Gas Wells Now Need Air Quality Plan Approval
The Pennsylvania Department of Environmental Protection announced last week that operators of unconventional gas wells will no longer be unconditionally exempt from seeking an air quality plan approval for well sites. Plan approval authorizes the construction and temporary operation of air emissions sources.
Revised technical guidance, released by DEP, explains that the agency may grant such operators a permitting exemption, provided that they implement controls and practices more stringent than federal rules.
DEP has submitted a formal notice announcing the change for publication in this week's edition of the Pennsylvania Bulletin.
"Gov. Corbett's continued leadership on energy and environmental issues has put Pennsylvania in a unique position - air quality has improved over the past few years at the same time the state's energy portfolio continues to expand the development and use of natural gas," DEP Acting Secretary Chris Abruzzo said.
"We fully expect both of those trends to continue, and this strategy builds on existing federal requirements by continuing to set the high, but fair, bar we have come to expect," Abruzzo added.
In April 2012, the U.S. Environmental Protection Agency announced, for the first time, national air quality rules for oil and gas sites.
Earlier this year, Pennsylvania's DEP announced it was proposing to amend technical guidance detailing which emissions sources would not be required to obtain air quality plan approvals from the state. Oil and gas well sites in Pennsylvania had been granted blanket exemptions from obtaining approvals since 1996.
The final revised guidance affords each operator the choice between seeking an air quality plan approval from DEP, or demonstrating and implementing controls and practices more stringent than the federal rules.
The DEP guidance includes practices such as a leak detection and repair program for the entire well pad and facility, rather than just the storage vessels as required by federal rules. Any leaks must be repaired within 15 days unless the operator shuts the site down or is in the process of acquiring replacement parts.
Emissions of volatile organic compounds and hazardous air pollutants must also be controlled beyond levels required by the federal rules. DEP's guidance also requires that emissions of nitrogen oxides be less than 100 pounds per hour, half a ton per day and 6.6 tons per year; the federal rules do not address or limit such emissions.
Finally, while both the federal rules and the state's guidance allow for flaring (with the EPA requiring green completions at all wells by Jan. 1, 2015), open flaring is only allowed by the state on a short-term or emergency basis. Flaring used as emission control on storage vessels must be enclosed, resulting in reductions of volatile organic compounds and hazardous air pollutants. Such enclosed flares have been demonstrated to achieve up to 99.9 percent elimination of such pollutants.
The exemption criteria build on an existing and continually improving regulatory environment to ensure natural gas drilling happens responsibly. Earlier this year, DEP announced a revised general permit for compressor stations and gas processing facilities that included significantly lower allowable emission limits.
DEP has also conducted three short-term ambient air quality sampling studies in various drilling regions of the state, detecting no levels of any pollutant that would violate federal ambient air quality standards. A one-year, long-term study is underway in Washington County to further gather data regarding long-term exposure.
Source: Pennsylvania Department of Environmental Protection
Why Transmission & Distribution Utilities Need Digital Twins
As with any new technology, Digital twins can create as many questions as answers. There can be a natural resistance, especially among senior utility executives who are used to the old ways and need a compelling case to invest in new ones.
So is digital twin just a fancy name for modelling? And why do many senior leaders and engineers at power transmission & distribution (T&D) companies have a gnawing feeling they should have one? Ultimately it comes down to one key question: is this a trend worth our time and money?
The short answer is yes, if approached intelligently and accounting for utilities’ specific needs. This is no case of runaway hype or an overwrought name for an underwhelming development – digital twin technology can be genuinely transformational if done right. So here are six reasons why in five years no T&D utility will want to be without a digital twin.
1. Smarter Asset Planning
A digital twin is a real-time digital counterpart of a utility’s real-world grid. A proper digital twin – and not just a static 3D model of some adjacent assets – represents the grid in as much detail as possible, is updated in real-time and can be used to model ‘what if’ scenarios to gauge the effects in real life. It is the repository in which to collect and index all network data, from images, to 3D pointclouds, to past reports and analyses.
With that in mind, an obvious use-case for a digital twin is planning upgrades and expansions. For example, if a developer wants to connect a major solar generation asset, what effect might that have on the grid assets, and will they need upgrading or reinforcement? A seasoned engineer can offer an educated prediction if they are familiar with the local assets, their age and their condition – but with a digital twin they can simply model the scenario on the digital twin and find out.
The decision is more likely to be the right one, the utility is less likely to be blindsided by unforeseen complications, and less time and money need be spent visiting the site and validating information.
As the energy transition accelerates, both transmission and distribution (T&D) utilities will receive more connection requests for anything from solar parks to electric vehicle charging infrastructure, to heat pumps and batteries – and all this on top of normal grid upgrade programs. A well-constructed digital twin may come to be an essential tool to keep up with the pace of change.
2. Improved Inspection and Maintenance
Utilities spend enormous amounts of time and money on asset inspection and maintenance – they have to in order to meet their operational and safety responsibilities. In order to make the task more manageable, most utilities try to prioritise the most critical or fragile parts of the network for inspection, based on past inspection data and engineers’ experience. Many are investigating how to better collect, store and analyze data in order to hone this process, with the ultimate goal of predicting where inspections and maintenance are going to be needed before problems arise.
The digital twin is the platform that contextualises this information. Data is tagged to assets in the model, analytics and AI algorithms are applied and suggested interventions are automatically flagged to the human user, who can understand what and where the problem is thanks to the twin. As new data is collected over time, the process only becomes more effective.
3. More Efficient Vegetation Management
Utilities – especially transmission utilities in areas of high wildfire-risk – are in a constant struggle with nature to keep vegetation in-check that surrounds power lines and other assets. Failure risks outages, damage to assets and even a fire threat. A comprehensive digital twin won’t just incorporate the grid assets – a network of powerlines and pylons isolated on an otherwise blank screen – but the immediate surroundings too. This means local houses, roads, waterways and trees.
If the twin is enriched with vegetation data on factors such as the species, growth rate and health of a tree, then the utility can use it to assess the risk from any given twig or branch neighbouring one of its assets, and prioritise and dispatch vegetation management crews accordingly.
And with expansion planning, inspection and maintenance, the value here is less labor-intensive and more cost-effective decision making and planning – essential in an industry of tight margins and constrained resources. What’s more, the value only rises over time as feedback allows the utility to finesse the program.
4. Automated powerline inspection
Remember though, that to be maximally useful, a digital twin must be kept up to date. A larger utility might blanche at the resources required to not just to map and inspect the network once in order to build the twin, but update that twin at regular intervals.
However, digital twins are also an enabling technology for another technological step-change – automated powerline inspection.
Imagine a fleet of sensor-equipped drones empowered to fly the lines almost constantly, returning (automatically) only to recharge their batteries. Not only would such a set-up be far cheaper to operate than a comparable fleet of human inspectors, it could provide far more detail at far more regular intervals, facilitating all the above benefits of better planning, inspection, maintenance and vegetation management. Human inspectors could be reserved for non-routine interventions that really require their hard-earned expertise.
In this scenario, the digital twin provides he ‘map’ by which the drone can plan a route and navigate itself, in conjunction with its sensors.
5. Improved Emergency Modelling and Faster Response
If the worst happens and emergency strikes, such as a wildfire or natural disaster, digital twins can again prove invaluable. The intricate, detailed understanding of the grid, assets and its surroundings that a digital twin gives is an element of order in a chaotic situation, and can guide the utility and emergency services alike in mounting an informed response.
And once again, the digital twin’s facility for ‘what-if’ scenario testing is especially useful for emergency preparedness. If a hurricane strikes at point X, what will be the effect on assets at point Y? If a downed pylon sparks a fire at point A, what residences are nearby and what does an evacuation plan look like?
6. Easier accommodation of external stakeholders
Finally, a digital twin can make lighter work of engaging with external stakeholders. The world doesn’t stand still, and a once blissfully-isolated powerline may suddenly find itself adjacent to a building site for a new building or road.
As well as planning for connection (see point 1), a digital twin takes the pain out of those processes that require interfacing with external stakeholders, such as maintenance contractors, arborists, trimming crews or local government agencies – the digital twin breaks down the silos between these groups and allows them to work from a single version of the truth – in future it could even be used as part of the bid process for contractors.
These six reasons for why digital twins will be indispensable to power T&D utilities are only the tip of the iceberg; the possibilities are endless given the constant advancement of data collection an analysis technology. No doubt these will invite even more questions – and we relish the challenge of answering them.