Category: Electric utilities

Carbon Capture and Sequestration: Is It a Viable Technology?

As mentioned in my previous blog (‘What I Took Away From the Doha Clean Energy Forum’): “three speakers made a strong case for carbon capture and sequestration (CCS) as a means of addressing global warming and climate change, especially in heavily carbon emitting industries such as cement production. Lots of questions remain, and will be discussed in a future blog.” This is that future blog on a well trod but still controversial subject.

Wikipedia defines CCS as “..the process of capturing waste carbon dioxide (CO2) from large point sources, such as fossil fuel power plants, transporting it to a storage site, and depositing it where it will not enter the atmosphere, normally an underground geological formation.”

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Considerable literature exists on CCS, exhibiting a wide range of opinions on its viability as a technology to reduce carbon dioxide emissions. The principal argument for CCS is that the world today is fueled largely by coal, oil and natural gas and that this situation is not likely to change any time soon. In fact, as many developing nations industrialize and emerge from poverty, the demand for energy increases steadily and it is argued that only fossil fuels can meet that demand in coming decades. It is also argued that while solar and wind and other renewable energy technologies can eventually replace electricity from coal and natural gas power plants this will not occur quickly and people will need fossil energy during the long transition. In addition, some industries like steel and cement are not so easily ‘fixed’ and will continue to use fossil fuels in increasing amounts as global industrialization grows.

These points raised in support of CCS are countered by the following arguments:
– CCS is expensive, whether added to an existing power plant or industrial carbon dioxide source, or included in newly constructed facilities. The energy penalty for operating CCS is also high, requiring a fair amount of parasitic energy that reduces efficiency and revenues.
– When operating, CCS systems require large amounts of water.
– captured carbon dioxide must be liquified and stored for indefinite periods of time in such a way as to avoid leakage and large ‘burps’ that can be toxic. This requires identification and development of storage sites (depleted oil and gas wells, coal mines, underground aquifers), infrastructure to transport liquid CO2, adds additional costs and raises questions of liability if something goes wrong and stored CO2 is accidentally released.
– the time required for development, demonstration and large-scale deployment of CCS technology that can have a meaningful impact on global warming is too long compared to other options.

Proponents of CCS (see http://www.globalccsinstitute.com) argue that CCS costs can be brought down significantly with a sufficient number of demonstration projects and economies of scale associated with large-scale deployment. Nevertheless, at the recent Doha Clean Energy Forum even one of its supporters admitted that an impactful global CCS system will cost an estimated 3.6 trillion USD (and I did say trillion). My immediate reaction was that for $3.6 trillion I can deliver an awful lot of renewable energy that will replace coal, oil, and natural gas use in power generation and transportation. Nevertheless, there is the argument that the CO2 emissions from some industries will still be there in large and growing amounts even with large-scale deployment of renewables and CCS is the only way to limit these emissions.

These are strong arguments for some attention to CCS R&D and demonstration, but, in my view, not at the expense of rapid development and deployment of renewables. This creates a conundrum as CCS demonstrations are expensive, and the money for them would have to come from somewhere. Government funding is at best problematic in current budget situations. Other possibilities are the fossil fuel industries themselves, which have a vested interest in continued purchase of their commodities. Countries with large reserves of fossil fuels – e.g., the U.S., with large reserves of coal – will also see value in CCS allowing extended use of secure domestic energy reserves.

In a world committed to reducing carbon emissions CCS offers a helping hand but not a definitive one. It may offer a partial answer for the rest of this century, but governments are unlikely to provide the needed funds for large-scale deployment. Let’s see if the private fossil fuel sector is willing to step up to protect its vested interests.

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Off to Doha – international Herald Tribune’s Global Clean Energy Forum

I will be leaving on Sunday, October 6th to spend most of a week in Doha, Qatar. This will largely be to participate in the International Herald Tribune’s annual Global Clean Energy Forum. My next blog(s) will be based on what I experience and learn at the Forum. (Note: as of October 15th the IHT will formally be relabeled New York Times International).

The following description is from the 2013 Forum web site (http://www.ihtconferences.com/gcef-2013.aspx):

“Sustainability in the new energy reality

The 2013 Global Clean Energy Forum will explore the new energy reality – that of abundant fossil fuels, cooling political sentiment towards renewables and risk-averse investors.

It will examine the new role of clean energy within the overall energy mix, and the complete journey towards a sustainable future which will include cleaner hydrocarbons and nuclear 2.0.” The full agenda and other Forum details can be found at the web site.

Solar PV

Specifically, I will be a speaker in the October 9th interview session labeled ‘The new energy mix’ (details below):

“On-stage keynote interview: The new energy mix
Shale gas, and increasingly shale oil, are changing the dynamics for the whole energy industry – especially in the US, but with global repercussions. What does this mean for renewables?

How will renewable energy prices be affected by the rise of shale?
What part will gas play in the transition to clean energy?
What next for onshore and offshore wind?
What is the place for Concentrated Solar Power in tomorrow’s energy mix?
How can the water energy nexus be balanced?
Dr Allan Hoffman, Visiting Professor of Renewable Energy and Desalination, GORD (Gulf Organization for Research and Development) and former Senior Analyst, Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE)
Santiago Seage, CEO, Abengoa Solar
Omran Al-Kuwari, CEO & Co-founder, GreenGulf Inc.”

Meetings such as this are becoming more common and needed as renewables enter the energy mainstream.

Solar Energy: The Unstoppable Transformative Technology

As most readers of this blog will know solar energy comes in two broad categories: photovoltaics (PV) and concentrated solar power (CSP). The latter category includes concentrated solar thermal power (as in parabolic troughs, …) and concentrating photovoltaics (CPV). This blog will focus on PV; concentrated forms of solar energy will be discussed in a subsequent blog.

PV is a now a well-known and widely deployed form of renewable energy in which radiation from the sun is converted directly into electricity via panels of solar (or PV) cells. They can be roof-mounted or ground-mounted, as shown below, or used in many other ways to provide smaller amounts of electricity to handheld calculators, roadside telephones, battery chargers, remote microwave relay stations, solar lanterns, water pumping, and numerous other applications. It is a modular technology that can be scaled up in kW size as needed. It also lends itself to integration with various building and other materials – e.g., as roof tiles, building facades, blankets, clothing, and other flexible materials. There is an extensive and rapidly growing literature on PV – one hardly knows where to start. One useful starting point I would recommend is
http://wwww.eia.gov/kids/energy.cfm?page=solar_home-basics-k.cfm
Another useful source of information is the web site of the Solar Energy Idustries Association: http://www.seia.org

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Roof-mounted PV

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Ground-mounted PV

There are two energy technologies that I consider transformative (some people prefer the term ‘disruptive’), i.e., they change the way we generate and use electricity. These are fuel cells, which use hydrogen as a ‘fuel’ to generate electricity, water and heat (and will be discussed in a future blog), and PV, the focus of this blog.

PV is transformative because it can be used wherever the sun is shining (e.g., in space to power satellites and space stations, and even on Mars to power robotic vehicles), it can generate power where it is needed without the need for power lines, it is modular, and its cost is coming down significantly as more and more PV is manufactured. Our infrastructure is already highly dependent on PV – think about satellites used for wireless telephony and GPS, and terrestrial PV that increasingly is supplying electricity to individual homes and businesses as well as utilities.

i would also note that our use of terrestrial PV is only beginning. An industry that started in 1973 in the U.S. (PV had been used earlier for space applications) now employs more than 120,000 people in the U.S., will add more than 4 gigawatts (yes, I said gigawatts) in the U.S. alone in 2013, on top of 8.5 GW already installed in the U.S. and 102 GW worldwide. Global additions in both 2011 and 2012 totaled 31 GW, and PV today is, annually, a multi-billion dollar industry and growing.

The above discussion clearly indicates that PV is an unstoppable energy technology, as the German electric utilities have learned and U.S. utilities will eventually learn as well. The problem that PV presents to utilities is its decentralized nature and the fact that PV generation is maximum at peak periods of electricity demand when utilities are used to charging higher than average kWh prices. If this peak demand on the utility systems is reduced by home- or business-generated electricity then utility revenues are adversely affected based on current utility business models.

It seems clear that this business model will have to change, and, based on experience, that utilities will resist this change as long as they can. The German utilities faced this problem first because the German government introduced a feed-in-tariff (FiT) for PV in the 1990’s, stimulating a massive deployment of PV in Germany ever since. Today Germany leads the world in PV deployment with about 30 GW installed. I would even note that on one very sunny summer day last year more than half of Germany’s electrical demand was met by PV. When faced with this reality German utilities got into the PV business and are now even offering energy storage services to the German public.

The U.S. federal government has not yet seen fit to offer a FiT to the American public but several states are taking the lead in stimulating PV and other renewable energy use. U.S. utilities are clearly behind the German curve and some are resisting the new PV reality by making hookup to the grid unnecessarily complicated, by proposing extra charges for homes that install PV and battery storage systems, and not incorporating PV into their own generating systems. This will change, hopefully sooner rather than later, as utilities take advantage of these new business opportunities.

Flywheels: A Way To Change the Utility Business Model?

Flywheels and other energy storage systems have the potential to change the way electric utilities operate. A while ago I put down my thoughts on flywheels in a 2010 article I share below in this blog.

The context for my thoughts is that the large central station model for utilities is changing as we move toward more decentralized power generation (think renewables). People are also beginning to react to the vulnerability of the current system to outages, whether accidental or deliberate, that leave thousands of people without power for extended periods of time.

Storage of energy, whether electrical or thermal, can reduce this vulnerability and allow greater use of variable (intermittent) renewable energy sources such as solar and wind. Pumped hydro, compressed air energy storage, and batteries have received the most attention to date. For batteries the major barriers have been insufficient storage capacity, purchase and maintenance costs, space requirements, and the inconvenience of replacement of heavy batteries.

Lead acid batteries have been used in cars, boats, buoys, aircraft and other applications requiring portable electricity sources for many years, and will be used for many years into the future. An interesting aspect of lead acid battery use was their powering of electrical vehicles in the early decades of the 20th century when electric vehicles were the dominant form of personal transportation. In fact, Mrs. Henry Ford drove an electric vehicle. This situation changed because of limited range then available with existing batteries and the advent of high energy density liquid petroleum fuels.

This may be changing today with the emergence of more energy dense and lighter lithium ion battery technologies, but cost is still a major consideration. While cheaper lithium ion cells are coming and lithium ion battery packs are being explored actively for a wide range of applications, including electric vehicles and utility power storage, I would like to suggest that flywheels may also have a role to play in our electric utilities’ future. This idea has been swirling around in my head for many years, and has been mentioned by others, but with the advent of advanced flywheels in recent years I believe it is time to take a serious look at using flywheels in individual homes.

An additional consideration is that as decentralized power systems such as solar roofs become more widely accepted, and utility intermediate- and peak-power sales are reduced, utilities are having to think about getting into the solar energy and energy storage businesses, as is already happening in Germany. I expect this to happen in the U.S. as well.

Using Flywheels to Supply Residential Electricity Demand (July 2010)

Flywheels have always appealed to me as an interesting and potentially widely useful energy storage technology. For many years I have thought about using flywheels at individual homes to supply residential electricity demand during waking hours, using less expensive utility electricity at night to recharge the flywheel (i.e., get it up to maximum rotational speed and stored energy). Limitations have been the physical stresses on flywheel components at the high rotational speeds needed to store appreciable amounts of energy (i.e., tens of kWh) and cost. The use of advanced carbon-fiber materials may now have addressed the first limitation, and cost reductions will be associated with large scale manufacturing of the devices (still to come). The purpose of this note is to explore the feasibility and stimulate discussion of such an approach ( a few others have discussed this possibility as well), which has the potential to reduce utility peak power demands, reduce consumer costs by taking consumers off the grid at peak periods, and transform the nature of utilities. It is offered as a personal thought and does not reflect my responsibilities at the U.S. Department of Energy (2013 note: from which I am now retired).

I start by looking at residential consumer demand. According to the U.S. Department of Energy’s Energy Information Administration: “In 2008, the average annual electricity consumption for a U.S. residential utility customer was 11,040 kWh, an average of 920 kilowatt-hours (kWh) per month. Tennessee had the highest annual consumption at 15,624 kWh and Maine the lowest at 6,252 kWh.” This corresponds to an average daily demand of 11,400/365 = 31.2 kWh. Flywheels that can store 25 kWh are commercially available today (see www.beaconpower.com), and it is not unreasonable to assume that slightly larger flywheels could be easily manufactured. Thus, the idea of a flywheel providing a residence’s daily electricity demand is not unreasonable.

How do flywheels work? To quote from the Beacon Power website (there are other flywheel manufacturers as well): “Flywheel energy storage works by accelerating a cylindrical assembly called a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. The energy is converted back by slowing down the flywheel. The flywheel system itself is a kinetic, or mechanical battery, spinning at very high speeds to store energy that is instantly available when needed.

At the core of Beacon’s flywheel is a carbon-fiber composite rim, supported by a metal hub and shaft and with a motor/generator mounted on the shaft. Together the rim, hub, shaft and motor/generator assembly form the rotor. When charging (or absorbing energy), the flywheel’s motor acts like a load and draws power from the grid to accelerate the rotor to a higher speed. When discharging, the motor is switched into generator mode, and the inertial energy of the rotor drives the generator which, in turn, creates electricity that is then injected back into the grid. Multiple flywheels may be connected together to provide various megawatt-level power capacities. Performance is measured in energy units – kilowatt-hours (kWh) or megawatt-hours (MWh), indicating the amount of energy available over a given period of time.

Beacon’s Smart Energy 25 flywheel has a high-performance rotor assembly that is sealed in a vacuum chamber and spins between 8,000 and 16,000 rpm. At 16,000 rpm the flywheel can store and deliver 25 kWh of extractable energy. At 16,000 rpm, the surface speed of the rim would be approximately Mach 2 – or about 1500 mph – if it were operated in normal atmosphere. At that speed the rim must be enclosed in a high vacuum to reduce friction and energy losses. To reduce losses even further, the rotor is levitated with a combination of permanent magnets and an electromagnetic bearing.”

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An obvious issue associated with flywheels is catastrophic failure. With rotors moving at high rotational speeds and the flywheel structure experiencing large physical stresses, what would happen if a flywheel flew apart? The industry’s answer is that they’re designed for safety, which is probably correct, but people will need additional reassurance, at least for a while. Thus, my proposal would be to place the flywheel unit under garage or carport concrete floors with a removable protective cover, to allow maintenance as needed. Flywheels can also be shielded in other “containers” as well.

Issue #2 is how long does it take to charge up a flywheel at night from full discharge? First we note that there is an energy loss associated with charging/discharging flywheels, and round-trip efficiencies have routinely been quoted in the 70-85 percent range. Recent literature quotes over 90 percent, and for purposes of calculation I shall assume 85 percent as a reasonable number to start with. Thus, to have 31.2 kWh available for useful discharge we will have to supply 31.2/0.85 = 36.7 kWh to the flywheel. A dedicated 40-amp 220 volt circuit provides power at 8.8kW. Thus, fully charging the flywheel from full discharge would require a little more than 4 hours, and this power would be purchased at low overnight rates when utility demand is lowest (at least at present). This could all change, obviously, if charging of hybrid-electric and electric vehicles, and flywheels, becomes widely used. In any case, overnight rates should be lower than daytime rates, especially peak rates.

To utilize a flywheel generator for a home a reliable control system will be required. Much design effort is going into control systems at present (e.g., for hybrid electric vehicles and smart grids), and this application would benefit from these efforts, but it would be an extra cost for the residential customer. Such costs, in addition to the cost of the flywheel and its enclosure and related electrical costs, would have to be balanced against the savings from using cheaper electricity at night. An important counterbalance is the potential set of savings to the utilities of reduced peak demand and the savings from using their currently underutilized generating equipment more fully at night. This raises the possibility of a utility advancing the costs of a flywheel system to its customers, based on its long term savings, as was done with customer installation of ground source heat pumps that also reduced utility peak demand. The advance is then paid back to the utility as an additional charge on the customer’s bill that is reduced by the use of the flywheel.

These are just initial thoughts that I hope will stimulate lots of additional thoughts and reactions. I await your feedback.

(Note: this blog was re-published in the August-September 2013 issue of The Alternative Energy eMagazine, which can be found at http://altenergymag.com/emagazine.php)