It is proposed that HEAT networks should be installed in future housing development projects, rather than natural gas distribution lines, and that such networks should over time replace the use of natural gas in existing homes. HEAT stands for Heat Exchanger Access Terminals. These are terminals that would provide heat extracted from the ground to heat pumps located within the houses. The network of terminals would be connected to heat exchangers inserted in boreholes (typically 200m deep) that extract the heat. The heat is replaced in the summer, so the ground really serves as a storage facility rather than as the source of heat. It is proposed that the boreholes should be located on city-owned property and that the cities should operate the HEAT networks, just as they presently provide water and sewer services.
Although private ground source heat pumps have been in use for decades, and have a good record for reliability and economy over the lifetime of the installations, the high initial cost of the borehole heat exchangers has discouraged their widespread use. Having the city provide the service eliminates this disincentive. The city would recover the costs via annual fees, but since such fees would be less than the cost of the natural gas that would otherwise be used the homeowner gains in both the initial cost and in the operating cost. Compared to the cost of windmills or nuclear power stations on a per kW basis the capital cost of HEAT networks is much lower so this is a win-win choice for everyone.
Note that there is a fundamental technical difference. Conventional ground source heat pumps use the ground as a source of energy, largely relying on the slow diffusion of heat from the surrounding ground to replace heat that has been extracted from a borehole. HEAT networks draw the heat in the winter but replace 100% of that heat in the summer by extracting heat from the warm summer air. As a consequence, an array of boreholes can have the holes placed close together, and the efficiencies of both the heat exchangers and the heat pumps are much higher, leading to both lower costs and to electric power consumption rates that are much lower than those of existing homes that use natural gas for heating and electric air conditioners and refrigerators.
The boreholes can be located under any city owned property – parks, streets, parking lots, etc. While the obvious initial application is in new housing developments, where the HEAT networks can completely replace natural gas lines, such systems can also be retrofitted into existing residential, office and shop areas. The use of fossil fuels for heating and cooling applications can be eliminated altogether for both urban and rural applications. That eliminates the pollution caused by burning fossil fuels, reduces the pollution generated in producing electricity, and would make our cities permanently sustainable. So long as a modest allowance is provided for land for the HEAT networks' storage areas our cities can expand without limit.
The only significant drawback of the HEAT networks concept is that it requires the cities take the initiative to build and operate the systems, and needs the support of senior governments who control energy policies. Currently, Canadian governments at all levels favour solutions offered for profit by private corporations, a philosophy that is carried to the point of fanaticism. Huge amounts of money are being spent on building liquid natural gas (LNG) regenerators and distribution systems that will make Canada dependent on imported natural gas as our rapidly dwindling Canadian reserves peter out. According to a recent official (U.S.) government report (www.eia.doe.gov, Feb., 2005) Canada's natural gas "production will completely deplete reserves in 8.6 years". Billions are being spent on “conservation measures” that make homeowners install more efficient gas furnaces. Those funds would be much better spent on eliminating the use of fossil fuels, not extending our dependence on fossil fuels for another decade.
Moreover, Canada has signed the Kyoto agreement, pledging to reduce its carbon dioxide emissions by 6% from its 1990 level. Our current emission rate per capita is a staggering 18.9 metric tonnes per year. Total emissions have increased by over 100 million metric tonnes since 1990. Rolling back that huge increase, providing energy for a rapidly increasing population, and meeting the additional 6% reduction target will only be achievable by making some radical changes. Natural gas accounted for 30% of our energy production in 2002, it is near the point of exhaustion, and it is the most easily substituted energy source, using the HEAT networks, so it should be the primary target for reform.
Ground source heat pumps have been the most economical source of energy for homes and larger buildings for many decades. There are over one million ground source heat pumps in operation worldwide, of which over 30,000 are in Canada. They are popular for large buildings and for groups of buildings because they are reliable and inexpensive on a life cycle basis. However, they have not been widely adopted for home heating because of the lack of an approach that would permit widespread deployment. The HEAT network concept provides that missing link. The concept does not require new development. From a physical point of view it doesn't matter at all that the heat will be extracted from city-owned land instead of private land. HEAT networks could be deployed immediately. The only requirement is the will to do so.
A comparison of carbon dioxide production: Nuclear vs. Renewables
The following links provide details on the design and implications of HEAT networks:
See "Greenspace Could Save $Billions", the original proposal (now partly obsolete).
Click on one page PDF flyer outlining the concept, prepared for the Ottawa Environmental Advisory Committee.
The most important component, the heat exchanger.
The source of heat, Active Heat Restoration.
HEAT networks reduce electric power consumption.
NEW !! Using HEAT networks downtown.
How cities can achieve Energy Sustainability. (pdf file) Prepared for the Ottawa Forest and Greenspace Advisory Committee
Presentation to the Planning and Environment Committee (pdf file)
Greenhouse gas emissions