Waste Heat - the 'sleeping giant' of all energy
Our contention is that well over 8.4 million megawatts of free energy is there for the taking, and we do not need invent brand new technology to get a very significant portion of it. That 8.4 million megawatts is based on the rough assumption that the global average thermal efficiency of 40% applied to the 'total world energy consumption of 14 terawatts for 2003' (‘and 30 to 60 terawatts by 2050' per Nobel prize winner Dr. Richard Smalley, Rice University, June 23 2003)
This is true zero pollution, zero emissions, free energy. The fuel to create it is already paid for and consumed, and by definition we are only dealing with the waste heat that otherwise is lost up the stack. If applied in a blanket manner across future commercial onsite distributed energy systems, waste heat recovery also becomes a local pollution solution by reducing the total electrical demand through waste heat driven (non-electric) air conditioning production.
Bigger than oil, coal, natural gas and nuclear…Combined
In simple terms that means 60% of all world energy becomes waste heat. On this basis Waste Heat Energy is bigger than oil, coal, natural gas and nuclear - combined.
Waste Heat recovery makes green energy greener
Are you exempt if you are working with ‘green energy’, ‘renewable energy’, ‘biofuels’ or some developing ‘clean’ energy system like fuel cell power? A big No! Waste heat recovery and its reapplication will improve the thermal efficiency for almost all systems. While low temperature PEM fuels cells have been the rage, a recent recognition that much less expensive SOFC and PAFC Fuel cells can more than compete if offered in combined cycle mode. In this waste heat utilization mode they create low energy steam or hot water to be converted into refrigeration (through adsorption or absorption chillers). Some solar energy companies design heat collectors directly under the voltaic cells to provide electricity and adsorption refrigeration from the sun. Low grade heat geothermal systems are driving proven organic Rankine cycles to make power, or can use new cascading refrigeration cycles to produce both power and refrigeration.
I am probably underestimating the most recent (and quite costly) advances in gas turbine materials, combustion systems, and inlet chilling technologies. We can also argue the same for the new 3D twist steam turbine condensing section blade technologies. Though I am less familiar, I sure there are equal efficiencies improvements in lean burn reciprocating engines. So let’s assume a 20% efficiency increase over the current average efficiency position. This pushes the recovered waste heat potential down closer to 50%. So put us down for ‘only’ 7 million megawatts.
Realistically, most locations are probably just too remote or too distributed to justify heat recovery. But Stirling heat engines have run been off cooking fires in rural Africa. Maybe the available recovery and conversion technology proves just too difficult, or just too costly to implement right now. Lastly, basic system efficiencies, such as steam being from 20% to 35% overall, will put a realistic lid on the amount of heat energy that can be converted. So in total let’s plan to recover only 1/10th of the total waste heat - or 5% of all energy consumed in 2003.
So we are down to a ‘paltry’ 350,000 megawatts. At an avoided cost basis of $0.05 per kilowatt-hour this equals over $153 billion each year of free and non-polluting energy!
Say that slowly
‘One-hundred-fifty-three-billion-dollars-per-year-of-zero-pollution-energy’. It is a bit hard to comprehend. Try it this way - the waste heat energy market could support 1000 companies each with an average annual revenue stream of over $150 million.
What’s the catch?
In today’s post ‘dot-com’ economy this is a fair question to ask. So is ‘Where are the strings’, and more specifically ‘Where are these companies?’ Well, the only catch is that heat energy recovery may not be actually branded as “Waste Heat”. Developments in this area may go under other more common or accepted industry names like ‘Cogeneration’, ‘CHP’, ‘Combined Cycle’ or ‘Trigeneration’. But “Waste Heat” is actually a more correct all encompassing term, since not all recovered heat energy will drive ‘Co’ or ‘Tri’ generation, or drive Combined cycle/heat & power systems. A key point is that since it is a bit hard to directly transport BTUs by wire (or by internet), some of the most interesting waste heat recovery technologies convert low grade heat directly into refrigeration for local consumption.
Sorry, but they must be nano-strings cause I just can’t see them. It is inevitable that waste heat recovery will blossom as a de facto ‘industry’. This will probably happen well before we see profitable returns from simple cycle fuel cells, micro-turbines, and engines. And certainly decades before we could hope to ‘see’ any nano-scale energy systems (the holy grail of energy?).
Waste Heat’s compelling arguments
Waste heat energy recovery and conversion will grow due to its simple and compelling reasons. Waste Heat Energy is free. Waste Heat Energy has zero pollution. Waste Heat energy recovery is very profitable when using yesterday’s technologies for large systems, economical when using today’s technologies for medium systems, and will be justified using tomorrow’s systems on small distributed power systems.
May you live in exciting times . . .
We have all had enough of the wrong type of excitement recently. But maybe now it is time for engineers to lead industry towards a positively exciting time of zero-pollution-free-energy. This is only available now through the application of new waste heat technologies. How can an energy engineer not be excited? New organic Rankine cycle and cascading heat cycle energy systems are being quietly developed. Two hundred year old Stirling heat engine technologies are being dusted off, improved, and 'introduced' as cutting-edge. New adsorption and absorption heat-to-cold technologies are being rapidly installed within the high energy cost states. True technological leaps like thermo-acoustics (heat-to-sound-to-cold) are now happening in the research wings of universities, and in the garages of Edison-like inventor entrepreneurs, and some startup ventures.
Even steam is back ‘in’
The oldest and still the most prolific waste heat technology of them all, steam, is expanding its market downward through new smaller higher efficiency designs. The ‘Twin-Turbine’ (photo) from Kühnle Kopp and Kausch for 1 to 10 MW claims ‘multistage efficiency at single stage prices’ due to its low cost modular construction. Even smaller high speed direct generator drive steam turbine gensets are under beta testing by several companies who claim efficiencies of 70 to 80% for outputs below 200 kW.
The hidden cost of doing nothing
Waste heat recovery is the purest form of energy conservation. And since the oil and gas industry has provided most of my income over the last 25 years, don’t get me wrong with my next comments. There is a huge undefined cost of not making waste heat energy happen. Every megawatt saved by energy recovery, it is one less megawatt of petroleum energy that needs to be researched, drilled, developed, pipelined, transported, (occasionally spilled, recovered, cleaned), refined, converted, transported, (occasionally spilled, recovered, cleaned - again), protected, and basically globally ‘influenced’. If anyone could really add those combined costs of remote world oil and gas research and production and our associated increase in military requirements, the number would have to be truly staggering. And guess who gets that bill?
When does Waste Heat start to happen?
It is happening now. Do an online search on ‘waste heat systems’, ‘organic Rankine cycle’, ‘thermo acoustic’, ‘adsorption chiller’ and see all the current activity. I think it will be main stream sooner than you or I think. Wake-up calls are being placed to this true ‘sleeping energy giant’ by many small Waste Heat technology developers. Relatively low tech heat energy recovery technologies like steam and hot water are being combined with remote monitoring to allow unmanned operation distributed waste heat powered systems. If you listen carefully, you can already hear the hum of new products like direct drive high speed steam turbine gensets, ORC expanders, and Stirling heat engines finishing their Beta testing . Or you may pick up the heartbeat of the first six silica gel (same stuff as in the new VCR box that says ‘do not eat’) adsorption chillers in North America. Or you may even get a whiff of a pentane or a steam-ammonia cascading refrigeration cycle.
You will know when you missed out . . .
You will know when the waste heat ‘energy giant’ is on his feet when the obvious conglomerate energy equipment & system companies, and some not so obvious energy companies, start to grow Waste Heat’s marketing presence through acquisition. Regardless of how it happens, as these new systems gain more experience, waste heat energy will quietly grow, project by project, becoming the paradigm shift for local or distributed energy production and consumption.
But why wait for your profits?
Until that shift takes place, the early developers will have a chance for ground floor entry into a growing energy play. And early adopters will enjoy an area of competitive advantage through hidden profit recovery. Most of the components of the new waste heat recovery technologies are already commercially available. Feasibility and front end engineering studies of most waste heat systems are affordable and take only a few weeks. Such studies allow more informed ‘go/no-go’ budget decisions even for the smallest commercial heat generator.
Last week I was in a northeastern state standing on a ladder in 20ºF winds on top of a roof pointing my remote temperature sensor into three incinerator exhaust stacks. Depending on that project’s successful study outcome, and more likely of course my client’s permissions, for my next article look for a real-world case study for waste-heat-to-energy options for this modest $10,000 per month natural gas fuel consumption industrial heat recovery client.