When a 50-year-old business that is vital to a remote Canadian community needed to upgrade its cogeneration installation, it turned to new gensets fitted with exhaust gas heat exchangers, writes Steven Jackson.
A cogeneration system using Bowman heat exchangers has halved electricity costs in a remote Canadian community and could transform power generation across the whole region.
Bowman charge air and exhaust gas heat exchangers have been installed in an upgraded cogeneration system that brings vital power and heat to Fort Providence in Canada’s Northwest Territories. This small hamlet of about 800 people is situated on the MacKenzie River, about 2000 km north of Canada’s border with the US.
Fort Providence is ‘similar to many small communities in the North,’ says Jeff Phillipp, owner of Fort Providence’s SnowShoe Inn, which hosts the cogeneration system. The town ‘is challenged with a lack of economic development and local jobs,’ he says. ‘There is a critical shortage of affordable housing. Fewer young people are finishing school, and those that do are leaving the community due to lack of opportunity. Businesses have closed due to very high operating expenses, the most critical being the cost of power (followed closely by heat), which is easily four times higher than in the south.’
As with many northern communities, winters in Fort Providence are very cold, with temperatures falling as low as -40°C. Power and heat are highly valued and very expensive commodities. In 24 of 32 communities in the Northwest Territories, electricity is produced using diesel generators. The commercial rate per kWh ranges between C$0.51 ($0.42) and C$0.61, four or five times the utility rates in southern Canada. Diesel is trucked or sea-lifted long distances from the south, hence the high cost of power.
|Temperatures in Canada’s Northwest Territories can drop to -40°C in the winter months
Credit: Bowman Heat Exchangers
However, Phillipp says a fuel switch or dual-fuel system is not the best solution for Northern communities that currently use diesel. ‘In most of these communities the only available fuel is diesel and the transition to anything new would need to be carefully planned,’ he explains. ‘Given the prevalence of diesel engines and high demand for heat in these communities, the most practical solution is to capture more of the existing energy through a combined heat and power system.’
In Fort Providence the current heat load is only about one third of the energy requirement, says Phillipp. ‘This is low because the community was never designed with a district heating system in mind, so each building is isolated,’ he adds. ‘With planning, more of the community’s infrastructure could be connected to the district heating system, which would increase the demand, making an investment in CHP upgrades very easy to justify.
‘We are currently exploring the possibility of a biomass boiler, using wood chips harvested locally, to work in combination with diesel cogeneration as we expand the district heating system to include more of the community.’
|SSI’s CHP unit Credit: Bowman Heat Exchangers|
The SnowShoe Inn (SSI), founded by the Phillipp family in 1965, is Fort Providence’s commercial hub and largest employer. It provides much of the community’s commercial and retail facilities, including a motel, restaurant, bar, gift shop, general store, commercial rental facility and equipment garage/warehouse, occupying an area of over 100,000 square feet (9300 m2).
Since 1973 SSI had used a diesel-fired cogeneration plant to provide all required off-grid electricity and heat for its operations, comprising two diesel generators (120 kW/208 V) for power, with waste heat captured from the cooling water and the exhaust gases for heating. However, during the coldest months of the year, additional heat from a 900,000 BTU waste oil burner was required to ensure indoor temperatures were maintained. The waste oil burner was added in the late 1990s.
In 2013, working closely with Ottawa-based custom fabricator Pratt Diesel, Philipp oversaw a major upgrade to the cogeneration system, replacing the old 120 kW/ 208 V diesel generating sets with new 150 kW/600 V state-of-the-art units. The new gensets were customised by removing standard accessories such as the radiator, charge air cooler and exhaust piping, and custom fabricating a new water manifold to connect the Bowman exhaust gas heat exchanger and charge air cooler to the district heating system. In addition to the mechanical modifications, Philipp said ‘extensive enhancements’ were made to the existing sensor data to ensure that all relevant data is captured.
|The Bowman charge air cooler at SSI Credit: Bowman Heat Exchangers|
‘The new design incorporates a more fuel-efficient engine,’ Philipp says, ‘which means we burn less fuel per kWh. At the same time the newer engines are better at capturing the heat. When we are done modifying a stock engine we have improved the overall energy capture efficiency from an average of approximately 30% (for a typical diesel genset) to closer to 75% in our CHP unit. The mechanical modifications to improve energy capture, and our custom web-based monitoring platform makes our newest CHP solution as “state-of-the-art” as it gets today,’ he explains.
By adding Bowman units to a genset, waste heat energy from the water jacket, exhaust gases, charge air and lubricating oil can be recovered and utilised to provide a ‘green’ CHP solution that delivers heating and hot water – or even more power, with no additional fuel requirement. In addition, genset efficiency is significantly increased – with up to 90% of waste heat being recovered and turned in to valuable ‘free’ energy.
‘The Bowman units are performing extremely well, with at least a 60% gain in heat capture due to the massive improvement in efficiency,’ Philipp noted. ‘This is reflected in a reduced need for backup heat from the waste oil burner. In fact, due to improved heat capture, the 900,000 BTU waste oil burner has now been replaced by a modern 500,000 BTU unit. Today, Snowshoe’s amortised cost per kWh is C$0.24, compared to C$0.51 for commercial grid power (and climbing annually), a 52% saving.’
The combination of high efficiency gensets fitted with Bowman heat exchangers has delivered huge savings in heat capture – results that Phillipp believes could have implications for scores of other remote communities in Northern Canada.
|SSI opened in 1965 and has become vital to Fort Providence
Credit: Bowman Heat Exchangers
A vision for the North
‘Most of the electricity in Canada’s North is generated by diesel and the cost per kWh is excessively high, consuming a large percentage of community revenues that could otherwise be used for much-needed economic and social development projects. There are 100+ remote diesel plants – none of which capture and utilise the waste heat,’ Phillipp says. He emphasises that he is determined to modernise power production in the North, using his home community as a showcase to be replicated elsewhere.
‘Converting existing diesel plants into highly efficient cogeneration systems is a key first step. We are also exploring the possibilities provided by evacuated solar tubes, in-ground thermal energy storage, and hydrogen fuel cell technology,’ he says.
Elsewhere in Canada, Alberta’s Drake Landing Solar Community has developed a unique in-ground thermal storage system, which stores excess heat from traditional plate-style solar collectors. ‘Our goal for Fort Providence would be to explore the use of a similar ground thermal heat storage facility to store the excess heat from our diesel power plants over the six warmer months of the year,’ Phillip says. ‘At present we are forced to reject approximately 2.5 billion BTU of heat energy between May and October. To put it in perspective, this is the same amount of heat that would be produced by 68,200 litres of heating oil. At a current cost of C$1.42 per litre in Fort Providence, this equals an energy value of C$96,800. When measured in terms of electric heat, the value is much higher. It would take 732,500 kWh to produce this heat at a cost of C$0.57 per kWh, equalling a total of C$417,500. Clearly it makes economic sense to capture and store this wasted heat.
|Power and heat are expensive commodities in northern Canada
Credit: Bowman Heat Exchangers
‘If our ground thermal storage tank works well, we would expand the underground storage volume and add evacuated tube solar collectors, mounted on rooftops or on a vacant lot, to increase the amount of energy we could capture and store over the summer period. Every bit of energy we contain between May and October reduces the cost of energy during the winter months.
‘Solar thermal technology is definitely worth experimenting with in the North given the many months of the year where we have direct sunlight combined with very cold (<-40C) temperatures. Adding thermal storage significantly improves the return on investment both in diesel cogeneration and alternative energy sources.’
In addition to heat capture and storage, Phillipp also believes there is a growing opportunity to use off-peak energy, whether from green sources or unused diesel capacity, to generate and store hydrogen, which can then be utilised through fuel cells to provide additional electrical capacity to help mitigate the load at peak hours. Hydrogen can also be incorporated into the city/municipal transit programme, further reducing greenhouse emissions.
Philipp is currently working closely with political leaders and key government agencies responsible for power production in the North. Canada’s three territorial governments and the federal government are anxious to resolve the region’s energy challenge, to find long-term solutions to reduce the cost of living while improving opportunities in the communities.
The Government of the Northwest Territories (GNWT), where Fort Providence is located, has a three-year plan with emphasis on the reduction and more efficient use of diesel and the enhanced support of alternative energy sources and technologies, including biomass, solar and wind. Phillip is in communication with many of the elected politicians as well as the local native groups, who he believes must have a stake in such important local infrastructure. His ultimate goal is to revitalise the community of Fort Providence by partnering with the local governments to build a showcase of what is possible using simple ideas and local drive. Critical to achieving this vision is affordable energy, which means building on Snowshoe’s current CHP plant. By creating a more efficient energy production system that includes biomass, solar thermal and hydrogen, Phillip believes that Fort providence can become the model for northern communities, most of which are facing the same uncertain future due to the excessive cost of diesel energy.
Steven Jackson is Sales Manager at EJ Bowman (Birmingham) Ltd