By Dave Hewitt | Tue, May 28, 19
Natural gas creates carbon dioxide when we burn it to heat buildings and water. But it also leaks methane, an even more potent greenhouse gas, into the atmosphere when it does not make it all the way to our furnaces and water heaters. Older natural gas lines are more likely to leak. Sometimes the leaks get to explosive levels and make the evening news, but on a regular basis there are smaller leaks that emit methane into the atmosphere and contribute to climate change.
Home Energy Efficiency Team (HEET), started in Boston as a grassroots organization focused on community action to reduce energy waste, found a different kind of waste that also costs consumers money – leaking gas pipes. It dug into the pipeline issue (pun intended) and has had tremendous success in getting more attention on identifying and correcting the worst leaks.
Now HEET is asking a slightly different question. Should gas utilities start to spread heat rather than natural gas through their pipes when old pipelines need to be replaced?
Using utility-reported data, HEET estimates that gas utilities in Massachusetts are expected to spend $9 billion over the next 20 years to replace aging infrastructure. From HEET’s consumer-oriented perspective, it questions whether additional ratepayer investments in a natural gas infrastructure is the best investment when meeting climate goals creates a very uncertain long-term future for natural gas. Pipeline investments may become stranded assets that create financial burdens for consumers and utilities.
The alternative that HEET is exploring is GeoMicroDistricts, a design concept that could replace some portion of these aging gas pipes with district heating pipes instead. The GeoMicroDistrict concept would start with just one street segment that employs a neighborhood-shared hot water supply and return loop under the street. Water is heated at a small pump station by a ground source heat pump pulling thermal energy off shallow geothermal boreholes. This could expand to cover larger areas through gradually connecting micro-districts, potentially growing a new business model for the gas utilities to sell clean renewable thermal BTUs instead of therms of natural gas.
From HEET’s grass roots perspective, its concerns for the consumer are clear and raise issues about how the transition to renewable energy can reach all customers:
“This utility-scale approach to renewable thermal, where heat and hot water are provided by the local utility instead of through individual household investment in renewable technology, addresses inequity of access to a clean energy future, making transition accessible to all instead of just those with discretionary income.”
HEET has contracted for an initial statewide feasibility study of GeoMicroDistricts that should be out in the next month. It’s a modest $50,000 study for a multiple billion dollar question, but it focuses on excellent questions with long-term implications for our energy future. Should major gas infrastructure investments continue? Are there competing infrastructure investments that may be more beneficial? How do states and cities ensure that affordable renewable energy reaches all consumers? These questions really do need to be answered.
The feasibility study by BuroHappold Engineering (an international firm that created NYC’s 80 x 50 plan) has finished the engineering component of the study, finding that 100 percent of the cooling and heating load of all but the most dense sections of cities like Boston can be created through shallow boreholes in the gas company’s right of way in the street (perhaps with some borehole arrays under a few parking lots in the denser areas), so long as the system is interconnected so waste heat and cooling can be used or stored. For instance that data center would heat a lot of homes. The heat or cooling could be stored in the earth for years at a time so long as the temperature of the ground wasn’t changed by more than 10 percent per season. The gas utilities would manage this temperature balancing, discharging for instance excess cooling for instance into nearby rivers during the summer to cool them down to where they should be.
Since the ground is always around 55 degrees, during summer heat waves or extreme winter cold, the ground coupled heat pumps would be more efficient than the air source heat pumps, reducing the peak loads. Reducing the peak load is critical so we can charge the growing market of electric cars too without bringing down our current electric grid.
The more I look at decarbonization, the more I see solutions appear to be very specific to regions. In warmer climates where both whole house air conditioning and space heating are required, it can be less expensive for the consumer to replace the two units with one advanced heat pump when either the furnace or air conditioner dies. From the consumer perspective, that’s a pretty simple strategy with both immediate and long-term benefits. Even this approach, however, will still need a lot of support and education in order to happen. From an infrastructure perspective, the electric grid can grow renewable power and supply the need, although both buildings and community-scale systems will be active participants in a modernized grid infrastructure.
In colder climates like the Northeast and Upper Midwest, the answers will be much more complicated, especially for existing homes and buildings. While cold climate air source heat pumps (ccASHPs) will become much more common, the nature of the incumbent heating systems, the older building stock, and the colder climate make the solutions more expensive. And in very cold conditions, additional backup systems may be required.
Community scale systems can play a critical part in meeting community energy needs. Shared ground source heat pumps systems and systems based on other low-grade heat sources, such as sewer lines, will likely be important players. The HEET study will be useful for thinking through the initial options. Also if paid for by the utility, these systems can serve all and not just those with discretionary income. The utilities have the money and a lot of the expertise to be able to scale our transition to a local clean renewable energy system.
Community scale systems bring alternative financing methods and ownership models into play, which enables individual consumers to participate in ways that may be more accessible to them, such as monthly payments rather than up-front costs, leasing, or shared ownership options. It is possible that a common ground source infrastructure could exist under a community garden space or that a heating system built for a new multi-family structure is shared with neighboring homes and businesses. Another possibility is a local institutions such as Community Development Corporations engaging in a new activity, or a new mechanism such as Community Choice Aggregators find another role they can play in energy development. But long established regulated gas utilities might find a renewable energy strategy that uses their access to capital and engineering expertise, but drops the fossil fuels.
When infrastructure development will be required just to maintain access to heat, the economics of alternative, future-focused developments will be considerably more attractive. We know we need to make some kind of investment, now we need to more carefully consider exactly what investment to make and who is in the best position to develop and maintain that new infrastructure.
Innovation is necessary to find the best renewable energy strategies to reach all customers. We need to find new ways to reduce the capital costs requirements of converting to new heating systems. HEET’s initial project in this area challenges the traditional boundaries of what energy infrastructure needs to be in the future. Their analysis will hopefully spur additional development and pilot projects to better serve the community in decarbonizing buildings.
This blog is part of Building Decarb Central, a series of blogs and other resources aimed at providing a constant flow of information on building decarbonization. Be sure to check out our web portal for more stories, resources, and information.