Monday, November 23, 2020

Shift to electric vehicles in emerging markets will ‘end oil era’ - China leads transition that may slash growth in global oil demand by 70% – Nothing to lose but your chains: The emerging market transport leapfrog

China is leading a switch to electric vehicles (EV) in emerging markets which will save governments $250 billion a year in oil imports and cut expected growth in global oil demand by 70%, finds a new report from the financial think tank Carbon Tracker published on Friday.

It’s thought to be the first study to reveal that transport in emerging markets accounts for more than 80% of all expected growth in oil demand up to 2030, based on an analysis of the International Energy Agency’s business as usual scenario. Half of the growth is forecast to come from China and India.

But the report notes that these countries are already reducing their dependence on oil and actively supporting EVs as prices fall close to those of petrol and diesel vehicles. China leads the world in the deployment of EV and India is following the same path.

“This is a simple choice between growing dependency on what has been expensive oil produced by a foreign cartel, or domestic electricity produced by renewable sources whose prices fall over time. Emerging market importers will bring the oil era to an end.” notes Kingsmill Bond, Carbon Tracker energy strategist and report lead author.

Most governments have strong incentives to electrify their transport systems. Emerging markets – India, China, South East Asia and most of Africa – spend huge sums on oil imports every year, and two thirds (68%) is used for transport. Oil imports cost 1.5% of China’s GDP and 2.6% of India’s GDP.

Nothing to lose but your chains: The emerging market transport leapfrog calculates that a switch to EVs could save emerging markets up to $250 billion a year collectively on oil imports by 2030, more than enough to pay for the infrastructure needed to support electrified transport. Annual savings would be over $80 billion in China and over $35 billion in India.

There are also strong public health grounds to cut oil use. Pollution linked to road transport causes 285,000 deaths a year in oil-importing emerging markets, including 114,000 in China and 74,000 in India, reports the International Council on Clean Transportation.

Battery prices have fallen 20% a year since 2010, stimulating huge new markets for EVs. The next few years will see them fall from $135/KWh to below $100/KWh, the point at which EVs become as cheap to buy as conventional vehicles. By 2030 they will be cheaper still – BNEF forecasts a battery price of $61/KWh while carmakers like VW and Tesla expect $50/KWh.

Chinese central planning has supported the country’s EV industry for many years as a means to reduce oil dependency and establish a lead in the emerging technology. China’s BYD is now the world’s fifth biggest carmaker, with a larger market capitalisation than General Motors.

In 2019, EVs accounted for 61% of China’s two-wheeler sales and 59% of bus sales, and the government plans that by 2025 one in five cars sold will be an EV. President Xi Jinping’s recent commitment to achieve net zero emissions by 2060 implies that all car sales in China will need to have an EV drivetrain by 2035.

Other countries are poised to follow. The Indian government plans for EVs to make up 30% of car sales by 2030, but local forecasters believe that by that date 30% of cars and 80% of two-wheeler sales could be electric.[1]

Shift to EVs will pay for itself

Countries can finance the shift to EVs from the huge savings they will make on oil imports. Carbon Tracker calculates that the cost of importing oil for the average car is ten times higher than the cost of the solar equipment needed to power an equivalent EV.[2]  The annual cost per car of imported gasoline is almost the same as the total cost of local charging infrastructure for an EV.[3]

Moreover, switching to EVs brings wider economic benefits by cutting the price of any remaining oil imports. Emerging markets are the single biggest driver of expected growth in demand for oil, so if that trend plays out it could contribute to prices falling by up to a quarter.

Thursday, November 12, 2020

Lead in Drinking Water and Birth Outcomes: A Tale of Two Water Treatment Plants

The recent drinking water crisis in Newark, New Jersey's largest city, has renewed concerns about the lead-in-water crisis becoming a persistent and widespread problem owing to the nation's aging infrastructure. We exploit a unique natural experiment in Newark, which exogenously exposed some women in the city to higher levels of lead in tap water but not others, to identify a causal effect of prenatal lead exposure on fetal health. Using birth data that contain information on mothers' exact residential addresses, we find robust and consistent evidence that prenatal exposure to lead significantly raises the probability of low birth weight or preterm births by approximately 1.4 to 1.9 percentage points (14-22 percent), and the adverse effects are largely concentrated among mothers of lower socioeconomic status. Our findings have important policy implications in light of the long-term impact of compromised health at birth and the substantial number of lead water pipes that remain in use as part of our aging infrastructure.
With infant health being an important predictor of later-life outcomes, these estimates are critical towards evaluating the cost-benefit calculus of infrastructure investments, including replacing all of the nation’s lead service lines, an initiative supported by the EPA as well as many states and communities at a potential cost of between $29 to $47 billion (EPA, 2019)... The EPA (2019) noted 6.1–10 million lead service lines (LSL) nationally, with an average estimated replacement cost of $4,700 per LSL
In March 2019, Newark commenced a program to remove and replace all of the city’s lead service lines in the water system at no cost to the homeowner, at a projected public cost of $90–$180 million. With the lifetime societal economic burden of a preterm birth estimated to be approximately $66,331 2018 dollars. The Institute of Medicine (2007) estimated the societal burden of a preterm birth to be $51,589 in 2005 dollars. The societal cost of the lead crisis in Newark could amount to $1.99–$2.65 million per year, just from an estimated increase of 30 to 40 preterm births linked to the heightened lead exposure each year. [30 (or 40) preterm births×66,331 per preterm births = $1.99 million (or $2.65 million)],

Assuming a discount rate for public policy of 2 percent based on the social rate of time preference (Council of Economic Advisers, 2017), societal cost savings from averting this adverse fetal health could be between $100 and $133 million, significantly offsetting the cost of public infrastructure investment. [There is ... debate as to the appropriate discount rate to apply for public policy (see for instance, Council of Economic Advisers,2017; Li and Pizer, 2018) depending on the social rate of time preference or the social opportunity cost of capital, and the length of the time horizon under consideration. The U.S. federal guidance requires agencies to use both a 3% and a 7% real discount rate in regulatory cost-benefit analyses. Under this guidance, the societal cost savings of averting the adverse fetal health would be between $66.3 million and $88.3 million (social discount rate of 0.03) and between $28.4 million and $37.9 million (social discount rate of 0.07). Clearly, the cost implications are sensitive to the discount rate employed. With long-term real interest rates decreasing substantially over the past decade, a recent issue brief by the Council of Economic Advisers (2017) recommends lowering the estimate of the social discount rate in applications to public policy cost-benefit calculus.
by Dhaval M. Dave & Muzhe Yang
National Bureau of Economic Research (NBER)
Working Paper 27996; October 2020

Monetising the savings of remotely sensed data and information in Burn Area Emergency Response (BAER) wildfire assessment

We used a value of information approach to demonstrate the cost-effectiveness of using satellite imagery as part of the Burn Area Emergency Response (BAER), a US federal program that identifies imminent post-wildfire threats to human life and safety, property and critical natural or cultural resources. We compared the costs associated with producing a Burn Area Reflectance Classification map and implementing a BAER when imagery from satellites (either Landsat or a commercial satellite) was available to when the response team relied on information collected solely by aerial reconnaissance. The case study included two evaluations with and without Burn Area Reflectance Classification products: (a) savings of up to US$51 000 for the Elk Complex wildfire incident request and (b) savings of a multi-incident map production program. Landsat is the most cost-effective way to input burn severity information into the BAER program, with savings of up to US$35 million over a 5-year period.
by Richard Bernknopf, Yusuke Kuwayama, Reily Gibson, Jessica Blakely, Bethany Mabee, T.J. Clifford, Brad Quayle, Justin Epting, Terry Hardy, and David Goodrich
International Journal of Wildland Fire -
Published online: 22 October 2020 

Combining information on others’ energy usage and their approval of energy conservation promotes energy saving behaviour

Households reduced their electricity use the most when they learnt both that they were using more energy than their neighbours and that energy conservation was socially approved. This suggests that efforts to use social information to nudge conservation should combine different types of social feedback to maximize impact.

Messages for Policy
  • The content of social information messages determines their impact on energy conservation.
  • Combining descriptive information on neighbours’ efficient energy usage and injunctive social approval for energy efficiency maximizes the effectiveness of social information.
  • Delivering inconsistent descriptive and injunctive information reduces the impact of each piece of feedback.
  • Simply adding more pieces of feedback of the same type has a limited effect.
Based on J. Bonan et al. (2020).

The policy problem
Home Energy Reports (HER) are a popular means of encouraging energy conservation, reaching millions of energy utility customers across many countries. HERs typically rely on social information about the energy usage of a customer’s neighbours (descriptive feedback) and their social approval of energy conservation (injunctive feedback) to nudge recipients toward more energy-efficient behaviour. The specific content of both types of feedback depends on how the recipient’s energy usage compares to that of their neighbours (Fig. 1). Available evidence indicates that the impact of HERs on energy consumption varies significantly both across countries and across individuals. This raises the question of whether the heterogeneity in the effectiveness of HERs can be attributed to how social information feedback is conveyed. Answering this question could inform the design of more effective communication campaigns relying on social information.

Fig. 1: Home Energy Report.
a–c, Layout and content of a Home Energy Report for a user receiving three thumbs-up (a); and a user receiving two thumbs-up (b). Both versions of the report contain injunctive feedback, that is, the thumbs-up (top), and descriptive feedback, that is, the bars displaying actual energy consumption (bottom). The figure also displays the position of the randomized descriptive or injunctive norm primes, whose text is shown in (c). Reproduced from Bonan, J., Cattaneo, C., d’Adda, G. & Tavoni, M. Nat. Energy (2020). Copyright 2016-2020

The findings
Energy customers who received two different types of social feedback (descriptive and injunctive) encouraging them to save energy reduced their consumption more than low-energy users for whom conforming with the descriptive feedback would entail consumption increases, at odds with the injunctive feedback praising energy saving. The addition of a second piece of information of the same type (for example, adding a second descriptive messages that encouraged energy saving) had a limited impact. When feedback was inconsistent, the piece of feedback delivering the strongest message prevailed, where strength reflected the difference between the user’s energy consumption and that of their neighbours (descriptive feedback) and the intensity of social approval conveyed through visual cues (injunctive feedback). These results suggest the significance of synergies between different types of feedback, rather than the superiority of any one type of feedback. The results may be specific to the precise wording and graphical representations used to provide feedback in our HER (Fig. 1), and may not generalize to the whole customer base.

The study
We carried out a randomized controlled experiment in Italy in which households received HERs. We disentangled the impact of descriptive and injunctive feedback in two ways. First, we exploited the discontinuities in the injunctive feedback, which changed discretely as users’ consumption crossed certain thresholds, for instance shifting from one to two ‘thumbs-up’ as a user’s consumption dropped below the average of their neighbours. Second, we randomly assigned customers to receive a message at the bottom of the HER emphasizing either a descriptive or an injunctive norm of energy conservation (Fig. 1). Using data on the content of the HERs received by users and on their energy consumption, we were able to evaluate the impact of each piece of feedback in isolation, and when combined with others of the same or of different types.
by Jacopo Bonan, Cristina Cattaneo, Giovanna d’Adda & Massimo Tavoni 
Nature Energy Policy Brief
Volume 5, Published: 02 November 2020; Pages 832–833 (2020)

The main article "The interaction of descriptive and injunctive social norms in promoting energy conservation" by the same authors published on the same day at (pages900–909) notes
the magnitude of the average savings from the programme (−0.353%) is outside the range of those generated by similar ones in the United States (minimum = 0.88%, maximum = 2.55%), they are in line with the existing evidence from Europe. Various factors, such as lower average consumption in Europe than that in the United States, the specific features of the programme we studied or differences in beliefs across contexts, may be responsible for these differences. The heterogeneous effects, although not robust and only marginally statistically significant, are qualitatively in line with the existing evidence on the larger impact of social information on high electricity users and on the absence of boomerang effects among low users

These results provide initial, albeit weak, support for our conceptual framework. For high users, normative and injunctive feedbacks pull behaviour in the same direction, which results in a reduction in electricity almost twice as large as that in the average treatment effect. For low electricity users, conforming to the reference groups’ behaviour motivates a consumption increase (’boomerang’), but the injunctive feedback included in the eHER counterbalances the negative effect of the descriptive feedback. 

We Energies to retire 1.8 gigawatts of fossil fuel; utility adding solar, wind, battery storage

Wisconsin’s largest utility plans to replace nearly half its coal-fired generation with a portfolio of solar, wind, batteries and natural gas plants as part of a $16.1 billion spending plan that the company says will generate profits for investors and save money for ratepayers.

WEC Energy Group plans to retire 1,800 megawatts of fossil fuel generation — including the South Oak Creek coal plant near Racine — over the next five years while adding 1,500 megawatts of clean energy and storage capacity along with 300 megawatts of natural gas generation.
Oak Creek, Wis., coal-fired electrical power stations. Coburn Dukehart/Wisconsin Watch
Utility chairman Gale Klappa announced the capital plan during a call with investors Tuesday, in which he said it would help WEC meet its goal of carbon neutral electricity by 2050 and achieve a 55% reduction in carbon emissions by 2025.

Klappa said the spending plan, which is $1.1 billion larger than the previous five-year plan, will increase company profits by 5% to 7% a year while also saving ratepayers what amounts to $50 million a year over the next two decades.
In broad terms, the plan calls for building 800 megawatts of solar generation and 100 megawatts of wind generation coupled with 600 megawatts of battery storage, which can be used to balance those intermittent renewable resources.

“The data show that battery storage has now become a cost-effective option for us,” Klappa said.

The announcement comes as Wisconsin’s first utility-scale solar plant came online. Jointly owned by WEC subsidiary Wisconsin Public Service Corp. and Madison Gas and Electric, the 150-megawatt Two Creeks Solar Farm in Manitowoc County began commercial operation Monday.

Curtis Waltz Wisconsin Public Service Corp

WEC also intends to purchase a 200-megawatt share of Alliant Energy’s new West Riverside natural gas plant and build 100 megawatts of natural gas-powered peaking plants.

The company said those acquisitions will allow it to retire the 1,100-megawatt South Oak Creek power plant, whose four generators are all more than 50 years old, in 2023 and 2024.

WEC’s oldest coal-fired plant, South Oak Creek is the single largest source of toxic metals dumped into Lake Michigan, according to a Chicago Tribune analysis of federal data.

Last year, the Department of Natural Resources gave WEC until the end of next year to stop using water to remove ash from the boilers, a process that can lead to mercury and other toxins seeping into groundwater.
Klappa said closing an older plant like South Oak Creek could save $50 million a year in operational and maintenance costs.
Consumer advocates cautioned that ratepayer savings will depend on how regulators handle the hundreds of millions of dollars WEC has invested in fossil fuel plants over the past two decades.
On Thursday the Public Service Commission approved a plan for WEC to refinance $100 million of its remaining investment in pollution controls at its Pleasant Prairie coal plant, which WEC retired in 2018 saying it would save millions of dollars for ratepayers.  The financing arrangement, known as securitization, is expected to save ratepayers about $40 million.  Consumer and environmental advocates, as well as regulators, say securitization could be a key tool for paying off plants that are no longer economic to run.

Despite attempts by the Trump administration to prop up the coal industry, South Oak Creek is the 329th U.S. coal plant targeted for retirement since 2010, according to the Sierra Club.  Over the past decade, U.S. utilities have retired or replaced 95,000 megawatts of coal-fired capacity in response to tighter air pollution standards and increasingly unfavorable economics, according to the Energy Information Administration. Another 25,000 megawatts of coal capacity are expected to retire by 2025.  In the first six months of 2020, the U.S. electric power sector consumed 30% less coal than in the first half of 2019, according to recent data from the EIA.
Alliant Energy, which plans to add 1,000 megawatts of solar generation in Wisconsin, this year has announced plans to close its 415-megawatt Edgewater plant in Sheboygan by the end of 2022, while the company’s Iowa utility said last month it would also close a 275-megawatt coal plant in Lansing on the Mississippi River.

by Chris Hubbuch 
Kenosha News
November 6, 2020

Wednesday, November 11, 2020

Building Performance Standards: Lessons from Carbon Policy

This paper reviews the relevant design elements of carbon and environmental markets and explores how they could influence the design of Building Performance Standards (BPS) programs. Carbon and environmental markets have existed for more than three decades, giving policymakers experience with scope and target setting and the design of flexibility provisions. The paper also sketches out how the sector-specific BPS programs overlap and interact with existing cross-sectoral programs—state-level clean energy and renewable portfolio standards (RPS), the Regional Greenhouse Gas Initiative (RGGI), electricity markets, and transport electrification.
BPS programs can use several design options pioneered in the carbon markets— multiyear compliance periods, absolute or benchmarked targets, and various flexibility mechanisms—to provide flexibility, help balance environmental goals and compliance costs, and even generate revenues to fund related building efficiency programs. Initially focusing on the largest buildings or largest emitters allows a program to capture the bulk of the relevant emissions or energy consumption while lowering the administrative burden. Because BPS programs have a small geographic scope, leakage is a risk: the highest emitters, notably data centers and industrial sites, would have an incentive to exit the city if compliance costs become significant. This risk can be mitigated with tailored baselines, special allocation provisions, or a broader geographic scope—all strategies that have been used in carbon markets.

Understanding how trading of compliance obligations affects building owners’ retrofit decisions, compliance costs, and savings opportunities requires knowledge of the building sector’s abatement options and costs. Including tradable markets in a BPS design increases compliance flexibility, both across entities and across time when allowance banking is permitted. However, for a market to work effectively, building owners must have a clear understanding of the cost and the energy or emissions savings of various retrofit packages for their properties. The benefits of trading within a corporate bubble versus across all covered entities is difficult to gauge without an indepth understanding of the ownership structure of the city’s covered building stock.

BPS policies target both electricity and energy consumption and thus interact with other environmental programs. These interactions can take different forms, which are not always intuitive:

• The environmental benefits can be additive. For example, the New York City BPS should create demand for local renewable energy that is supplemental to the state’s Clean Energy Standard since New York State RECs can be sold only to compliance entities.
• Program-related emissions reductions could be offsetting. That might be the case with RGGI if emissions reductions tied to a BPS reduce the compliance burden for RGGI generators but not the RGGI cap.
• Buildings might be subject to conflicting measures if, for example, the state RPS drives emissions reductions that are not fully factored into a city BPS program’s algorithms used to calculate emissions, or if electric car charging stations increase electricity consumption covered by the program.

Although that list reveals potential policy and market interactions with BPS policies, further quantitative analysis is required to understand the magnitude of these interactions and their effects on emissions. As they develop future policies and modify current designs, municipal officials should recognize these interactions and adapt policy designs as necessary to counter or limit adverse consequences.
The first carbon market design question is, Which entities should be covered? The answer must balance two goals: capturing as much of the sector’s emissions as possible while keeping the number of compliance entities reasonable. Carbon markets therefore do not cover individual homes or vehicles but set the point of compliance at the power plant, refinery, or point of fuel distribution. BPS program designers must choose whether to regulate entities based on their size or based on their consumption or emissions level.
Price Formation
Regulatory programs entail compliance costs that can be expressed as cost per unit of emissions or energy consumption reduced. These compliance costs are reasonably transparent in tradable programs, which have transactable prices, and they are implicit in nontrading programs. This section uses a very simple conceptual model to illustrate price formation and trading dynamics in BPS programs.

Our hypothetical program targets energy reductions, which can be translated into carbon reductions. It has five buildings and two owners. All buildings face a 10 percent reduction target in the first phase of compliance. Each building has three abatement options: a lighting retrofit, the addition of window films, and an HVAC retrofit; not all options are available to all buildings (Table 3).

In reality, buildings have many options to reduce consumption and emissions. The Department of Energy’s Scout16 building efficiency software has close to 30 built-in commercial energy efficiency measures. The Tokyo program lists 20 distinct measures that span demand-side management and operational measures, appliance and lighting efficiency, heating and cooling systems, software, and sensors. Organized from lowest to highest cost per unit of avoided consumption or cost per unit of avoided emissions, these measures form the buildings’ marginal abatement cost (MAC) curve. In our conceptual example, lighting retrofits cost $0.90 per square foot for an assumed 12 percent reduction in building consumption. Using average office building consumption data, this represents a cost of $0.10 per Btu reduced: it is the most cost-effective option. Window film abatement costs are $0.13 per Btu, and HVAC upgrades’ cost-effectiveness is $0.44 per Btu. Our example builds an abatement cost curve in units of dollars per thousand Btu reduced; however, it could also be translated into dollars per ton of greenhouse gas reduced, given information on emissions rates and time of use for various energy forms, electricity in particular. The MAC curve is built by aggregating the effectiveness of the available measures over the building stock (Figure 1). For the five buildings at hand, the three measures can reduce consumption by almost 2 mmBtu, which represents 30.2 percent of the total consumption.

Wednesday, October 28, 2020

EVs Offer Big Savings Over Traditional Gas-Powered Cars - A Consumer Reports study shows that total ownership cost savings can more than make up for an electric vehicle's typically higher purchase price

When it comes to buying an electric vehicle, many consumers might like the idea, but they sometimes balk at the purchase price, which is typically higher than that of an equivalent gasoline-powered vehicle. However, new research from Consumer Reports shows that when total ownership cost is considered—including such factors as purchase price, fueling costs, and maintenance expenses—EVs come out ahead, especially in more affordable segments. (Download a PDF of the fact sheet and the complete report.)

The savings advantage can be compelling in the first few years and continues to improve the longer you own the EV. Our study shows that fuel savings alone can be $4,700 or more over the first seven years.
When comparing vehicles of similar size and from the same segment, an EV can cost anywhere from 10 percent to over 40 percent more than a similar gasoline-only model, according to CR’s analysis. The typical total ownership savings over the life of most EVs ranges from $6,000 to $10,000, CR found. The exact margin of savings would depend on the price difference between the gas-powered and EV models that are being compared.

For lower-priced models, the savings on ownership costs over the lifetime of the vehicle (200,000 miles) usually exceed the extra money paid for a comparable EV. For example, a Chevrolet Bolt costs $8,000 more to purchase than a Hyundai Elantra GT, but the Bolt costs $15,000 less to operate over a 200,000-mile lifetime, for a savings of $7,000, our study found. In the luxury segment, operating cost savings are often aided by a tighter price differential. The Tesla Model 3 is priced lower than the gas-powered BMW 330i, and priced only about $2,000 more than an Audi A4. But the savings on operating costs for the Model 3 are about $17,000 when compared with either of the popular German gas-powered sedans....
Says Chris Harto, CR’s senior policy analyst for transportation and energy, and the leader of the study. “As battery prices and technology improve, prices come down, and more attractive models hit the market, it’s only going to get better.”

Fuel savings: The study shows that a typical EV owner who does most of their fueling at home can expect to save an average of $800 to $1,000 a year on fueling costs over an equivalent gasoline-powered car.
Maintenance and repair: The study also found that maintenance and repair costs for EVs are significantly lower over the life of the vehicle—about half—than for gasoline-powered vehicles, which require regular fluid changes and are more mechanically complex. The average dollar savings over the lifetime of the vehicle is about $4,600.

Depreciation: CR’s analysts also found that newer long-range EVs are holding their value as well as or better than their traditional gasoline-powered counterparts as most new models now can be relied on to travel more than 200 miles on a single full charge. As with traditional gasoline-powered vehicles, not all EVs will lose value at the same rate as they age. Class, features, and the reputation of the vehicle’s manufacturer all have an impact on depreciation.

Currently, EVs and plug-in hybrids account for less than 2 percent of overall new vehicle sales, although that number has been on the rise since the first viable EV models began to appear on the market almost a decade ago. EVs have been forecasted to constitute anywhere from 8 to 25 percent of the new-car market by 2030. Falling manufacturing costs for the lithium-ion batteries used to power EVs and plug-in hybrids has also brought down prices, although many consumers may still balk at the price difference between EVs and the most fuel-efficient gasoline-powered cars. Tesla announced this month that it would introduce a $25,000 EV within the next year, signaling that EV prices could be falling in the near future.

To be sure, total cost of ownership can vary depending upon region, electricity-service rates, access to charging, and a number of other variables. For example, someone who lives in an extremely cold region with high electricity rates and low EV incentives from state and local government agencies will pay more over the life of the vehicle than someone who lives in an area with a mild climate, inexpensive electricity, and favorable tax incentives.
Some states—such as Arizona, Texas, Alabama, and Arkansas—impose high fees on EVs that could hurt the economics of EV ownership. Also, some EV models are eligible for a federal tax incentive of up to $7,500.

The amount of money a consumer can save on fueling depends on the size of the vehicle and length of ownership, according to the study. Car owners could save an average of $800 the first year, whereas pickup owners could save $1,300 in the same period. Savings in the SUV class falls in between. After seven years of ownership, an EV in the car category will save its owner $4,700, while overall savings for electric pickup owners balloons to almost $9,000. Savings over the lifetime of a vehicle approach $9,000 in the car category and $15,000 for trucks.
By Benjamin Preston
For Full Story Go To:
Consumer Reports Ad-free. Influence-free. Powered by consumers.
October 08, 2020

Temperature and economic activity: evidence from India

This paper investigates the impact of temperature on economic activity in India, using state-level data from 1980–2015. We estimate that a 1∘C increase in contemporaneous temperature (relative to our sample mean) reduces the economic growth rate that year by 2.5 percentage points. The adverse impact of higher temperatures is more severe in poorer states and in the primary sector. Our analysis of lagged temperatures suggests that our effects are driven by the contemporaneous effect of temperature on output; we do not find evidence of a permanent impact of contemporaneous temperatures on future growth rates.

by Anuska Jain,Roisin O'Sullivan &Vis Taraz
Journal of Environmental Economics and Policy  via Taylor Francis Online
Published online: 20 Feb 2020

Neglected No More: Housing Markets, Mortgage Lending, and Sea Level Rise

In this paper, we explore dynamic changes in the capitalization of sea-level rise (SLR) risk in housing and mortgage markets. Our results suggest a disconnect in coastal Florida real estate: From 2013-2018, home sales volumes in the most-SLR-exposed communities declined 16-20% relative to less-SLR-exposed areas, even as their sale prices grew in lockstep. Between 2018-2020, however, relative prices in these at-risk markets finally declined by roughly 5% from their peak. Lender behavior cannot reconcile these patterns, as we show that both all-cash and mortgage-financed purchases have similarly contracted, with little evidence of increases in loan denial or securitization. We propose a demand-side explanation for our findings where prospective buyers have become more pessimistic about climate change risk than prospective sellers. The lead-lag relationship between transaction volumes and prices in SLR-exposed markets is consistent with dynamics at the peak of prior real estate bubbles. 
Miami during a king tide (October 17, 2016)

by Benjamin J. Keys & Philip Mulder
National Bureau of Economic Research (NBER)
Issue Date October 2020

Tuesday, October 27, 2020

No Place Like Home: Fighting Climate Change (and Saving Money) by Electrifying America’s Households

Many Americans feel powerless to confront the enormity of climate change, especially when it seems that switching to clean energy at home — by buying electric cars or installing solar panels, for instance — is prohibitively expensive.
But [this] new report shows that the average American household can both fight climate change and save money at the same time. We can do it using existing technology, without sacrificing any comforts of home. In other words, we’ll have the same number of cars, ovens, dryers, refrigerators, air conditioners and heaters, but at dramatically lower cost and without the indoor and environmental pollution that accompany burning fossil fuels. If done right, we would create millions of new, good-paying jobs in every zip code, save each household on average between $1,050 to $2,585 per year on its energy bills, and dramatically reduce economy-wide greenhouse gas emissions — all the while enjoying zippier cars and smarter appliances.

[This paper models] two scenarios for decarbonizing the American household. We are showing that if we want a moon shot — zero-carbon energy in every home — here's how to build the rocket.
We spend more on electricity ($1,496) than we do on education ($1,407). We spend more on natural gas ($409) than dental services ($315). And we spend more on gasoline ($1,929) than we do on meat, poultry, fish, eggs, fruit and vegetables combined ($1,817).
We see some variation state–to–state, but going electric saves significant energy across the board.

The electrified U.S. household uses substantially less energy than current homes. One area of enormous savings is the elimination of thermoelectric losses in electricity generation, assuming we will provide our future loads with renewables. The efficiency of electric cars over internal combustion engine (ICE)
vehicles also generates substantial savings.
Similarly, [the report] shows the substantial savings derived from the high efficiency of heat pumps for space and water heating.

Today, a household electrification upgrade is expensive Using price estimates5 to find the difference between fossil-fueled and electric infrastructure, we find that today it would cost a household around $70,000 to completely decarbonize, something only the wealthiest households can afford. Below, we show the capital costs by state, using the electrification plan described above. ...

We need to prioritize lowering these costs using regulatory reform and industrial scaling. We also need to prioritize financing to help American households afford these items.

The table below summarizes the most important model parameters

For reference, Australia already installs rooftop solar at around U.S. $1.20/W, and the DOE’s Sunshot program is on track to systematically bring costs down to less than $1.00/W. Batteries are available at $120/kWh in packs, and scaling predicts prices below $75/kWh by 2030.

Costs are falling, and massive scale is key As a natural trend of huge industrial scale, clean energy solutions are getting exponentially cheaper. With every doubling in delivered solar modules, the price is dropping 22%. The same watt of electricity that cost $4 in 2000 now costs just $0.26,10 and at the scale of this study, just $0.18. For battery storage, every doubling reduces price 20%. The battery pack that cost $1,000 in year 2000, now costs $130,11 and at the scale implied by this study, just $65 (even lower than we have assumed).

All of these households saving money adds up to large savings on a national scale. In the Great scenario, more than $320 billion dollars in household savings will flow into the larger economy

By Saul Griffith and Sam Calisch
Rewiring America
October 2020 | By Saul Griffith and Sam Calisch

Net zero emissions target for Australia could launch $63bn investment boom - Modelling shows moving towards a net zero emissions economy would unlock financial prospects in sectors including renewables and manufacturing

Australia could unlock an investment boom of $63bn over the next five years if it aligns its climate policies with a target of net zero emissions by 2050, according to new economic modelling.

The analysis, by the Investor Group on Climate Change (IGCC), finds the investment opportunity created by an orderly transition to a net zero emissions economy would reach hundreds of billions of dollars by 2050 across sectors including renewable energy, manufacturing, carbon sequestration and transport.

However, if the country keeps to its current targets and climate policies, investment worth $43bn would be lost over the next five years, growing to $250bn by 2050.

The Investor Group on Climate Change represents investors in Australia and New Zealand who are focused on the effect of the climate crisis on the financial value of investments.  The organisation commissioned the consultancy Energetics to examine the domestic investment opportunities that would arise from an orderly transition to net zero emissions by 2050.

The report finds a net zero scenario would unlock $63bn in investment over the next five years, including $15bn in manufacturing, $6bn in transport infrastructure such as charging stations, and $3bn in domestic green hydrogen production, as companies and governments moved towards the stronger emissions goal.

Carbon sequestration – or carbon farming – would emerge as a major investment asset class, with estimated investment worth $33bn in nature-based solutions such as tree planting and assisted regeneration of deforested land.
Windy Hill Wind Farm, Atherton Tablelands, Queensland

The investment potential would reach hundreds of billions of dollars over the longer term to 2050, including $385bn in clean electricity, $350bn in domestic green hydrogen, $104bn in transport infrastructure and $102bn in carbon sequestration.

“What it shows is that the investment opportunities extend well beyond just the renewables industry,” said Erwin Jackson, the IGCC’s director of policy.  “Renewables are the backbone of the transition but there are massive opportunities in other sectors such as manufacturing, restoring the land, and electrification of transport.”

The report, which targets governments, companies, investors and financial regulators, says its estimates are conservative because they do not factor in the export potential of industries such as clean hydrogen.
It argues that if governments set stable policy, and companies and investors collaborate to align their decisions with the goals of the Paris agreement, then billions of dollars over the short and long term could support the jobs and wealth of millions of Australians, particularly in regional areas.

The Morrison government has refused to commit Australia to a net zero emissions target and has focused its climate policy on a new technology roadmap covering hydrogen, energy storage, “low carbon” steel and aluminium, carbon capture and storage, and soil carbon.  Under the roadmap, the government claims it will invest $18bn in technologies over 10 years.

The IGCC report notes that more than half of Australia’s two-way trading partners have set targets to reach net zero emissions by mid-century.

Morrison's rejection of 2050 net zero emissions target is at odds with Paris agreement, experts say

It warns that a business as usual “hothouse” scenario in Australia – with no net zero emissions target – would produce $43bn less in investment over five years and $250bn less by 2050 than what would be possible with a net zero target.

“Put bluntly, capital is global and it wants to invest in climate change solutions because they see it as delivering more on their long term investments,” Jackson said. “They’re going to invest more in countries that have durable, credible policies to achieve net zero emissions by 2050.”

John Connor, the chief executive of the Carbon Market Institute, said the reality Australia faced was its economy was running “below capacity and it needs a new direction”.  He said clean technologies like renewable energy and transport represented significant opportunities for Australia in a post-carbon world and the country’s vast land mass, with landscapes in need of regeneration, gave it a competitive advantage in carbon sequestration.
by Lisa Cox
The Guardian www,
13 Oct 2020

Monday, October 26, 2020

Finding the Right Policy Mix to Safeguard our Climate

Unaddressed, climate change will entail a potentially catastrophic human and economic toll, but it’s not too late to change course.  Global temperatures have increased by about 1°C since the pre-industrial era because of heat-trapping green-house gases accumulating in the atmosphere. Unless strong action is taken to curb emissions of these gases, global temperatures could increase by an additional 2–5°C by the end of this century. Keeping temperatures to levels deemed safe by scientists requires bringing net carbon emissions to zero on net globally by mid-century.  Economic policy tools can pave a road toward net zero emissions by 2050 even as the world seeks to recover from the COVID-19 crisis.

In the latest World Economic Outlook we make the case that economic policy tools can pave a road toward net zero emissions by 2050 even as the world seeks to recover from the COVID-19 crisis. We show that these policies can be pursued in a manner that supports economic growth, employment and income equality.

The manageable costs of mitigation
Economic policies can help address climate change through two main channels: by affecting the composition of energy (high- vs. low-emission sources), and by influencing total energy usage. The costs and benefits of different policies are determined by how they exploit these distinct channels.
For example, a carbon tax makes dirty fuels more expensive, which incentivizes energy consumers to shift their consumption towards greener fuels. Total energy consumption falls too because, overall, energy is more expensive.

In contrast, policies that aim to make green energy cheaper and more abundant (subsidies or direct public investment in green energy) increase the share of low-emissions energy. However, by making energy cheaper overall, green energy subsidies continue to stimulate total energy demand or at least do not reduce it.

In line with this intuition, our latest analysis suggests pairing carbon taxes with policies that cushion the impact on consumers’ energy costs can deliver rapid emissions reductions without major negative impacts on output and employment. Countries should initially opt for a green investment stimulus—investments in clean public transportation, smart electricity grids to incorporate renewables into power generation, and retrofitting buildings to make them more energy efficient.

This green infrastructure push will achieve two goals.

First, it will boost global GDP and employment in the initial years of the recovery from the COVID-19 crisis. Second, the green infrastructure will increase productivity in low-carbon sectors, thereby incentivizing the private sector to invest in them and making it easier to adapt to higher carbon prices.
Our model-based scenario analysis suggests that a comprehensive policy strategy to mitigate climate change could boost global GDP in the first 15 years of the recovery by about 0.7 percent of global GDP on average, and employment for about half of that period leading to about 12 million extra persons being employed globally. As the recovery takes hold, preannounced and gradually rising carbon prices will become a powerful tool to deliver the needed reduction in carbon emissions.

If implemented, such a policy program would put the global economy on a sustainable path by reducing emissions and limiting climate change. The net effect would approximately halve the expected output loss from climate change and provide long-term, real GDP gains well above the current course from 2050 onward.

Transition costs
Despite the long-run benefits, and an initial boost to economic activity, such policies do impose costs along the transition. Between 2037–50, the mitigation strategy would hold global GDP down by about 0.7 percent on average each year and by 1.1 percent in 2050 relative to unchanged policies. These costs seem manageable, however, considering that global output is projected to grow by 120 percent between now and 2050. The drag on output could be further reduced if climate policies incentivize technological development in clean technologies—through R&D subsidies, for instance. Moreover, the package would be neutral for output during that period if important benefits in the form of better health outcomes (due to reduced pollution) or less traffic congestion are considered.
The transitional output costs associated with the policy package vary significantly across countries. Some of the advanced economies may experience smaller economic costs or even see gains throughout the transition. Given their earlier investments into renewables, these economies can more easily ramp up their use and avoid large adjustment costs. Countries with fast economic or population growth (India, especially) and most oil producers should expect larger economic costs by forgoing cheap forms of energy, such as coal or oil. Yet these output costs remain small for most countries and need to be weighed against avoided climate change damages and the health benefits from reducing the use of fossil fuels.

Sunday, October 25, 2020

How a Plan to Save the Power System Disappeared - A federal lab found a way to modernize the grid, reduce reliance on coal, and save consumers billions. Then Trump appointees blocked it.

On August 14, 2018, Joshua Novacheck, a 30-year-old research engineer for the U.S. National Renewable Energy Laboratory, was presenting the most important study of his nascent career.... Novacheck was sharing the results of the Interconnections Seam Study, better known as Seams. The Seams study demonstrated that stronger connections between the U.S. power system’s massive eastern and western power grids would accelerate the growth of wind and solar energy—hugely reducing American reliance on coal, the fuel contributing the most to climate change, and saving consumers billions.... 

Democrats in Congress have recently cited NREL’s work to argue for billions in grid upgrades and sweeping policy changes. But a study like Seams was politically dangerous territory for a federally funded lab while coal-industry advocates—and climate-change deniers—reign in the White House. The Trump administration has a long history of protecting coal companies.... Trump officials would ultimately block Seams from seeing the light of day....

A nearly impermeable electrical “seam” divides America’s eastern and western power grids. These giant pools of alternating current on either side of the Rockies contain a total of 950 gigawatts of power generation by thousands of power plants. (A third grid serves Texas.) But only a little over one gigawatt can cross between them. Western-grid power plants in Colorado send bulk power more than 1,000 miles away to California, for example, but merely a trickle across the seam to its next-door neighbor Nebraska. That separation raises power costs, and makes it hard to share growing surpluses of environmentally friendly wind and solar power. And years of neglect have left the grids—and the few connections between them—overloaded and ill-prepared to transition to highly variable renewable energy.  The Seams study set out to determine whether uniting America’s big grids would pay....

The fallout was swift: The lab grounded Bloom and Novacheck, prohibiting them from presenting the Seams results or even discussing the study outside NREL.... The $1.6 million study itself disappeared. NREL yanked the completed findings from its website and deleted power-flow visualizations from its YouTube channel.
Withholding NREL’s grid research is an example of what experts such as Arjun Krishnaswami, a policy analyst at the Natural Resources Defense Council, calls the “deep politicization” of DOE and its national labs under Donald Trump. At a moment when Europe, China, and others are racing ahead with advanced long-distance energy-transmission technologies, grid experts say that technology has gone nowhere in the United States—thanks to a failure of leadership in Washington.,,,

Bloom showed off his team’s sophisticated methodology using high-resolution video simulations. One simulation showed a hypothetical heat wave in August 2038, causing air conditioners to drive up power demand. As the rising sun swept across the U.S., yellow circles representing solar plants expanded. Surplus power from solar plants in the West flooded eastward, limiting the need for pricier and dirtier midwestern coal power. And as the sun set, the Midwest’s expansive wind farms began to spin, sending power westward and minimizing use of the West’s coal- and gas-fired generators....

As expected, the simulations showed that exchanging power across the Rockies enables generators on either side to serve a wider area, reducing the number of plants required, and trims operation of the remaining fossil-fueled generators. And they demonstrated that the resulting savings in fuel and equipment more than pay for the added transmission. The benefits were particularly dramatic for the carbon-price scenario. It would eliminate up to 35 megatons of CO2 emissions a year by 2038—equivalent to the current annual carbon emissions from U.S. natural-gas production and distribution. And it would return about $2.50 or more for every $1 invested in transmission....

The design that delivered the largest cost reduction linked up transmission lines to form a new transcontinental network: a “supergrid.” Seams simulated a 7,500-mile supergrid that would ship bulk power around the U.S.—a network reaching from Washington State to Florida. Even in the study’s less-ambitious scenario, the supergrid was saving consumers $3.6 billion a year by 2038.

But there was a problem: Improving the energy grid would reduce America’s reliance on coal

Enhanced grid resilience was a likely outcome of the Seams expansions....

According to Susan Tierney, a former assistant secretary of energy who chairs NREL’s External Advisory Council, national labs have operated with considerable independence in the past: “There was an understanding that the labs have a duty to perform quality research. I was not familiar with situations where there was an editorial thumb on the scale.”

But under Trump, political appointees have made unprecedented moves to regulate how science is conducted, according to a historical analysis and warning by experts in science and the law in the journal Science. And other scientific studies—especially those related to climate change—have been similarly slow-walked or buried. One of them was a DOE-commissioned study on grid resiliency, completed in April 2018. Michael Webber, an energy expert at the University of Texas at Austin and the study’s leader, notes that his conclusion—that increased transmission, not just fuel-storing generators, helps grids respond to extreme events—conflicted with statements made by DOE leaders. “I never got a message from anybody saying ‘Please do a study that concludes coal is magical,’ so there was never direct pressure on me for that. But I could sort of read the winds,” Webber says.

In the case of Seams, DOE’s interference has had a real and practical impact. Caspary says he has been waiting for access to Seams’ simulation tools to do follow-up studies for the Southwest Power Pool. There’s a growing backlog of wind and solar projects seeking to use the Pool’s lines....

... The power-industry expert Peter Fox-Penner, who runs the Boston University Institute for Sustainable Energy, says the U.S. is falling behind other major economies when it comes to creating the big grid links that make a transition to renewable energy possible. As Fox-Penner writes in his 2020 book, Power After Carbon: Building a Clean, Resilient Grid, “Without better integrated planning, we can’t even guess at the amount of transmission we need and where and how it should be built. Europe, Australia, and other countries are starting to get a good handle on these questions while the United States lags well behind.” The International Energy Agency has estimated that China’s growing interregional transmission could save its consumers and industries $9 billion a year.

Meanwhile, the nationwide report on grid congestion that DOE is required by law to update every three years—a crucial component of grid planning—is two years behind schedule.

And there are more signs of trouble at NREL, where two more grid-modeling studies are now missing in action....

by Peter Fairley, journalist who covers energy, technology, and climate change.
The Atlantic
August 20, 2020

Tuesday, October 20, 2020

Green roof and green wall benefits and costs: A review of the quantitative evidence

• Review of existing research on green roofs and green walls benefits and costs.
• Focus on building scale benefits, urban scale benefits and life-cycle costs.
• Variability identification and average quantification assessment.
• Fewer studies have quantified green walls benefits and costs.
• There is high variability in data across all benefits and costs.

... Green infrastructures, like green roofs and green walls, have multiple associated environmental, social and economic benefits that improve buildings performance and the urban environment. Yet, the implementation of green roofs and green walls is still limited, as these systems often have additional costs when compared to conventional solutions.

Recent studies have been comparing these greening systems to other solutions, balancing the long-term benefits and costs. Also, there is significant research on green roofs and green walls benefits. Although, green roofs and green walls economic analyses don't include all benefits due to measuring difficulties. The associated uncertainty regarding the quantification of the benefit makes it difficult to compare the research outcomes.

This paper aims to provide a research review of existing benefits and costs of different types of green roofs and green walls. These were divided between building scale benefits, urban scale benefits and life cycle costs, focusing on the identification of results variability and assessment of their average quantification.

The analysis shows that in general, there [is little] ... data regarding intangible benefits, as the promotion of quality of life and well-being. Also, there are still few studies quantifying green walls benefits and costs. High variability in data is mostly related to the different characteristics of systems, buildings envelope, surrounding environment and local weather conditions.
Green roofs, also known as ecoroofs, living roofs or vegetated/vegetative roofs, refer to all systems which enable greening roofs, allowing the growth of different types of vegetation on top of buildings. Green roofs include a set of layers that protect the support and improve system performance. They commonly include the vegetation, growing medium (substrate), filter layer and drainage layer. These solutions are normally applied over waterproofed roofs with a root barrier and the insulation layer. Also, the green roof system must be applied over a layer with a minimum slope of 2% to drain the excessive rainwater along the roof. Compared to conventional roofs, green roofs tend to be more expensive, requiring extra maintenance depending on the vegetation type and irrigation needs. If the substrate thickness is significant the system may need an increased weight load capacity of the roof to be able to be implemented.
In general, green roofs are more energy-efficient than black roofs in all climates. Table 1 shows that maximum energy savings are obtained when comparing intensive green roofs to black roofs, especially over non-insulated roofs, reaching to 84% energy savings in the cooling season and 48% in the heating season. Also, in Csa climate, green roofs can be more effective than white roofs in the heating season, especially in buildings that are not insulated. However, in this climate green roofs are not as effective in the cooling season, except for intensive green roofs due to substrate thickness.

In the Tropical climate (Af), where only cooling is necessary, tests developed by Wong et al. in a commercial building in Singapore, demonstrate that extensive green roofs show higher energy savings than black roofs also in non-insulated buildings, obtaining average energy savings of 63%. In the Tropical desert climate (Bwh) the application of extensive green roofs was tested by Zinzi and Agnoli. Results from Cairo city in Egypt, demonstrate that in the heating season extensive green roofs are more effective than black and white roofs, reaching 22% and 52% energy savings, respectively. However, in the cooling season results are not as promising, as white roofs reveal to be more effective. In the Semi-arid hot climate (Bsh) a semi-intensive green roof was analysed by Ascioni et al.. Energy savings for cooling of this green roof reached an average of 7,25% compared to a traditional roof and were not as effective as white roofs. In cold climates (Cfb and Dfb), where winters require more heating loads, all types of green roofs have proven to be more effective than black and white roofs. In summer green roofs demonstrate to reduce energy loads when compared to black roofs but not as much as in warmer climates. In Table 1 maximum energy savings were also obtained with extensive green roofs in the Oceanic climate (Cfb) revealing to be highly effective in the cooling season reaching to 84% in insulated buildings and 100% in non-insulated buildings, but not in the heating season.

More recently some authors have studied green walls potential to improve energy efficiency in buildings, due to surface temperature reduction and shadowing provided by plants. Studies demonstrate that, in Csa climate, when compared to a conventional wall, green façades can have an energy efficiency of 34% and living walls 59% to 66%, during the cooling season.
Table 2 shows some research studies demonstrating that the addition of an extensive green roof to a building can have a significant impact on sound transmission reduction. The decrease in noise levels varies from 5 dB to 20 dB, depending on the frequencies. However, sound transmission reduction may vary according to the type of support, substrate composition and its depth, water content, and types and stage of plant species development 
Some authors have proven that green walls also have good sound absorption properties compared to other cladding materials. Like green roofs, green walls sound absorption depends on green coverage type, variety of plant species and materials used in the system. Pérez et al. obtained also a 2 dB increase in soundproofing with a living wall and a 3 dB increase with a green façade
New solutions and technologies for water recovery and water treatment can significantly contribute to buildings reduction of potable water consumption. Greywater decentralized treatment and recycling requires simpler treatment systems and reduces the impact on urban wastewater management. Local greywater recycling can achieve potential water savings of 9%–46% within the household.
Results indicate that green walls can remove 80%–90% of total suspended solids (TSS), over 90% of biological oxygen demand (BOD), 30%–50% of total nitrogen (TN), 15%–30% of total phosphorus (TP), 30%–70% of chemical oxygen demand (COD) and 20%–80% of Escherichia coli (E. coli).
Current conventional roofs include a waterproofing membrane that usually lasts between 10 and 20 years, while green roofs could ensure an in-service life of 50 years or more. However, old green roofs exist in Berlin for more than 90 years without being replaced
Current conventional roofs include a waterproofing membrane that usually lasts between 10 and 20 years, while green roofs could ensure an in-service life of 50 years or more. However, old green roofs exist in Berlin for more than 90 years without being replaced

Green roofs and green walls add property value to buildings. Several authors use several methodologies (e.g. hedonic pricing method) to estimate how the presence of green spaces, like green roofs and green walls, influence property value. Fig. 4 presents the results obtained by different authors regarding the average property value increase due to the presence of green areas, including green roofs and green walls. Based on these results an average increase of 8,24% was determined. Ichihara and Cohen estimated an increase of 16,2% in rental prices in buildings with green roofs. Perini and Rosasco identified a 2%–5% increase in property value due to the presence of green walls.


... Solutions such as green roofs or green walls, can contribute to evaporative cooling from evapotranspiration, shading, increase the surface albedo (0,7 to 0,85 versus 0,1 to 0,2) and emissivity, and complement the building insulation. The [Urban Heat Island] (UHI) mitigation potential of greening systems is conditioned by several variables as i) climate conditions (solar radiation, outdoor temperature and humidity, wind and precipitation); ii) optical variables (surface albedo and emissivity); iii) thermal variables (thermal capacity and thermal transmittance); iv) and hydrological variables (latent heat loss through evaporation by plants and soil) ... Overall, the average reduction of the surrounding temperature collected in these studies is l, 34 °C, varying between a minimum and a maximum average of 1 °C to 2,3 °C.
Table 3 shows the results obtained by different authors regarding the potential of living walls to contribute to urban noise reduction. Results indicate a variation along different frequencies and between systems. A total average urban noise attenuation of 5,5 dB was obtained, ranging between 0 and 10 dB.
Regarding extensive green roofs, high variability was identified across studies, ranging between an average minimum stormwater runoff reduction of 33% and a maximum average of 81%. Overall, extensive green roofs contribute in average 57% to decrease stormwater runoff.

Concerning to intensive green roofs, Fig. 7 also shows a 79% average stormwater runoff retention, which represents a 22% higher water retention capacity compared to extensive green roofs. This increase may be due to substrate depth. This difference is also notorious when comparing stormwater runoff average results between green roof solutions in similar climates (Cfa and Cfb), representing a 31% difference in Cfa and 10% in Cfb climates.

Fig. 10 illustrates the pollutants removal capacity of green roofs obtained by different authors through dry deposition. All values were converted to grams (g) per area unit (m2) per year. These studies show higher average removal capacity of O3 (1,96 g/m2.year), PM10 (1,47 g/m2.year) and NO2 (1,03 g/m2.year). Significant average results were also obtained for SO2 (0,41 g/m2.year), CO (0,41 g/m2.year).

Bianchini & Hewage [69] mention two examples of incentive policies. In New York City a tax reduction incentive is applied when building owners include extensive and intensive green roofs in their properties, covering at least 50% of the total roof area. This way can benefit from a tax reduction of 43€/m2 (49 USD/m2), reaching a maximum of 90.000 € (approximately 101.700 USD). Also, the city of Portland applies a stormwater fee discount of 35% for properties that reduce their impervious surfaces, including the application of green roofs.
Fig. 11 presents the installation cost of extensive, semi-intensive and intensive green roofs respectively, obtained by different authors. Results demonstrate a high variability in systems cost between countries. An average installation cost of 99 €/m2 (112 USD/m2) was identified for extensive green roofs. Semi-intensive systems tend to be more expensive than extensive green roofs as they usually include a wider variety of plant species. Results indicate an average installation cost of 130 €/m2 (147 USD/m2) for semi-intensive green roofs. Intensive green roofs tend to be more expensive to install, as they include more material and heavier plants (e.g. small trees) reaching an average installation cost of 362 €/m2 (409 USD/m2).

                                                                Fig. 11. Installation cost (€/m2) of extensive green roofs

Fig. 12 refers to the results obtained by different authors regarding the installation cost of green façades and living walls. Significant differences were also obtained between green wall systems. Green façades have an average installation cost of 190 €/m2 (215 USD/m2), as they require less material. Living walls can have more differences in cost, as there are several different systems on the market. An average installation cost of 750 €/m2 (848 USD/m2) was obtained for living walls.