Navigant Research Blog

(Geo)Engineering a Climate Change Solution

— March 5, 2015

Climate engineering, or geoengineering, refers to the deliberate and large-scale intervention in the Earth’s climatic systems with the goal of reducing the effects of global warming. While I would argue that mitigation and fossil-fuel emissions reductions should be the primary course of action on climate change, it is also undeniable that achieving concerted and coordinated political action has been monumentally difficult. As outlandish as some geoengineering proposals may sound, changing the behavior of billions of people and overcoming the basic political and industrial challenges of drastically reducing fossil fuel consumption may prove to be even more difficult.

Although significant progress has certainly been made globally in the areas of renewable energy generation, energy efficiency, and improving transportation efficiencies, the international community as a whole has thus far failed to design and agree upon policies that will drastically reduce the amount of CO2 released into the atmosphere in any climate-impactful way.

More Research Needed

This lack of progress on climate change through emissions reductions leads to the conclusion that other approaches should at least be considered and adequately studied to determine efficacy. In early February, a panel of scientists at the National Academy of Sciences released a report arguing that more research on geoengineering needs to be conducted in order to better understand the associated risks and potential benefits. President Obama’s science advisor also publicly backed the initiative in 2010.

There are at least seven geoengineering proposals that are currently being hypothesized as potential climate intervention strategies:

  • Spraying sulfate aerosols into the atmosphere: While risky due to possible ozone layer deterioration, the idea is to reduce the Earth’s absorption of sunlight (much like ash from volcano eruptions).
  • Trapping CO2 in carbon scrubbers: Researchers at Columbia University are working on a carbon scrubber that would remove 1 ton of CO2 from the atmosphere per day. Projected to be available in 2 years, such scrubbers would cost $200,000 apiece, according to the Columbia scientists.
  • Fertilizing trees with nitrogen: This would theoretically increase the trees’ ability to absorb CO2.
  • Aerial Reforestation: Battling rampant deforestation, and the resultant loss of CO2 absorption capacity, airplanes would drop tree seedlings encased in biodegradable containers over large areas of land.
  • Adding powered limestone to the oceans: Such schemes would attempt to reduce ocean acidity and increase carbon sequestration.
  • Ocean iron fertilization: This process would increase the rate of photosynthesis in phyto-plankton in order to absorb more CO2.
  • Enriching soils with biochar: Biochar, a fine-grated charcoal that is highly resistant to decomposition, would hypothetically enrich soils and soak up excess CO2.

This is by no means an exhaustive list of proposals; reflecting sunlight back into space and many other ideas exist. However, it should be noted that there are also many legitimate controversies around geoengineering proposals. Spraying sulfate aerosols into the atmosphere, for example, could degrade the ozone layer. Many of the proposals are too expensive, and most offer an imperfect fix–even if the global average temperature of the earth is reduced, nothing would be done to stop the other consequences of fossil fuel burning such as ocean acidification and air pollution.

While no one knows for sure which  geoengineering proposals offer the most promise, I would argue that they should at least be more openly debated and further researched as a possible climate solution (particularly for a crisis situation where the reduction in CO2 needs to be immediate). Unfortunately, the international community has thus far made very little progress in addressing one of the world’s most serious problems, and in the case of climate change, we are in no position to reject promising ideas out of hand.

 

Intellectual Property Battles Roil the Wind Power Industry

— February 11, 2015

Wind turbine vendors vigorously pursue intellectual property (IP) advantages in technology and ruthlessly defend them to maintain an edge over their competitors. The 2010 clash between GE and Mitsubishi over low-voltage ride-through and variable speed operation reportedly caused Mitsubishi to start sweeping its cavernous exhibit booth at trade shows, on the lookout for electronic surveillance devices planted by rivals. In another example, IP battles between Kenetech and German supplier ENERCON—the world’s third-largest wind turbine vendor by market share in 2013—resulted in ENERCON abandoning the U.S. market entirely.

One of the latest patent fights to spill into the headlines is between ENERCON and Siemens, over so-called de-rated operation. Who will win this round is anyone’s guess, but it’s another example of the rapidly advancing technology that continues to improve the performance, efficiency, and grid-friendly capabilities of wind turbines.

Slowdown, Not Shutdown

De-rated operation is the ability of a wind turbine or an entire wind plant to operate below its maximum capacity during times of high wind speed. Traditionally, when wind turbines reach their thresholds for maximum wind speed (around the 25 meter per second range), they will enter a cut-out and shutdown mode to protect the rotor, tower, and drivetrain from damaging stress. However, this process takes the electricity production offline, which can destabilize the broader power grid. As the commercial-scale deployment of wind turbines increases, this becomes a larger concern.  De-rating uses a range of control methods, from pitch control of blades to generator torque control to operate a wind turbine at below its maximum capacity.

For example, instead of a 2 MW wind turbine shutting off once it encounters its threshold cut-off wind speed parameters, it can reduce its output to (for example) 50% capacity, or 1 MW. This ensures that the wind plant remains operational, balancing the grid, and that kilowatt-hours continue to be produced instead of lost due to a full shutdown. There are also economic inefficiencies associated with stopping and restarting wind turbines that can be avoided by running at reduced load. This approach can be used to continue the operation and revenue generation of a wind turbine that is experiencing high operating temperatures within the turbine drivetrain, which can trip a control system that shuts everything down to prevent damage to the turbine. De-rating can allow power production to continue while temperatures are reduced to acceptable levels without entirely shutting the turbine down.

Storm Warning

ENERCON named its system Storm control; Siemens calls its system High Wind Ride Through (HWRT). GE Energy—likely as a way to avoid a similar IP battle with ENERCON—uses a de-rating approach that collectively de-rates all of the wind turbines at a wind plant. Spain’s Gamesa fought a 3-year battle to invalidate ENERCON’s patent, but lost in February 2014. Other vendors currently have or are bringing to market similar strategies—and all are certainly watching this patent fight closely from the sidelines.

 

A New Dawn for Lead Batteries

— October 2, 2014

Donald Sadoway, a materials scientist at the Massachusetts Institute of Technology, is considered one of the smartest and most creative battery scientists in the world.  So admired is Sadoway that, when former Microsoft CEO Bill Gates wanted to learn about batteries, he took Sadoway’s course.  Afterwards, he approached Sadoway and the two discussed the topic of how to rethink battery design from a blank page of paper.  That discussion led to the founding of Ambri, a startup company that is based on Sadoway’s ideas for how to build a better battery.  And at the heart of Ambri is Sadoway’s concept of a high-temperature liquid metal battery whose cathode and anode literally float one on top of each other.

Ambri’s first attempt at a prototype involved the metals antimony and magnesium.  The concept worked, but the high melting point of magnesium (650 degrees Celsius) and the relatively high cost of that material made the prototype battery too expensive to compete against lower-cost batteries like lithium ion and lead-acid.  So Sadoway and his research team kept working.  In a paper just published in the journal Nature, the team released the results of their second prototype, which uses an old standby material of the battery industry: lead.

Melting Point

The battery consists of three basic inputs: lithium salts, lead, and antimony.  The lithium serves as the anode, or negative electrode, which holds the energy in storage while the battery is being charged.  Alloyed together, the lead and the antimony form the cathode, or positive electrode, which releases electrons during the discharge of the battery.  Once the battery is heated so that the alloy mixture and the metallic lithium melt into liquids (which requires a temperature of 253 degrees Celsius), the battery can start cycling through charges and discharges.  The lower temperature means that there are fewer parasitic losses during cycling, which makes the battery more efficient (the paper claims a 73% round trip efficiency, which is similar to the efficiency of many flow battery technologies).

More interestingly, Sadoway’s team calculates that the cost of input materials for the battery would be a mere $68 per kWh, which compares favorably to almost every other battery chemistry.  Finally, the Nature paper shows that accelerated testing of the battery predicts that, after 10 years of daily 100% cycling, the battery will still have a usable capacity above 85% of the capacity the battery had when it went through its first charge/discharge cycle.  In that regard, it compares to accelerated testing of other high quality batteries.

Lead Leader

Will Ambri’s new battery take over the market share of the other incumbent battery technologies?  It’s not likely.  Because the battery needs to be kept at a high temperature, it won’t function well in situations that require maximum flexibility and uncertainty.  However, it will be an excellent choice for any application that requires a long-duration and highly consistent charge/discharge cycle.  Although that’s a niche of the overall stationary energy storage industry, it could eventually be a large one.  Decades from now, when people talk about lead batteries, they might just be referring to Ambri’s molten battery, not their car starter batteries.

 

On the Grid, Time Is of the Essence

— October 2, 2014

The precise calculation of time is at the bedrock of nearly all modern technology, including mobile telecommunications.

In technology, we’re talking really granular time – time measured in milliseconds or less.  Early telecommunications were based upon time-division multiplexing (TDM), and telecoms today still depend upon successors to TDM.  Newer smartphones have onboard accelerometers and gyroscopes to measure velocity in three dimensions – all time-based.

Electric grids are no exception.  An instructive example is the time-synchronized phasor measurement unit (PMU).  Synchrophasors are networks of PMUs that measure the phase angles of the alternating current (AC) at various points along a high-voltage network.  Power flows from higher angles to lower angles, so some difference in phase angles (the phase shift) is expected, but not too much.  As wide area situational awareness tools, synchrophasors can supply an early indication that something is amiss in a high-voltage transmission network.  After-the-fact analysis shows that during the Great Northeast Blackout of 2003, phase angles that were normally shifted by 25 degrees had increased to a 135-degree shift.  Had synchrophasors been widely available and deployed at the time, it is likely that much of the outage could have been foreseen and prevented.

Obey the Time

But time is critical to synchrophasors’ performance.  To ensure coordination, all the PMUs in a network take their time stamp from a single GPS satellite.  The time stamp is added to the reading and sent to a phasor data concentrator (PDC).  This typically happens 30 times per second.  Comparisons at the PDC or other central sites indicate whether or not phase shifts are within expected tolerances at each PMU.  Out-of-tolerance measurements indicate that immediate action is required.

Here’s the problem: if the time stamp is unreliable, then a valid comparison of phase angles is impossible.  Synchrophasors are but one example, and for sure there are worse things that could result from the loss of reliable time service – loss of geospatial information systems, for example.  But the point remains: time is key.

All of this leads to time as an attack surface for smart grids.  PMUs are one of many devices in a grid that rely upon synchronized time to give utilities control of their networks.  Newer clip-on line sensors promise to make distribution management more granular as well, by taking thousands of readings per second.  Again, those readings must be accurately time-stamped to be of any use.

Point of Vulnerability

Disrupt time and you disrupt the grid.  How many ways are there to disrupt the time signal across a synchrophasor network?  Taking out a satellite is an extreme possibility, but there are simpler earthbound approaches.  My paranoid security mind just won’t let me list them in this blog however.

We depend upon time for much of what we do.  We need time readings to be there for us reliably, down to the millisecond or less.  And yet, time is not defined as a U.S. critical infrastructure sector.  Where is the defense for this irreplaceable asset?

I must credit Frank Prautzsch of Velocity Technology Partners for raising time as an issue at a recent cyber security conference.  Frank’s point, which I hope I have amplified here: while we consider complicated attack scenarios against smart grids, there are some really basic things that must also be defended.  Time is among the most basic of them all.

 

Blog Articles

Most Recent

By Date

Tags

Clean Transportation, Electric Vehicles, Policy & Regulation, Renewable Energy, Smart Energy Practice, Smart Energy Program, Smart Grid Practice, Smart Transportation Practice, Smart Transportation Program, Utility Innovations

By Author


{"userID":"","pageName":"Science & Technology","path":"\/tag\/science-technology","date":"5\/23\/2015"}