Sustainable Energy At Airports

I have just returned from the 4th IASME/WSEAS International Conference on Energy, Environment, Ecosystems and Sustainable Development held at Faro, Portugal. It was a great experience to attend this conference and present a paper that I co-authored entitled Sustainable Energy Options for the Future Airport Metropolis.

The conference had a wide variety of sessions, approximately 120 in total. I attended around 50. Some of the topics presented were:

• GIS-based software tool to visualise the noise impact of wind turbines
• Harvesting of Napier Grass in Taiwan for bio-fuel
• Prototype for new solar panel tracking mechanism
• Analysis of various chemical cycles for producing Hydrogen

Cogeneration was a common theme amonst many of the sessions, and also Hydrogen. There were some interesting sessions about converting waste into various types of fuel, and another common area being discussed was second-generation biofuels.

The conference lasted for 3 days and included an opening keynote by Professor Kostic from Northern Illnois University which was a wide ranging presentation on the big picture of world energy demands - past, present and future. Global warming and climate change was hardly mentioned; the key focus was on the unsustainability of fossil fuels, and what can be done about it.

Another keynote was at the conclusion of the conference and was by Professor Nijkamp, Free University, Amsterdam - a great speaker who weaved together a long presentation - again addressing the big picture of global energy demands - that flowed neatly from one idea to the other with the use of barely 5 powerpoint slides.

I was amazed by the amount of solar panels installed in Munich where I had an overnight stay in transit. There are many panels installed on roof-tops, and also solar farms where large stretches of land have been fitted out with “strings” of panels. The German government has enacted a generous feed-in tariff for solar PV electricity sold to the grid, and such installations can produce a profit.

I wonder how much more profitable such a farm can become when new generation materials start being produced, which increase yield, and in increasingly mass-production focused factories? German firm Q-Cells and American firm First Solar are both building new factories in Malaysia for mass-producing their solar PV products.

RETScreen gets it solar data from NASA. This data, and other similar data, is publicly available at the NASA SSE website. For both RETScreen and another energy modelling tool - HOMER - NASA provides packaged data which these tools embed into their shipped product.

RETScreen currently has no API, so an interesting proposition to test is whether there is an API for the weather data itself directly. SSA provides a front-end website to access this data, but unfortunately there is no web service or other API for programmatic access.

That leaves “screen scraping” as the only alternative, and it would be a really bad design decision to follow his path. The problem is that many assumptions need to be made about the parameters in, and the location of the data returned within the response HTML.

A minor cosmetic change to the website could alter the structure of the HTML, even only slightly, and completely break the parsing routine that extracts the output data.

There is other data sets available such as monthly averaged data in text files, subsets of data by region, and daily data, but again these are not accessible programmatically. A software system or tool could not make use of this data without a user having to navigate to the website, login, and download a file or submit a web query.

So, while it is nice of NASA to provide a web front-end to this data, and share it with RETScreen and HOMER, a web service API would be a real advance in providing accessibility to a much wider audience.

In the previous post, I looked into a few of the existing software tools that can help with sustainable energy planning. RETScreen is one of these and it is a very powerful system. Its power lies in the vast collection of data that it centralises and makes available for feasibility analysis. It is described as a feasibility tool because it provides enough information to allow preliminary decisions to be made about potential projects.

I mentioned the idea of integrating a GIS-based front end with RETScreen.  RETScreen is implemented as a series of Excel spreadsheets.  There is no API provided, although it is possible to programmatically integrate with Excel via its COM automation object model.  This works fine for desktop solutions, but is not recommended for server solutions.

Unfortunately, a server-side solution is what I have in mind, so it is a matter of waiting for the API to be developed - this has been promised for the next version.  In the meantime, I can elaborate more on my overall system design and delve into the GIS framework side.

My design for the tool consists of a web-based GIS front-end that allows the user to select a geographical area - perhaps a rooftop space, or some vacant land, and calculate the area.  This then gets passed to RETScreen, along with the coordinates of the location, and a selection from the extensive RETScreen product database of the type of solar product for installation (eg. Mitsubishi poly-SI 120W panels).

It is then possible to return to the user the estimated yearly kWh output as calculated by RETScreens energy model.  I would also like to return estimated Greenhouse Gas emissions avoided (t CO2-e) and perhaps some reference comparisons such as number of average houses powered by the selected configuration.

As I pointed out, this tool fits in the planning/pre-feasibility analysis space.  Why is this useful?  Well the answer boils down to project characteristics.  I think that when it comes to a project like a major rooftop solar installation, construction is the easy part.  It is actually getting the organisation to the point of making a decision and signing off on the go-ahead that is the hard part.

A tool like this is perfect for helping communicate the vision.  It can be used by project champions to reinforce their convictions and they can use it to get the buy-in of other project stakeholders.  A simple web-based application is perfect as it can be accessed from conference rooms with network connection to give presentations, or simply from the desktop.

I have chosen Google Maps for the GIS layer of my prototype of this tool.  It has a great API, and is fully web accessible. It allows me to host the maps from within my own web page and I have total control over the UI.  The framework that I have commenced building can be viewed here.

I am now at the point of waiting for the RETScreen API to be released.  I am hopeful that it will be architected in the form of a web service similar to Google Maps API.  In the meantime I plan to do a post on the weather database contained within RETScreen and look to an existing web-based interface into this data hosted by NASA.

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.

Of the various forms of renewable energy, solar is perhaps the most applicable to large airports. The abundance of land and rooftop area provides numerous locations for installation. The generation occurs on-site, right where there is a large demand, so there is minimal transmission losses, and any excess production can be sold back to the grid. The peak production times of a solar array also correlate nicely with the peak demand of many airports - the hottest part of the hottest days when big terminals and other facilities are consuming lots of energy to run HVAC systems.

This is more so for regions where the solar radiation is higher; roughly speaking this is regions closer to the equator. Airports based in regions further from the equator can also benefit from solar installations, although their peak demand periods tend to not so closely correlate as they are during the colder months when they have a high heating requirement.

Airports are becoming very inventive with their choice of location for solar installations. For example, car parks are being shaded by elevated solar panels. Airports are unlocking the value of otherwise unusable land that buffers runways by utilising it for solar installations. And of course those big buildings have vast roof areas that can be fitted out with solar.

Solar at airports is not new. But lately, the momentum has been building, and projects such as those at Denver and Fresno commercial airports, and Nellis military airport are rapidly showing that airports can embrace renewable energy in a financially viable way and increase the overall sustainability of their operations.

During the course of this solar series I will post on these and other specific standout examples of solar being used in an Airport context. I will also post about some of the academic research in this area.