READ MORE: Reduce and Retire
Burning fuel to drive engines or generate steam always results in significant energy being wasted. Not only does the exhaust from burning fuel release pollutants and greenhouse gasses, there are practical and physical limits to how much of the fuel can be converted into useful work or electricity. A visual depiction of this wasted energy is shown in the energy flow diagrams published annually by Lawrence Livermore Labs in the US (See below link). In Nova Scotia, where a similar mix of fuels is employed, the proportion of waste would be similar.
Typical thermal electricity plants convert only 30 to 35 % of fuel energy to electricity. Biomass plants burning wet material, like fresh cut wood fibre are less efficient as some energy in the fuel is needed to first evaporate the water in the green wood.
Slightly better, combined cycle thermal plants burn fuel, typically natural gas, but add a second stage that makes use of the heat in the exhaust. These plants convert almost half of the fuel energy to electricity. New units 4,5 and 6 added to the Tuft's Cove facility in Dartmouth are of this type.
Most efficient, co-generation facilities capture the heat from thermal plant exhaust and use it to heat buildings or to supply hot water and steam for domestic or industrial use. In mid latitude climates like Nova Scotia, co-generation can convert approximately 80% of fuel energy to electricity and useful heat annually.
Unaccounted in energy flow analyses is the energy required to heat or cool buildings because heating or cooling is considered a useful service and not waste. In 2008 56% of commercial and residential energy use was to heat buildings (Energy Use Data Handbook, 1990 to 2008, Natural resources Canada). What if the energy to provide the actual service - personal comfort - could be greatly reduced?
For most buildings in Canada, this is the case. Improved building standards, careful insulation and thorough air gap sealing can dramatically reduce the amount of heat needed to keep building interiors comfortable. In new construction, it is now possible to all but eliminate the need for a heating system.
Some initiatives, like LEED and R2000 programs reduce building energy by around 1/3 compared to conventional practice. See (Do LEED-certified buildings save energy? Yes, but..., NRCC-51142). Likewise, model energy codes and industry standards (ASHRAE 90.1, for example) work towards incremental reductions in building heating. Continuous improvements in the Ashrae 90.1 standard has decreased energy use levels in buildings designed to the standard 48% since 1979.
Suggested Reading: http://lgstdept.wharton.upenn.edu/igel/William_Braham_May8.pdf
Within these standards, there remains room for improvement. For example, Advanced Energy Design Guides, developed by the US DOE offer 50 to 30% reductions beyond current best energy practice.
Suggested Reading: http://www.energycodes.gov/advanced-energy-design-guides
Following stricter standards can yield greater savings and because building have a very long useful life, it is important to adopt stringent standards as soon as possible. Net-zero energy initiatives and the Passivhaus standard standout as leading examples:
Net-zero Initiatives: http://living-future.org/lbc
Passivhaus Website: http://www.passivehouse.ca/
The Canadian Green Building Council in addition to LEED oversight in Canada works to accelerate high-performing and healthy buildings in Canada. They continue to work to improve standards, develop best practiceadvocate for green building and educate it's members and the public about sustainable design and construction.
Some of the most efficient homes in Canada are built here in Nova Scotia. To learn how, explore the Canadian Solar Home Design Manual developed by and available from Solar Nova Scotia.
Solar Nova Scotia Website: http://www.solarns.ca/
In industry, the potential for reduced energy use is also high. Equipment is often selected for low initial cost with little consideration for it's lifetime energy use. For example, a piping system laid out for low initial cost will use small diameter pipes with straight piping runs and multiple elbows to minimize design, material and assembly cost. The result is a system that requires a powerful pump to circulate fluid through the system. The same function can be served using a small efficient pump, larger piping with care taken to minimize bends and flow restrictions. While initially more expensive, the lifetime operating cost can be dramatically reduced.
Careful design can yield systems that use 1/10th the energy of traditional systems. For more information see the Rocky Mountain Institute (RMI) initiative, Factor Ten Engineering:
Existing buildings can be renovated to use less energy. When undertaken during major maintenance or renovation activities, the additional expense can be small. For consumers to make informed choices, it is important for building energy use to be known. Building labeling programs like the Energuide Rating System and the ASHRAE Building Energy Quotient provide building owners and and renters the ability to compare choices based on energy costs.
Energuide Rating System: http://oee.nrcan.gc.ca/residential/personal/16352
ASHRAE Website: http://buildingenergyquotient.org/index.html
CLEAR THE AIR
Beyond the climate effects from greenhouse gasses, our fossil fuel use produces many compounds that damage our health. While some emissions are regulated (mercury, nitrous oxides, sulpher oxides), medical studies identify significant health damage results from the fine particles that escape power plant scrubbers. In addition coal plants emit lead, cadmium, hexachlorobenzene, dioxins and furans, polycyclic aromatic hydrocarbons, and arsenic. Living in close proximity to coal power plants increases risks for many diseases and loads the local environment with many toxic compounds. One estimate suggests that closing coal plants in Ontario 4 years early saved 1000 lives.
Suggested Reading: http://cape.ca/permalinked/capenews-winter2011-english.pdf
In Alberta, it is estimated that coal emissions contribute to 100 premature deaths each year:
The American Lung Association writes in their report, Toxic Air, The Case for Cleaning Up Coal-ﬁred PowerPlants:
"Everyone faces increased risk of harm from exposure to these hazardous air pollutants.However, many people face greater risk because of their age, health conditions, or exposure to the pollutants. They include:
• Children and teenagers;
• Older adults;
• Pregnant women;
• People with asthma and other lung diseases;
• People with cardiovascular diseases;
• People with low incomes;
• People who work or exercise outdoors; and
• Others with existing health problems."
Natural gas, a limited resource with considerable production concerns, burns with lower GHG emissions and with much lower toxic emissions. Natural gas plants operate more efficiently and can respond quickly to changing demand, making them a good backup power source for renewable generation, in particular wind energy.
PLAN WITH CARE
Converting thermal plants to burn natural gas, as has been undertaken at Tuft's Cove, can be a cost effective way to retain some fossil backup as we learn to work with renewable energy. Likewise, new, more efficient, combustion turbines equipped with heat recovery steam generators (combined cycle plants) are more efficient, compact and economical. Careful study is needed to identify the best options when switching fuels. Even in the face of natural gas price uncertainty, conversion often makes sense, (http://bv.com/Home/news/thought-leadership/energy-issues/paper-of-the-year-a-case-study-on-coal-to-natural-gas-fuel-switch).
NO SILVER BULLET
It is important to consider natural gas as a transition fuel to be used sparingly to support delivery of increasing quantities of renewable energy. In particular, recently developed fracking methods to produce natural gas present many risks:
• increased greenhouse gas effects from escaped natural gas (methane)
• local water contamination
• increased low level earthquakes
• non-renewable use of fresh water resources
• toxic and radioactive chemical releases
• increased ecosystem disruption (high density of roads, well sites and increased local road traffic)
• regulatory risks - will established regulations be monitored effectively?