Efficiency is Crucial to a Green Future

Thank you for informing me of this study and providing a link. It provides for very interesting, informative and hopeful reading. I completely agree that efficiency is a critical aspect of a renewable energy future. Greatly increased efficiency and conservation can have a huge impact on our total energy consumption, as is shown in the graph above. This includes a whole host of things at every level, from the level of energy production, to energy delivery and consumption. On a personal level, it involves numerous small details, such as switching to CFLs and LEDs, A+ fridges, washers, dishwashers, etc., energy-efficient laptops and TVs, elimination of vampire loads, better transformer 'cubes', use of motion-sensors to switch lights and thermal sensors to control heating systems, use of small fuel-efficient cars and hybrids, more use of bikes, public transport, walking and telecommuting, smaller better insulated and designed homes, passive solar and passive cooling design, and so on and on. None of these things individually is anything impossible or impractical to do. We simply have to make people aware of all of these host of things that need to be done to improve efficiency and conservation and thereby reduce energy consumption and its consequent GHG emissions.

I just want to emphasize that the role of efficiency is more of an issue for "upstream processes" and of course increasing efficiency there(ie: the power plant) would make the world much better in terms of environmental degradation due to use of fossil fuels. However, this is not relevant to the average individual when accessing his or her actions-- instead the average person should be concerned with their consumption. Do you really need everything that you think you need? Lowering consumption and getting rid of unnecessary processes has a larger impact than simply increasing efficiency of the appliances in your home (it does nothing to replace an incandescent with a CFL if you are still using lights that you don't need). Unfortunately, the average individual needs a lot more than political will and cool gadgets to really make the difference.

Look at the two biggest waste flows in that chart: electric power generation and tranportation. Guess what, both of those run primarily on heat engines with a theoretical maximum thermal efficiency of 50% and an effective actual thermal efficiency between 15 and 45%. You can't change the laws of physics, and you can't turn fuel into work at anything close to 100%.

From your waste ratio I surmise systemic inefficienies are included? A coal powerplant of older technology, for example, is about 35% efficient, and new iGCC plant will push that to 45%.

If so, then it will be a long struggle to put a dent into that. Without a doubt efficiency is a critical component to energy growth and co2 reduction. Recent cost analysis by McKinsey suggests that 30% of required CO2 reductions can be achieved just with better CAFE standards, house insulation, etc. But your argument suggests that efficiency is all we have to do, which is incorrect.

using both the heat and the electricity can increase the overall efficiency of many plants quite a bit, but the choices we have are not just coal plants that are more or less efficient and gasoline cars that are more or less efficient: We need to develop an infrastructure that has clean energy sources and clean transportation. It's not even a choice, we can't keep going in the direction we are going now...

It truly is amazing to see the amount of waste that takes place on the consumption end. From electronic products that consume energy even when they are off to consuming energy unintentionally (leaving things on), conservation needs to be emphasized more than it has been.

Part of the answer is combined heat and power, CHP. Stop worrying about whether the efficiency of the plant is 35% or 45%, by reclaiming most of that waste heat to boost the overall efficiency to 80% or 90%.

The plants must be smaller and located closer to where the heat is needed (so they will probablly not be coal-fired).

Efficiency and CHP are two big steps in a better direction. Let's go now.

@Devin Ben-Hur

You are right that you can't fight physics. If we look at the electrical system, though, most of the inefficiency comes from the way we choose to design the electrical grid. We MOVE electricity long distances because we have centralized the power system that favors large power companies consolidation of resources and control.

When you redesign for distributed power generation, one that favors local thermal, small scale hydro, solar and wind energy sources, you can gain the use of most of those distribution losses with the added benefit of reducing the use of fossil fuels and lowering the chance of state wide black outs like NY and CA have been experiencing these last few years.

You can't fight physics, but you can fight bad design.

Heat engines (power plants, ICEs, air conditioners, and so on) do have a rather low thermodynamic efficiency limit. Cogeneration is one way of offsetting this. Another is not using heat engines. The reason why we use heat engines is that we have a lot of experience doing it, they are relatively cheap to build, and fuel costs are low compared to construction.

It is perfectly possible (and it has been done, just not on a very large scale) to design fuel cells that run on oil, natural gas, or even coal that would get much higher efficiencies. Just look at the Gibbs free energy compared to the total energy released by combustion and you'll see that it is theoretically possible to achieve

For transportation, more efficient, lighter vehicles are essential, because if we can achieve that it will be much easier to figure out where to get the electricity/fuel/whatever.

For power generation, the equation is more complicated. Today, ~60% of energy released by combustion never becomes electricity; it is lost as heat. ~25% of the remaining energy is lost in grid transmission. This loss could be greatly reduced through local cogeneration. However, it is easier to control and monitor emissions when they occur at a centralized location. So, cogeneration systems should probably be limited to cleaner energy sources than coal: natural gas, solar+solar hot water, small wind+electricity storage in batteries or hydrogen, and so on.

If grid power came primarily from renewable sources (and from wherever such power was stored for use at times of low production) then we would not lose energy as heat at the point of production, but transmission losses may be greater since for many people power would be coming from farther away. Unless, of course, we can make rooftop power generation virtually universal, in which case there could be power aplenty from local sources.

But barring that, improving the grid, while helpful, won't be enough to get grid transmission losses drastically lower. That would require remarkable (and unexpected) new materials; the ideal would be a cheap, room temperature superconductive material; other dream materials for really low (though non-zero) resistance are bulk single crystal gold or silver, or metallic single-walled carbon nanotubes.

On a more down-to-earth level, I would argue that end-user efficiency improvements are as important as upstream ones. In fact, the more inefficient upstream processes are, the more my personal changes matter. Eliminating one watt of power use in my home eliminates 4 watts of primary energy that my power company must consume. And if someone leave on lights all day long, then having them switch to CFL's saves 6 times as much energy as someone who only uses their lights four hours a day. Do we need to encourage behavioral changes to reduce waste? Of course, obviously. But better behaviors and better technologies are not mutually exclusive options; they can and ought to work together in harmony.

Heat engines (power plants, ICEs, air conditioners, and so on) do have a rather low thermodynamic efficiency limit. Cogeneration is one way of offsetting this. Another is not using heat engines. The reason why we use heat engines is that we have a lot of experience doing it, they are relatively cheap to build, and fuel costs are low compared to construction.

It is perfectly possible (and it has been done, just not on a very large scale) to design fuel cells that run on oil, natural gas, or even coal that would get much higher efficiencies. Just look at the Gibbs free energy compared to the total energy released by combustion and you'll see that it is theoretically possible to achieve

For transportation, more efficient, lighter vehicles are essential, because if we can achieve that it will be much easier to figure out where to get the electricity/fuel/whatever.

For power generation, the equation is more complicated. Today, ~60% of energy released by combustion never becomes electricity; it is lost as heat. ~25% of the remaining energy is lost in grid transmission. This loss could be greatly reduced through local cogeneration. However, it is easier to control and monitor emissions when they occur at a centralized location. So, cogeneration systems should probably be limited to cleaner energy sources than coal: natural gas, solar+solar hot water, small wind+electricity storage in batteries or hydrogen, and so on.

If grid power came primarily from renewable sources (and from wherever such power was stored for use at times of low production) then we would not lose energy as heat at the point of production, but transmission losses may be greater since for many people power would be coming from farther away. Unless, of course, we can make rooftop power generation virtually universal, in which case there could be power aplenty from local sources.

But barring that, improving the grid, while helpful, won't be enough to get grid transmission losses drastically lower. That would require remarkable (and unexpected) new materials; the ideal would be a cheap, room temperature superconductive material; other dream materials for really low (though non-zero) resistance are bulk single crystal gold or silver, or metallic single-walled carbon nanotubes.

On a more down-to-earth level, I would argue that end-user efficiency improvements are as important as upstream ones. In fact, the more inefficient upstream processes are, the more my personal changes matter. Eliminating one watt of power use in my home eliminates 4 watts of primary energy that my power company must consume. And if someone leave on lights all day long, then having them switch to CFL's saves 6 times as much energy as someone who only uses their lights four hours a day. Do we need to encourage behavioral changes to reduce waste? Of course, obviously. But better behaviors and better technologies are not mutually exclusive options; they can and ought to work together in harmony.

Heat engines (power plants, ICEs, air conditioners, and so on) do have a rather low thermodynamic efficiency limit. Cogeneration is one way of offsetting this. Another is not using heat engines. The reason why we use heat engines is that we have a lot of experience doing it, they are relatively cheap to build, and fuel costs are low compared to construction.

It is perfectly possible (and it has been done, just not on a very large scale) to design fuel cells that run on oil, natural gas, or even coal that would get much higher efficiencies. Just look at the Gibbs free energy compared to the total energy released by combustion and you'll see that it is theoretically possible to achieve

For transportation, more efficient, lighter vehicles are essential, because if we can achieve that it will be much easier to figure out where to get the electricity/fuel/whatever.

For power generation, the equation is more complicated. Today, ~60% of energy released by combustion never becomes electricity; it is lost as heat. ~25% of the remaining energy is lost in grid transmission. This loss could be greatly reduced through local cogeneration. However, it is easier to control and monitor emissions when they occur at a centralized location. So, cogeneration systems should probably be limited to cleaner energy sources than coal: natural gas, solar+solar hot water, small wind+electricity storage in batteries or hydrogen, and so on.

If grid power came primarily from renewable sources (and from wherever such power was stored for use at times of low production) then we would not lose energy as heat at the point of production, but transmission losses may be greater since for many people power would be coming from farther away. Unless, of course, we can make rooftop power generation virtually universal, in which case there could be power aplenty from local sources.

But barring that, improving the grid, while helpful, won't be enough to get grid transmission losses drastically lower. That would require remarkable (and unexpected) new materials; the ideal would be a cheap, room temperature superconductive material; other dream materials for really low (though non-zero) resistance are bulk single crystal gold or silver, or metallic single-walled carbon nanotubes.

On a more down-to-earth level, I would argue that end-user efficiency improvements are as important as upstream ones. In fact, the more inefficient upstream processes are, the more my personal changes matter. Eliminating one watt of power use in my home eliminates 4 watts of primary energy that my power company must consume. And if someone leave on lights all day long, then having them switch to CFL's saves 6 times as much energy as someone who only uses their lights four hours a day. Do we need to encourage behavioral changes to reduce waste? Of course, obviously. But better behaviors and better technologies are not mutually exclusive options; they can and ought to work together in harmony.

Out of the ~97 quads ... generated from various sources in the US in 2002 (nuclear, hydro, biomass, natural gas, coal, petroleum), 56.2 quads ... were wasted, lost, unused for any valuable work.

Am I correct in assuming that, for electrical generation from steam in any case, this figure is about right given the maximum possible efficiency of steam-powered turbines?

56.2 / 97 = 0.579 wasted, or 42.1% useful work. A heat engine has a maximum theoretical efficiency of ~60% for a combined gas cycle turbine (pretty rare in power plants so far), whereas supercritical coal plants peak at around 45%.

Transmission losses take another dent of around 6-8%.

So while better energy efficiency at the generation point is important, what really matters (from an electricity perspective anyhow) is (A) increased energy efficiency at point of use (since cutting 1 joule of electricity use in a house could be worth about 2.5 joules at the coal plant, and (B) decentralized, renewable power generation to eliminate both the lost power of the heat cycle engine, and the CO2 emissions from fossil fuel sources.