State of the Planet

News from the Columbia Climate School


Distributed Generation and Renewables in New York City

As climate change threatens an increasing frequency of heat waves like the ones New York City has been experiencing, we city-dwellers turn to our air conditioners and window fans to keep cool.  It’s an act of adaptation: we adapt to the heat by cooling off our homes – but it counters mitigation, as increased electricity consumption puts added strain on the electrical grid, and power plants burning fossil fuels need to amp up production to meet demand.  All that added carbon contributes to global warming – a positive feedback loop of warming the climate and turning the AC on to cool off, thus further contributing to warming.

While in New York City we receive much of our energy from natural gas, rather than coal, the burning of fossil fuels for electricity is a leading contributor to our greenhouse gas emissions.  PlaNYC’s last emissions inventory indicates that roughly 34% of our citywide carbon emissions, or 18.2 million tons of CO2, were the result of electricity production and consumption in 2008.  The report notes that a cool summer in 2008 accounted for a reduction in GHG emissions; given this summer’s heat, though, emissions this year are sure to surpass those of 2008.

Thus summer heat both stresses the grid, and leads to increased emissions, highlighting the need for alternatives to present methods of production.  What solutions are then available?  How can we reduce reliance on an overtaxed grid while simultaneously reducing our GHG emissions?

Distributed generation (DG) – particularly wind and solar – seems to be one viable solution.   DG is defined by the Department of Energy as a range of small-scale, and often on-site, devices used to produce energy close to consumers.  The benefits are substantial: not only does it relieve stress on centralized power stations and the infrastructures needed to transport the electricity produce there, it makes urban renewable energy feasible for local production.  Photovoltaic arrays and wind turbines are easily scalable to a size able to fit atop an urban warehouse, apartment building, or skyscraper.

The expansion of distributed solar energy in particular is being pursued by NYC city government and local sustainability organizations.  PlanNYC and Sustainable CUNY are presently surveying the city’s solar potential by laser-sighted flyovers, also called solar mapping.  Using laser scans, the project determines which roofs are flat or slanted, and which receive the most sunlight and are therefore best suited for a distributed solar network.  The project is slated for completion this autumn.

The NYC Solar Map is a Sustainable CUNY project on behalf of the NYC Solar America City Partnership

Solar mapping has already caught on in other cities, spurred by subsidies from the Department of Energy.  San Francisco and Boston, in particular, offer online databases for residents to determine the solar potential of their homes.  As the Times reports, solar mapping could help NYC to eventually produce up to 1/5th of its electricity, or 18% of peak load, from rooftop photovoltaic arrays by 2020.

Solar potential goes beyond the mapping project, though.  Solar One, Consolidated Edison, government agencies, and Sustainable CUNY have already identified Solar Empowerment Zones that present substantial solar potential.  Technical and incentives assistance, data monitoring systems, education, and streamlined permitting for home- and business owners who want to develop arrays on their buildings are made available.  The zones can be found on Staten Island East, Downtown Brooklyn, and Greenpoint-Gateway, a vast swath of east Brooklyn and southwest Queens. Solar energy development is already underway in New York City.

While most city policy is related to distributed solar generation, there’s a potential for distributed wind in the city as well.  Distributed wind is much more common in rural areas where zoning is less strict and there are fewer neighbors to take offense at the sight of a windmill.  But as Yale Environment 360 recently reported, an 8-story apartment building dubbed the Solarium in Long Island City has a small, commercially-available wind turbine perched upon its roof .  Six feet in diameter and weighing only 170lbs, the Solarium’s windmill can supply as much as 30% of an average home’s annual power needs if winds blow ten miles-per-hour on average.

On of the advantages that wind has over solar is the cost — residential turbines like the one used on the Solarium are much less expensive to install.  The cost of installing solar can be prohibitive for very tall buildings – cranes must be rented to install arrays, buildings must be fortified, and many feet of cables must be installed to distribute the energy from high altitudes to low ones.  But at only 170lbs, small-scale turbines  can be transported and installed on rooftops through service elevators and stairwells, and while the kW h potential for solar might be more substantial (and more reliable) than wind, small turbines can have greater appeal for individual homeowners looking to reduce their strain on the grid.  Urban wind is beset by other challenges, too – the risk of mechanical failure due to the turbulence created around skyscrapers can lead to prohibitive safety costs.  But several architects have addressed this issue by incorporating wind into their building designs, and newer turbine designs that include a surrounding case have significant safety advantages.  The Bahrain World Tower [LINK], or the earlier designs for One World Trade Center [LINK], are fine examples of how wind power can be integrated into building design.

The two towers of the Bahrain World Tower funnel wind into its turbines, providing the building with 18% of its energy needs.

While NYC is not pursuing small-scale wind energy as a matter of policy, a March 2010 report from the American Wind Energy Association notes its rapid expansion through the United States – growing 15% in 2009, despite an economic recession.  Indeed, the report notes, half of that growth occurred in the last 3 years of the industry’s 80-year history, finally reaching 100 MW of power produced nationally in 2009.  The AWEA attributes this rapid growth with government incentives associated with the American Reinvestment and Recovery Act, which begs the question: if federal incentives have produced such a substantial proliferation of distributed wind energy, what would additional city incentives mean for the future of NYC energy?

But perhaps most promising is the potential for wind and solar to complement one another.  When there is less sun, there is often more wind and vice versa.  Slippery Rock University has an online monitoring system demonstrating how this works.  Without feasibility studies, though, it’s impossible to know how much of NYC’s energy demand could be met with a combination of wind and solar.  But considering that solar can account for 18% of peak demand, and a wind turbine can produce up to 30% for an average household (not including the fact that New Yorkers use less residential electricity than the average American), a study of the compounded potential of these two distributed generation sources is necessary.  And as our workplaces and homes become more energy-efficient with the advent of LED lights, better insulation, and further development of the smart grid system, it seems that the potential to move off-grid and off fossil fuels is considerable.

Science for the Planet: In these short video explainers, discover how scientists and scholars across the Columbia Climate School are working to understand the effects of climate change and help solve the crisis.
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solar installers uk
12 years ago

I’m all for alternative energy – I’m personally have solar thermal panel and PV panels and now away to do biomass– I think the fact that large scale e.g tidal power hasn’t taken off is concerning since we are signed up to the kyoto protocol and are far from reaching the mandate.

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