Building A Renewable Energy Future Through Cities

social solar renewable energy cities

According to the United Nations, more than half of the world’s population now lives in cities, a number that is projected to increase to two-thirds by midcentury. This trend represents both a blessing and a curse as it relates to climate change. On the positive side, urban modes of living are quite sustainable in relative terms. City-dwellers are far more likely to utilize public transportation rather than personal automobiles, and typically live in smaller spaces in buildings with shared heating and cooling systems, allowing for efficiency gains. All this is to say that as the planet’s population continues to grow, sustainability goals are more easily accomplished if its residents are living in cities.

Unfortunately, cities are also particularly vulnerable to the effects of climate change. Due to historical reasons, cities tend to be located along coasts and rivers, putting them at the mercy of increasingly violent weather events, namely hurricanes, bringing storm surges and floods. We saw this play out in New York with Hurricane Sandy in 2012, where a storm surge inundated many of the city’s low-lying areas. Seven years on, New York is still cleaning up, with the most notable Sandy casualty probably being the L Train-carrying Canarsie Tunnel under the East River. More recently, Hurricane Harvey’s historic deluge of 40 inches of rain in four days over Houston resulted in catastrophic flooding, essentially drowning the city. In dense urban areas, catastrophic storm events can result in incalculable damage.  

City Challenges

Given cities’ unique vulnerability to the effects of climate change, they cannot simply rest on their residents’ relatively small carbon footprints. Cities cannot afford to be passive actors in the fight against climate change. Central to their role in this fight is a conversion to renewable energy sources. Within that, however, converting cities away from fossil fuels is an extremely challenging task, particularly in dense urban areas dominated by multifamily buildings and large office towers. The task of converting carbon-driven cities to renewable energy cities is extremely complex, and involves a number of separate but interrelated challenges.

Dense urban agglomerations like New York City stand out in that their chief source of carbon emissions is not vehicular transport, as it is in most of the United States, but instead buildings. In order to become renewable energy cities, these buildings must utilize renewable energy sources. In many cases, however, this is far more challenging than it would seem. For one, buildings may be able to produce some energy through the use of solar panels or wind turbines, but they are still dependent on renewable energy sourced from the electric grid. In order for buildings to help cities along the path towards a renewable energy future, the grid needs to be prepared to supply renewable energy to match demand. Currently, while our grid has become cleaner over the last decade, this has been in large part due to the advent of cheap, plentiful natural gas replacing coal. Utilities are still a long way from meeting 100% of our energy needs with renewable sources.

Electrification Futures

Alongside the challenge of a greener grid is that of electrification. Currently, many of our buildings are dependent on fossil fuels for their heat and hot water. Fuels used vary by building, with the worst offenders burning highly polluting diesel fuels. Combustion-based heating and hot water systems represent a health hazard to local communities while contributing disproportionate quantities of climate change-inducing greenhouse gases. In many cases, the systems our buildings depend on essentially represent small oil and gas power plants in the midst of our cities. We would object to an oil burning power plant being situated across the street from our homes, but we accept it in our own buildings as a necessary evil.

Residential buildings in New York City that burn residual fuel oil were concentrated in Northern Manhattan and the Bronx, as of late 2015.

Long term, electrification is central to moving our cities towards a renewable energy future. Electrification is the process of shifting energy use from localized combustion of fossil fuels – think furnaces – to grid-supplied energy. Buildings currently burning oil and gas to supply heat and hot water would shift these systems over to electric. Ultimately, oil and gas are not and cannot be renewable energy sources. They must eventually be retired if our cities are to minimize their respective carbon footprints and undergo a large-scale shift to renewable energy sources.

As it pertains to greenhouse gas emissions, however, electrification poses challenges of its own. Primarily, our grid is still quite dirty as currently composed, with coal, oil, and natural gas continuing to play a major role in electricity production. It can reasonably be predicted that grid power will get significantly greener in the coming years as large solar and wind projects, including offshore wind, come online alongside improved and scaled up battery storage. This transition will take time, however, and in the interim the grid will become more carbon-intensive as comparably clean nuclear plants reach the end of their lifespans and are subsequently decommissioned. New York City is at the front lines of this challenge, where the Indian Point nuclear facility supplies approximately 25% of power used in the city, essentially emissions free. With the plant set to be closed by 2021, the carbon intensity of New York City’s grid stands to increase in the short-term.

Greenhouse Gas Emissions

Converting building systems is not a simple or quick process. Just as a homeowner installing a new furnace expects it to last twenty years or longer, buildings operate on capital plans that span decades. These long timespans represent a complicated signal as we push for electrification. In the short-term, the reality of electrification might be increased carbon emissions, in light of the grid getting dirtier before it gets cleaner. But without electrification, buildings installing new combustion-based systems in the next few years will be polluting unnecessarily a decade from now, with the current goal being for renewables to make up 50% of New York State’s grid power by 2030. While we know that electrification is the answer in the long run, how to address the process in the short term remains a challenge.

Energy Efficiency in Buildings

Beyond electrification, improving buildings’ energy efficiency is also crucial to limiting their carbon output. Many buildings, particularly in older cities like New York, are quite inefficient in their use of energy. Residents on upper floors often have scorching hot apartments in January, necessitating that they open their windows, resulting in wasted energy. Residents on lower floors, on the other hand, are often freezing. Many boilers supplying heat and hot water rely on technologies developed generations ago, and do not take advantage of subsequent advances in engineering. Windows are often drafty, releasing warm air in the winter and cool air in the summer, reducing the effectiveness of heating and cooling systems. Improvements in building energy efficiency allow for improved resident comfort while also limiting energy needs, and can often be economically beneficial to building owners, as they reduce energy costs.

Some cities are utilizing innovative policy solutions to address the issue of building emissions. Tokyo stands out as a leader in this area with the world’s first emissions trading scheme addressing building emissions. Tokyo’s program utilizes a system commonly known as cap-and-trade, wherein its large buildings are limited in how much they are permitted to emit. If they go beyond that limit, they are required to buy credits from other participants in the system. These other participants generally receive their credits for reducing emissions below what the threshold required, thus providing an incentive for building owners to exceed mandated carbon reductions while also providing an alternate compliance pathway for buildings where energy efficiency measures are more expensive. New York City is in the process of following Tokyo’s lead, with a bill limiting building emissions brought before the City Council in December. Needless to say, conversion to renewable energy is central to such mandates, as its utilization allows for buildings to use energy that does not count against their carbon allowance.


While buildings often may make up a majority or plurality of carbon emissions in dense urban areas, this is not to say that that transportation is not a significant source in its own right. Urban residents’ carbon emissions from transit tend to be lower than those of suburban and rural dwellers for two key reasons. For one, zero-emissions forms of transit, namely walking and biking, are much easier when you live near things that you can walk and bike two. Secondly, and arguably more important, is that buses and trains are shared, and the emissions per passenger are far lower than for personal vehicles that often carry just one or two passengers.

Within this, however, there is still room for cities to improve their transit-oriented carbon output. Municipal rail lines are typically powered by grid electricity, and increases in renewable energy sources’ share of the grid can offer carbon emissions abatement in that area. Buses, meanwhile, typically still rely on the combustion of fossil fuels. While the fact that they can carry many passengers makes much more efficient use of these fuels, that does not change the fact that they result in carbon emissions.  This is an area where transitioning to more fuel-efficient hybrid buses or electric buses can make a huge difference. Electric buses in particular have yet to see widespread adoption, but New York City is currently conducting a pilot study utilizing vehicles from two manufacturers.

Electric buses have benefited greatly from the decline in battery costs over the last ten years, and typically offer cost savings in terms of both energy – grid power being less expensive than fuel – and maintenance, as their mechanics are less complex and undergo less wear and tear than combustion-powered conventional buses. As with other modes of electrification, electric buses are only as green as the grid, but in the long-term they represent an opportunity for us to shift transportation’s energy burden to renewable sources.

Personal Transportation

Cities can also work to speed the adoption of electric personal vehicles. Adoption of electric vehicles has exploded in recent years, with Tesla probably the most prominent example, accompanied by models like the Nissan Leaf and Chevy Bolt. Unfortunately, however, these vehicles are often a better fit for suburban homes featuring garages with plugs than they are for curbside urban street parking. As it currently stands, vehicle-owning urban residents are limited in their ability to switch to electric vehicles in that they often do not have a convenient place to charge them. Some companies are working on this issue, with technologies geared towards allowing for easy, unobtrusive curbside charging. In moving our cities towards a renewable future, this is a crucial gap to solve for.

Public Health

The focus on converting to limiting our carbon emissions and converting to renewable energy sources tends to be on climate change, but there are also significant localized public health benefits to a shift away from combustion-based energy. When our buildings burn oil or our cars burn gasoline, it is not just carbon that they emit; they also spew out a range of co-pollutants that poison our air, resulting in a range of health problems including stroke, heart disease, lung cancer, and respiratory problems. In some cases urban residents ingest pollutants equivalent to smoking a pack of cigarettes a day. Shifting away from fossil fuel combustion in our urban areas means removing major pollutants from those areas, promising significant health benefits. As such, in assessing the potential cost of shifting to renewable energy, we should not merely look at the cost-benefit of renewables versus carbon fuels, but also include the carbon combustion-associated health costs currently impacting our cities. A shift to renewables does not merely help in the fight against global warming, it also offers urban residents a pathway to more healthful lives.

Clearly, converting our cities to renewable energy is not something that can happen overnight. Our urban built environments reflect the reality that the combustion of carbon fuels built our current economy. Recognizing, that, however, there is a way forward to a renewable energy future. Our buildings can become more efficient and rely increasingly on electricity. Our grid can shift to more renewable sources like wind and solar. Our transportation can move away from combustion and towards batteries and electrification. In concert, this transition promises healthier, cleaner, more livable cities, benefiting residents both present and future.

Grid-Sourced Renewables

Social Solar grid sourced renewables

Unprecedented wildfires in California. 1,000-year flood events happening on what seems like an annual basis. Massive polar vortexes bringing bone-chilling cold. With climate change evolving from a distant danger that people hear about on the news to something that effects their daily lives, there is increasing interest in renewable energy sources.

While solar has conquered suburban subdivisions across the United States over the last decade, people tend to be much less familiar with other renewables, particularly as they relate to where power to their homes comes from. Thankfully, while the thread of climate change is real and omnipresent, our energy grid is increasingly shifting towards renewable sources.

What is renewable energy?

In better understanding renewable energy as it pertains to the grid, it is important to first understand what exactly constitutes a renewable. According to the US Energy Information Administration, renewable energy sources are those that are “naturally replenishing but flow-limited.” Essentially, these sources represent finite potential energy in any moment in time but are inexhaustible over a longer period. Under this definition, potential renewable energy sources include solar, hydroelectric, wind, geothermal, and biomass. Essentially, the earth replenishes renewable energy sources on a human-scale timeline of days, years, and decades, whereas carbon-based fuels are produced on a geologic timeline measuring in the millions of years.

In human terms, renewable energy sources also represent a return to our energy roots. Energy from the sun is what makes life possible, and humans have harnessed its power to warm homes and dry food for millennia. The origins of water power are hazy, but historians date the use of the first water wheels back approximately 2,000 years, and it has played a crucial part in the grid since the first hydroelectric power plant was constructed at Niagara Falls in 1879. Widespread use of windmills dates back approximately 1,000 years, having been used to move water for irrigation and break down hard kernels of grain into flour for bread. The use of the earth’s geothermal energy is also quite ancient, with evidence of paleolithic humans warming themselves in geothermal baths, and later Chinese and Roman bathhouses situated to take advantage of hot springs. Biomass-fed fire, meanwhile, represents the first energy source humans truly harnessed.

Needless to say, renewables have evolved significantly from their respective original forms to represent sizable and growing grid energy sources. Home solar installations have become omnipresent throughout the United States, growth driven by a combination of technology improvements and government incentives, allowing for home owners to lower their own energy bills while feeding sun-powered electricity back into the grid. The energy independence afforded by home solar, offering every home the chance to be its own miniature power plant, would have been a radical concept just a few decades ago. Moreover, residential solar represents a consistent source of clean power for utility companies seeking to meet renewable energy mandates while planning for a more resilient future.


Beyond home solar, large scale solar energy projects, often dubbed solar farms, have been initiated and brought online by major grid energy suppliers. China’s arid Inner Mongolia region currently plays host to the world’s largest solar farm, roughly ten times the size of Central Park at 43 km2 and with enough generation power to light 1.5 million homes. Closer to home, California’s Solar Star represents the largest solar project in the United States at 559 megwatts, narrowly edging out two other California solar projects that each clock in at 550 megawatts. Speaking to the technology’s maturity, Disney recently completed a 50 megawatt project in Florida, enough to power two of its theme parks. With projects like these having proven solar energy’s ability to scale, we can expect to see its share of grid power increase in the coming years.


As noted, hydroelectric represented one of the first large scale sources of electricity in the United States. Hydropower differs significantly from solar in that its effectiveness is limited at a smaller scale. Hydro projects represent massive capital investments, and the dams resulting from them can often be disruptive to communities situated near water sources. As such, these are massive, complex, challenging projects that often take decades to see through completion. More importantly, most major water sources in the United States, particularly on the East Coast, have already been dammed, meaning that building more dams does not represent a simple renewable solution to our climate woes. Hydropower also faces environmental concerns in its own right, as its utilization often requires the damming of rivers, altering local environments and preventing riparian migrations of fish and other animals. The challenges associated with hydropower mean that it does not represent a panacea to our emissions woes.

Hydropower’s major advantage is that water never stops running. This stands in contrast to solar and wind, where cloudy skies and still air result in reduced energy production. Constancy in production of electricity is critically important to meeting baseload needs, baseload being the electricity needed to meet the grid’s needs at times of minimal usage. Solar and wind are not ideal sources for baseload power, given their intermittent nature, as there might be a time when it is either not sunny – nighttime –  or not windy, and production drops. Water, however, runs all the time, making hydropower the ideal renewable source for meeting our baseline needs.


Despite humans having harnessed wind power more than a millennium ago, widespread use of wind for electricity generation at scale is a relatively new development. Nonetheless, wind played an often overlooked but crucial role in supplying electricity to rural areas prior to the extension of the modern grid, providing the only source of electricity for many remote North American farms. Though windmill use for historic uses, namely to pump water, remained common throughout the 20th century, it was only in the later decades of the 1900s that global interest in wind power began in earnest. Over the last two decades, wind power has become a crucial component of the grid’s power supply both at home and abroad. Currently still under construction, at 7-megawatts the UK’s Hornsea Wind Farm will be the world’s largest when completed in 2020. New York, the 15th windiest state in the US, currently has 20 wind projects in development. With a single turbine

Wind’s moment has arrived, and it stands to play a crucial role in the future of New York’s downstate electric grid. Offshore wind represents an infinite energy resource for the region. Wind does suffer one major drawback relative to some other sources in that it is intermittent and, to a degree, unpredictable. In addition, wind may not produce electricity when grid demand is at its peak, evidenced by Texas utilities providing nighttime electricity free of charge due to surplus production of wind energy. To mitigate for intermittence and allow for wind power to reach its maximum potential, large scale energy storage technology – batteries – also needs to mature, allowing for the storage of cheap power produced during peak periods.

While still intermittent, offshore wind is significantly more reliable than its onshore counterpart, an advantage to New York given its proximate access to the former. Moreover, while offshore wind installations are currently more expensive than those onshore, A 2017 report from McKinsey stated that this is largely due to offshore being a more nascent technology, and predicts that prices will fall quickly as the technology scales and comes to match the maturity of its onshore counterpart. Adding battery storage to the mix and allowing for wind generated power to serve the grid at peak demand – and thus peak price – can only help in this regard, allowing for better optimized pricing of wind-generated power.


When people think of geothermal power, they typically think of hot springs and geysers, and they are not wrong. Geologically active Iceland, for example, sees almost 100% of its energy come from renewable sources. Geothermal power makes up a large portion of this, with nine out of ten Icelandic homes heated by geothermal sources. We see something similar in New Zealand, where geothermal power generation makes up 13% of installed capacity. The largest geothermal plant in the world is here in the United States, the Geysers Geothermal Complex in Northern California. Generally speaking, geothermal power is similar to hydroelectric in that it produces power at a constant rate, avoiding the issues with intermittency that we face with sources like wind.

Though the focus of this article is grid-sourced renewable energy, the growth and maturity of home geothermal installations bears mentioning. Installing geothermal in your home does not require that you live next to a volcano. Geothermal heat pumps instead make use of the earth’s temperature constancy at depths greater than 20 feet. This temperature constancy allows heat pumps – generally using grid electricity – to pull heat from the ground when seeking to warm the air, and to force heat from warmer air into the ground when seeking to cool a home. These systems are extremely efficient, and allow homeowners to take advantage of the planet’s constant core temperature regardless of where they live. 


Biomass is a broad energy category representing organic matter that is used for fuel. Sources of such organic matter vary widely, including both virgin agricultural products and waste products from other applications. Biomass burning for energy production is generally a simple process akin to the use of fossil fuels, where heat is converted to energy. The similarity to fossil fuels does not end there, which is largely why biomass represents the most controversial renewable energy source. While biomass fits the technical definition of a renewable in that sources are replenishable on a human timescale, it can also be a significant polluter in its own right, emitting carbon during the combustion process.

Emissions stemming from biomass complicate the source’s potential as a component of a renewable-centric grid. Biomass’ environmental impact is largely tied to fuel source, both the organic matter used and where that organic matter was grown. Suffice it to say, there exists a fundamental difference in terms of carbon output between growing crops for fuel on otherwise unproductive land and cutting down virgin forest for biomass to use in electricity. Biomass’ overall impact can be significantly mitigated if land is replanted after harvest, allowing for the next crop of organic matter – whether that be trees, sugarcane, corn, or some other potential fuel product – to capture carbon equivalent to the matter combusted as fuel.

Some of biomass’ more interesting applications involve the use of waste products for electricity production. The UK supermarket chain Sainsbury’s, for example, is diverting food waste from landfills and instead converting it to biofuels and electricity production. Efforts like these are particularly important in the fight against climate change, as anaerobic decomposition of organic matter produces methane, a highly potent greenhouse gas. Globally, animal farming accounts for approximately 15% of total greenhouse gas emissions, with much of that coming in the form of methane from manure. An ongoing project in North Carolina seeks to use manure as a fuel source, turning hog farms into biogas producers by converting their methane emissions into biogas. In a similar vein, Oswego, NY plays host to a waste biomass plant, combusting waste from municipal and industrial sources for local power generation. The above efforts represent the best of biomass-driven energy production, converting what would otherwise represent organic waste into organic energy production.

Renewable Future

If our energy future is to be a renewable one, we cannot depend on any single renewable energy technology. The sun does not always shine. Droughts occur. The wind does not always blow. A resilient renewable energy future is a diversified one, maximizing the utility of renewable technologies while determining what fits best where on a case by case basis. We need hydropower for our baseload needs, wind and solar for their cheap utility, geothermal where it is available, biomass to keep waste out of our landfills, and batteries to help distribute it to times of peak demand. While the grid of the 20th century assumed the existence of cheap, plentiful, consequence-free fossil fuels, that assumption has become rather faulty in the 21st, requiring a deep rethink of our energy future.