Distributed energy systems can range from the micro sized do it yourself systems being installed on rooftops and on hilltops to small scale systems ranging up to around 20MW (megawatts) of capacity, although it must be understood that this is a pretty fuzzy boundary. The defining characteristic of distributed energy systems is that they generate energy close to the point of use where that energy will be consumed; hence the admittedly fuzzy 20MW upper boundary for their size. If an energy generation facility becomes much larger than this it produces far too much power to be consumed locally (except in a few rare exceptional cases where large industrial consumers are nearby). The excess power must then be transmitted to distant markets and the energy system can no longer be described as being a distributed energy system.

Besides being relatively small scale distributed energy systems are usually understood to be powered by renewable energy sources such as solar or wind, but also biomass or other systems such as tidal, wave and geothermal and that to put it another way they do not rely on fossil energy supplies. Many however also include micro-turbines, fuel cells and the more traditional gas or diesel powered backup generators in this category by virtue of their small scale.

Some Advantages of Distributed Power Systems

Distributed electric energy systems offer many advantages over the current energy topology of a smal number of massive thermoelectric fossil fueled power producing plants that feed a vast grid with essentially a uni-directional flow of current through a whole series of transformer sub-stations that both step voltage up then step it down along the way to the consumer at the far end of the very long pipe.

• It is suited to regions currently lacking well developed and maintained grid infrastructures. This is the case in much of the less developed world, but also includes remote areas in the US and other industrialized nations.
• By off-loading demand from the grid it can reduce or avoid the necessity to build new transmission/distribution lines or upgrade existing ones.
• They can avoid the line loss associated with transmitting electricity over long distances and in the process of stepping voltage up and then down in transformers in order to put power onto these very high voltage transmission systems and to pull it down off from them before being able to use it.
• Because of its smaller scale it avoids the large increment problems faced by large scale utility sized plants of Gigawatt scale. In other words it can more smoothly fit actual current use patterns and can be installed in easy small increments as needed and does not tie up massive long term capital for a single project.
• Because it is easy to bring small scale distributed systems on and off line when compared to large thermoelectric plants they can function as backup and emergency power sources and help prevent blackouts and brownouts.
• Distributed systems (such as hydro, or biomass, but also micro-turbines, fuel cells etc.) can be configured to produce power during peak load times when the grid is under its greatest stress and energy is most costly.
• Distributed systems are well suited for and promote the diversification of power supplies, which makes them particularly suitable for renewable energy sources.
• By virtue of their smaller scale distributed energy systems are more suitable for co-generation. Co-generation uses the waste heat from a one process, such as power generation, to provide space heating for buildings. Small biomass, micro-turbine, fuel cell, or combined solar facilities are naturally suited to also being sources of co-generated heat. Heat that would otherwise need to be produced by some other means.
• Last, but not least, distributed electric energy systems can help to make our country more secure. Because they are widely dispersed and do not depend on a small number of central facilities they are much less vulnerable to disruption – either through accident or hostile action. Distributed electric energy systems are inherently more survivable than a centralized grid relying on a very small number of fixed facilities and key transmission nodes.

The System We Have

Our current electric energy infrastructure is characterized by massive thermoelectric plants, mostly fired by burning mountains of coal but also by the heat released through nuclear fission. These plants are typically massive driven by economies of scale to reach up into the Gigawatt capacity order of magnitude. Our entire grid system is characterized by this centralized power infrastructure. Of course it is true that a small amount of energy comes from renewable sources– around 6% of the total electric energy generation comes from (often massive) hydro-electric plants and currently a little less than 1% from wind power — but our energy infrastructure is mostly dominated by massive thermoelectric plants with coal burning plants comprising almost half of the nations electric energy generation capacity.

This has lead to a grid structure of correspondingly massive scale and of a similarly centralized nature. But will it always be so? Are we destined to continue down a path of massive power plants feeding a highly integrated grid with power that needs to stepped up to very high voltages for long distance transmission then transformed down in stages until it finally reaches the industrial facility, home, or commercial building where it is ultimately consumed. Is this way of doing things really suited to the nimble and diversified future that awaits us just around the corner of the curve of diminishing fossil energy reserves and spiking costs as increasingly marginal fossil energy supplies are developed to feed our future energy needs?

Recent Trends Seem to Indicate that Distributed Power is Finally Taking Off

Distributed power may finally be taking off, driven by the continued rapid drop in the cost of renewable energy sources, by the increasing incidence of brownouts and blackouts in an over-taxed grid, by the inability of the grid to adapt to future needs, by a desire amongst many to exert more control over their how they get their power and by a growing awareness of global warming.

Solar Energy Sector

A recent report by Pike Research that is focused on the growth in small scale distributed solar photovoltaic power systems predicts that the global market for these systems, which is currently at $30 billion per year (2008 figures) will grow to almost $60 billion by 2013. That is a compound annual growth rate of 22%. Of all the opportunities in PV, Pike Research finds that the most compelling growth potential lies in decentralized electricity generation, whether in small rooftop or large commercial installations. Solar PV has the advantage of being truly modular, which makes it particularly well suited for distributed energy systems.

In addition the modular small scale solar thermal systems suitable for distributed power systems are also taking off. For example Sterling Energy Systems a solar company based in Scottsdale, AZ has recently released an the production design of its SunCatcher system that is a solar thermal dish system that uses concentrated solar energy to run a high efficiency sterling engine. This system has been in development for ten years. Each dish unit can generate 25 kilowatts of energy and has been certified by Sandia National Laboratories as having the highest sun‐to‐grid energy conversion in the world; last year one of the original SunCatchers set a new solar-to-grid system conversion efficiency record by achieving a 31.25 percent net efficiency rate, toppling the old 1984 record of 29.4

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Stirling Energy Systems in partnership with Tessera Solar are building a 1.5MW field Peoria, Arizona. The modular nature of these types of systems makes it a good fit for smaller scale and more widely dispersed distributed solar generating systems, because they are easily scaled to fit current energy market conditions.

The Wind Energy Sector

According to a the Small Wind Global Market Study a study on the market for small wind turbines from The American Wind Energy Association (AWEA), the U.S. market for small wind turbines, which it defines as those with capacities between 20and 100 kilowatts (kW), grew by 78 percent in 2008. It must be said that the installed base is still very small – the total new capacity is a little over 17 megawatts (MW) – however the rate of growth is impressive if it can be sustained.

In the report manufacturers predict a 30-fold increase in the US market in as little as five years, even under current economic conditions. Primary drivers include the eight-year 30% federal investment tax credit enacted in October 2008, recent and potential private equity investment, and greater equipment manufacturing capabilities.

Conclusion

Distributed electric energy generation can help alleviate many of the critical problems facing our current over-taxed grid and avoid the need in many cases to lay down thousands of miles of new high voltage transmission lines. Distributed power as an idea seems sensible, especially in a post fossil world where power is gathered from low density and widely scattered variable sources, such as the wind or the sun. While there are some factors encouraging economies of scale – for example large turbines are more efficient than smaller ones – alternative energy seems well suited to a distributed energy topology typified by a large number of smaller scale facilities that are, in many cases, closely sited to consumers. In this manner power is delivered almost straight to the consumer and the grid becomes increasingly a kind of peer to peer power network re-distributing surplus power to regions of energy deficit – the grid as a more of a load balancer than a one way power pipeline from a few massive thermoelectric plants to the multitude of consumers.

© 2009, Chris de Morsella. All rights reserved. Do not republish.

The Obama administration has announced $350 million in stimulus funds to help expand geothermal resources and break down technological barriers that stand in the way of its development. This is a huge jump in funding, dwarfing all previous government commitments and is more than all the funding for geothermal energy put together over the last 20 years. It also represents a dramatic reversal of previous trends of diminishing funding for this often overlooked renewable energy sector.

“We have a choice. We can remain the world’s leading importer of oil, or we can become the world’s leading exporter of clean energy,” said President Obama announcing the new funding. “We can hand over the jobs of the future to our competitors, or we can confront what they have already recognized as the great opportunity of our time: the nation that leads the world in creating new sources of clean energy will be the nation that leads the 21st century global economy. That’s the nation I want America to be.”

“We have an ambitious agenda to put millions of people to work by investing in clean energy technology like solar and geothermal energy,” Energy Secretary Steven Chu said. “These technologies represent two pieces of a broad energy portfolio that will help us aggressively fight climate change and renew our position as a global leader in clean energy jobs.”

What is Geothermal Energy and What Makes it so Important?

Geothermal energy is a source of renewable energy that harnesses heat from the Earth to provide heating for buildings and for electricity generation. A recent MIT study has estimated that the US has somewhere around 100 gigawatts or more of geothermal energy capacity that could be developed with a reasonable investment in this sector.

This is important not only because it would represents a significant contribution to the overall electric energy generating capacity mix, but also because geothermal energy is a highly predictable energy source. In fact, geothermal plants can operate around the clock and provide uninterrupted “base load” electricity. Base load capacity is the minimum amount of power a utility must provide to its customers. Unlike wind or solar energy, which are subject to variable output depending on weather conditions geothermal energy plants will be able to provide reliable power onto the grid regardless of current weather conditions or time of day. The ability to provide “base load” capacity is a critically important quality and one that distinguishes geothermal energy from other renewable sources such as wind or solar. In this regard geothermal energy is like the large coal or nuclear fired thermal electric plants; it provides a steady flow of energy onto the grid.

To explore a different form of geothermal technology called geothermal heat pumps that uses the ground below us to heat and cool our buildings and provide hot water while using much less energy to do so, see our post: Geothermal Heat Pumps: Good for the Bottom Line, Good for the Nation and Good for the Earth

Recovery Act Funding Will Support Projects in Four Crucial Areas

These are: geothermal demonstration projects; Enhanced Geothermal Systems (EGS) research and development; innovative exploration techniques; and a National Geothermal Data System, Resource Assessment and Classification System.

Geothermal Demonstration Projects will receive $140 Million to support demonstration projects that profile new technologies that enable geothermal energy development in new geographic areas, as well as geothermal energy production from oil and natural gas fields, geopressured fields, and low to moderate temperature geothermal resources.

Enhanced Geothermal Systems Technology Research and Development will receive $80 Million in funding to support research of EGS technology to allow geothermal power generation across much of the country. Conventional geothermal energy systems must be located near easily-accessible geothermal water resources that only exist in a few regions (mostly in the Western States) of the country. EGS makes use of available heat resources that can be found everywhere if one drills far enough down. It proposes to create engineered reservoirs – in suitable rock formations that have a suitable cap rock over the engineered reservoir. These engineered geothermal reservoirs can then be tapped to produce electricity. This is a long term project that many believe holds promise to eventually generate cost competitive clean electricity. The funding is designed to promote enabling research and development that will be required in order to demonstrate the EGS technology.

Innovative Exploration Techniques is slated to get $100 Million in funding to support projects that include exploration, siting, drilling, and characterization of a series of exploration wells utilizing innovative exploration techniques. The upfront exploration costs inherent in geothermal energy projects are one of the principle blocking factors to increased investment and development in this sector. The DOE hopes to help develop and validate new innovative exploration technologies and methods that can help reduce this level of upfront risk and investment in green field projects and in this manner promoting the discovery and development of geothermal resources.

National Geothermal Data System, Resource Assessment, and Classification System will receive $30 Million of funding, which will fund a nationwide assessment of geothermal resources, working through the USGS and other partners; establish a national geothermal data system to make resource data available to academia, researchers, and the private sector and develop a geothermal resource classification system for use in determining site potential. Building a detailed database and characterization of geothermal energy resources nationwide is important for the long term success of geothermal energy.

Conclusion

Geothermal energy certainly has a lot of potential and could become a very important part of our future energy mix. This will be especially true if enhanced geothermal systems technology proves feasible and engineered geothermal reservoirs can be created very close to the large urban power markets. In this case EGS geothermal energy could become the single most important energy supplier of both electricity and co-generated heat resources for much of the nation. It would have the advantage of being able to be sited close to where power was needed, to be able to deliver heat as well as electricity and as with all geothermal resources it would contribute to the base load generating capacity that is so critical to the grid’s functionality.

It is no over statement to say that geothermal energy will be around as long as Earth has a molten core – and that is a very long time. It is essentially renewable and inexhaustible, although fields can become temporarily discharged if over-exploited.

So what’s not to like? One thing that is missing from the funding is any funding for technology or processes that make geothermal energy cleaner. In fact many hot steam geothermal resources and the plants that exploit them are a source of a fair bit of air pollution including hydrogen sulfide emissions. Geothermal energy will need to solve its own emission problems if it truly wants to wear the green mantle that it otherwise truly does deserve.

© 2009, Chris de Morsella. All rights reserved. Do not republish.