Decarbonization of Buildings’ Heating and Cooling Systems

Two Approaches To Buildings Decarbonization

By Klaus Bundgaard, Climate Project Manager, City of Copenhagen,
and Jenna Tatum, Director, Building Electrification Initiative

Approaches to decarbonizing heating and cooling systems in buildings depend on whether the city provides an extensive district-scale heating and cooling system (as many European cities do) or uses a market in which individual buildings purchase and operate their own systems (which is the prevailing practice in Asia and North America). In this edition of the Game Changers Deep Dive, we have two guest contributors. Klaus Bundgaard, Climate Project Manager to the City of Copenhagen, invites you to learn more about how Copenhagen has worked to achieve a state-of-the-art district heating system. Jenna Tatum, Director of the Buildings Electrification Initiative (BEI), offers a deep dive into how BEI works to make the switch to heat pump technology in the North American market, as illustrated by two city case studies in Burlington, Vermont and New York City.

Copenhagen’s District Heating System

In the start of the twentieth century, Copenhagen was once heated like most other cities. Individual heating supplied every home, which meant the city was heavily polluted from coal, petroleum and coke burned in stoves locally. In 1925, due to rising electricity demand, more power plants were constructed within the city, which led to an increasing amount of excess generated heat. A smart person proposed the idea of utilizing the heat by pumping it out as steam to the nearest households through a network of pipes, and hereby the first district heating network in Copenhagen was established.  Now, 90 years later, Copenhagen has built one of the world’s most extensive district heating networks, supplying more than 99 percent of the city with sustainable and efficient heating. Between 1925 and now, more than 1,400 kilometers of pipes were installed, providing heat to more than 500,000 Copenhageners. More impressively, the district heating network in the City of Copenhagen is a part of four connected networks covering 17 surrounding municipalities in the Greater Copenhagen Metropolitan, and the assembled network covers a fifth of Denmark’s total heat demand.

Establishing a district heating network makes so much more sense in a dense city, since the density of end-users cuts the price of constructing the transmitting network. Of course, the economic business case has been favorable and helped with the expansion of the district heating network, but another important measure was the mandatory connection to the network introduced up through the 80s and 90s. With this regulation, all property owners in Copenhagen had to be connected to the network within a limited time, otherwise they would have to pay an annual fee.

Our road towards a carbon neutral heating will probably be less bumpy than other cities, since we – together with surrounding municipalities – own the utilities. Due to this ownership model, our vision is also shared by the utilities. Today, 65 percent of the heat supply is carbon neutral, and we expect an increase by next year that will allow us to go above 80 percent, due to the opening of the BIO4 power plant. This is a new biomass-based power plant unit that will replace an old unit running on coal, and hereby also highlight the end of coal-based power plants in Copenhagen. This means that our main inputs for heat production will come from waste and biomass with a sustainable certificate. The remaining 20 percent of carbon dioxide will derive from plastic and other fossil fractions in the waste, and further the need for peak-load capacity.

Amager Bakke Energy Plant, a combined heat and power waste-to-energy plant in Copenhagen, Denmark. Photo credit: Amager Resource Center.

To overcome this, we plan to add carbon capture technologies to the waste-to-energy plants, removing the carbon dioxide emitted from the remaining plastic and fossil fractions, which is roughly 165,000 tons. We’re collaborating with our waste-to-energy plant, Amager Resource Center, and have recently completed a technological screening of a possible carbon capture facility. It is still undecided whether the carbon dioxide will be stored underground or used for producing new e-fuels. Adding this technology to the list of solutions related to district heating offers a huge potential as a game changer, due to the possibility of producing energy with a ‘negative’ carbon footprint, if it is coupled with biomass. Through the annual CNCA Innovation Fund, we received funding for a project focusing on Carbon Capture Storage and Usage from a city perspective. It is our hope that together with the cities of Amsterdam, Helsinki, Oslo and Stockholm, we can join forces and share knowledge while pushing each other closer to implementation.

The district heating network is constantly evolving, and it’s not only the transition to biomass that makes it more sustainable. Currently the remaining steam-based pipes are being replaced with low temperature water-based pipes, which will reduce the heat loss by 140 GWh, equivalent to 6,000 family homes, and further cut costs for operation and maintenance by 90 percent. Also, with the increasing amount of wind turbines introduced into the energy system, there is a need for new solutions to balance the grid. Here, Copenhagen’s district heating network can become an integrated part of the future energy system that will utilize renewable energy. On windy days with lots of excess electricity, large scale heat pumps and electric boilers could raise the temperature of the water in the district heating network and function as a storage capacity. Creating flexibility in the energy system is something that is being tested and demonstrated in the project EnergyLab Nordhavn.

While some parts of EnergyLab Nordhavn relate to more systematic changes, it also tests solutions within the households of our citizens. The previously mentioned peak-load capacity is a challenge since it relies on backup from oil or gas turbines. On a calm and cold day in January, most people wake up and go to the shower while heating up their household, which creates a peak load. But what if the utility centrally could manage their room temperature and could raise the room temperature a couple of degrees before people wake up, and thereby move forward the demand a couple of hours? We call this ‘flexible heating customers’, and they should of course be rewarded for this service.

Lastly, why limit yourself by only installing a network for district heating? In the center of Copenhagen, we’ve now installed a new district cooling network utilizing the sea temperature in the harbor through cooling exchangers. As for now, it is voluntary to connect your property, and it is still only in certain central areas. But in the future, we expect the network to expand as it delivers some clear benefits such as substantial reductions in cost and carbon dioxide and further requires less space and produces less noise.

The Buildings Electrification Initiative (BEI) and Switching to Electric Heat Pump Technology

Why Building Electrification?
In cities across North America, fossil fuels used to provide heating, cooling, and hot water in buildings account for a significant portion of greenhouse gas (GHG) emissions—accounting for between 15% and 40% of emissions in a typical U.S. city. This is particularly true in heating-dominated climates like the Northeast. In New York City, for example, on-site fossil fuel use in buildings accounts for 42% of the city’s GHG emissions, which is the largest single source of citywide emissions.[1]

In the North American market, where individual building owners generally purchase and operate their own heating, cooling, and hot water systems, the most viable option is to convert these systems to cold climate air source heat pumps (ASHPs) and heat pump water heaters (HPWHs). These are highly efficient electric technologies that use a compressor to pull heat from the outdoor air to provide indoor space heat and hot water—essentially an air conditioner that can run in reverse.

Because these technologies are so energy efficient, heat pumps reduce emissions in nearly all parts of North America today, and they have the potential to dramatically reduce emissions even further over the long run by using electricity increasingly powered by clean and renewable sources. During warmer seasons, ASHPs can also provide high efficiency cooling, which is an increasing need across North America as cities experience increased heat and waves due to climate change. Electrifying building systems also has the potential to dramatically reduce indoor and outdoor air pollution and reduce the risk of fire from gas infrastructure—over the past two decades, there have been over 640 gas distribution accidents, resulting in 221 fatalities across the U.S.[2]

In the long term, major utility investments and state regulatory action will be needed to fully transition buildings away from fossil fuels. In the short term though, city action can spark the development of new markets and equitable approaches for transitioning to high efficiency electric building systems. This action will deliver immediate GHG and air pollution reductions, while also providing information on best practices and laying the groundwork for more ambitious efforts that will be needed at all levels of government.

The Building Electrification Initiative
The Building Electrification Initiative (BEI) equips cities with the tools, knowledge, and resources they need to implement strategies to accelerate the transition of building heating and cooling systems away from fossil fuels. BEI currently works with six leading cities: New York City; Washington D.C.; Boulder, CO; Burlington, VT; Berkeley, CA; and Salt Lake City, UT.

BEI emerged from the “Thermal Decarbonization Initiative for Cities,” a project launched in 2016 with startup support from the USDN and CNCA Innovation Funds. Under this Initiative, cities conducted market analysis and developed roadmaps for accelerating building electrification in their communities. They also began forming critical partnerships with states, regional organizations, utilities, manufacturers, and others to co-invest in solutions and coordinate regional action.

Building on these activities, BEI has developed a Theory of Change for how it will scale up these initial efforts and deploy city leadership to accelerate the transition away from fossil fuels in buildings.

Theory of Change
When it comes to building electrification, it is important to recognize the scale of the problem. There are over seventy million homes and businesses that burn natural gas, oil, or propane on-site in the U.S. for space heating and hot water production.[3] Electrifying all or most of these buildings would be a massive investment. For example, electrifying all the residential homes in Boulder alone—a city of roughly 100,000 people—would require an estimated investment of at least $1 billion. Moreover, there are tens or hundreds of billions of dollars of gas infrastructure assets across the U.S. that will need to be depreciated or phased out.

In general—but particularly in regions with colder climates—heat pump technologies have not moved beyond the “innovators” or “early adopters” and into the mainstream market. However, because heating systems have 15-20 year replacement cycles, it is critical to begin installing high efficiency electric heat pump systems today in order to minimize the cost of the large-scale transition and reach broad market scale by 2050.

Given the scale, voluntary market development alone will probably not be sufficient to achieve these goals; it will require robust local, state, regional, and federal policy regimes to transition away from fossil fuel-based building systems. Supporting market development activities will also be necessary to improve existing heat pump products, train and qualify contractors who can install them, and ensure there are customers who want heat pumps and understand their value.

Reaching scale will also require major investments in frontline communities to ensure these communities are not negatively impacted by the transition and that benefits are equitably distributed. Cities have long been on the frontlines of historical societal inequities, and are now facing a growing affordability crisis that threatens to displace many of their existing communities. Climate change will only exacerbate this rising inequality. Moreover, enacting transformative policies will require building new and broad coalitions of support. Communities who are most likely to be impacted will need to help create these policies, and can also become key allies for policy implementation. If implemented well, these policies can also help address cities’ equity and affordability needs by creating better quality and more affordable housing, providing new economic and job opportunities for those who need them, and mitigating against climate, health, and safety risks.

Cities can take the lead on developing strategies that pave the way for an equitable transition. Cities play an outsize role in their regional markets due to their size and population density. They can develop “proof of concept” programs and policies that can pave the way for future state, regional, and federal policy action on building electrification. They can also participate as strong voices within coalitions advocating for the necessary policy changes at other levels of government, and help ensure that these efforts equitably distribute benefits to frontline communities.

By equipping cities with the tools, knowledge, and resources they need to implement these strategies today, BEI aims to achieve a widespread transition away from fossil fuels in buildings by 2050 while delivering major investments that prioritize benefits for frontline communities.

The Building Electrification Initiative’s Theory of Change

City Highlights: Burlington, VT
Burlington is Vermont’s largest city, with a population of approximately 42,000. In 2014, Burlington became the first city in the country to source 100% of its electricity from renewables, and today is poised to make the transition to net zero energy in the building and transportation sectors.

Achieving Burlington’s goals will be no easy feat, given its cold climate, older housing stock, and the fact that more than 90% of housing units use natural gas for heating, which is relatively low cost compared to electricity. Fortunately, Burlington has a municipal electric utility, the Burlington Electric Department (BED), which is committed to supporting Burlington’s climate goals and has delivered innovative energy efficiency programs for nearly 30 years.

In 2018, BED launched a cold-climate heat pump rebate program that includes a combination of weatherization services and installations of high-efficiency electric heat pumps for customers using oil and propane for heating, which are more expensive than natural gas. In this program, BED prioritized low- and middle-income customers so they can be first to benefit from energy savings and gain access to cooling. To date, BED has provided incentives to over 300 customers to convert to cold climate heat pumps. Additionally, the City has found that cold-climate heat pumps are becoming a popular option for new multifamily buildings, due in part to the cost-savings that come from avoiding the installation of gas infrastructure to the development.

Building on its progress, going forward, Burlington will explore the potential to create new policy options for installing heat pump retrofits in new and existing multifamily buildings. To ensure their focus on equitable building electrification, these efforts will include an emphasis on building new partnerships between the City and representatives of low-income communities and communities of color to ensure these policies are implemented as successfully and equitably as possible.

City Highlights: New York, NY
New York City is the largest city in the U.S., with more than 8.5 million residents and over one million buildings. To achieve New York City’s commitment to 80×50, the City estimates that over half of these buildings must convert to high-efficiency electric heating and more than 90% will need to electrify their domestic hot water.

Through a detailed market segmentation analysis, the city identified over 175,000 small residential buildings that are the best candidates for heating electrification in the near-term based on a combination of technical, market, and socio-demographic characteristics. This includes more than 75,000 buildings located in the borough of Staten Island. Based on the market opportunity, the City is collaborating with its electric and gas utility, Consolidated Edison, the New York State Energy Research and Development Authority (NYSERDA), and Mitsubishi Electric, one of the world’s largest manufacturers of heat pumps, to propose a coordinated outreach and assistance program to scale up heat pump installations in Staten Island. To ensure that the program delivers equitable benefits, New York City plans to develop a strong workforce development and job access component to connect un- and under-employed New Yorkers in frontline communities to new HVAC contracting jobs.

New York City is also piloting heat pump installations in larger multi-family and commercial buildings through its NYC Retrofit Accelerator program. As part of this initiative, the City is publishing case studies and technology primers that will help accelerate future action across other real estate owners and developers. The City has also compiled a list of technology needs to improve existing heat pumps for the NYC market and has begun working directly with manufacturers to identify opportunities to develop these new systems. As a result of these efforts, New York City will begin to unlock its huge market and help drive the long-term transformation away fossil fuel use in buildings.

[1] New York City Mayor’s Office of Sustainability, New York City’s Roadmap to 80×50.×50

[2] Reuters, based on data from the U.S. Pipeline and Hazardous Materials Safety Administration

[3] Rocky Mountain Institute, The Economics of Electrifying Buildings, based on data from the U.S. Environmental Protection Agency.

Natural Carbon Sequestration

Three Reasons Why Cities Need to Get in the Sequestration Game and Five Ways to Do it

By Brett KenCairn, Senior Policy Advisor for Climate, Sustainability and Resilience, City of Boulder Climate Initiatives

Last year brought more sobering news about climate change from the world’s scientific community.  Both the IPCC report on the Paris Agreement and the US National Climate Assessment used uncharacteristically direct and urgent warnings that climate change is proceeding faster than expected and the time remaining to avert large-scale catastrophic impacts may now be less than two decades.  Within these reports are three critical points relevant to anyone engaged in efforts to stabilize climate.

1. Emissions reduction will not be enough to stabilize climate

An important focus of these two reports was the emphasis on the insufficiency of emissions reduction strategies alone to stabilize climate. In even optimistic future emissions scenarios, the accumulated carbon budget to stay within manageable climate change will be exceeded. These reports and many others all point to the inescapable fact that large-scale carbon recapture/sequestration must now be scaled up rapidly if we are to maintain a livable planet.

2. Near-term carbon capture is critical to buy time for longer-timeframe infrastructure change

As those actively engaged in efforts to change energy systems are well-aware, the essential process of large scale infrastructure change—from residential buildings to energy delivery and production infrastructure—is an immensely expensive, logistically complicated, and politically difficult transition to enact rapidly. With a shrinking timeframe within which to effect this change, we need to find ways to reduce the warming factors as fast as possible in the near-term. Many biological systems—both terrestrial and aquatic—have both rapid and large-scale capacity to recapture carbon in the near-term while working toward longer timeframe structural transitions.

3. Carbon-rich ecological systems are more resilient to climate change

As we now also face the reality that climate change is already underway and having increasing impacts on cities and surrounding landscapes, a growing body of information demonstrates that healthy carbon-rich soils, landscapes, and aquatic systems are more capable of buffering climate extremes. Cities with carbon-rich water and nutrient-holding ecosystems will be more resilient to heat island impacts, flooding, wildfire behavior, air and water quality improvement and other environmental extremes that will occur with increasing frequency and intensity in the coming decades.

Taking Organics Out of the Waste Stream

Recycling organic waste, instead of disposing of it in landfills, ends the emission of CO2 and methane due to decomposing organics in landfills. As much as 5% of global GHG emissions emanate from the solid waste sector, most of it from rotting organics. The emissions from organics are extremely problematic because methane is about 25 times more potent than CO2 in trapping heat in the atmosphere.

Recycling organic waste can also replace fossil fuel-based products with renewable ones. Composting uses microorganisms to break down organics into the essential component of soil (called humus), which can replace fossil-fuel based fertilizers. Cities also use anaerobic digestion facilities to turn organic waste and sewage into biogas, providing clean fuel for buses and other heavy vehicles instead of fossil fuels. When cities sell their compost and biogas for use, they generate revenue that covers some of the cost of the organics recycling system—the beginning of a “circular economy” model.

Composting reduces GHG emissions in yet another way. Compost added to the soil can draw CO2 out of the atmosphere and enhance the soil’s capacity to sequester/hold the carbon—especially in no-till situations, such as in orchards, vineyards, and grazing lands, where the soil is not disturbed in ways that would release the CO2.

Turning organic waste into a decarbonizing asset involves the mandatory collection and sorting of food waste, yard clippings, and other biodegradable waste from residences, businesses, and institutions (hospitals, schools, etc.) so that it is kept out of landfills where it would generate GHG emissions. The organics are separated from the rest of the waste stream and recycled into carbon-capturing compost for sale to nearby farms and landscape use or bio-gas for vehicles and industry.

High Impact City Sequestration Opportunities

While few cities currently have active efforts to assess, develop and implement sequestration strategies, there are at least five major entry points accessible to almost every city to begin exploring this opportunity.

1. Direct sequestration on city lands
Most cities have land holdings. In addition to parks, some have larger open space holdings. Boulder’s urban parks encompass over 1,500 acres. The city’s agricultural holdings encompass over 15,000 acres. Chicago, as an example of a larger city, has 500+ parks covering over 7,500 acres. A variety of soil management techniques including compost, biochar, biological inoculums, and mineral treatments show significant promise. A combination of these treatments could enable the soil to capture significant amounts of carbon: 1-5 tons of carbon per year by some projections. When converted to its CO2 equivalent, this pure carbon represents over 3½ times that amount of CO2. By some projections, soil treatments on 2,000 of Boulder’s open space lands could result in capturing over 35,000 tons of CO2. In contrast, the city’s long-standing residential and commercial energy efficiency programs reduce carbon emissions by around 2,000 tons annually.

2. Indirect sequestration: urban green waste to land-applied compost
San Francisco has done an extensive analysis of its urban green waste and the potential for directing this to land-application composting. The city currently generates approximately 187,500 tons of urban green and food waste per year which when processed yields 70,000 tons of compost.

While San Francisco captures over 50% of its organic waste stream this is an outlier of success in most cities. For most cities in the US 50-60% of waste is organic materials, the majority of which ends up in landfills resulting in the powerful climate forcer, methane. The pioneering work of the California Marin Carbon Project demonstrated significant carbon sequestration potential for compost applications in managed agricultural sites like orchards and vineyards, and in open range applications. Through strategic use of these urban carbon and nutrient flows in land-based sequestration, cities both reduce future landfill methane emissions from landfills and facilitate land-based carbon recapture and soil/land productivity and resilience improvements.

Following the findings of the Marin Carbon Project, if San Francisco used its 70,000 tons of compost to treat degraded range lands with 1/4 inch of compost, that would allow them to cover 1,200 acres every year. Starting in 2020 and going to 2030, using conservative estimates, this would result in just over 400,000 metric tons, or 10% of San Francisco’s 2016 carbon footprint, being sequestered. And for every ton of CO2e sequestered, upwards of 50-70 tons CO2e are avoided upstream.

3. Ocean/aquatic sequestration
Aquatic systems have enormous potential to capture carbon because of rapid carbon cycling, particularly in ocean and estuarian ecosystems. Groups like the Climate Foundation are pioneering “marine permaculture” that regenerates multi-layered ocean ecosystems that both fix carbon and rapidly restore improved ecosystem conditions. Yokohama, Japan, has developed an exciting initiative called “Blue Carbon” (funded in part by the CNCA Innovation Fund) that includes support for developing a local coastal seaweed production paired with the development of an offset market to subsidize the initial development of the sequestration system. This project demonstrates that while cities may not control large areas of aquatic environments, they can serve as early hosts for innovation around aquatic sequestration/regeneration. This emulates the pivotal role cities have played in many cases around energy systems change.

4. Biomass Energy + Carbon Capture and Sequestration (BECCS)
A major focus in the climate stabilization scenarios put forward by IPCC and others is the large-scale development of biomass energy systems that are paired with carbon capture and storage. These schemes depend on many as-yet unworkable elements including cost-effective capture and stable and accessible storage. A far simpler, more scalable and much less expensive alternative is the use of biochar systems that capture and utilize the released heat as a renewable thermal energy and generate long-term stable carbon (biochar). The base “fuel” for these systems is low grade biomass: urban wood waste, fire hazard reduction thinnings, agricultural waste and other low grade biomass. The resulting biochar can be used in land applications to both capture more carbon and improve water retention. Boulder is hosting a pilot scale bioenergy-biochar system in the summer of 2019 that will be used to assess the feasibility for larger scale distributed deployment of these technologies.

5. Offsets to local sequestration projects
Given the bundle of values that can be derived from the development of both terrestrial and aquatic carbon recapture projects in and around cities, we believe this represents a powerful opportunity to explore local voluntary carbon markets that support local ecosystem regeneration/carbon sequestration projects. Yokohama has already initiated aspects of a local offset program, initially targeting large sporting events. Boulder is exploring expansion of its current marijuana energy impact offset fund as a potential foundation for a local carbon offset fund. Boulder and San Francisco are also exploring emerging initiatives to link carbon capture projects with block-chain based digital currencies using tonnes of carbon as the denomination that is valued.

Next Steps

The active engagement of cities in emission reduction initiatives has been a major factor increasing both issue profile and innovation around energy system transitions. With the emerging realization that emissions reduction alone will not stabilize climate unless it is paired with rapid development of carbon recapture efforts, cities once again have a potential role in both raising awareness and fostering innovation in this sector. A unique aspect of this area of action is the significant additional local benefits that carbon sequestration initiatives could bring to cities.

The next steps for cities interested in further exploration of this sector would be to conduct initial assessments of assets and knowledge in a number of key areas including:

  • Assessing sequestration potentials
    • Land within city control or influence that could be receive sequestration enhancing treatments
    • Ocean-aquatic zones within city control or influence
  • Assessing biomass waste opportunities: Inventory existing green wastes and available infrastructure for composting or other biomass processing
  • Assessing potential BECCS: Conduct renewable thermal opportunity assessment, particularly in larger scale commercial industrial settings
  • Considering local offsets opportunities: Explore the creation of a local carbon offset market directed to projects in terrestrial or aquatic sites in and around cities that generate multiple benefits

For more information or to be a part of the CNCA Sequestration Working Group, please contact Brett KenCairn or Trude Rauken.