Sustainable Energy At Airports

My area of research is to investigate energy models and software tools that might assist an airport metropolis to achieve more sustainable energy use. The research project I am part of aims to deliver a DSS, and ideally I can contribute to this system with a tool that I have developed.

I did some background investigation and found 3 existing tools of interest. The first is LEAP, which stands for Long-range Energy Alternatives Planning system. This tool is targeted at the Government level of policy and planning, and allows various policy scenarios to be played out - it is useful for countries and regions, but can also be applied to the city level, so may be of interest in the airport context.

Using its fictional country “Freedonia”, here is an example to describe its use is: Freedonia is expecting population growth of 1.2% per annum over the next 20 years. During this time energy demands will grow by 4% per annum. Freedonia would like to commit to reducing its GHG emissions by 40% over this time. How would a mandated 15% ethanol component of diesel (biofuel), and a 20% minimum of solar PV supply, to be implemented within 10 years, help to achieve this target? LEAP can be setup will the current parameters of Freedonia’s energy supply mix and demand characteristics and then project out based on the hypothetical scenario(s). In this way it can guide policies and target setting.

The second software tool of interest is HOMER. This is an optimisation tool used for designing power systems. An example of its use is say you are planning to build a monitoring station in a remote location where there is no grid connection available. For electricity supply you could install a diesel generator, or a wind turbine with battery storage and diesel generator backup. HOMER lets you optimise the configuration of the system in terms of total battery capacity required, backup generator capacity required, and so on, based on the goals you specify such as lowest cost and minimal wastage of energy. You could run it over various scenarios allowing you to compare them on a cost-benefit basis. You might discover that a pure diesel generator system is cheapest, but that an optimised turbine/battery system is not too much more expensive, but with the added environmental benefits.

The third software tool is RETScreen. This is pitched as a “pre-feasibility” planning tool. It comprises a collection of Excel spreadsheets covering most of the renewable supply scenarios (e.g., solar PV, wind, bio-mass heating, geothermal heating), and also some energy efficiency scenarios (e.g., micro combined heat and power) . Each spreadsheet follows a similar methodology where it allows you to tinker with some parameters and test what the end result would be for a potential project in terms of its effectiveness (e.g., kWh supplied), sustainability (e.g., GHG emissions), and cost (i.e., $$$ !!).

Looking specifically at the solar PV spreadsheet, it is actually very powerful as it contains a complete meteorological database with insolation levels for many locations world-wide. It also has a product database which allows you to select the type of PV system you want, the size of it, the location, and it will tell you how much electricity it will generate per year, and the cost.

The meteorological data comes from NASA. It is an amazing aggregation of data. I have started to consider the possibilities for integrating with this tool, and will post more on this soon.

Fresno Yosemite International airport is currently constructing a 2MW solar PV system which is due for completion mid-2008. There are 2 installation locations, totalling 10 hectares (25 acres). The first location is 2 hectares worth of solar panels installed over a new car-rental parking lot. In a greenfield project such as this, there is a saving to be made by utilising solar panels for shading if the project design requires some sort of shading to be installed anyway.

The second installation location is on land in the air-field that had a zoning designation of “no construction”. This is excellant land-use planning as it opens up land that was previously unusable for standard construction, unlocking its value to the airport operator. Solar PV panels are not reflective and therefore no safety danger is posed to aircraft. (Solar thermal installations, such as those incorporating parabolic trough designs, are reflective, so these would obviously need extra planning if being installed at airports).

Fresno is a medium sized airport, located in California, east of San Francisco, and handles around 1.3 million passengers per year (pax/pa). The installation is projected to supply roughly 3,000 MWh per year, meeting around 40% of their current demand. In the US, it is the south-western states, particularly California, Nevada, Arizona and New Mexico, that receive the highest insolation, which is the term used to quantify the amount of solar radiation reaching the earths surface.

Denver International airport (quite larger - 50 million pax/pa in 2007) is also embarking on a 2MW solar PV project - estimated to provide around 3,500 MWh per year. Denver is located in Colorado, which is reasonably close to the south-west of the US so it also receives a fairly high level of insolation.

Both of these projects are being built by WorldWater and Solar Technologies Corp, and financed by MMA Renewable Ventures.

Here is a key quote from the Denver press release that underlines some of the motivation for such a project from the airport’s point of view:

“DIA has a long-standing commitment to sustainable operations and environmental protection. This solar energy system will provide cleaner air and reduce greenhouse gas emissions in the city and county of Denver and serve as a highly visible environmental statement to the millions of passengers that travel through our airport each month,” said Turner West, aviation manager for Denver International Airport.

Nellis air force base is a military installation for the US Air Force, located a short distance from Las Vegas in the state of Nevada. In December 2007 a solar PV power system with 14.2 MW of capacity was completed and became operational. The estimated yearly energy output is approximately 30 GWh. The installation occupies around 56 hectares (140 acres) and is a tracker type system, made up of 5,821 SunPower T20 units.

This is easily the largest solar PV system at a US airport, and could even be the largest PV system in the world, although larger ones are being built such as the 40 MW “Waldpolenz” solar park in Germany, due for completion in 2009, and a 154 MW “heliostat” solar concentrator PV power plant being built in Victoria, Australia due for completion in 2013. The largest commercial airport solar PV system is 2MW (currently under construction at both Fresno and Denver airports).

It is estimated that the power output at Nellis will supply 25% of its requirements, which it should be pointed out is quite large as 12,000 people live and/or work there. To put its 14 MW capacity into context, a solar thermal (parabolic reflectors) power station is being built not too far away at Boulder City called Nevada Solar One, and this will have 64 MW generating capacity. The 9 solar thermal power plants built in the Californian Mojave Desert during the 1980’s have a combined capacity of 354MW.

The cost of the system is stated as USD 100 million. But this project is a good example of innovative funding operating under incentives offered through government policy. The arrangement is that MMA Renewable Ventures has financed the construction and owns and operates the facility, and sells (green) power to Nellis at a guaranteed rate for 20 years. It also sells renewable energy credits to the central utility - Nevada Power - to help them meet their mandated renewable energy targets.