Passivhaus: A Tool for Carbon Neutrality

Natural gas, primarily used for building heating, constitutes 16% of the greenhouse gas emissions in the City of Seattle.  As I noted in a previous post, a city seeking carbon neutrality can shut down the natural gas distribution system, bringing these carbon emissions to zero in one fell swoop.  Building heat and hot water can be provided by several energy sources, including electricity. 

Mini-B Passivhaus on display at the Phinney Neighborhood Center

But where will all the electricity to replace natural gas come from?  In Seattle, we are blessed with carbon-free hydropower.  But we have a limited supply, and any additional electricity would need to be purchased on the open market or come from new generation.  However, the cheapest electron is the one you never need to generate, due to energy efficiency.

Passivhaus is an emerging standard for buildings that uses up to 90 percent less energy than conventional construction; a maximum of 4.75 kBTUs/square foot/year for heating.   The Passivhaus standard uses thick insulation and high-performance windows to prevent heat losses, and recovers heat from exhausted air through a Heat Recovery Ventilator (HRV).  A 300 square foot Passivhaus, the Mini-B, is on display at the Phinney Neighborhood Center in Seattle.

By building new construction to Passivhaus standards and developing cost-effective Passivhaus remodeling strategies, the electric demand for building heating can be vastly reduced.  Which will leave the hydropower electricity available for other uses when we move away from fossil fuels in buildings.

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Trolley Trucks, a Tool for Carbon Neutrality

St. Petersburg trolley truck (Source: Wikimedia)

Commercial trucks constitute 18% of the greenhouse gas emissions in the City of Seattle.  Moving freight without oil is one of the major technological hurdles for carbon neutrality.  Smaller local deliveries may be made in battery electric trucks such as the Newton or the Zaptruck XL.  But battery electric trucks have limitations, all related to the batteries.  The weight of the battery packs displaces cargo capacity, limiting the cargo weight to battery power ratio.  The process of recharging batteries induces electrical losses, and the batteries themselves require disposal and replacement at the end of their useful life.  Battery power is fundamentally never as efficient as a direct electrical connection.  Electrical trolley buses are the starting point for another solution for carbon neutral goods movement.  Seattle, like many other cities around the world, has a network of electrical overhead contact systems (OCS) over city streets, directly powering buses on frequent routes.  Electrical trolley buses are 100% electric and the technology has been in use for over 60 years.  Could the same technology provide power to trucks?

Siemens Mining Truck with Trolley Power

As a matter of fact, it has.  Mining operations, in the U.S. prior to early Bush-era cheap oil and to today in Southern Africa, utilize trolley trucks for heavy and steep loads.  Electric traction has advantages over diesel in acceleration, hill-climbing and braking.  If heavy mining trucks can be adapted for electric trolley operation, highway trucks can be designed for it as well.  Trolley-powered trucks are used in the Ukraine and Russia for urban local deliveries.  An electric-trolley powered freight hauling system has been proposed for freeway truck traffic to the Ports of Los Angeles and Long Beach.

Trolley trucks could be introduced in Seattle in conjunction with an expansion of the existing electric trolley bus system.  The key enabling technology is a wireless smart meter, mounted on top of the truck at the connection point to the trolley poles, which would bill the truck’s registered owner for power supplied through the trolleys (an open trolley power system).  City policies could favor the purchase of dual powered (electric trolley/battery or diesel) trucks.  For example, all large city vehicles (fire trucks, garbage trucks under contract) could use dual power systems.  When travelling on arterials with trolley infrastructure, the driver would raise the trolley poles (with the touch of a button) to directly use electric power and recharge on-board batteries.  When turning onto a local street without trolleys, the driver would lower the poles and rely on a battery backup.  Sound fanciful?  A city serious about carbon neutrality should develop an open trolley infrastructure.  In the excellent book “Transport Revolutions: Moving People and Freight Without Oil,” Gilbert & Perl argue that in the case of oil scarcity, “grid-connected vehicles” will emerge as a solution for mobility. 

Real world scenario of how this could play out: the City has facilitated expansion of the electric trolley bus system to include all routes within city limits, and banned diesel buses.  Every Safeway supermarket in the City is now on a trolley bus route.  Instead of sending diesel-powered big rigs through city neighborhoods to supply the supermarkets, at each store Safeway could add a short section of trolley wire from the street to the loading dock.  If the Safeway distribution center was on a trolley-powered street, the company could use trolley trucks for all deliveries to its Seattle stores.  And the distribution center could be served by electrified freight rail for bulk food deliveries. 

High-speed trolley wire could also be added to certain lanes of freeways, for bus and truck use.  The Port of Seattle could also develop a program to promote trolley-truck usage for freight.  There are many possibilities such as these yet to be explored for carbon neutral movement of freight.

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Carbon Neutrality: Policy, Culture or Technology

The City of Seattle has made developing a goal for citywide carbon neutrality by 2030 a priority.  In September 2010 the City held a forum in which workgroups gave presentations on carbon neutrality strategies in various disciplines.  At the time I noted a lot of incrementalism, and very little vision of a city at zero emissions.

For each significant category (>3% of the total emissions) in the City of Seattle 2008 carbon emission inventory, below I list whether reaching zero emissions is primarily a matter of government policy, culture or technology.

Transportation
Cars (20% of total): Policy and culture.  Walking, biking, electric transit and electric vehicles can entirely eliminate fossil-fueled personal vehicles.

Trucks (18%): Technology.  Battery power is unlikely to be effective for freight trucks due to energy density, weight and cost.  Rails aren’t everywhere that goods need to go.

Air (18%): Technology.  Non-fossil fuel solutions to air transport are yet to be determined.  Reducing air travel is an interim step.

Buildings
Natural Gas (16%): Policy.  The City can shut down the natural gas distribution system.  Users, given sufficient notice, can migrate to electric appliances and/or retrofit for energy efficiency.

Industry
Cement production (11%): Policy and technology.  Policy can force install of the best available emissions reduction processes, or fund low-carbon cement research.  But technology is needed to go to zero.

(Other sources combined are 17% of emissions.)

The City of Seattle has the capability to be carbon neutral  in several categories by 2030 through policy only.  The city is blessed with carbon-neutral hydropower for electric supply.  For neutrality, the city’s electrical demand needs to be kept within the capacity of the hydropower system, supplemented by other renewables such as wind.  The key to achieving this is to be aggressive about electrical efficiency as activities are transitioned from other fuels, such as personal vehicles or natural gas furnaces, to the electric supply. 

Technological progress is needed in three major categories to reach zero: trucks (goods transport), air travel and cement production.  I will write about each of these items in upcoming posts.

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Carbon Neutral Community Forum: Big Ideas, Small Ideas, Zero not yet in Sight

The Seattle City Council hosted a community forum tonight regarding one of their sixteen priorities: making the City of Seattle carbon neutral.  Community-based workgroups gave presentations of their findings and recommendations to Council in each of 8 categories: land use, neighborhoods, energy, green careers, transportation, food systems,  youth and zero waste.  It was an inspiring and thought-provoking event, looking at the issue of carbon neutrality from a wide variety of angles.  I am glad to see that a carbon neutral goal has taken off in Seattle, starting from Alex Steffen’s vision at a talk in Seattle last November (viewable here).  The environmental community is now abuzz with discussions and initiatives for carbon neutrality.  I am particularly encouraged that the City Council has picked up the gauntlet, and is funding technical plans (the Stockholm Environmental Institute is involved) and organizing community groups. 

Yet no one has produced a vision of how a carbon neutral city would actually look.  Yet no one is grappling (at least out loud) with the very significant policy initiatives and cultural changes required for carbon emissions to go to zero… or with the size of forest the City would need to purchase and forever protect to offset our carbon emissions. 

The City commissioned an inventory of the City’s carbon emissions in 2008.    How did the recommendations proposed tonight address the largest categories of current emissions in that inventory?

1. Cars and Light Duty Trucks (1.4 million tons):  The transportation, land use, youth and neighborhoods proposed policies to make biking, walking and transit the most convenient ways to travel.  The land use group recognized that dense neighborhoods reduce the need for travel-miles.  No one could estimate a %reduction in carbon emissions by implementing these policies, or describe the infrastructure needed for zero carbon emissions from personal transportation.

2. Trucks (1.2 million tons): Not explicitly addressed by any group, although the food system presentation recommended increasing local food production, which would reduce food being trucked into the city.

3. Sea-Tac Airport (1.1 million tons): The transportation presentation noted that these emissions will need to be addressed eventually (no plan yet).

4. Commercial Buildings (0.9 million tons): The energy presentation was the most visionary of the 8 committees, promoting self-sufficient  energy districts and Passivhaus construction.  The presenters went beyond carbon neutrality and proposed net clean energy exports.  Short on practicalities however.  Converting our commercial buildings to Passivhaus standards (is that possible for existing buildings?) and converting all building energy away from natural gas and oil and towards clean electricity can actually lead us to carbon neutrality.

5. Cement production (0.7 million tons): One presentation (I’ve forgotten which) noted the definitional challenges for reducing cement batch plant emissions.  If the goal is carbon neutrality within Seattle city limits, regulating the cement plant out will eliminate these emissions within city limits.  However, the owner of the plant is likely to ramp up cement production elsewhere, so the emissions have only been displaced, not eliminated.

6. Residential buildings (0.6 million tons): The land use presentation noted that dense living results in lower energy consumption due to shared walls.  And the discussion of commercial buildings above applies here: district energy production and passivhaus construction can lead us towards zero.

The City of Seattle has made a great start in even studying carbon neutrality.  But we need to move beyond short-term 5% to 10% reductions and map out a feasible plan to reach actual neutrality.

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