Market Forces

Study: Renewables played crucial role in U.S. CO2 reductions

This blog was co-authored with Jonathan Camuzeaux, Adrian Muller, Marius Schneider and Gernot Wagner.

After a nearly 20-year upward trend, U.S. CO2 emissions from energy took a sharp and unexpected turn downwards in 2007. By 2013, the country’s annual CO2 emissions had decreased by 11% – a decline not witnessed since the 1979 oil crisis.

Experts have generally attributed this decrease to the economic recession, and to a huge surge in cheap natural gas displacing coal in the U.S. energy mix. But those same experts mostly overlooked another key factor: the parallel rise in renewable energy production from sources like wind and solar, which expanded substantially over the same 2007-2013 timeframe.

Between 2007 and 2013, wind generated electricity grew almost five-fold to 168 TWh and utility-scale solar from 0.6 TWh to 8.7 TWh. During the same period, bioenergy production grew 39 percent to 4,800 trillion BTUs.

Given these increases, how much did renewables contribute to the emissions reductions in the United States? In a paper published this month in the journal Energy Policy, we use a method called decomposition analysis to answer just that.

Unpacking the Factors

Decomposition analysis is an established method which enables us to separate different factors of influence on total CO2-emissions and identify the contribution of each to the observed decrease. The factors considered here are total energy demand, the share of gas in the fossil fuel mix (capturing the switch from coal and petroleum to gas), and the share of renewables and nuclear energy in total energy production.

Introducing a new approach for separately quantifying the contributions from renewables, we find that renewables played a crucial role in driving U.S. energy CO­2 emissions down between 2007 and 2013 – something which has previously largely gone unrecognized.

According to our index decomposition analysis, of the total 640 million metric ton (Mt) decrease (11%) during that period two-thirds resulted from changes in the composition of the U.S. energy mix (with the remaining third due to a reduction in primary energy demand). Of that, renewables contributed roughly 200 Mt reductions, about a third of the total drop in energy CO2 emissions. That’s about the same as the contribution of the coal and petroleum-to-gas switch (215 Mt). Conversely, increases in nuclear generation contributed a relatively minor 35 Mt.

While the significant role of renewables in reducing CO2 emissions does not diminish the contribution of the switch to natural gas, it is important to note that the climate benefits of switching from coal and petroleum to gas are undermined by the presence of methane leakage along the natural gas supply chain, the extent of which is likely underestimated in national greenhouse gas (GHG) emissions inventories.

Methane, of course, is a powerful greenhouse gas. Methane leakage from increased natural gas use could have wiped out up to 30% of the short-term GHG benefit (on a CO2-equivalent basis) calculated in this paper of switching from coal and petroleum to natural gas. For the natural gas industry to truly sustain the claim that it has made a positive contribution to reducing the country’s carbon footprint, the methane emissions associated with natural gas must be substantially reduced.

These results show that past incentives to support the expansion of renewable energy have been successful in reducing the country’s emissions, and that decreasing costs for renewable energy offers some hope for continued progress even despite the current administration’s refusal to address climate change.

Such progress, however, will never be sufficient without ambitious climate and clean energy policies- whether at the federal or at the state level – that can drive further emission reductions.

Posted in emissions, Energy efficiency / Leave a comment

Dysfunctional gas market cost New England electric customers $3.6 billion

This blog post was co-authored with Levi Marks, Charles Mason and Matthew Zaragoza-Watkins

New England natural gas and electricity prices have undergone dramatic spikes in recent years, spurring talk about the need for a costly new pipeline to meet the region’s needs as demand for gas seemed ready to overtake suppliers’ available capacity to deliver it. For example, during the polar vortex of 2013-14, the gas price at New England’s main gas trading hub regularly exceeded $20/MMBtu (million British Thermal Units, the measure commonly used in the gas industry) and reached a record high of $78/MMBtu on January 22, 2014, compared to the annual average of $5.50/MMBtu.

In an efficient market, we would indeed expect prices to be high during events like the polar vortex. We would also expect pipelines delivering gas to regions like the Boston area – in this case the Algonquin Gas Transmission (AGT) pipeline – to be fully utilized. But this is not what we observed when we analyzed the scheduling patterns on the AGT pipeline from 2013 to 2016.

What 8 million data points told us about artificial shortages

Our research group spent 18 months looking at eight million data points covering the three-year period from mid-2013 to mid-2016. We discovered that during this period, a handful of New England gas utilities owned by two large energy companies routinely scheduled large deliveries, then cancelled orders at the last minute. These scheduling practices created an artificial shortage when in fact there was far more pipeline capacity on the system than it appeared.

As a result, we estimate that New England electricity customers paid $3.6 billion more over this period than they would have if the unused pipeline capacity had been available to deliver gas for electricity generation (for more information on how we calculated this number, visit our methodology page). As for the need for a new pipeline, our analysis shows that energy prices over this period were inflated, which means they should not be used to assess how much, if any, additional pipeline capacity is needed. Both conclusions illustrate why it’s so important (and how valuable it could be) to fix the interface between the gas and electric markets.

Why unused pipeline capacity impacts electricity prices

Although it was natural gas that was supposedly in short supply over this period, electricity prices also experienced large price spikes. That’s due to the way electricity prices are set, and the fact that much of the electricity in New England, as in much of the country, is increasingly generated using natural gas.

About half of the electricity traded in New England’s wholesale electricity market, ISO New England (ISO-NE), comes from gas-fired generators. For any given hour, the wholesale electricity price for all generators in this market is determined by the last (highest) bid needed to meet customer demand (or “clear the market”). This market clearing price is typically (75 percent of the time) set by a natural gas plant, which means their cost for gas and pipeline transportation tends to drive the price of electricity. That cost is largely determined by the spot price of natural gas at Algonquin Citygate, New England’s main gas trading hub, served by the Algonquin Pipeline.

Policy paper: Aligning natural gas and electricity markets »

The figure below shows a stylized generation supply curve for ISO-NE. The lower cost resources to the left (typically solar, wind and hydro) are generally used before the higher cost plants to the right (coal, gas, petroleum). The plants situated where demand meets the supply curve set the overall market price in any given hour (bids are submitted a day ahead of time in the day ahead market). This is typically one of the natural gas plants represented by the red dots on the middle part of the curve. A higher spot price for natural gas increases the marginal cost of gas-fired generators, shifting the generation supply curve up as seen in the second panel. This translates into a higher marginal cost of meeting a given level of electricity demand and thus a higher wholesale electricity price P*.

 

Stylized generation supply curve for ISO-NE.

What price do electric generators pay for gas? The secondary market for natural gas

In New England, as in many other markets, gas-fired electricity generators generally procure gas from a secondary market, where sellers are usually natural gas utilities that purchase long-term contracts at regulated prices directly from the pipeline company. The secondary market exists because these long-term contracts allow contract holders to sell any unused capacity at unregulated prices to gas-fired generators or others.

Generators buying in the secondary market for gas do so because they have decided it is more cost-effective to procure natural gas transportation that way than to grapple with rigid, long-term contracts for pipeline capacity that don’t fit their highly variable needs.

While the amount of pipeline capacity available to deliver natural gas to New England is fixed, demand for gas fluctuates significantly with external factors such as temperature, as seen by the price spikes experienced during the polar vortex

On days like these, holders of long-term contracts can pocket the difference between the price that buyers in the secondary market are willing to pay for gas deliveries, as indicated by the Algonquin Citygate spot price, and the regulated price they themselves pay the pipeline for that same capacity. In the case of utilities, revenues from such sales are typically to a large extent refunded back to the ratepayers that paid for those long-term contracts in the first place.

How could pipeline capacity go unused during the polar vortex?

We see four local gas utilities (two owned by Eversource, two by Avangrid) that scheduled far more pipeline capacity the day before gas delivery than they ended up using the next day. Repeatedly, these companies downscheduled their orders only at the end of the gas delivery day–too late for that unused capacity to be made available to the secondary market.

The threshold at which last-minute down-scheduling of gas orders impacts gas and electric prices varies depending on daily demand. As a proxy, we looked at how far the scheduling patterns at delivery “nodes” on the pipeline operated by Eversource and Avangrid-owned utilities deviated from the overall system average.

  • On 434 days during the study period, at least one Eversource node made downward scheduling changes more than two standard deviations larger than the average scheduling change made by all firms on the pipeline.
  • On 351 days, at least one Eversource location had a schedule change more than three standard deviations larger than the average.

The Eversource utilities primarily made large downscheduling changes on cold days, while Avangrid made large scheduling cuts far more often.

  • On 1043 days, at least one Avangrid location made downward scheduling change more than two standard deviations larger than the average.
  • On 1031 days, at least one Avangrid location made a downward change more than three standard deviations larger than the average.

Total unused capacity exceeded 100,000 MMBtu on 37 days in the three-year period we looked at, which is roughly 7% of the pipeline’s total daily capacity and 28% of the typical total daily supply to gas-fired generators. That these large amounts of downscheduled pipeline capacity were not made available to New England’s gas-fired generators raised both the gas price for generators as well as the price of electricity for New England’s electricity customers. We estimate that unused pipeline capacity increased average gas and electricity prices by 38% and 20%, respectively, over the three-year period we study.

While this behavior may have been within the companies’ contractual rights, the significant impacts in both the gas and electricity markets show the need to consider improvements to market design and regulation. The gas transportation market must become more transparent and flexible to better ensure that existing pipeline capacity is optimally utilized and that unbiased price signals in both the gas and electricity markets lead to cost-efficient investment in energy infrastructure.

 

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Benefits of Clean, Distributed Energy: Why Time, Location, and Compensation Matter

solar-panels-new-yorkNew York is preparing for a future in which clean, distributed energy resources – such as energy efficiency, electric vehicles, rooftop solar panels, and other types of local, on-site power generation – form an integral part of a more decentralized electric grid. This is the future the New York Public Service Commission (PSC) wants to see realized through its signature initiative, Reforming the Energy Vision (REV).

This vision means the role of the customer is changing: from recipient to both user and provider of electricity and other grid services. By investing in clean, distributed energy resources, customers can make the electric system more efficient and contribute to a cleaner environment, while gaining greater control over their energy bills. Read More »

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