World ASPO Conference - Final thoughts

I have learned that ASPO-USA will be posting the PowerPoint presentations from the conference in a week, so I will spare myself the labor of transcribing my notes. That is, unless there is a great popular outcry for immediate gratification.

I will, however, offer up some observations about what I heard and saw over those two days.

The ASPO crowd, both presenters and audience, were a heterogeneous lot. I saw a lot of business suits and professional casual, and a few “soul patch” beards and dreadlocks. Some were touting oil shale and coal liquefaction, while others dismissed that and promoted renewable energy. There were contradictory presentations in sequence by Bill Reinert, the president of Toyota USA and Andy Frank of UC Davis on the speed and feasibility of the introduction of plug-in hybrid vehicles (PHEVs). Reinert spoke of a slow, difficult development and introduction with a long time before serious market penetration, while Frank said exactly the opposite.

Nevertheless, there was general agreement on some main points. These had a lot to do with the timing of both fossil fuel depletion and the responses to it.

1) There’s not a huge gap between the optimists and the pessimists on peak oil.

The range of predictions for peak oil varied from December of 2005 to 2020, with a cluster around 2012. Robert Kaufmann, one of the old hands of depletion modeling, pointed out that one could vary the number for the amount of oil reserves left by a factor of two and still not shift the peak by more than about six years.

2) Increased exploration and drilling isn’t paying off.

David Hughes, a Canadian Government geologist, along with a number of others, pointed out that the physical and financial efforts around the world to find more gas and oil have been increasing dramatically. Meanwhile, the actual amounts of gas and oil discovered are holding steady or declining. The best case scenario is analogous to the Red Queen in Alice in Wonderland, running as fast as she can to stay in one place. The oil and gas situation is worse, with companies multiplying their investments for diminishing returns. Quadrupling the number of gas drilling rigs in North America since 1996 has kept the reserve to production ratio (the theoretical “out of natural gas” date) about ten years ahead, with a 3% decline in production.

3) Worldwide demand is increasing despite high prices

Oil is so vital, so interwoven into developed economies, that high price doesn’t destroy demand. In fact, many people in the developing world are trying to get their hands on more of it. In a recent poll, 13% of people in the three largest cities in China intended to buy a car in the next year. At present rates of growth, the number of cars in the world could triple in the next two decades. That is, if there is still enough oil to fuel them. We are cruising towards the peak with the pedal to the metal.

4) The most optimistic assessments keep getting shot down by new data.

For example, the EIA has downgraded its initially optimistic predictions for natural gas production every year since 2001, as new data came in. What was once a healthy graph headed for the sky is now flat.

5) Major oil producers have inflated their reserve numbers, generally by a factor of two.

If you look at a graph of stated reserves for OPEC members, each line, somewhere in the last 25 years, has a sudden jump, with no apparent justification.

6) The alternatives to conventional crude oil are expensive and a long way off.

You can’t pull a coal to oil plant out of your pocket. After all the design and permitting, it still takes about four years to construct and start up. This increases to eight years for an oil shale facility. The cost per barrel is really unknown, except that it will be $70 a barrel and up, with huge upfront capital costs. Likewise, renewable energy sources, although they can deploy quickly, are an infinitesimal part of our present energy picture. Even at breathtaking expansion rates, it would take decades for them to make a significant impact.

7) Many alternatives to conventional oil take too much energy to be practical.

Cutler Cleveland pointed out that even if we take the most optimistic energy profit ratio (EPR, energy used compared to energy gained) for ethanol, it would be impractical to run our present fleet on it. As he put it, “Two thirds of us would be working in the ethanol industry.” The energy profits on oil shale and coal liquefaction are low, as are those for tar sands.

8) The energy profit on fossil fuels is declining

The EPR of newly discovered oil used to be 100:1, that is, it took the energy of one barrel of oil in exploration, equipment, and pumping to get 100 barrels out of the ground. Now newly discovered oil is well below 10:1 and dropping. When we look at numbers for oil reserves, we should consider that the last 20% in the ground might take more energy to extract than it contains, rendering it useless. Some of the new deepwater oil drilling that is being touted as saving us may soon be futile.

9) Market forces won’t work.

The price of oil is so volatile that oil markets can’t get clear signals. Even if they could, these markets hardly ever look more than a couple of years out, and with volatility, even less. Relying on market forces to drive our reaction to oil depletion is like putting an impact sensor on your car’s bumper to tell you that it is time to design and construct a seatbelt. We need a level of forward thinking, hard nosed policy that is now lacking in government at all levels.

10) All the factors above will combine to impose sudden and dramatic lifestyle changes on us.

The effects of fossil fuel depletion and our lack of preparation will have economic, political, military, and social consequences the like of which we have not seen since the first half of the 20th century. We are looking at economic depression, inflation, and rising interest rates, partly due to energy inflation and partly due to the collapse of the dollar as an international reserve currency. We will experience the effects of political unrest at home and abroad. Many of the services, conveniences, and activities we now take for granted will be increasingly expensive. As I have noted in a previous post, some economic models predict that a 4% shortfall in supply would produce a price per barrel of $160. How would you be living if the gasoline that gets you to work, the diesel that grows and delivers your food, and your heating oil all cost $7 a gallon?

The only thing that could change fast enough to make a difference would be human behavior. Likewise, only changes in human behavior can be implemented fast enough to forestall the inevitable shortfall till we are halfway ready for it. The answer lies in the boring inconvenient things: driving less, carpooling, using mass transit, turning the lights off, and easing back on the thermostat, and so on, and so on….

Tragically, it always comes back to our bad habits.

World ASPO Conference, Friday morning, continued

ASPO Conference, Friday morning, continued

Transportation

John Heywood, MIT, Sloan Automotive Lab

The world has a rapidly rising stock of vehicles, especially in the developing world. We could go from 750 million today to three times that number in a few decades, assuming there is fuel for them.

Transportation is 30% of U.S. primary energy use.
Personal transportation is 60% of that, air travel 10%, and freight 30%.
The scale of U.S. transportation fuel use is vast, 550 billion liters a year.
Transportation is dominated by internal combustion engines on land and turbines in the air, both powered by petroleum based fuels.
Scale of use is a big problem.

Over the last 25 years the auto industry has managed a 1% efficiency improvement per year.
Europe has developed high efficiency, high performance diesels, but suffers from the high emissions.
Cheap fuel and emissions regs have discouraged diesel use in the U.S.
If we had used all this efficiency improvement to reduce consumption, we could have achieved 30% savings. Instead, we used it for performance improvements – acceleration and power.

Technical options:
Evolutionary improvements in weight, drag, transmissions, and engines
Alt fuels, both fossil and biofuels, althogh fossil alt fuels have a high CO2 penalty
More radical transitions to new vehicle concepts – lighter, smaller, electric. Fuel cells in the long term only.

Amory Lovins calculated: A car in actual use is only 10% efficient, and the payload is 10% of vehicle weight, so only 1% of the fuel consumed actually moves the payload – you.

There is the possibility of improving the energy eff. of engines and transmissions by 3 by 2025
Given the 17 year life of a car, it would be difficult to achieve more than a 5% market share from 2010 to 2025. Plug in hybrids would be best.
A 10% weight reduction would result in a 5% efficiency improvement.
The problem is that performance competes with efficiency and the market drives for performance.
Technology alone will not work – behavioral change is necessary.

Bill Reinert, President of Toyota USA

Restrictions on fast design change: Product cycle is 5 years. Design is restrained by new requirements for pedestrian safety, rollover protection, and side impact protection. Cars can have a 15 to 20 year life span.

Car designers need to work with urban planners as cities expand.
The Middle East and Asia have a youth population boom – future consumers.

Biofuels have problems:
Biomass feedstock requires bulk transportation
Biomass crops grown mostly over the depleting Oglalla Aquifer

Toyota Approach
Balance impacts with consumer demand
Recognize the need for mass market appeal – there is a lack of consciousness, so a too radical car doesn’t sell
Have a consistent energy policy over time
Multiple path on fuels, but all through a hybrid system

US buyers prefer performance over efficiency

Toyota looks beyond a “well-to-wheels” energy assessment to a life cycle energy assessment
Their engineers have a carbon budget as well as a money and weight budget
Steel vehicles actually have a lower life cycle energy than carbon fiber – CF has very high life cycle CO2
Another CO2 source – precious metals for catalytic converters

Going towards plug-in hybrids, although CO2 impact varies with coal use for electrical generation.

Andrew Frank, UC Davis Mechanical and Aeronautical Engineering Dept. and Director of the Hybrid and EV Center

Plug-in Hybrid Electric Vehicles (PHEVs)as storage for Renewable Energy Sources

15-30 kilowatt hours (kWh) per car for 30-60 mile All Electric Range (AER)
Our current energy infrastructure is the 120 volt outlet and the gas station
Use smart 2-way outlets to provide distributed energy storage, controlled using existing power company technology for water heaters and air conditioners – charge off peak
Average car sits idle 21 hours a day – available to store or provide power

A plug in hybrid has no weight increase – engine size reduced
Design for an AER of 60 miles
Deplete the battery to 20% of charge and then maintain at 20%
Never use engine to recharge the battery
Engine 1/3 the size, made up by electric motor
Vehicle operates on 90% electricity, 10% liquid fuel
1/10 to 1/3 the cost per mile

Solar electricity pays back better when used as substitute for gasoline
A 10 kW array produces the equivalent of a gallon of gas per hour
Gives a 6 year payback instead of 30
A plug in hybrid gives 3-4 times the range per RE kWh vs hydrogen fuel cells

PHEVs can use and store large scale wind power
PHEVs can provide emergency power for a home

A 660cc engine with a 100 hp electric motor and a constant velocity transmission can equal a 3 liter engine with auto tran in performance. The CVT offers a 10:1 parts reduction.

An average PHEV could run on 100 gallons a year, about 1/10 the average fuel consumption of today. Therefore, we could transition to ethanol without an increase in the present supply.

If 10% of the fleet was 40 AER PHEVs, it would reduce US gas consumption by 300 mbpd, 4.5% of US oil use.

There is tremendous excess capacity in the grid for off peak charging. 20% fleet penetration would use less than half of excess capacity. It would improve economics for consumers and power companies.

I took a lot of notes. You'll have to wait till tomorrow for the rest.

World ASPO Conference, Friday Oct. 27

World ASPO Friday Morning

Again, these are rough notes from the conference. Don’t expect well formed prose.

Robert Kaufmann, Director CEES Department at Boston University
“It’s the economy, stupid.”

There are information externalities in the oil market. Investors want to get into alternative market after peak. To be before the curve means that the investor has to wait for return. The peak is unpredictable, so investors hold back. Markets won’t work for transforming the energy economy because they will be too late.

Will OPEC increase production for us? NO. A 3% increase in output resulted in a 10% drop in price. OPEC won’t accept reduced revenues.

The total quantity of oil reserves doesn’t affect the date of peak all that much. A wide variation in total quantity gives a range between 2012 and 2032.

A new Saudi Arabia of capacity will be needed in the next decade to make up for depletion.

William Clark, author, “Petrodollar Warfare”
The Geopolitics of Peak Oil and the Macroeconomics of Multiple Petrocurrencies

Warfare has traditionally been for access to resources. During the 20th century there have been a half dozen wars involving oil resources.

The US dollar had world supremacy from 1945 to 1971. The dollar was backed by gold at $35/ounce and became the world reserve currency. Debt from the Viet Nam war weakened the dollar around 1968-1971. We transferred from the gold standard to the oil standard. Essentially, we horse traded with Saudi Arabia – they sell oil for dollars and we get them more votes with the International Monetary Fund. The petrodollar remained dominant till recently.

Our trade imbalance ($805 billion in 2005) puts petrodollar dominance in jeopardy. International banks, Asian currencies, and commodities may soon move away from dollars. So far we have used coercion and horse trading to keep dollars as the oil currency.

We can export inflation with petrodollars. Middle Eastern nations buy goods from Japan, China, and other Asian countries with dollars. These countries then recycle these dollars by buying U.S. treasury bonds. 45% of our $1 billion a day deficit is funded by petrodollars.

Iraq was proposing to sell oil for Euros – one of the reasons for invading.

The European Central Bank is pushing President Putin of Russia to sell oil for Euros. The EU has a trade surplus with OPEC.

Iran’s President Ahmedinejad points out that the political war is obvious but the economic war is almost undetected.

Sidebar: Iran’s oil production peaked in 1974 at 6.1 mbpd. At that point the Shah of Iran wanted to develop nuclear power – oil was “too precious to burn.” This was approved by the Ford Administration, including his staffers Dick Cheney and Don Rumsfeld.

Iran is starting a non-dollar oil bourse (trading operation) on the island of Kish. It would trade upwards of 25 mbpd (out of 84 mbpd worldwide) for a mixture of dollars, Euros, and Iranian Rials. One of the stated purposes is to insulate Iran from U.S. financial problems.

The U.S., having failed on UN financial sanctions, is asking Japan to bar financing transactions with Iran.

China is also opening an oil bourse using a basket of currencies.
These multiple currency oil trading markets have serious implications for the value of the U.S. dollar.

Roger Bezdek, Management Information Services, Inc.
Economic Impacts of Liquid Fuel Mitigation Options

The exact date of peak oil is arguable, but the impact would be significant: inflation, unemployment, recession, stagflation, high interest rates.

He notes that Energy Information Agency forecasts on natural gas production are downgraded every year, ending up dramatically lower in 2006 than in 2001. He doubts theiroptimism about long term world oil production.

His firm produced a report in 2006 on liquid fuel mitigation – time required to get conservation and production on line, costs, and economic impacts. It assumed a crash program with as much money as required. It included:

Vehicle efficiency ramp up by 50% in 8 years
3 new coal to liquid fuel plants per year, each producing 100,000 bpd. 4 year delay for construction.
Enhanced oil recovery amounting to 175000 bpd more each year, with a 4 year delay
Oil shale development with an 8-10 year delay

All these options, if fully implemented, would still leave a 5 mbpd gap (25%) in 2025. There would be a decade delay from implementation before initial impact, and two decades for significant impact.

All of this will be costly - $120 up to ??? capital investment per bpd offset. $4-6 trillion capital costs over 20 years. Something like our present military budget every year just for this.

Another problem is labor shortage. The average coal miner is 56 years old. Petroleum industry workers average 45 years old, but there would be an increase of 18% in this labor force.

There would be a large positive local economic impact.

Not cheap, not easy, not quick. Demand destruction is the default solution.

Federal initiatives needed: Higher car mileage standards, substitute liquid fuel programs
State: Smart growth, telecommuting, mass transit
All levels: Educate the public

World ASPO Conference, Thursday Afternoon, Oct. 26

World ASPO Conference Thursday afternoon

This is, of necessity, brief notes, but I have tried to get the basics.

Natural Gas, LNG, Unconventional Fuels

David Hughes, Geological Survey Canada

Canadian Tar Sands

Tar sands only have a 2:1 energy profit ratio, that is, it takes a unit of energy to create two units of energy. In general only a small percentage of unconventional resources, such as tar sands or oil shale, in the ground can actually be extracted. Talk of huge reserves is misleading. What matters is what can actually be turned into useful fuel at an energy profit. In the case of oil shale it is just a few percent.

The other problems include:

Huge cost overruns in constructing the mining and processing infrastructure
Uncertainties in extraction potential, meaning that getting investment is difficult.

Jim Bartis, Rand Corporation

RAND has been studying the energy economics of biofuels.

Alcohol and biodiesel have low oil displacement, perhaps ½ a barrel of oil displaced by a barrel of biofuel. This is because of the high fossil fuel inputs. There are also the problems of limited acreage and the competition of biofuel production with food crops. The conclusion of their studies was that without major technical advances the contribution of biofuels will be insignificant.

He also spoke about biomass gasification to produce liquid fuels. Here there is a conflict between economics of scale and the economics of material handling. The complexity of the process requires a large plant in order to be economical. Conversely, as the plant demands biomass from a larger and larger radius, the energy and economic cost of transporting the biomass grows.

He went on to discuss oil shale production. Oil shale is porous rock that contains a substance called kerogen, the precursor of crude oil. All it needs is a few million years of heat and pressure. The shale can be mined, crushed, and cooked under pressure. There are huge shale resources in a small area at the intersection of Utah, Colorado, and Wyoming. The entire resource is equal to 1 trillion barrels of oil, roughly four times that of Saudi Arabia. Sounds good, right?

Problems:
It is hugely energy intensive. The mining and processing gives it a high cost and very low energy profit ratio. It could be produced at a price of $70-95 a barrel. It can also be processed in situ by drilling wells and putting heating elements underground. The heat processes the kerogen in place, which is pumped out of conventional wells. Again, this is energy intensive. It could be produced at $30-40 a barrel. Still, there are many unanswered questions about technology and environmental impacts. The major resource is in the Colorado River watershed. The effects on groundwater chemical contamination and salinity could be profound. The process requires about 3 barrels of water to produce a barrel of oil.

There are surface impacts as well, considering the 200 wells drilled per acre. The process produces 1.5 to 2 times the CO2 of conventional oil. It has an uncertain future. Given the present state of development, RAND estimates that oil shale could produce only about 3 mbpd 30 years from now. (About 1/7 of U.S. present consumption) RAND recommends slow and careful development, with no government promotion unless private companies are willing to get into it for real profit rather than government subsidy.

Coal to oil conversion also has unclear prospects. Plant costs and performance are unknown. RAND estimates that it would take a $5 billion plant to produce a mere 50,000 barrels a day, a cost of $100k per barrel per day. Crude oil would have to be at least $55 a barrel for profitability. It produces twice the CO2 of conventional oil. Proponents have talked of pumping the CO2 back underground to permanently sequester it, but can’t predict leakage rates. Face it, if there is a 5% leakage rate, then all the CO2 would be back in the atmosphere in 20 years anyway.

Ezra Hausman of Synapse Energy Economics spoke about the importation of liquified natural gas (LNG). LNG is produced by cooling NG to –259 F. It isn’t actually pressurized. This reduces the volume by 600 times. It is a highly capital intensive process with a 15-30% energy penalty.

Right now, the expansion in LNG receiving and regasification facilities exceed liquification facilities, meaning that there is competition for the resource.

He noted that most “new”discoveries of NG in the U.S. are actually the redevelopment of existing fields. The discovery of new fields have dropped by half over the last 15 years.

His proposed solution is “negatherms,” the conservation of natural gas energy. He pointed out that existing programs, if fully implemented, would offset all potential

Jim Gordon, Cape Wind Project

Jim has been touting the Cape Wind Project. Nothing new or striking, buuuut….

A crowd of protesters just invaded the conference room and started chanting about a diesel power plant in Chelsea MA. Apparently Jim Gordon, the present speaker is not only promoting the Cape Wind offshore wind farm, but also promoting a diesel fired power plant in a low income area. We have flyers on every table and banners over the balcony accusing him of environmental hypocrisy. The security people are shutting them up and herding them off the balcony. Well, what’s a conference without a protest?

May I be excused? My brain is full. More tomorrow.

Report from the World ASPO Conference, Boston University

World Association for the Study of Peak Oil Conference, October 26, 2006

I’m at the conference, hosted by Boston University, and while they are giving out the awards I’m going to give a brief account of the speakers this morning. Don’t expect a lot of prose – it has been a data barrage, with power point slides flashing montage style on the big screen. These presenters are some of the heavy hitters in the ofossil fuel industry.

The first speaker was Mike Rogers of PFC Energy, talking about non-OPEC oil depletion. Some bullet points:

Production peaks lag discoveries. Production exceeds discovery for some time, then declines when 50-60% has been pumped out of the ground.

- Major producers such as Brunei, China, Malasia and India are on the production plateau at 60-65% of reserves.
- The states of the Former Soviet Union (FSU) have been taking up the slack in non-OPEC production since 1998. Non-OPEC, non-FSU production has been flat since ’98.
- Non-OPEC, non-FSU countries have been out producing oil discoveries since the late 80’s and are hitting the 60% production range.
- There is an average 7% yearly production decline on wells drilled before 2000.
- At present rates of decline, non-OPEC/FSU production should drop from 30 million barrels per day (mbpd) now to 10 mbpd by 2015. (Compare to present total world production and consumption of 85 mbpd)
- If major oil companies achieve a high success rate with deep water oil exploration, they may slow the decline to 3% a year.
- Only Africa has had a positive discovery to production ratio since 1990.
- Prediction: Non-OPEC production will peak at 45 mbpd of conventional oil, 20 mbpd non conventional (tar sands, natural gas liquids (NGL)) in the early part of the next decade.
- Despite high prices, the discovery rate of new oil is the worst since WWII.
- Exploration will have to ramp up at dramatic rates to achieve predicted production. The problem is that it is hard to find a spare oil drilling rig right now.
- Prediction: A downward price trend through 2010-2012, what with new OPEC NGL capacity. Oil could fall into the $30-40 per barrel range.

The next speaker was David Hughes, who works for Geological Survey Canada, the folks up there who try to figure out what’s down there. He focused on natural gas supply.

His first point was that natural gas (NG) is a regional product. Most of it travels through pipelines. Only 7% of world NG is liquefied and transported across oceans. There is a 15-30% energy loss in liquefication.

There has been a 300% growth in NG use since 1965. Production and consumption is generally balanced because of the regional nature of NG. 4% of world reserves are in North America. He predicts a peak in conventional gas in 2025 and non-conventional (coal bed methane, deep offshore, shale) in 2045. Canada reached a non-conventional peak in 2002.

When you look at our reserves vs. our use in the U.S., we have 10 years left. Canada has 9 years of NG left. North America overall has about 10 years left.

In 1996 Canada drilled 4000 NG wells and produced 15 trillion cubic feet.
In 2003 they drilled 13000 wells and experienced a 3% decline.
In 2006 they drilled 16000 wells and still declined.
Productivity declined by half from 1998-2004.

Canadian production is on the beginning of a plateau that will last till 2007-2009.
They need to develop production of 3.3 billion cu. ft. per day every year just to hold the line.

In short, the U.S. and Canada are on a NG production treadmill, trying to discover enough new wells to replace the failing wells.

The U.S. is looking at a 10 trillion cu ft shortfall in 2025, 5 TCF around 2012, starting now.
We’d have to double the world liquid NG shipping fleet and terminal base to meet this shortfall. Meanwhile, we would be competing with Japan and N. Korea for LNG.

As for the Tar Sands of Alberta, a Canadian oil exec said, “Using natural gas to exploit oil sands is like turning gold into lead.”

Bottom line: We can only slow NG production decline.

Jeremy Gilbert, the former chief petroleum engineer for British Petroleum (BP), gave a presentation on oil reserves. He addressed the question “What are they?”

His main point was that the amount of oil you get out of a field is a fraction of the oil actually there. The oil isn’t just in a big pocket underground. It is absorbed in between small particles of sandstone, like a solid sponge. The structure of this sandstone sponge and its distribution underground, along with the water and gas pressure beneath it, determines how much of the oil that can be extracted. This varies from about 6-70%.

He spoke of primary, secondary, and tertiary oil. Primary oil is the oil that comes out naturally under pressure. 6-40% of the resource can come out this way. Secondary oil comes out when the drillers inject water and/or gas into the well. This brings up another 0-40%, inversely proportional to how much primary oil was extracted. Tertiary reserves are those extracted by injecting chemicals into the well or heating the oil to make it more liquid. This requires a heavy investment and only gets another 0-10%.

Tertiary extraction doesn’t make much difference in the long run.

He noted that there have been some sudden reserve increases stated by OPEC that are technically unsound. A polite way of saying that they were lying. He advised caution about anybody’s reserve numbers – they are either educated guesses by geologists or numerical models from engineers based on minimal data.

Matt Simmons, author of “Twilight in the Desert” and president of a major international oil financing group, talked about how he became a peak oil believer. He noted that he never ceases to be amazed at how consistently wrong the major oil companies are about predicting oil prices and production. He doubts all the hype about new oil production technologies – they always end up producing less than expected later than expected.

He noted that world demand increased from 66.5 to 82.5 mbpd between 1990 and 2005, even while demand in the FSU declined by 5 mbpd. If the FSU economy hadn’t slacked off we would now be in shortage mode.

Middle Eastern oil fields are old and hitting depeletion.
40% of North Sea oil rigs will be decommissioned in the next 10 years.
Unpredicted increases in reserves were common between 1940 and 1960, but no longer. The oil industry is still assuming that new tecnology will keep that up.

He suggests that we keep an eye on Table 11b of the monthly Energy Information Administration (EIA) report for world production. There was at least a temporary peak in December of 2005. If this isn’t exceeded in the next 6-12 months, we can assume that world oil production is permanently in decline.

Stuart Staniford, the editor of The Oil Drum, is a statistician with a specialty in statistical anomalies. He went through a barrage of graphs and charts that came to the conclusion that production is flat despite huge increases in drilling rig counts, and that production data shows a peak between 2007 and 2009.

That’s all so far. It doesn’t look good for SUV sales. More wonkery to come. Back to the conference.