More Building Matters
Some people say if we run our heat pumps and electric cars with renewable energy, we are not producing carbon emissions, so energy efficiency is no longer critical. They also say we will need far less energy than we do now because we are not turning most of it into waste heat and CO2, or what’s known as “rejected energy.” But in fact, we need the same amount of useful energy, and it will not be cheap or easy to find. That’s why serious energy efficiency in our homes and transportation modes is more important than ever.
Macarthur Prize–winner Saul Griffith is a proponent of the “electrify everything” concept. He claims in his book, Electrify: An Optimist’s Playbook for Our Clean Energy Future, that in an all-electric nation, we need only 42% of the energy we use now. Michael Barnard’s article “With Heat from Heat Pumps, U.S. Energy Requirements Could Plummet by 50%” makes corresponding claims. In both cases, the authors reference what I call “the chart that explains everything,” by which I mean the Sankey flowchart of energy consumption from the Lawrence Livermore National Laboratory. It demonstrates that by essentially subtracting all rejected energy, half or more of our energy requirements vanish.
I have never understood this. According to Livermore, we need 31.8 quads of “energy services” or useful energy after burning fossil fuels. We still need 31.8 quads (quadrillion BTUs) of useful energy if we run on wind and sunshine. Because, as Allison Bailes explained so well here, it isn’t really rejected energy; it is the cost of doing business when converting heat energy to useful work. Bailes doesn’t stress the importance of energy efficiency, noting, “There’s only one way to minimize that big grey block in the upper right part of the chart: Replace combustion with renewable energy.”
Griffith is more explicit, writing in Electrify: “The emphasis on efficiency ever since the ’70s is reasonable, since almost no one can defend outright waste, and almost everyone agrees that recycling, double-glazed windows, more aerodynamic cars, more insulation in our walls, and industrial efficiency will make things better. But while efficiency measures have slowed the growth rate of our energy consumption, they haven’t changed the composition. We need zero-carbon emissions, and, as I often say, you can’t ‘efficiency’ your way to zero.”
Griffith suggests we shouldn’t even bother trying to change our energy-extravagant ways:
“Americans will never fully support decarbonization if they believe it will lead to widespread deprivation—which many people associate with efficiency. We can’t address climate change if people remain fixated on, and fight about, losing their big cars, hamburgers, and the comforts of home. A lot of Americans won’t agree to anything if they believe it will make them uncomfortable or take away their stuff.”
Heat pumps and peak demands
But I keep returning to the Livermore chart, and the need for 31.8 quads of useful energy. We are getting all of 7.11 quads from wind, water, and solar, and water is going down, not up. Nuclear isn’t going anywhere fast, so we must find 16.56 quads of green electricity in a hurry.
Barnard makes the point that heat pumps can make a significant difference, reducing the energy needed by about two thirds. Converting from gas to electric heat pumps is about 2.6 quads in residential and commercial buildings, although I suspect that “heatpumpified” homeowners will find their new central air–conditioning systems are eating up a lot of those savings.
Barnard also suggests that heat pumps can supply a lot of lower-temperature industrial functions. But assuming he’s right, we still need at least 13.96 quads, which is more than one third of the useful energy we consume now. And none of this includes the overbuild required for intermittency, seasonality, and peak loads.
Seasonality, in particular, could be huge. In an article for Passive House Accelator, Skylar Swinford points to this study, which reports: “Meeting this [January] peak with renewables would require a 28× increase in January wind generation, or a 303× increase in January solar, with excess generation in other months.”
That sounds ridiculously high, but it is hard to store electricity for peak demands. Going with highly efficient buildings reduces this significantly, requiring by their calculations, 4.5x as much wind and 36x as much sola; and this doesn’t account for storage or interconnections.
A matter of resiliency
Some in the “Electrify Everything” gang suggest that with heat pumps and clean electricity, we can worry less about efficiency. I believe that the numbers show that we have to worry about it more. The reasons: Electricity will be expensive, and if we electrify everything, we will need a lot of it. Sun and wind may be free, but a lot of new infrastructure will be needed, including a rebuilt distribution network with some serious HVDC runs across the country. We are not just running heat pumps in homes, but millions of cars. To electrify industry, we will need to run electrolyzers to make hydrogen for steel and fertilizer production. We will need lots of juice and must be prudent and economical with it.
People worry about giving up gas because it keeps them warm when the power goes out, even though furnaces don’t run without electricity. But as Allison Bailes has noted, “Resilience starts with the building enclosure.” A well-insulated house can stay warm for a while when the power goes out; Passive House designs can stay warm or cool for weeks.
We have to shave the peak loads. Your home can be a thermal battery. There’s a lot of buzz now about Shifted Energy, a company that turns water heaters on and off to balance the grid during shifts in Hawaii’s wind and solar power. It is not a new idea, just a more sophisticated version of what Alex Wilson was writing about on GBA back in 2009. With properly designed efficient homes, heat pumps might well be controlled remotely to shut down at peak times, with the house staying warm or cool thanks to thermal storage in the house itself.
The bottom line: It’s going to be a lot tougher to electrify everything if we don’t still strive for efficiency.
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Lloyd Alter is a former architect and developer. His journalism career includes 15-plus years as design editor at Treehugger.com. Today he teaches sustainable design at Toronto Metropolitan University. His work can be found at Carbon Upfront.
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11 Comments
~24 quads of rejected heat from electricity generation and 21 quads in the transportation sector. A gas vehicle is around 30-35% efficient with the rest lost to heat. Diesel is closer to 40%. Shifting those to EVs will reduce our demand by 12-13 quads, since EVs are closer to 80-90%. The tech will continue to develop and we will get there.
The 24 quads of rejected heat from generation, I bet a large amount of that is coal and natural gas. Both run at 30% or so efficiency.
Basically, eliminate things that burn and our rejected heat will drop significantly. The conversion from heat to motion (turbine generators or wheels) has a lot of losses.
I am interpreting the numbers differently; I ignore the rejected energy side and just look at the useful energy. We still need to find about 5.65 quads of useful energy for transport, probably more since they are only 80 to 90% efficient, as you say. This is my point (and why I ride an e-bike)
That chart that "explains everything" is very useful for a lot of things, but I think it's really misleading for thinking about efficiency. If you look at the residential box, it's 65% efficiency, which implies that the best we could do is to reduce that 35% loss to 0% and reduce the energy input to homes by 35%. But if we look at, for example, heating and cooling, we could triple double the thermal resistance of the envelope and switch from 85% efficient furnaces to 300% efficient heat pumps, and reduce the energy used by 85%, or a factor of 7.
People tend to look at this chart and think the numbers are hard data. Some of them are, but the efficiencies used on the end-use sectors are only made-up approximations for the purpose of illustration.
We knew 40 years ago on how to build highly energy efficient and comfortable housing. It started in Canada with the double wall and superinsulation. Code built cold climate homes of today likely use 2 to 3 times the energy for heating and cooling as did those early double wall homes. What we fail to understand, there is and always has been an opposing force to better efficiency. Once you realize what the opposing forces are, the pieces of the puzzle start to fit. I think we need a better definition of what Net Zero energy buildings are. When does the carbon accounting start?
Mr. Alter has it exactly right, we need very highly efficient buildings. Electricity will never be cheap as it competes as a fuel source with fossil fuels. New buildings with airtight and well insulated envelopes can be heated and cooled at a low cost in a variety of ways, this is where the smart money will go. All of the expensive gadgets and gismos will not begin to cover a poorly designed and constructed building.
Doug
I think the use of electric vehicles and heat pumps should itself be viewed as a form of efficiency. But that doesn't mean their use should not also be subject to further efficiency scrutiny. And as mentioned, it may be peak power and not strictly total energy that plays a pivotal role in how efficiency measures are applied. If overbuilding renewables is part of the equation, there will likely be times when energy use is inconsequential to the budget, and when the less efficient processes we still rely on should be performed.
To digress a bit: In these types of discussion, I see tension between the notion of building a high efficiency society for the future, and being a low-consumptive one in the now. Can we make a highly efficient society (super insulated structures, heat pumps and EV's for everyone, updated public transit infrastructure, and last but not least, major renewable infrastructure buildout) while not 'breaking the bank' on our carbon budget?
Then there's Jevon's paradox. If we analogize society to the evolution of computers, we started with big power hungry machines that could perform only very basic operations. Fast forward to today, we have immensely powerful and complex machines at much smaller scale and with incredible efficiency. Yet how much power do we consume today running computers vs the dawn of their creation when they were little more than glorified slide rules?
I sometimes view our society as a self-organizing machine that is in a process of creating an ever more advanced, efficient, and complex self. A future of renewables and a massive electric grid—balanced with computer algorithms and fed by a complex web of highly processed materials collecting solar energy—may allow for this, may yield a more efficient future, and perhaps will take us to more 'advanced' states of being, but will it ultimately slow the growth of the machine which is entirely transforming pre-mechanistic earth systems? And perhaps someday (still distant) these mechanistic systems will entirely envelop what was once here (familiar with Dyson sphere anyone?), and it will become a new paradigm in earth's history: the machine organized earth.
That, or... a pandemic will speak it's word to the machine builders. Or perhaps the machine builders will self destruct.
This article seems to ignore the practical side of making buildings more energy efficient: it's really expensive and takes a lot of labor for every building we want to upgrade.
It's going to be much easier and cheaper to build 300x solar capacity than to retrofit a massive number of existing buildings.
Because of labor...
So is that an environmental disaster waiting to happen due to poor economic accounting?
300x the land no longer supporting agriculture or forests, but instead toxic elements that may or may not get recycled.
Yes, it could be devastating to parts of the environment if we foolishly replace agricultural land or forests with all of that solar. But we could also put that solar over parking lots, buildings, old landfills, in and around freeway interchanges, ocean barges, desert, bad lands, etc.
We can also combine some agriculture with solar to make dual use of the land (this only works with some crops). And we definitely need to put more resources into recycling of solar panels and batteries.
But even with all of that, it's certainly going to be quicker and cheaper to build out a lot of solar energy than a massive retrofit of existing buildings. And we'd still need a lot of solar to replace fossil fuels even if we did retrofit a lot of the existing buildings. Tackling the low-hanging retrofits to improve building efficiency like upgrading windows when they get replaced or adding attic insulation makes sense, but that's only going to reduce building energy requirements by a small amount (10%? 20%?). The rest of the energy still needs to come from somewhere.
"And we'd still need a lot of solar to replace fossil fuels even if we did retrofit a lot of the existing buildings."
Agreed.
"But we could also put that solar over parking lots, buildings, old landfills, in and around freeway interchanges, ocean barges, desert, bad lands, etc."
Yes those are good things, but unrealistic to fulfill the immense needs you are referring to. I just recently attended a webinar on this very subject where people extremely versed in this stuff essentially said that to build out the utility scale projects we need, using those types of places you mention will simply not cut it. That's not to say they shouldn't be used, but it's not going to cover it.
Perhaps more importantly, all those types of solar development cost more, and so won't be the way we build it out unless we intervene with incentives/disincentives-- something I am not sure we will see on a large scale.
I'm being a bit intentionally negative. I'm not suggesting solar/wind/batteries are going to be an apocalypse of development, but we should be realistic about their non-zero (to put it lightly) impacts.
Ultimately, a better economic accounting system (carbon pricing and other environmental externalities built in) would better guide the cost-benefit decision making process (of more solar vs other alternatives like retrofits and retained fossil generation).
Despite how it may come off here, I'm really not at all anti wind and solar... I'm just a bit skeptical about where it will ultimately get us if we view it as a 1:1 replacement for our business-as-usual way of operating a capitalistic society.
I'm struggling with this. Maybe someone can clarify.
"They also say we will need far less energy than we do now because we are not turning most of it into waste heat and CO2, or what’s known as “rejected energy.” But in fact, we need the same amount of useful energy, and it will not be cheap or easy to find. "
I'll outline a quick comparison and maybe this will help.
We have 2 fleets of cars, 100 gas guzzlers and 100 electric cars. Our electricity source is PV.
We want to drive each fleet 100 miles.
Do we need "the same amount of useful energy" for both fleets?
In terms of basic physics we're moving equal masses at equal accelerations over equal distances. So at that level it seems the answer is yes. On the other hand, there really is a lot less rejected energy with the electric fleet. So our energy input can be a lot less as well.
Have I got something wrong here?
I do think the way he lays out his argument is a bit confusing, but my take is that he's simply saying we still use a lot of energy even if we had perfect 100% input to output conversion.
Which is true, but it's also true that eliminating the rejected energy block would be a HUGE reduction from our current inputs.
The catch is that the nature of the inputs changes entirely-- for good and for bad both.
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