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A New Shade of Green

By Sherry Listgarten

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About this blog: Climate change, despite its outsized impact on the planet, is still an abstract concept to many of us. That needs to change. My hope is that readers of this blog will develop a better understanding of how our climate is evolving a...  (More)

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Can you Pay to Reduce your Carbon Footprint?

Uploaded: Jan 26, 2020
Google’s data centers are carbon-neutral. My household is carbon-neutral. Palo Alto Utility’s natural gas service is carbon neutral. How can this be? We purchase carbon offsets to cover our emissions. The payments we make go to fund projects that remove or prevent greenhouse gases emissions, essentially cancelling out our own. But does it really work? And even if it does, is it appropriate?

Here is a fictitious example that illustrates some of the problems with carbon offsets.

China is working hard to reduce the country’s emissions, cleaning up and (over time) shutting down coal plants, planting billions of trees, operating the largest electric bus fleet in the world, and so on. But the emissions reductions are not happening fast enough to meet their goals. They search around the world for where they can do more to help. They are very enthusiastic about biking so they look for places where more cyclists would make sense, settling on the Bay Area as a terrific example with its flat terrain and temperate weather. They donate 50,000 quality commuter bikes to a local organization to give away, and then offset the emissions for 50,000 average car commuters. Success?

Not exactly. How are the local distributors going to find people who want to bike? Many will just take the bikes and resell them. Other bikes will rust in backyards after a few attempts to commute, or after a rainy winter dampens any cycling enthusiasm. The local distributors try to verify that the people who took the bikes are using them to get to work, but they just hear over and over again that lives are too busy and jobs are too far away.

So the well-intentioned folks from China come back and observe that a key problem is that there is too little local retail in our area. They offer job training to help people switch from distant tech jobs to local retail jobs, providing a nice benefit for the residents (local retail!) as well as a big reduction in emissions because more people can now walk or bike to work and shopping. Success?

Ha. Tech pays a lot more than local retail, to start with, so it’s hard to recruit people. A few people do attend the job training, but they don’t have the skills to make a go of local retail, which is a tough market.

At this point, the Chinese give up on bikes and consider trees. Everyone loves trees. They learn that, in some places, Americans have cut down trees and shrunk parks to make room for new development. So they find a tree-focused local organization in the Bay Area, Canopy, and give them money to preserve all the trees in the local parks. They then offset the emissions that those trees will capture for the next 50 years. Success?

Hardly. This “works” in the sense that the trees aren’t cut down for 50 years. But they weren’t going to be cut down anyway so the emissions weren’t really saved. The Chinese did not understand that our local government was already committed to preserving these trees. Yet Canopy was only too happy to take the money and credit the emissions.

This is kind of a silly example. These projects would be far too expensive to make sense in reality, and Canopy is not likely to be so complicit. But the point is, it is not easy to establish good carbon offset projects. A good project needs to make practical and economic sense for the locals, but it also needs to be something that wouldn’t have happened anyway. Offset projects that involve renewable energy, for example, are not valid if they make such good economic sense that they would happen soon even without the offset investment. Offset projects involving forest preservation won’t work if they make little economic sense for locals who would prefer to clear a field and engage in more lucrative farming. Even if locals are offered an alternative livelihood, such as harvesting and selling brazil nuts, they may not have the ability to develop a new market. There are numerous other problems with offsets. For example, trees may be saved in one place but then cut down in another place. This is referred to as “leakage” -- emissions are essentially exported to places with weaker governance. Offsets can even worsen pollution in some cases. For example, if a coal mine is receiving credits for flaring its leaked methane (1), those payments could prolong the life of the coal mine that might otherwise be unprofitable. This is referred to as a “perverse incentive” -- overall pollution is actually worsened by the offsets. (This particular criticism was one of several recently written up about California’s use of offsets in its cap-and-trade program.)

Even in the cases when an offset pencils out in practice, there may be concerns with appropriateness. Would it be better for China (in the above example) to work harder at cleaning up its own coal plants, rather than coming to the Bay Area to reduce emissions, even with good intentions?

Because of these many difficulties, the carbon exchange processes established during the Kyoto Protocol (the Clean Development Mechanism, or CDM) are widely considered to be a failure. According to a recent analysis, “It is likely that the large majority of the projects registered and (credits) issued under the CDM are not providing real, measurable and additional emission reductions.”

Fortunately, operators are learning from earlier mistakes. Reports have been written enumerating the risks and suggesting best practices for carbon offset projects. Below, for example, is a table from a Stockholm Environment Institute report itemizing the types of projects that are more likely to provide real, long-lasting emissions reductions.

With attention to known problems, even the “higher risk” projects can be made to work. Zambia-based Biocarbon Partners (BCP) has been working hand in hand with rural communities for almost ten years to develop long-term forest conservation projects that improve the quality of life for locals while preserving habitat for endangered wildlife. (2) They are aiming to protect over 3800 square miles of critical wildlife corridor adjacent to national parks.

Biocarbon Partners protects the areas shown in dark green

I spoke with Gina Woolley, their REDD+ Technical Officer. “Rather than just treating the symptom, we look at the root cause of the forest degradation. Forests are cleared out for agriculture and for charcoal. There is a lot of poverty in these rural areas of Zambia. Villagers hunt wildlife for bush meat or to sell (for example, the endangered pangolin). This threatens trees and wildlife. So we partner with communities, we invest in people, to create long-lasting forest preservation.” BCP invests in education to raise awareness about ecology and sustainability. Training in conservation farming and an innovative “eco-charcoal” initiative reduce the need for clearing trees while also providing jobs. Bee-keeping and scouting/patrol provide more opportunities. Revenue from the offsets is also used for clean water (boreholes), agricultural tools like a hammer mill, buildings for schools and clinics, and more. BCP has created a program that works for the people, the wildlife, and the trees, while meeting the strict standards of carbon offsetting.

One of the keys to making this work is the local emphasis. “We are majority African-citizen owned and our team is 98% comprised of African-born staff. Our headquarters is in rural Zambia, amongst the communities and forests where we work; not in a capital city.” Their strategy to put the people front and center -- their mission is to “Make conservation of wildlife habitat valuable to people.” -- is another key ingredient to their success. As a result, BCP has attained top-notch verification of their offsets for many years running, and wildlife is beginning to return to some areas.

But how is a consumer to know if a project is good quality? Standards are evolving to better describe the qualities of the projects, and vendors are making it easier for buyers to find projects that are a good fit. I will talk more about standards and vendors towards the end of this post, but first I want to talk about pricing, which is pretty confusing.

Suppose you are interested in offering families who are cooking with coal or wood over an open fire the option of a cookstove that is healthier, faster, and cleaner. This cookstove project in Uganda costs $4.94 per tonne of carbon saved; this one in Malawi costs $8.50 per tonne, and this one in Peru costs $15.00 per tonne. Is the Peru project better? Not necessarily.

A variety of factors affect the price of a carbon offset, not just the type and location of the project. The Gold Standard has published a good overview of factors that affect offset pricing. For example, projects that have more oversight can be more expensive, as they strive to meet more comprehensive certification standards. Some verifiers may take a profit. Smaller projects are generally more expensive, since the certification overhead is relatively higher. Credits for projects that happened a while ago may be cheaper. Costs can change even within a project as it develops. (3)

So a cheaper project may remove just as much carbon as a more expensive project. And yet the cheapest offset may not be the best fit. A consumer may pay more for certifications that offer more assurances. The Gold Standard is particularly well-respected, as is the combination of VCS and CCB certification. The well-regarded Climate Action Reserve and American Carbon Registry standards focus on projects in the US, which some US-based consumers may prefer. (4) The “co-benefits” of a project (those beyond reducing emissions) may be significant for consumers and so will fetch a higher price. For example, some may prefer projects that benefit women or children, or that are located in developing countries, or that preserve crucial wildlife habitat.

A local offset vendor, Marin-based Cool Effect, is working to make it easier for consumers to purchase high-quality offsets that match their interests. After the founders led an effort to design and distribute cleaner cookstoves to homes in Honduras, they recognized a need to help consumers find projects that meet the strictest standards for offsets while also providing meaningful community benefits. Marketing Manager Blake Lawrence said that of the thousands of projects Cool Effect has looked at, they have visited 150-200, and of those sponsored 15-20. With interest in their offsets skyrocketing, they are working quickly to add more projects. (5)

Cool Effect puts a premium on transparency and financial efficiency. It is a non-profit that gives over 90% of its income to the projects. Project descriptions list risks alongside benefits so that consumers understand the challenges. But most of all they focus on the quality of their projects. They look carefully at the methodology for assessing offsets. For example, when deploying new cookstoves in Uganda, if a family takes the new one but also hangs onto their old one, then the emission savings are not counted. Strong community benefits help ensure the projects will last. One of Lawrence’s favorite projects involves installing biodigesters in rural farms. The digesters convert farm waste into methane, which is then used to power lights and stoves in the village. The result is cleaner, faster, and cheaper cooking, free electricity, and even less-smelly animal stalls, all while reducing emissions and helping to preserve trees. “Digesters are a great tool,” enthuses Lawrence. “You see immediate impact, improving peoples’ lives.” A short video taken on site reflects this.

A biogas digester being built for a project sponsored by Cool Effect

Are we being marketed to? Absolutely. Do vendors choose projects that will best appeal to guilt-ridden carbon emitters like us? Of course -- they need money to make an impact. But does “feel good” imply it does not “do good”? Not at all. Biocarbon Partners and Cool Effect, and others like them, are putting in a lot of effort to identify and manage projects that both feel good and do good. IMO it is a fine thing to purchase these offsets for emissions that we cannot easily avoid right now.

But (and there’s always a but). We need to keep top of mind that even the best carbon offsets (6) are a band-aid for countries’ unwillingness to make effective policy and for individuals’ unwillingness to reduce our own emissions. We have some choices to make. Do we want to save our natural resources at scale? Where and how should that happen? Recently (very expensive) mechanical offsets have become available through Climeworks, with precise carbon dioxide reductions but no co-benefits. Do we optimize for a world of mechanical carbon balance or of natural carbon balance? Which is faster? Cheaper? I prefer a natural balance, but I’m pretty sure that moneyed interests prefer a mechanical balance because there is more they can contribute (and earn) and more room for human innovation. What balance do we strike, and how? And how does that affect where you put your own money?

So, for now, yes, go ahead and offset your emissions. It can do good. But the voluntary offset model cannot match the scale and urgency of the challenges we face. Consider the other pillars of climate action -- individual action, political engagement, financial investment and divestment -- and think what more you can do, both at home and at work, to create the future you are looking for.

I’d love to hear your thoughts on carbon offsets, your experience with them, and how you believe they impact people (both beneficiaries and funders) and the planet.

Notes and References

1. Flaring (burning) methane converts the methane to carbon dioxide, which is an overall improvement in emissions since methane is a much more powerful greenhouse gas, at least while it persists in the atmosphere.

2. Biocarbon Partners says that Zambia’s deforestation is the highest in Africa, with an average of more than 1,000 square miles of wildlife habitat disappearing each year. The areas they are protecting provide habitat for the African wild dog, Temminck’s pangolin, the leopard, lion and elephant, among others.

3. In part because costs change over the lifetime of a project, offset vendor Atmosfair doesn’t publish the prices of its projects or give consumers a choice of project, as explained in its interesting FAQ on the topic. They charge a (rather high) flat fee of $25 per tonne of carbon.

4. I used to think that Americans should purchase offsets for US-based projects rather than projects in developing countries. Let’s clean up our own emissions before we interfere elsewhere. Let’s make our own country more sustainable. But now I see both sides. A dollar may go farther (clean up more emissions) elsewhere. Emissions from developed countries are hurting developing countries, so money should arguably flow in that same direction. And green improvements in developing countries can have more impact if they establish a working model for clean growth.

5. Lawrence says that interest in offsets “took off” after Greta Thunberg announced she would sail to New York. Purchases of individual travel offsets on the Cool Effect site have grown 700% since May. Business contracts have also “really stepped up. It’s night and day (from a year or two ago),” he says.

6. As I’ve tried to point out, offsets can be very “squishy”. It can be hard to establish an accounting baseline (what would happen if there were no project). It can be hard to ensure longevity. It can be hard to prevent leakage or problematic side-effects. The best offsets provide a constellation of social benefits as well as measurable reductions in greenhouse gas emissions, but even those have uncertainty. At the end of the day, reducing your individual emissions is the surest thing you can do, but you can also have some impact through quality offsets. Some people use offsets to cover flights (Atmosfair has a particularly informative interface for this), but others cover the entirety of their household emissions. Because of the uncertainty around offsets, you might consider doubling the amount you purchase and diversifying your purchases. But keep in mind that the better offset projects maintain a pool of credits to use in case of unexpected problems, so your purchase already has a buffer in it.

7. The Carbon Offset Research and Education (CORE) initiative produces an excellent, comprehensive overview of carbon offsets. It is particularly useful for companies looking to offset emissions. National Geographic has a much shorter overview more targeted to individuals, as does NRDC.

8. Two people at the University of Pennsylvania have written a more prescriptive but still very informative overview of carbon offsets. (They wrote this while figuring out how best to offset the SIGPLAN conference.)

9. The Gold Standard has an interesting post about what carbon credits are worth. Carbon pricing in general is a good topic for a whole blog post because each country prices it differently (if at all), and the “social cost” of carbon may be different from any carbon tax, or any carbon credits.

10. ProPublica published a well-read article about the failures of carbon offsets, as well as a rebuttal to criticisms about that article. Ecosystem Marketplace has an interesting interview about practical challenges preserving forests in Asia.

11. You can read about the projects that Palo Alto Utilities funds to offset its customers’ use of natural gas.

12. Thank you to Palo Alto resident Bea Crystal for her help reaching out to Biocarbon Partners.

Current Climate Data (December 2019)
From CarbonBrief’s summary of its “How the world warmed in 2019” report: “2019 was the warmest year on record for ocean heat content, showing a marked increase from 2018…. With modern-era sea levels also now at a record high and Arctic sea ice and global glacier ice both continuing their dramatic downward trends, the report highlights just how many alarm bells are currently ringing in the data.”

Global impacts, US impacts, CO2 metric, Climate dashboard (updated annually)

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Posted by Hottest decade in recorded history, a resident of Charleston Gardens,
on Jan 26, 2020 at 6:33 pm

“2019 was the warmest year on record for ocean heat content, showing a marked increase from 2018....

With modern-era sea levels also now at a record high and Arctic sea ice and global glacier ice both continuing their dramatic downward trends, the report highlights just how many alarm bells are currently ringing in the data."

I do *so* appreciate that you sneak in updated news on our climate disaster.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 26, 2020 at 10:38 pm

"A good project needs to make practical and economic sense for the locals, but it also needs to be something that wouldn't have happened anyway."

Especially that last part. A project can always be made to make practical and economic sense for the locals if the buyer fronts enough money, but the carbon offsets pencil out in the real GHG world only if the project's carbon sink activity is dedicated solely to the offset. No double-dipping.

Of course, nothing makes better sense than to not emit the carbon, while installing the carbon sink anyway.

Posted by John Baker, a resident of another community,
on Jan 27, 2020 at 12:08 pm

Thanks for your very informative article. My wife and I are involved with a small of group of folks that meet monthly to discuss assorted issues associated with our climate crisis.

Carbon offsets has been a recent topic of discussion, so I will pass this along to the group.

Of course using carbon offsets is better than not, but of limited use if not accompanied by doing everything possible (and within one's budget) to reduce carbon footprint. I think that it is possible to zero it out, travel aside. To me that means using the offsets for that purpose while being judicious in the amount of air travel we do.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 27, 2020 at 2:18 pm

Sherry Listgarten is a registered user.

@Curm -- Yes, it's important to avoid double-counting, and it's not always obvious, at least to me. Atmosfair writes (point 2) that it does not have any projects in the EU because the emissions savings would basically be double-counted by the EU's cap-and-trade program. I'm not sure why that has to be true, but it raises the question of whether that is also the case in California. And what if more states adopt cap-and-trade?

Here's a question. We know that every country reports its emissions. Suppose country P (for poor) gets lots of clean digesters and cookstoves from companies in country R (for rich). Country P's emissions have gone down. Yay! Presumably when Country P reports its emissions they will be lower because of the new cleaner appliances. Satellites could also in theory see that P's emissions are lower. But what about Country R? Satellites will see that emissions have not changed from those companies, but those companies will file reports to (some organization) that they are carbon-neutral. Do those reports roll up into Country R's emissions? They shouldn't, right? Both countries need to use compatible emissions accounting, but do they?

I do not understand how this works (or if it works). You can see why some people/countries get very frustrated when other people/countries seem to rely too much on strategies involving carbon trading, because it can seem like smoke and mirrors.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 27, 2020 at 4:16 pm

"I do not understand how this works (or if it works)."

That looks like a classic case of double counting to me. Country P's real emissions have declined by a given amount, say dE. Country R's real emissions are unchanged by the transaction. The planet experiences a real emissions reduction of dE. Full Stop.

Accounting rules may allow country R to claim an offset dE, but the planet does not experience an actual reduction of dE + dE. Like, one cannot cut a foot off one end of a blanket, sew it on the other end, and proudly possess a blanket one foot longer.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 27, 2020 at 4:47 pm

Sherry Listgarten is a registered user.

Right. But in practice I don't know how it works. I am guessing that the global agreements on emissions reporting anticipated this and have accounted for it, but I don't know how, and it's even possible they didn't do it thoroughly enough. (Double-counting is one of the things that is hanging up discussions on Article 6 -- carbon trading -- wrt the Paris Agreement.)

Posted by Curmudgeon, a resident of Downtown North,
on Jan 27, 2020 at 8:19 pm

I understand our utilities department does much the same thing. It buys some carbon offsets from renewable power generators in other parts of the country, who in turn sell their power to their local customers. In an honest real accounting, they would take the emissions rap while PA touts the credits it bought.

But I've never been clear if the remote sellers also get the emissions reduction credit, by virtue of their being the ones who actually reduced their emissions. That would be double counting. I've read rumblings to that effect regarding other similar transactions, but the accounting is always outlined qualitatively, not detailed quantitatively. Do you know someone in the utilities department who could enlighten us?

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 27, 2020 at 9:26 pm

Sherry Listgarten is a registered user.

@Curm: Ah, yes, you are talking about Renewable Energy Certificates, or RECs, and in particular unbundled RECs. The issue with those is generally *not* double counting, though, it's more subtle. IIRC it's about their overall impact on the clean energy market and whether the use of unbundled RECs does enough to encourage development of more clean energy. Palo Alto Utilities does use them (for example in low water years), and is supportive of them. I believe they help to lower costs. Peninsula Clean Energy, on the other hand, does not use them, and is not supportive of them. Unbundled RECs generally reflect out-of-state purchases of clean energy (typically purchases from states that do not have their own RPS requirements, but another example might be other states purchasing California's excess solar in the spring).

The state already limits how much of the RPS can be met using these unbundled credits. There is an upcoming change in reporting (on the power content labels) that will make the use of these more evident.

Some references:
- About RECs (EPA)
- About Unbundled RECs (EPA)
- About upcoming reporting changes (Sierra Club)

To explicitly answer your question, no, the state providing the unbundled REC does not claim the renewable energy credit. It gets the energy but not the credit. There is just one renewable energy credit, and only one user gets it. There is no double-counting with these.

Posted by Sophie88, a resident of Another Mountain View Neighborhood,
on Jan 28, 2020 at 4:42 pm

Thanks for this article. Carbon emissions credit (I forgot the official term) was available to trade in early 2000. EU countries usually purchased carbon emission credit From other countries to offset their carbon emission to claim neutral. I remember there use to be such Market organization can trade the carbon emission credit and I used to be a project manager to facilitate and validate those credits were legit. Anyway, now I lost track of such projects and am interested to learn the latest status..

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 28, 2020 at 5:37 pm

Sherry Listgarten is a registered user.

Hi Sophie. I expect you are talking about the Clean Development Mechanism that was developed as part of the Kyoto Protocol (which the US was not party to). It didn't work out so well. There is a huge report on it here, but you can read the executive summary to get an idea, or there are many other sources on the internet... There is an argument now about whether to allow those credits to be used as part of the new post-Paris trading. Most countries say no (it's not clear that they represent real emissions cuts), but a few countries (that have amassed a lot of credits) say yes.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 29, 2020 at 11:04 am

RECs have the effect of making us think our electric power is cleaner than it is, which disincentizes conservation. Worse, that belief leads to the counterproductive electrification push currently underway.

The bottom line is that using power in Palo Alto releases carbon. Full Stop. RECs can buy virtue but conservation is what saves the planet.

Thanks for running a great forum.

FWIW, there's a very instructive and impactful graphic at It's even fun to read.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 29, 2020 at 11:22 pm

Sherry Listgarten is a registered user.

@Curm: Yes, it is hard for people to understand why we need to conserve electricity, or use it at certain times, when our area’s power is already “carbon-free” (or “carbon-neutral” is the term that Palo Alto uses). We buy clean power but we don’t get clean power. Having a big, shared grid with trading and accounting schemes layered on top of it helps to keep costs down and use energy more efficiently, but it’s sure not intuitive.

FWIW, if you want to learn more about how these RECs fit into Palo Alto Utility’s strategy, there is a Utilities Advisory Commission meeting on February 5 at 7pm that will cover some of it. (They’ve been talking about it in previous meetings.) Or you can just read this and the various links in it.

Glad you like the blog, and that’s a great xkcd comic. Did we really do all that metalworking before inventing the wheel??

Posted by Heat pumps?, a resident of Downtown North,
on Jan 30, 2020 at 7:09 am

Heat pumps? is a registered user.

Can you explain more about "the counterproductive electrification push"?

We are about to get a heat pump water heater. Our water heater is around 30% of our electric use. The heat pump will save us money and it will reduce greenhouse gases even on today's grid. I see it as being like an LED light - a much more efficient way to heat water. It is expensive to install but the city provides a $1200 rebate. What am I missing? Aren't heat pumps a good way to conserve energy? We have gas now, and the occasional power outage is no big deal for us.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 30, 2020 at 4:32 pm

"Did we really do all that metalworking before inventing the wheel??"

Why not? Some cultures never did "invent the wheel."

Actually, the big leap was not the wheel itself--it's easy to conceive of rolling something heavy on a series of logs--the breakthrough was the axle. It permanently attached the rolling parts to a container and made it possible to transport heavy loads that weren't amenable to rolling over a bunch of logs.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 30, 2020 at 4:42 pm

"Our water heater is around 30% of our electric use."

Then shame on you. Electric energy is an extremely versatile form of energy which required millennia for some of the very best minds in history to conceive and develop. Making heat with it is a supreme waste, a mortal sin.

"We have gas now, and the occasional power outage is no big deal for us."


Posted by Heat pumps?, a resident of Downtown North,
on Jan 31, 2020 at 12:24 pm

Heat pumps? is a registered user.

I meant to say that our water heater is 30% of our gas use (not our electric use). That is why we are looking to an electric heat pump. We have upgraded our lights to LED, and see no reason our water heater shouldn't also be made more efficient with much lower emissions. The electricity is not used for heat, it is used to exchange warmer air for cooler, much like a refrigerator in reverse. I trust that is not a mortal sin, else we are all doomed.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 31, 2020 at 6:25 pm

"The electricity is not used for heat, it is used to exchange warmer air for cooler..."

True, that's what a refrigerator does. We're talking about using electric energy to heat water here.

The power plants that burn natural gas to get heat to boil water to make steam to run electric generators waste almost 2/3 of the heat energy released by burning the gas. It makes no sense to turn that hard won electric energy back into the heat it was so arduously extracted from when 1) It has much better uses, like lighting and communication and home refrigeration, which cannot be accomplished otherwise, while 2) The gas can be burned for direct heating on site at much higher efficiency than 1/3.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 31, 2020 at 7:49 pm

Sherry Listgarten is a registered user.

@Curm: Do you have a reference? I ask because I don't think what you say is true. Did you read this blog post?

Or take a look at this chart from the CEC, comparing an electric heat pump to a tankless gas water heater, using the electric mix on today's grid.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 31, 2020 at 8:32 pm

For the first, Web Link page 12. Useful number: 3412 BTU/kWh

I'll need help locating the original CEC chart so I can understand what data it's presenting.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jan 31, 2020 at 9:27 pm

Sherry Listgarten is a registered user.

Right. "Over the past five years, California has maintained an average heat rate of about 7,750 Btu/kWh". So that is 44% efficiency, not 33%. But that isn't my main point.

You need to incorporate the appliance. A modern gas furnace is 95% efficient. The best tankless water heaters are similar. A modern heat pump water heater is about 300% efficient. It (very cheaply) steals heat rather than generates heat.

The chart shows the ratio of emissions per unit of heat for the electric heat pump vs the gas heater. Green squares means the electric heat has lower emissions than the gas heat. The numbers indicate by how much. You can hear Martha Brook speaking about it here.

The chart assumes climate zone 3 using the electricity mix on the 2019 (or 2018) grid, for each hour of each month of the year. Fugitive emissions (methane leaks from transmission and distribution) are not included in the calculations behind this diagram, while the corresponding adjustments for electricity (transmission and distribution losses to the home) are included. A chart reflecting those fugitive emissions would be greener.

Posted by Curmudgeon, a resident of Downtown North,
on Jan 31, 2020 at 10:49 pm

OK, I was using the 8817 BTU/kWh (38% thermal efficiency) figure for 2017, on the presumption that the most recent numbers represent the latest and presumably best practices.

Time of use is a consideration. Especially during the morning and evening peak hot water demand intervals when the relatively inefficient peaker plants are most active. But that's maybe too much detail for present purposes.

How about we compromise on 40% = 2/5?

The point is that generating electric power from burning fuels involves generating a lot of heat, then discarding most of that thermal energy in order to squeeze out the electrical power fraction we do get. If you're going to extract power from heat, why then throw away your prize by converting it back to heat, when you can burn that fuel at home and utilize almost all of that heat?

What happened to totally no-operating-carbon solar hot water heaters? They were very popular a few decades ago.

Can you refer me to the document where you got the colorful CEC HP chart?

Posted by Sherry Listgarten, a Almanac Online blogger,
on Feb 1, 2020 at 12:10 pm

Sherry Listgarten is a registered user.

@Curm: Unfortunately, I don't have documents, just video. Martha Brook sent these to me after we talked. What information are you looking for?

I sound like a broken record, but the pumps do not generate heat. They just move it. So traditionally they haven't worked well in below-freezing temperatures, though manufacturers keep improving them.

FWIW, there is gobs of information about building electrification in presentations and videos from CEC workshops. You can find the 2019 ones here and the 2018 ones here. I realize it's a lot to go through, though.

Posted by Curmudgeon, a resident of Downtown North,
on Feb 1, 2020 at 6:01 pm

I was looking for a detailed explanation of how the authors of the CEC charts made their measurements.

You correctly point out what these charts should show: "the ratio of emissions per unit of heat for the electric heat pump vs the gas heater." But Brooks indicates they show the emissions ratio for the time intervals when both systems are operating.

In other words, the charts compare emissions rates, not net emissions. Since the gas appliance operates intermittently but intensely, while the heat pump churns away continuously at a low input power level (Brooks, ~1:00:00), the charts are meaningless regarding total emissions. I know that's harsh, but the CEC staff ought to know better.

Heat pumps generate heat. All electrical devices do, with 100% ultimate efficiency. HPs they achieve a, say, 300% efficiency rating because they move twice as much heat as they generate. In any case, their effectiveness (and likely efficiency) critically depends on chilling their outdoor heat exchanger to a lower temperature than the ambient air. Else they pump heat out of the water tank and into the environment. Result: cold showers.

I wonder if anybody makes a home air conditioner/water heater combo.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Feb 1, 2020 at 6:50 pm

Sherry Listgarten is a registered user.

@Curm: Yes, I'm sorry I don't have written documentation.

As you may know, Brook (no "s") has worked on efficiency at the CEC for decades. She does know better. What she is saying is that because the electric heat pump runs constantly during cool nights, while a gas furnace runs infrequently, the gas does relatively better during that time. Remember, red means gas is better. The chart, as you would expect, reflects a full hour of emissions for each type of heater for each square, using the emissions intensities of the 2019 grid.

And, yes, heat pumps work better in temperate climates. The chart is for zone 3, which is San Mateo County and areas north. Palo Alto is (just barely) in zone 4, where they work slightly better.

I'm not sure what else to add. Placing heat pump water heaters can be tricky. They take longer to heat water than gas. And it's important that the refrigerant never leaks, at least in traditional models. But do they work? And do they reduce emissions? Even on today's not-so-clean grid? Yes, they do.

Posted by Curmudgeon, a resident of Downtown North,
on Feb 1, 2020 at 8:44 pm

"because the electric heat pump runs constantly during cool nights, while a gas furnace runs infrequently, the gas does relatively better during that time."

If each maintains the same water temperature in the same water tank (or twinned tanks) at the same external temperature, their total heat energy outputs must be identical in the same time interval. How they distribute their energy outputs and inputs over that interval is irrelevant. What matters is the ratio of emissions per unit of heat for the electric heat pump vs the gas heater.

The prior chart in the series, which deals with space heating, clearly indicates something is seriously wrong with the CEC's methodology. For example, it is just incredible that emissions per unit of heat from a gas furnace are 800 to 1,040 times better than from a heat pump. But the early December morning entries say it is. The other winter months show similarly wild results. Stated gently, these charts are meaningless.

Somebody at CEC goofed. Such things happen. I'm not saying Brook is that somebody.

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