are quite distinct from the business that creates the waste heat.  In the case of a topping-cycle facility, a electric generator might be throwing away heat that could be used by a green-house operator.  In the case of a bottoming-cycle facility, a metals foundry might be throwing away heat that could be used to generate electricity.

PT also doesn't mention that while the laws of thermodynamics don't change, the technology for recovering waste heat and other circumstances do change.  This can make recovering waste heat more cost effective by (1) lowering equipment costs, or (2) creating a useful purpose for the waste heat near to its source where none existed formerly.  Government programs and free markets can play an important role in developing new lower-cost technologies and encouraging the colocation of waste heat producers and processes that can cost effectively recover such heat.

Finally, it should be noted that combined-cycle generation is a superb form of waste heat recovery that is commonly employed in gas-fired generation plants, despite the fact that it does not constitute cogeneraton and, as such, is not entitled to PURPA related, or other green energy, benefits.  In combined-cycle generation, waste heat in the form of hot exhaust gases from one form of generation (typically, gas-fired turbines) is used to raise steam which is sent through a steam-turbine generator to produce additonal electricity.   This form of heat reuse has thrived without special regulatory support precisely because it represents good engineering and is cost-effective.  Beyond that, additonal opportunies await.  For example gas-fired turbine generator sets can be installed upstream of a new or existing coal plant to provide preheated combustion air for the coal plant (in the form of the exhaust gas from the gas turbine).

Some of these opportunites make good sense right now, despite, or because of, low natural gas prices, but are being under utiliized.  Others will make sense as fuel prices rise, costs are imposed for emitting carbon dioxide, or technology or other conditions improve. 

Policy makers need to be aware of and understand  these technologies to ensure that they are given their appropriate place in the energy supply mix.

Erik J.A. Swenson




Poor Thermodynamics

As most engineers realize, the thermodynamics of waste heat recovery show far lower efficiency than conventional power sources, and consequently low temperature heat becomes a byproduct. 

I question the wisdom of widespread use of low temperature Rankin cycles; particularly in the South.    First, the low temperatue cycles use other working fluids - hydrocarbons, freons, ammonia ...  and all of these will lead to outcrys about hazardous chemicals in the area.     Just another reason for attorneys to charge big fees.

Second, all these cycles require heat rejection - note that most of the heat will still be rejected because of the low cycle efficiency.     Heat rejection at lower temperature benefits the cycles and the South does not offer the lower temperatures.    If a cycle is 20% efficient, then 80% of the heat plus pumping power must still be rejected - much capital equipment for little improvement.   

Guess what - that's why the heat is waste heat.