Featured Research

City-integrated renewable energy for urban sustainability


To prepare for an urban influx of 2.5 billion people by 2050, it is critical to create cities that are low-carbon, resilient, and livable. Cities not only contribute to global climate change by emitting the majority of anthropogenic greenhouse gases but also are particularly vulnerable to the effects of climate change and extreme weather. We explore options for establishing sustainable energy systems by reducing energy consumption, particularly in the buildings and transportation sectors, and providing robust, decentralized, and renewable energy sources. Through technical advancements in power density, city-integrated renewable energy will be better suited to satisfy the high-energy demands of growing urban areas. Several economic, technical, behavioral, and political challenges need to be overcome for innovation to improve urban sustainability.


Since 2007, a greater percentage of the global population has been living in urban areas than in rural areas. Increased urbanization is expected to continue, with two-thirds of the world’s population projected to live in urban areas by 2050, a net urban influx of 2.5 billion people (1). Cities today are generally not equipped to address dramatic urban growth and strain on existing infrastructure in a sustainable way, especially with respect to their energy systems.

To be sustainable, cities must themselves, or in the resources that they command, become low-carbon, resilient, and livable (2). Although there can be considerable variation in methods for evaluating the emissions footprint of cities (3), with 54% of the population living in urban areas, it is estimated that cities are currently responsible for 60 to 70% of anthropogenic greenhouse gas emissions (4). The two main strategies for transitioning to a low-carbon city are to shift from fossil fuels to cleaner energy sources and to reduce urban energy consumption levels. The low-carbon transition can be accomplished through energy-efficiency measures, behavioral interventions, and incorporating carbon sinks such as urban parks. Cities and their energy systems should also be resilient to natural and human-made threats (2). The energy systems of cities are increasingly vulnerable to the effects of climate change and extreme weather, including storms, flooding, and sea-level rise, and also to natural and human-induced disasters. In addition, urban energy systems directly affect the well-being and happiness of urban inhabitants. Health conditions, economic competitiveness, cultural appeal, and social, gender, and racial equality are influenced by high-energy sectors such as transportation, food production, and water quality.

Here we evaluate some of the more promising recent technological advancements that could help urban areas become sustainable cities. Many opportunities exist, but focusing on city-integrated renewable energy—defined as distributed, non–fossil fuel energy generated locally in urban areas—has the potential to help cities meet several sustainability needs. Many of these renewable sources increase regional energy independence and can be redundant with other sources, thus increasing resiliency. Although there are several existing barriers to their adoption, solutions will involve increased power densities of renewable energy technologies, improved infrastructure capable of supporting widespread integrated energy generation systems, and increased urban energy efficiency, particularly in the buildings sector.

City-integrated renewable energy

About 75% of power generated globally is consumed in cities (5). Generating city-integrated energy at the site of energy use could substantially contribute to the environmental, economic, and social aspects of urban sustainability. Four characteristic advantages of such distributed energy systems include the ability to (i) offer low to zero carbon emissions, (ii) offset capital-intensive investments for network upgrades, (iii) impart local energy independence and network security, and (iv) motivate social capital and cohesion (6).

With limited available installation space, renewable energy generation within urban areas poses particular challenges. We use the balance between the high energy demand of cities and the available energy density supplied by renewable sources as a starting point for an analytic framework for decarbonized urban spaces (Fig. 1). However, in the waves of innovation that will be needed, strategies ranging from space-based solar energy to small modular nuclear power systems, deep geothermal systems, and other generation options could transform the energy landscape. In addition to reducing greenhouse gas emissions, these strategies may reduce the consumption of water, air, and other resources.

Fig. 1 City-integrated renewable energy potential.

(A) Potential for renewable sources to satisfy total final urban energy consumption and (B) urban transportation energy demands. Solid lines represent typical performance. Dotted lines represent potential performance, based on optimal conditions and technologies currently available in the laboratory. All resources are evaluated based on electric power densities, except geothermal energy and solar hot water. Geothermal energy is evaluated based on thermal power densities for horizontal closed loops buried 1 to 2 m deep at the low end and boreholes at least 150 m deep at the high end. Data on total final energy consumption and region definitions are from (77), city population size and density data are from (78), and transportation data are from (79). “Waste” refers to LFGTE. PV, photovoltaics. Population is indicated by circle sizes, and regions are indicated by circle colors (ASIA, Asia excluding OEDC90 countries; LAC, Latin America and the Caribbean; MAF, the Middle East and Africa; OEDC90, member countries of the Organization for Economic Cooperation and Development as of 1990; REF, Eastern Europe and the former Soviet Union).

Solar energy

Recent economic and technical advances have made city-integrated solar technologies increasingly attractive. Since 2010, the installed price of solar energy has dropped by as much as 50% (7). Despite substantial economic progress and anticipated cost parity with fossil fuels, renewable energy technologies have often been criticized for their low power densities, making them inappropriate for urban applications. Conservative estimates of the power density of solar photovoltaics are around 10 W/m2 (8), assuming an average direct solar irradiation of 100 W/m2, which is typical for the United Kingdom, and a photovoltaic efficiency of 10%. However, the solar resource is highly region-dependent, and in some regions, annual direct solar irradiation can exceed 300 W/m2 (9). Many of the regions expected to experience the greatest increase in urbanization are located in solar-rich regions. For example, the majority of the total land area of India experiences an annual direct solar irradiation of over 200 W/m2 (10). Additionally, the efficiency of photovoltaics has increased steadily and has already surpassed 40% in the laboratory, using concentrated multijunction cells (11). Hence, under optimal conditions, the power density of photovoltaics could exceed 120 W/m2.

Several studies have estimated the photovoltaic potential of existing cities. City-integrated photovoltaics have the potential to satisfy 62% of the current electricity needs of Oeiras, Portugal (12), and 66% of the electricity needs of Bardejov, Slovakia (13). High-efficiency commercially available photovoltaics only on suitable rooftops could satisfy 19.7 to 31.1% of the daily electricity demand and 47.7 to 94.1% of the morning peak electricity demand of Mumbai, India (10). With a 20% adoption rate, solar-powered urban microgrids could reduce the grid demand in Cambridge, MA, to almost zero at midday (14).

Heating accounts for 40 to 50% of the global energy demand and 75% of the energy demand within the buildings sector (15). Urban solar thermal energy, specifically for space and domestic water heating, has been an area of particular research interest. With efficiencies up to 80% (15), solar hot-water systems offer a thermal power density up to 240 Wt/m2 under optimal conditions (Wt, watt-thermal), whereas the global averaged thermal power density of solar heat collectors is 67 Wt/m2 (16). Because domestic solar hot-water heaters are low-cost and compact, one study showed that 84% of urban households in China could install the system on their rooftops (17). Solar thermal energy is also used for passive and active space heating. A study of five Australian cities showed that the use of a Trombe wall could offer energy savings up to 17% (18). Seasonal solar thermal energy storage is an approach that stores solar thermal energy collected in the summer for heating in the colder months. This technology provides up to 91% of the total energy needs of a large residential building in Richmond, VA (19).

The exploitability of the solar resource is highly affected by urban form. Although taller buildings offer higher surface-to-volume ratios, allowing for increased facade-integrated solar technologies, they also increase the risk of vertical obstruction and shading (20). Although building facades provide almost triple the area of building roofs, they received only 41% of the total irradiation in Karlsruhe, Germany (21). However, an optimized urban form could increase the solar irradiation on facades by up to 45% in greater London, whereas an increase of only 9% is possible for rooftops (22).

Geothermal energy

Geothermal energy has been harnessed for both electricity and heat. A typical geothermal plant has an electrical power density of 283 W/m2 (23), but some plants are estimated to have a total power density of nearly 800 W/m2 (16). Geothermal plants can be placed on multiple-use lands, sharing space with activities such as farming and skiing. However, the surrounding land can be affected by subsidence, erosion, landslides, and induced seismicity (1623). When taking into account all such affected areas, the typical electrical power density of a geothermal power plant is estimated to be 50 to 80 W/m2 (16). Geothermal energy is more efficiently extracted as heat. Iceland’s Hellisheidi combined heat and power plant is able to generate hot water at 25,000 Wt/m2 (16). Most cities, however, are located in areas with far fewer geothermal resources. Conventional geothermal resources would only produce a mere 0.017 W/m2 of electricity in the United Kingdom (8), but deep (>10 km) geothermal power could transform this baseload resource into a far more substantial (>10%) element of urban energy supply (24). The power density of deep enhanced geothermal systems is between 0.59 and 1.19 W/m2, depending on the available resource temperature (25).

Although the use of geothermal energy for electrical generation in cities is limited, more than 60 countries are using geothermal energy for household, commercial, and industrial heat (16). The thermal power densities in most regions are relatively high, even at moderate depths. In the United States, the average thermal power density of ground-source heat pumps is 40 Wt/m2 for horizontal closed loops buried just 1 to 2 m deep and 100 Wt/m2 for boreholes at least 150 m deep (16). Ground-source heat pumps for heating and cooling in Chinese urban buildings could reduce energy consumption by 10 to 15% in civil buildings and 25 to 30% in public buildings (26). Ground-source heat pumps could also meet the heating demands of 58 to 70% of buildings in Westminster, London, and, if a well-organized district heating system was used, all heating demands could be satisfied throughout the urban area (27).

Urban areas may be particularly well suited for ground-source heat pumps because of the urban heat-island effect, a phenomenon in which human activities cause cities and metropolitan areas to be warmer than their surrounding rural areas. The increased anthropogenic heat fluxes into the subsurface of a city result in elevated groundwater temperatures, enhancing the geothermal resource. In Karlsruhe and Cologne, Germany, the anthropogenic heat fluxes could sustainably provide 32 and 9% of the annual residential space heating needs, respectively (28). The anthropogenic influence on the subsurface temperature is greater in megacities such as Shanghai, where the existing heat content in the urban aquifer is 22 times the annual heating demand of the city (29).

Wind energy

Urban wind energy provides opportunities for not only renewable electrical generation but also ventilation, pollution dispersion, and mitigation of the urban heat-island effect. Urban wind energy has not been widely adopted, largely because of challenges and concerns related to installation space, low and turbulent urban wind-speed characteristics, vibration, noise, safety, shadow flicker (periodic shadows cast by the rotating blades of wind turbines), and aesthetics (30). Although modern wind farms typically produce 2 to 3 W/m2 with horizontal-axis wind turbines (HAWTs), counter-rotating vertical-axis wind turbines (VAWTs) can achieve 30 W/m2 (31). In addition to increased power density, VAWTs offer several advantages that are particularly relevant to the urban environment. These include lower dependence on wind direction, ability to handle higher turbulence and varied wind speeds, lower manufacturing costs, and decreased impact on birds and aircraft (30). Another benefit is that the generator and gear box can be installed at ground level, allowing building-mounted turbines to be more easily serviced (30).

Numerous researchers have investigated urban wind-flow characteristics, resulting in estimates of its potential for urban electricity generation. Excluding thermal energy needs, urban wind could provide 33% of residential building electricity needs with HAWTs in urban areas of New Zealand (32) and 40% with VAWTs in San Cataldo, Sicily (33). There are limited examples of existing urban wind projects. In Bahrain, the World Trade Center twin towers use three vertically arranged HAWTs, providing 11 to 15% of the electrical energy needs (30). Although the two VAWTs installed at the Pearl River Tower in Guangzhou, China, provide only 5% of its energy needs (30), they offer several design advantages. The curved glass facade of the building funnels air to the VAWTs at speeds of 1.5 to 2.5 times the ambient wind speed, allowing the turbines to generate 15 times more energy than freestanding wind turbines could (34). Additionally, by allowing wind to pass through the building, wind-induced forces on the building are reduced, which in turn reduce the quantity of steel and concrete needed to maintain the building’s stability (34).

Biomass energy

Power densities for biomass energy are highly dependent on the regional climate, because it affects which plants are able to grow locally. Conventional crops have a range of power densities from roughly 0.05 to 1.7 W/m2; the highest densities come from crops grown in tropical locations with genetic modification, fertilizer, and irrigation (8). The ongoing debate over biofuel sustainability and social and environmental justice considerations places this potential energy source in a complex and unsatisfactory position. Direct combustion of urban biomass offers at least a clearer life-cycle path to evaluate than conversion and use of biomass as biofuels. If short-rotation poplar was grown on marginal lands in Boston, for example, it could satisfy 0.6% of the yearly primary energy demand in Massachusetts (35).

Given the low power densities, urban agriculture may be better suited for food than for energy. Urban farms help reduce urban heat-island effects, mitigate urban stormwater impacts, and lower the energy needed for food transportation (36). A life-cycle analysis of a community farm in South London has shown that urban food supply systems can achieve reductions in greenhouse gas emissions that are potentially larger than those of parks and urban forests (37).

Energy from urban waste

Although not entirely renewable, energy from waste could play a key role in sustainable urban energy. Urban residents produce roughly twice the waste of their rural counterparts (38). Increased global urbanization is expected to result in increases in municipal solid waste (MSW) (Fig. 2). Typical management strategies include recycling, burning, or landfilling. Although recycling can reduce the life-cycle energy, it may not be economically or energetically realistic for some waste.

Fig. 2 Estimates of current and projected generation of urban waste.

The amount of MSW that is generated daily (solid bars) and the projected daily waste production by 2025 (striped bars) in each region are indicated on the right axis [data are from (38)]. If all urban waste were to be burned in WTE plants, the corresponding energy that would be generated, based on an average waste energy value from (40) that includes nonrecyclable plastics, is indicated on the left axis.

Energy from waste may be derived from landfill-gas-to-energy (LFGTE) systems and waste-to-energy (WTE) plants. Landfill gas is generated through the biological degradation of organic materials in MSW, typically consists of methane (50 to 60%) and carbon dioxide (40 to 50%), and can be collected and burned to generate energy. The average LFGTE power density that could be extracted from this gas is estimated to be 4.1 W/m2, but, if optimized, a theoretical power density of 10 W/m2 is feasible (39). In a WTE plant, MSW is incinerated, generating 0.6 MWh per ton of MSW on average (MWh, megawatt-hour), with the potential to generate up to 1.8 MWh per ton (40). Additionally, many WTE plants use cogeneration, providing useful heat. If all of the MSW generated in the United States in 2011 was sent to WTE plants, enough energy would be produced to power and heat 12 and 8% of American households, respectively (40). Additionally, carbon-capture systems can be integrated into WTE plants, reducing carbon dioxide emissions by an estimated 90% (41).

Opportunities for reducing energy consumption

Two major sectors for reducing energy consumption are buildings and transportation. To limit global climate change to 2°C above preindustrial levels, the greatest global investment is required in the buildings sector (an estimated incremental expenditure of $300 billion/year for 2015–2020) for both retrofitting and constructing new buildings to high energy-efficiency standards (42). The next largest investment is required for transportation vehicles, with an estimated additional expenditure of $70 billion/year (42).

Building efficiency improvements

Buildings account for 40% of the world’s energy consumption and 30% of annual greenhouse gas emissions (43). To accommodate the growing urban population, new buildings are needed. Eighty percent of all buildings that will stand in India in 2030 had yet to be constructed as of 2010 (44). This new construction creates opportunities not only for energy-efficient and climate-resilient buildings but also for local optimization of urban form. New buildings could be made 70% more efficient than existing buildings through the use of insulated windows, modern gas and oil furnaces, and more efficient air conditioners (45). Strategies for zero-energy buildings involve minimizing the energy use of a building, especially for heating and cooling, and adopting renewable energy technologies to meet the remaining minimal energy needs (46).

Retrofitting existing buildings saves embodied energy, avoids generating waste from building demolition, and is often more cost-effective than constructing new buildings. Despite these advantages, the rate at which the current building stock is retrofitted is startlingly slow. In the United States, the existing commercial building stock is being retrofitted at a rate of roughly 2.2% a year, with the median energy savings from these retrofits at roughly 11% per building (47). Most of these retrofits consist of minimally invasive measures with short payback periods, such as lighting and HVAC (heating, ventilation, and air conditioning system) replacements. Integrated energy-efficiency measures are needed to reach savings as high as 50% (48). These measures include upgrades to the building envelope, mechanical systems, lighting and electrical systems, and system controls, as well as changes in tenant behavior (48).


The five potential metrics for the decarbonization of urban transportation are (i) fuel carbon intensity, (ii) energy intensity, (iii) vehicle occupancy rate, (iv) trip distance, and (v) the number of motorized trips (49). These metrics are each discussed below.

Fuel carbon intensity

Fuel carbon intensity is a measure of greenhouse gas emissions per unit energy. To reduce this metric, cleaner energy sources are required and may be achieved through fuel substitution or vehicle electrification. Although fuel substitution with biofuels requires minimal changes to the vehicle and fueling infrastructure and reduces global carbon dioxide emissions when evaluated over the life cycle of the fuel, tailpipe carbon dioxide emissions may be comparable to those produced by fossil fuels (50). To eliminate tailpipe pollution, vehicles powered by hydrogen or electricity may be better suited for urban transportation. Although roughly 96% of hydrogen production today uses conventional methods with fossil fuels (51), there are numerous emerging low-carbon production methods (52). However, cost and energy storage remain major obstacles. The electrification of the transportation sector is expected to grow rapidly, with plug-in hybrid vehicles predicted to account for 58% of new light-duty vehicle sales in the United States by 2030 (53). This growth requires improvements in low-cost, compact, long-lasting battery technologies and vehicle charging infrastructure. The environmental benefit of electrifying urban transportation will largely depend on the emissions from the electricity generation. The required energy needs for transportation could be achieved, or partially achieved, using city-integrated renewable energy (Fig. 1B).

Energy intensity

Energy intensity is the energy required to move a vehicle one kilometer. Achievable advances in engine technology can improve the fuel economy of automobiles by over 50% and trucks by over 30% (54). Although such improvements are possible, the greatest reduction requires a systems approach, taking into account numerous other factors including vehicle lightweighting, accessory load management, powertrain systems optimizations, and aerodynamics. Advances in lightweight materials show particular promise: Passenger vehicle fuel efficiency can be improved by 6 to 8% for each 10% reduction in weight (55).

Vehicle occupancy rate

Public transportation and carpooling are commonly used strategies to increase vehicle occupancy rates. A higher urban density increases the attractiveness of public transportation. For reasonable spatial and temporal availability, the urban density threshold for public transportation is estimated to be 5,000 people/km2 (56). Cities with population densities below this threshold are those with the highest percentage of their transportation needs being met by private motorized vehicles (Fig. 3).

Fig. 3 Relative use of private motorized vehicles.

Plotted are the percentages of trips taken using private motorized vehicles, relative to urban population densities. Data are from (79).

Trip distance and number of motorized trips

Trip distances and the numbers of trips taken per year per person depend on the built environment. A city with high density and mixed-use development allows for shorter trips that are more conducive to nonmotorized means, such as walking and biking. The built environment must include safe infrastructure to facilitate nonmotorized transportation. A study of five U.S. cities found that bicycle ridership increased between 21 and 171% within one year of building protected bicycle lanes (57). Bicycle use and walking are much more common in other areas of the world. Globally, 37% of trips are nonmotorized, with the greatest use of nonmotorized transport (50%) in the Asia-Pacific region and Africa and the least (8%) in North America (58).

Other factors

The urban transportation landscape is changing with increased car-sharing programs and the emergence of self-driving cars. It is still somewhat unclear what effect these will have on energy consumption, because they may result in increased low- or even no-occupancy motorized transportation. One model predicts that shared autonomous vehicles could reduce the number of cars in use by a factor of 10, but the total motorized distance traveled would increase by 11% (59).

Challenges of dramatic urban decarbonization
Economic challenges

Some believe that it is too expensive to invest in dramatic decarbonization; however, it may be even more expensive not to. Global infrastructure needs for 2015–2020 are ~$6.7 trillion/year under business-as-usual scenarios, and the incremental costs of low-carbon infrastructure are on the order of −$70 billion/year to $450 billion/year (60). Although these are global estimates, port cities with populations over 1 million are particularly vulnerable to infrastructure expenditures related to coastal flooding. Nearly 40 million people and $3 trillion of assets are currently exposed to a 1-in-100-years coastal flood event (61). By the 2070s, the exposed population could grow by a factor of 3 and the value of vulnerable assets could increase 10-fold under the combined effects of sea-level rise, subsidence, increased urban populations, and economic growth (61). Despite the global need for climate adaptation, investment in adaptation is a small part of the overall urban economy. In a study of ten megacities, investment in climate adaptation was at most 0.33% of a city’s gross domestic product (GDPc) and substantially less in developing countries (62).

Technical challenges

Some of the main technical challenges for implementing city-integrated renewable energy are the uncertainty and variability in urban energy use and the methods used to account for the associated emissions (3). Municipal governments typically measure emissions using a territorial approach, primarily counting emissions that enter the atmosphere within the jurisdiction’s geographic boundary (63). There is increasing interest in accounting for emissions on a consumption basis, allocating all emissions in global supply chains to the points at which products and services are consumed (64). This approach emphasizes the mitigation potential of households and includes a wider range of emission sources, including transportation, energy, food, goods and services, water, waste, and home construction.

Cities differ in both their energy needs and their available energy resources. Hot and cold climates have substantial air conditioning and heating needs, respectively. Cities with more industrial processes typically consume more energy; however, they also have increased potential for district heating and combined heat and power. Urban form also strongly influences transportation energy needs. Available energy resources depend on the status of the electrical grid, location of renewable resources, and socioeconomic conditions. There is considerable variation in energy use not only between cities but also between neighborhoods within the same city. For example, average household carbon footprints in the San Francisco Bay Area vary between neighborhoods according to income, vehicle ownership, household size, home size, carbon intensity of electricity production, population density, and other factors (Fig. 4) (65).

Fig. 4 Neighborhood variation in household carbon footprints.

The map shows the average household carbon footprint of census block groups in selected San Francisco Bay Area cities. The color gradient indicates deciles from the lowest to the highest carbon footprint. Data are from the model developed in (65) and are available at http://coolclimate.berkekey.edu.

Given the uncertainty and variability in urban energy systems and urbanization dynamics, a flexible and adaptive solution is necessary. Poor visibility, aging infrastructure, and spatially and temporally variable energy generation from distributed renewable energy sources have made the current electrical grid susceptible to frequent disturbances that can lead to cascading failures. One solution would be a smart grid with integrated energy storage. A smart energy grid should not be limited to electricity; rather, electricity, thermal, and gas grids should be combined and coordinated, emphasizing the role of district heating in future sustainable cities (66). Even if a smart gird is well monitored and controlled, the high variability of renewable energy resources requires adequate storage. As the prices of batteries go down and their performances improve, distributed electrical storage shows potential not only in standalone units but also in the electric vehicle fleet. Electric vehicles can provide ancillary services to the grid, such as voltage and frequency regulation, peak power leveraging, and reactive power support to enhance the operational efficiency, secure the electric grid, and reduce power system operating costs (67). Electric vehicles couple well with renewable resources. For example, installation of photovoltaics in parking lots in Frauenfeld, Switzerland, could supply 15 to 40% of the future electric vehicle energy demand in that city (68), and urban electric vehicle strategies in cities in developing countries could particularly benefit the poor.

Opportunity for thermal storage is growing. Using thermal storage could double the photovoltaic capacity of Shanghai, for example (69). Although water remains the most widely used material for sensible heat storage, other methods, such as packed beds and phase change materials, are emerging (70). Thermochemical heat storage offers the greatest potential energy density and does not suffer from heat losses during storage, but development efforts are at an early stage.

Behavioral challenges

From the mundane decisions of whether or not to unplug a cellphone charger or take public transportation to more momentous decisions such as installing solar panels on a roof, behavior shapes how we live our lives and the energy choices we make. On an individual level, the effect is minimal, but in aggregate it is substantial. Occupant behavior, for example, can double the energy consumption of a building (71). Similarly, driving style can influence a vehicle’s fuel consumption by up to 20% (72). A lack of information, or selfishness, may lead us to make poor energy choices, even when they are not in our individual and collective best interest (73).

Conventional power generation systems, typically located outside of cities and neighborhoods, are out of sight and, therefore, out of the minds of general consumers. This apathy has led to major misunderstandings. For example, only 12% of Americans could pass a basic electricity literacy test (73). There is not only a lack of understanding of electricity fundamentals but also of the economic value of energy efficiency and renewable energy generation. For example, most businesses remain uninterested in investing in renewable power, because energy generation is outside their core business goals, despite the increased profit margins that these installations could enable.

A harmful misconception is that freedom and social well-being are best achieved through abundance and excessive consumption. Often, efficiency improvements are outpaced by increased consumption. For example, the floor area of new single-family detached houses in the United States has increased so much since 1978 that single-family housing uses more energy than multifamily housing both per household and per person, despite the efficiency gains achieved through the enforcement of new building codes (74). Even WTE programs indirectly encourage increased consumption. Coupled with increased consumption is a strong sense of entitlement. Whereas conventional power plants have typically been located outside of cities and neighborhoods, renewable energy generation is best placed in resource-optimal sites and/or close to the end user. Unfortunately, there has been strong resistance to this, because many people prefer such development to happen elsewhere (“not in my backyard”). Individuals often find their time and comfort to be more important than that of others and choose private vehicle use over public transportation, leading to increased congestion, delays, and inconvenience for the broader community. Not only do individuals need to understand how their behavior affects energy use, society, and the environment but, more importantly, they need to care.

Policy challenges

Although each country suffers its own political challenges, similarities can be found in the treatment of renewable energy and energy-efficiency measures. The research and development funding in these areas is nonexistent in some countries and undersupported in others, slowing innovation. Global research and development funding in renewable energy fell 3% in 2012 and 2% in 2013 (75).

Subsidies and incentives are often inconsistent. Unlike those for conventional generators, policies aimed at encouraging renewable power technologies have changed frequently, discouraging widespread adoption of the technologies (73). When incentives are removed abruptly, projects can be abandoned before completion and companies can be bankrupted. Additionally, frequently changing subsidies make it increasingly difficult to obtain financing for renewable energy projects. In the United States, policy variation between states deters investment, complicates compliance, discourages interstate cooperation, and encourages tedious and expensive litigation (76). An effort to promote renewables has to be sustained, orerly, substantial, predictable, credible, and ramped (73).

Policy-makers have focused their efforts on technical challenges. Although there are still opportunities for technical improvements, more comprehensive policies are needed to overcome economic and behavioral challenges. Emphasis is needed on government efforts to increase public understanding of energy systems and the environmental impact of behavioral choices.

An innovation agenda for urban sustainability

Achieving a sustainable urban energy system will require a dramatic rethinking of our infrastructure, information systems, and critical social and environmental justice issues. We pose here a number of immediate opportunities to “green” the process of urban evolution, as well as pressing research questions for sustainable cities, both theoretical and practical. We recommend analysis and practice to reach sustainability goals, accompanied by a new suite of data-intensive metrics on which to base planning decisions.

Renewable generation and reductions in consumption

Although city-to-city and regional variations are important to consider, many city governments could immediately (i) encourage energy storage and low-carbon generation at the building level through smart net-metered urban distribution networks; (ii) reclassify electric vehicles as appliances, so that electric vehicle purchases could be amortized into building capital budgets; and (iii) provide intra-city and city-suburban mass transit in the cleanest and most inclusive forms possible. In the near term, the following research questions should be addressed.

Can networked smart buildings themselves become the building blocks of a low-carbon city? Buildings that are designed to create clean energy, store excess generation, and feed this stored energy back into the regional matrix when demand or prices warrant would be key elements of an energy-smart network.

Do cities have an optimal size or density? Urban infrastructure exists at scales that are immediate in terms of buildings and transportation embarkation-disembarkation points but also complex and decentralized in terms of networks that supply food and water to the formal city center and suburbs. Many services that are seen as “citywide” may, in fact, be better suited to regional distribution or even remote management. The trend toward megacities, particularly in Asia, presents opportunities for improvements to infrastructure, such as mass transit, and livable high-density housing. At the same time, walkability and quality of life, as well as the potential for reduced carbon emissions, are all degraded if urbanism forces the mass movement of people, goods, water, and energy. Similarly, although increased population density may reduce transportation energy use, the resulting increased power density demand may not be appropriately met by city-integrated renewable energy, unless multiple sources are combined. These linkages of physical and managerial infrastructure open both theoretical and practical questions of scale in provision and planning.

Overcoming challenges to dramatic decarbonizatio

Economic, technical, behavioral, and policy challenges have been identified as barriers to dramatic urban decarbonization. However, there are several immediate actions that can be taken to begin to address these: (i) Economically value clean urban environments specifically through the positive environmental justice benefits, and use this valuation to invest in disadvantaged communities. (ii) Standardize carbon and water accounting to improve resource efficiency today and enable a transition to resource and pollution markets over time. (iii) Mix fee-bates (fees associated with polluting vehicles that finance clean vehicle purchases) and congestion pricing to improve urban air quality and reclaim city centers for pedestrians and social spaces. Meanwhile, the following pressing research questions remain.

Can urbanization in emerging economies become a force for sustainability and equality? The unprecedented growth in population and resource demands in large Asian cities has made the urban environment more polluted and more of a resource drain than any other demographic trend over the past four decades. Resource allocation, combined with a new focus on quality of life, should become a means to reverse the trends that have swept Asia. These development trends will ultimately be played out in Africa and elsewhere.

How will we give environmental justice a more central role? Arguably the most central issue in urban sustainability is whether city management can move to a paradigm where environmental justice is not an occasional response to crises of inequality but one where we reap the benefits of proactive and inclusive planning, design, and operation. It is important that renewable energy generation, improved energy-efficiency technologies, and low-carbon transportation are widely accessible, particularly to low-income populations that typically lack ownership of their residential buildings and have the longest commutes. Improvements in walkability, urban parks, and air quality should make cities more livable for all inhabitants.

Ultimately, these and other questions will require a new coordination of technical, social, behavioral, and market innovations. Cities planned around resource demands, or personal automobiles, have been tried and ultimately found lacking in their ability to create sustainable spaces. A wave of innovations in physical form, function, and ideally justice and equity offers a new path toward low-carbon sustainable cities. The challenge is to accelerate innovation and deployment so that cities can substantially reduce greenhouse gas emissions in ways that make them more livable and equitable, not less so.

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Adolescent Health Care: Aligning Policy with Practicality

Serving adolescents properly with health care has always been difficult. Utilization of adolescent health care services (AHCS) is far below where it should be, to the detriment not only of patients, but to the nation's health as a whole. When we know that illnesses often begin in adolescence, and that they could be avoided – or at least detected early and treated at that time—why are they so underutilized?

An article last year in Pediatrics by Hargreaves et al. cites a survey of adolescents and parents. What were the impediments to seeking health care for the teenagers? The results were interesting.

  • 37.2% - unmet need perceived to be of low importance
  • 32.0% - non-financial access problems
  • 22.7% - negative consequences of health care
  • 14.8% - cost

Now, that's pretty amazing. It would seem that beliefs and inconvenience were the major reasons these kids didn't get the care that experts believe they needed. A mere 15% said that the money it would cost to get these services was an impediment.

This is an inconvenient conclusion. We love to solve problems by throwing money at them, but these results would seem to suggest that money isn't the issue. Does that mean we will actually have to think this thing through? What a bother that would be!

My thought is that, yes, we'll have to think it through, but not to worry, at the end we can throw some money at the problem with some hope of success, although not immediate. These things do take time. So here's the way I put it together.

First, I bet that the newness of adolescent medicine (AM) as a concept is part of the difficulty. Instead of simply a way station between childhood and adulthood that must be endured, we now see adolescence as a separate stage of life, with its own epidemiology that features major components such as injuries, suicide, drug and alcohol problems, mental and behavioral disorders, and sexual/reproductive issues. It is only in recent years have we have recognized that primary prevention, early detection, and interventions in these issues can not only be effective in helping the kids in the present time, but can also pay dividends in better health for decades to come. It is also only in recent decades that adolescent medicine (AM) has been seen as a distinct entity to be served by pediatricians, with its own subspecialty professionals as sources of instruction and as providers of care to difficult cases. In other words, it's new. Indeed, when I was in training in pediatrics at UCSF, we were not allowed to see patients after their 13th birthday! That's how new it is.

I also bet that this newness hasn't filtered down to the general populace fully. The families and the patients are not aware that there are issues in adolescence that should be approached medically. Adolescents typically feel invulnerable as their prefrontal cortexes are still myelinating, so they don't want to come in, and families just don't realize the potential value of ACHS. In addition, I'm sure the difficulties of confidentiality and embarrassment dissuade adolescents from accessing the services.

Also, note the 32% of the survey who said there were non-financial access problems. Lots of patients don't think of the pediatrician as someone to turn to for adolescent problems—although this is changing—and many pediatricians don't really like to deal with adolescent problems that much, and there are many places where full fledged pediatric services aren't available.

OK, so that's “beliefs” and “access,” rather than a direct financial barrier, which only 15% cite as the problem. Still, it seems to me as a health care policy analyst who tends often to think in economic terms, that money can still be an important part of the problem. And as a usually liberal Democrat, I think I can see my way clear to throw money at the problem. But if we are going to do that, we will have to diminish the salience of that 15% number.

First of all, I'm not sure that 15% is the right number for people who are deterred by cost. People do a lot of rationalization when they give reasons for acting as they did. It is very difficult for many people to think, “I didn't give my kid enough care because I wanted to save money.” It's more comfortable to think, “I didn't go to the doctor because I didn't think it would help,” or, “I didn't think doctors took care of that,” or, “I figured he would grow out of it.” Those ex post facto explanations still allow a parent to think that he or she was acting as a good parent. So I'm pretty sure that the 15% number is factitiously low.

Second, even though the ACA was supposed to make care “affordable,” we all know that there are still significant financial barriers to care. Well child visits are now free, but many teens and young adults still lack coverage, and for those who have it, high deductibles and high coinsurance are still problems, many policies are not covered by the ACA and have even higher barriers, and coverage of just those conditions often experienced by teens—mental health, behavioral, and sexual/reproductive services—are often under-covered or uncovered.

So, I would contend that direct financial barriers are still a problem, much in excess of the 15% reported who are affected by it.

Indirect effects of insufficient financing are also important. Clinicians are paid poorly for ACHS. It is well known that procedural specialties are more generously paid than the so-called cognitive specialties, which would include providers of ACHS. But even within the cognitive specialists, ACHS services are particularly undervalued. For instance, there are special billing codes for preventive care services—that is, well child visits. It is so, so much harder to see a 14 year old than a 7 year old. Yet the clinician is paid only a few dollars more to see the 14 year old, which is ridiculous. It is just hard to get paid for visits where the clinician does a pelvic exam, or where the clinician delves into a teen's depression, which over 10% of teens have. For payment, then, a case could be made for AHCS being the lowest of the low.

What does this low payment pattern lead to? For one thing, it leads to general pediatricians providing fewer AHCS than they otherwise would. That's just straight economics. If you are paid poorly for a service, you will tend not to encourage patients to patronize you for that service.

Second, well-financed services can use their money to construct attractive and even luxurious physical settings, to employ a host of aides, and to advertise to the public. I challenge anyone to think of AHCS settings and advertising to rival that of cardiac surgery.

Third, practitioners of financially favored fields hold positions of great respect in society. They are revered. It is hard to think of someone in AH being revered for preventing a suicide.

Fourth, physicians in training vie for positions in the fellowships that will grant them not only the ability to do good, but the ability to do well. AH fellowships are subject to much less demand even though there are fewer such positions available. It is hard for someone to choose a fellowship for three years at the end of which one will be qualified to provide services that will earn one less than one could make at the beginning of the fellowship from being a general pediatrician. Specialists in AM are generally not the major purveyors of ACHS; general pediatricians generally do that. But it is the graduates of the AH fellowships who will train the general pediatricians and give them enthusiasm for the field. As it is, however, training in AM for the primary care pediatricians is far from extensive, as training programs continue to concentrate on hospital-based services and specialties. If the financial rewards were more attractive, basic economics tells us that enthusiasm would be greater.

In sum, then, although patients might not cite financial obstacles as the key for their not obtaining services, there is a strong basis for thinking that if the field were better financed, increased utilization would follow.

What to do, then? Here are just a few suggestions, just illustrative, not definitive:

  • Change the focus of health care cost controls when it comes to AHCS. For much of medicine currently, the aim is to cut costs. For AHCS, the aim should be to increase costs. One could double or triple the cost of AHCS and it would have no impact whatsoever in the national health expenditures. Increasing expenditures would establish a better balance of expenditures and result in better health and eventually lower costs, as adult health improved and costs declined as the well-served adolescents age.
  • Change the ACA provisions for AHCS. Make all outpatient visits for teens have no deductible and only minor copays.
  • Equalize physical and mental health payments for teens.
  • Increase the requirements for AH training in all pediatrics residency programs. Introduce business case training in these programs to teach future primary care pediatricians how they can make money in adolescent health.
  • Change the Relative Value Units assigned to teen well visits – I would increase them by at least 50%.
  • Develop a set of standards for health status for adolescents under the care of larger health care institutions, and require that measurements be taken under supervision at regular times, and that the results be published.
  • Institute Pay For Performance measures specific to AH applicable for smaller practices, and require insurers to pay significant amounts to practices who achieve measures in stepped amounts according to percentile.

AH is a lot more important than people realize. There is a lot that can be improved by grants and special programs, I'm sure. But for a long lasting and relatively simple effort, I would support the basics of human economic theory – pay them more, and measure the results.

Budd Shenkin is a public health professional who has almost forty years of experience in the health world, spanning the sectors of pediatric practice, health administration, and health policy. He graduated from the Goldman School of Public Policy with a Master of Public Policy in 1971.

This essay first appeared on his blog, Budd's Blog.

Estate Taxes Vital Tool for Fighting Income Inequality, Raising Revenue

Alice and Jim Walton, above, are each among the 20 richest people in the world, each valued at over $32 Billion. They owe their wealth to the inheritance of the estate of their father, Sam Walton, of Wal-Mart fame.

It’s no secret that the past thirty years have been tough ones for state and local governments looking to preserve revenue for key public services. The ideologically-driven assault against taxes of any stripe have not only reduced the ability of state and local governments to fund vital public safety, infrastructure, and public health initiatives, but it has also hampered the ability of governments to promote equality of opportunity in their jurisdictions, a key goal of an equitable system of taxation. An especially damaging tax reduction has been the 2001 Bush Administration estate tax reductions.

The value of an estate tax is simple to understand from an equity standpoint: the most straightforward way to limit intergenerational concentration of wealth is to limit the ability of the rich to bequeath large sums of money to other rich folks like themselves (usually their children).
Unfortunately, anti-government advocates have worked hard to preserve the fortunes of wealthy children by launching a fierce war of words against it. Giving it the new label of the “death tax,” these right-wing radicals shifted the conversation from the problem of income inequality to a sympathy for the unfortunate rich man who was being “taxed twice” on his income through a tax that is levied after his death.

No matter that federal estate taxes only apply to estates of $5.45 million and above in 2016. No matter that this argument of “double taxation” is never mentioned around sales taxes, which fall heavily on the poor. No, the estate tax has become a particular source of derision by anti-tax advocates, leading up to the 2001 federal cut that applied to the very rich who were then subjected to the tax.

Lost in the important conversation about income inequality, however, is the fact that the estate tax is also a significant revenue generator for state and local governments. When the federal government gutted its estate tax in 2001, a number of state governments decided to institute their own estate taxes. These taxes apply to estates at their lowest from $675,000 and up (New Jersey) to their highest at $5.45 million and up (Delaware, Hawaii, and Maine).

These taxes have proven to be significant revenue generators. In 2015, New York and Pennsylvania each raised over $1 billion in revenue from their estate taxes. Estimates by the Center on Budget and Policy Priorities say that if California instituted an estate tax with a fairly high exemption of $3.5 million (meaning it would only apply to estates worth that much or more), the state would raise a similar amount per year. A lower exemption that applied to all millionaires would generate $1.7 billion in revenue a year. For perspective, that is the same size as the state’s annual expenditures on business, consumer services, and housing.

The estate tax is an equitable, vital tool for policymakers to both reduce income inequality and generate revenue for public services. States like California should seriously consider reinstating the estate tax if they are truly committed to ensuring an even playing field for all their residents and not leaving dollars on the table that can be put to good public use.

Rob Moore is a Master of Public Policy candidate at the Goldman School of Public Policy and an editor at PolicyMatters Journal where this article was originally posted.

Voting for a Healthier Community

Over the past decade, the Alameda County Public Health Department (ACPHD) has been at the forefront of efforts to re-conceptualize the role of a public health agency. In 2008, it adopted a health equity framework that focuses not only on the traditional downstream factors that influence individual and community health outcomes (e.g., individual health behaviors like smoking), but also on the upstream or socio-ecological factors that determine health (e.g., discriminatory beliefs, institutional power, and social inequities). In order to monitor and address the impact of socio-ecological factors on health outcomes in the County, ACPHD has developed and implemented a number of initiatives and programs aimed at addressing the social determinants of health. 

Despite designing and implementing a number of community capacity building and civic engagement programs over the past decade, efforts to monitor the levels of voter participation—a key indicator of political empowerment and social capital—have been very limited. Troubled by a recent drop in the County’s voter turnout rates, ACPHD’s Legislative Council Coordinator, Pam Willow (’01), brought me on to work on a new Voter Turnout Initiative. 

The goal of this initiative is to learn more about how voter participation affects both community and individual health; what the Department can do to address low levels of voter registration and turnout; and how it might implement a pilot program aimed at improving voter participation rates in the upcoming 2016 elections, particularly among low-income people of color who have historically been underrepresented in the political system. 

Working on this project for my Applied Policy Analysis (APA) has been an incredible learning experience that has required me to use every skill in my policy analysis tool set. I applied my newly-acquired quantitative skills to identify emerging trends in voter participation as well as connections between voter participation rates and health outcomes. Most of my work, however, has involved interviewing much of ACPHD’s staff, its sister agencies, community partners, and clinical practitioners. Here my Introduction to Policy Analysis (IPA) experience has been invaluable as it proved to be a training ground for working within an agency context, learning about interview protocols, and practicing how to organize and synthesize large amounts of qualitative data into concise and useful pieces of information for a decisionmaker. Through this process, I have conducted an organizational analysis of ACPHD’s operational capacity and resources to identify ways in which different public health programs can contribute to the work of the initiative’s three phases: voter registration, public education, and voter turnout. 

I am now in the process of using all of the research I have conducted to inform the design of an implementation plan that ACPHD can use. I recently learned that the recommendations I put forth in my APA report will be put into place this summer and fall in the lead up to the November general election. In fact, we are recruiting first-year GSPP students to serve as interns that will implement and evaluate the plan in the coming months. Reflecting back, this project truly feels like the culmination of my two years of professional development at the Goldman School. The project seeks to see a problem as an opportunity, to use policy analysis to inform decisionmaking, and to create positive change in our community.


Vanessa Cedeño received her Masters in Public Policy from the Goldman School in 2016 and is currently a policy consultant at Alameda County Public Health Department.

This article originally appeared in the Spring 2016 edition of Policy Notes.