Clean Energy Overview

Bob Freeston - NY Solar Energy Society
& Douglas P. Casper


Energy efficiency retrofits to existing buildings & renewable energy are the fastest growing industries, globally, right now. Energy efficiency retrofits to existing buildings accounted for over one trillion dollars, spent in the following market segments: building insulation, high-performance windows, high-efficiency appliances and HVAC & R equipment. Annual use of renewable energy was $140 billion. Domestically, we have just reached a “tipping point,” where economies of scale are beginning to accelerate the rate of change to new technologies. This revolution began in Europe & Japan and has established a foothold in northern California, centered on the Silicon Valley area (San Jose). Per capita energy use in Europe & California is only 50% of the US average, with a lot higher percentage of that being from renewable sources. Photovoltaic production has been doubling every 2 years, increasing by an average of 48 percent each year since 2002, making it the world’s fastest-growing energy technology.

“Grid Parity” is paying the same price for energy from renewable sources as it would if that energy came from coal. The predictions are pointing to the world reaching a point of grid parity by as early as 2011. We already have reached grid parity in Southern Italy and Hawaii.

The following renewable energy technologies are perhaps the most promising, when considering the “triple bottom line,” discussed in green circles. Triple bottom line, also known as TBL or 3BT, refers to a state of being equally concerned about: economic, ecological and social issues.

Photovoltaics (PV)

Installed Photovoltaic installations worldwide are over 15,200 Megawatts, by the end of 2008, with Japan, the US & Germany leading the way. The fact that Germany is in a temperate climate similar to the northern US, but yet is the leader in this field bodes well for future installations. The benefits of a solar installation in a state like Arizona or New Mexico 10-14 kWh/m2/day, compared to New York (2-3) or Wisconsin (4-6) - yet it still may make sense to install PV in these areas.

Note: 1 kWh/m2/day = 317.1 Btu/ft2/day

There are more than 10 types of PV, most of which are commercially available, including: crystalline silicon, amorphous silicon, thin film, cadmium telluride, CIGS, concentrators, bi-facial, multi-junction, quantum dots, holographic, UMG, etc.

Moore’s Solar law states that every doubling of capacity leads to a 20% drop in price. We have witnessed similar phenomena in areas such as video cassette recorders, personal computers, microwave ovens, etc.

Solar Thermal

The use of utility scale concentrators can increase heat storage capacity. This new technology was developed in Spain. Solar thermal technology has a 70% efficiency, compared to only a 20% efficiency for Photovoltaics. Solar thermal systems use steam to drive turbines that produce electricity.

Building Integrated Photovoltaics

This approach involves utilizing materials such as glass or roof shingles, which have the photovoltaic sensors embedded directly onto the material’s surface. Building integrated photovoltaics was used at the School of Environmental Science at Oberlin College (Will McDonough) and in San Francisco at Renzo Piano’s government buildings. This approach is available, but very expensive (approximately $150.00/ square foot). It has seen greater use, to date, in Europe but it is available in this country, as well.

Power Purchase Agreements (PPAs) This is a methodology that allows people to purchase electricity at a very reasonable price. It is commonly used on the west coast now, as well on the east coast for large commercial projects. It consists of an arrangement where a third party installs, owns & maintains a PV system, usually on a building roof The advantage for the operators is that they can take advantage of the Federal tax rebate. Several states are offering additional incentives, as well.


The harnessing of wind energy is really taking off. From 2000 to 2004 wind use in the US doubled. The US led the world in new installations in 2005 & 2006. There are presently 100,000 wind turbines (worldwide) employing 200,000 people. In other parts of the world, such as Denmark, wind power is being harnessed on a massive scale. It employs 20,000 people and is providing 20 percent of Denmark's total power. To illustrate how powerful wind energy is - one 310 foot high wind turbine can generate power for 750 homes. Wind turbines can be located remotely, even at sea, and the energy generated can be stored either as compressed air or in hydrogen fuel cells for use in motor vehicles and for buildings. When hydrogen fuel cell technology improves: wind power will be even more viable than it is today. Wind farms can be located up to 1,000 miles away from where the (electric) power is needed. Wind farms are being built in Texas, the Dakotas, Kansas, Oklahoma, and Pennsylvania. The American Wind Energy Association (AWEA) has been holding national conventions since 2001. As an indicator of how fast wind power is growing, domestically – AWEA’s 2001 conference drew 1,000 attendees, with 25 booths. In 2009 the conference had over 23,000 attendees and 1280 exhibitors. The conference is now bigger than AIA or CSIs’ national conventions and almost as big as the USGBC’s GreenBuild.

Geothermal is made up of the following types:

Geothermal – Shallow

The year-round temperature at five feet below the earth’s surface is 52° F. Pipes with a mixture of water and glycol can be pumped through this earth and used for winter heating and summer cooling in buildings.

Either horizontal or vertical loops can be used. Pipes can circulate through a nearby lake as well. The details of the system design are determined by the amount of available land, soil conditions & cost.

Engineered (or Enhanced) Geothermal

Temperatures at the planet’s molten core reach 9,000° Fahrenheit. As this heat wafts through the mantle, there is a tremendous amount of heat energy that can be harnessed. In Germany right now, they are building 3 to 10 Megawatts power plants utilizing this technology. In Germany district heating already commands a market share of around 14 % in the residential sector. The present connected heat load is around 52.729 MW, comes mainly from coal & natural gas fired cogeneration plants.1 Volcanic Geothermal This method taps the actual hot gas flows from deep below the earth’s surface. Locations where this method is prevalent include California, Montana, Nevada, New Zealand & Iceland where geothermal provides 50% of the country’s energy.

Cogeneration Cogeneration is a process where excess heat generated in power plants can be reused. Cogen plants can even use gases from sewers or even biogases produced in agriculture. Cogen eliminates the standard 7% long-distance transmission lass suffered by most systems and it doubles the plant’s efficiency.

Most large power plants in the US and Europe are only 35% efficient. In Thomas Edison’s first power plant excess heat was captured and reused; the plant was a lot more efficient than today’s plants.

Water Water is a precious resource It covers 78% of the globe but only 3% of that is fresh water and only ¼ of that is usable. As evidenced by the dire water shortages already experienced on both coasts, it is imperative that we do a better job of conserving water. The first step is to acknowledge that it is a precious resource. Potable water should never be used for landscape irrigation.

Water from sinks, showers and washing machines can be easily filtered and reused as “grey” water for toilets and landscape irrigation. Or it can be filtered back to the potable state. Waste or “black” water can be filtered and reused, as well. Rainwater can be collected, filtered and reused, as well.

A comprehensive filtering process, including the conversion of black water to potable can be done at a wastewater treatment plant. These plants need not be large; they can occur in a nondescript building, about the size of a small barn.

We are accustomed to using flush toilets, however – the basic process involved is wasteful & extremely detrimental to the environment. A much less intrusive, more ecological, and quite viable solution is to use natural composting toilets. This system uses the natural process of composition to turn solid and liquid waste into compost which is, in turn, used for nourishing crops. This system is well-liked by people/ institutions that use it and has been successfully employed at homes, highway rest stops, as well as cultural institutions, such as zoos and botanical gardens.

Green Building

We are already building zero net energy buildings. The Solar Decathlon competition requires all entrees, teams of students & faculty from major universities, to design & build zero energy houses. There have been a handful of other projects that are zero energy as well, for example a conference center in Wisconsin and municipal buildings in Kansas.

To produce a successful green building project, one must heed to three basic, underlying principles: building envelope, building performance & recycling of waste. You need a super-insulated building shell. The walls and roof must have, respectively, minimum R-30 and R-50 for the northern US and R-20 & R-35 for the southern part of the US. To be a zero energy building – renewable energy sources must be used to the maximum degree possible. The choices include geothermal, solar electric, solar hot water hydro power & bio-fuels. What portion of the building heating, cooling & incidental electric needs for lighting and power that cannot be met by renewable sources must be satisfied using “Green Power.” “Green Power” is electricity purchased from the utility company that has been certified to have come from renewable sources (such as wind, photovoltaic & hydro power).

The third principle that must be met has to do with how the building (during construction, as well as during final occupancy). The mantra “reduce, reuse & recycle” must be followed. The initial planning of the building must respect the concept that a minimal footprint, that preserves more of the natural ecosystem, is always preferable. Paved areas should be minimized and the paving should be permeable, allowing rainwater to be returned to the natural aquifer.

If the building can be located near public transportation stations, the use of nonrenewable energy by building occupants who would have otherwise had to drive a private motor vehicle to and from work is avoided!

Construction and demolition waste must be kept to an absolute minimum. Pain should be taken to ensure that the materials of construction have a good amount (say 10-20%) recycled content and that they originated from nearby (hopefully at least 10-20% within a 500 mile radius of the project site). The recycling of “post consumer” waste, that which is produced by the general population and would otherwise end up in a landfill is considered to be twice as valuable as reducing “post industrial” waste, that which is produced as a by-product of the manufacturing process. The reason for this is that post consumer waste, if not immediately recycled, is adding to the waste stream, immediately, whereas post industrial waste has a better chance of being reused anyway, as part of the manufacturing process.

Zero Cost Upgrades of Existing Buildings

This area is going to figure heavily in the short-term future, as perhaps the best way to save energy in buildings. Many buildings are spec-built by developers and, therefore, have not incorporated the most sophisticated mechanical and electric systems and may not have an efficient envelope. From a sustainability perspective, it is always better to renovate an existing building and adapt it to new uses – as opposed to tearing it down and starting from scratch. There is a tremendous amount of embodied energy in the materials that went into that structure which will be lost of the building is demolished. It has been said that the most efficient light bulb is one that has not been turned on. By that logic, a parallel statement regarding existing buildings is that: “the best existing building is one that is renovated, rather than replaced.”

Transportation The American Solar Energy Society supports the utilization of plug-in hybrids, vehicles using lithium batteries & ultra capacitors. Vehicles have, at this point incorporated some solar and wind powered features. They can interact with the smart grid. The vehicles can now serve as battery storage for grid support and household emergencies. In most domestic markets the energy cost is around $1 per gallon equivalent.

The Economy The current recession we are experiencing is hurting us in the short term because the development of new technology requires large initial cash outlays, which pay back over a much longer period of time. Historically, the economy is a cyclical thing, with every down-cycle followed by an uptick. Good things can come out of bad. A good example is that the photovoltaic industry has had a worldwide supply shortage. The current downturn is a correction process that will allow supply to balance with demand.

Meanwhile, as the traditional auto industry tanks, renewable energy industries are growing bottom-up and are beginning to get politically active on the state and national levels. In Washington D.C., however, the problem is the entrenchment of a very powerful fossil fuel lobby. Removal of production tax credits for large wind and solar projects were turned down eight times in 2008, until they were attached to the bank bailout bill. The new administration in Washington D.C. is much more supportive of renewable energy and we are beginning to see the results!

Renewable energy and energy efficiency should, logically, be our solution to the current economic problems we are experiencing. We are introducing Zero Net Cost, on a very large scale. A lot of the high-tech “smarts,” centered in places like Silicon Valley, California and the high-tech corridor in the Boston area is now being applied to renewable energy technologies and will enable us to unleash the power of renewable energy for the betterment of mankind.

All this bodes extremely well for the field of architecture and its sister professions. A very fertile area for design professionals to engage in, right now, is energy-efficient upgrades of existing structures. These types of projects require collaboration between architects & structural, mechanical, electrical & environmental engineers. Working with the municipalities & the power authorities – professionals can take advantage of all the federal, state & local tax incentives to be able to deliver projects that will have a relatively short payback period. The already impressive array of renewable energy tools at our disposal will allow us to keep busy through the recession and create a truly sustainable world.

Footnotes: 1. Wikipedia, article on district heating: