creating value from steam pressure - midwest chp ... more expensive, more co 2-intensive power from...

Creating Value from Steam Pressure

The best technology you’ve never heard of

• Turbosteam’s products are:– The most efficient form of power generation ever invented– Cheaper, on a $/installed kW basis than the state of the art

combined cycle gas turbine technology – at less than 1/500th the size

– An environmental win/win – every installation saves money and improves the environment through reduced emissions of every major criteria pollutant

– Based on technology that has been commercially available since 1886.

How we do it: typical steam plant design

Boiler

FuelFeed water

H.P. steamHeader

High pressure steam process load

Medium pressure steam process load

Low pressure steam process load

PRV*

PRV*

*PRV = Pressure Reducing Valve

Our solutions deliver the same pressure drop as a PRV -- but produce useful electricity in the process.

Low Pressure steam out

Electricity out

High Pressure steam in

This “opportunistic electric power” is virtually free – thereby displacing more expensive, more CO2-intensive power from the grid.

This modest investment turns a steam loop into…

Boiler

FuelFeed water

H.P. steam

Low pressure steam process load

PRV

Pump

…A Rankine cycle…

Boiler

FuelFeed water

H.P. steam Low pressure steam process load

Pump

Backpressure Steam Turbine-Generator

..but with phenomenally better economics

TraditionalTraditional RankineRankine CycleCycle Backpressure Turbine GeneratorBackpressure Turbine Generator

Boiler + Turbine Generator + Steam Piping + Pump + Condenser

$1,000/kW + installed

Turbine Generator + Minor Piping Modification

$300 – 1,000/kW installedCapital Costs

Boiler + Turbine Generator + Steam Piping + Pump + Condenser + Labor

0.5 – 1.5 cents/kWh

Turbine Generator 0.01 – 0.5 cents/kWhMarginal Maintenance Costs

Pay for all cycle losses: 50%+ of losses are in reject heat to condenser

20 – 40%

Pay for marginal cost of make up steam enthalpy + generator losses

75 – 85%Power Generation Efficiency

Fuel cost / cycle efficiency + O&M4.4 c/kWh

(@ $3/MMBtu, 30% η, 1 cent O&M)

Fuel cost / efficiency + O&M 1.4 c/kWh

(@ $3/MMBtu, 80% η, 0.1 cent O&M)

Marginal Cost of power generation

500 MW (?) 50 kWMinimum economic size

>7 years <2 yearsTypical Simple Payback

If you have a steam pressure drop, Turbosteam backpressure turbines can be highly cost effective.

Points represent costs of all turbogenerators sold over the past 15 years, and are not indicative of current prices, nor have they been adjusted to equivalent dollars.

Equipment Cost Curve

$0

$200

$400

$600

$800

$1,000

$1,200

$1,400

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 200,000

Steam Flow Rate, lb/hour

Equi

pmen

t cos

t, $/

kW u

nins

talle

d

These steam flows correspond to power outputs of 50 – 6,000 kW – although systems up to 12 MW are available.

Points represent costs of all turbogenerators sold over the past 15 years, and are not indicative of current prices, nor have they been adjusted to equivalent dollars.

Equipment Cost Curve

$0

$200

$400

$600

$800

$1,000

$1,200

$1,400

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000

Rated Power Output, kW

Equi

pmen

t cos

t, $/

kW u

nins

talle

d

Electric Price & CO2 Emission Variation, by State

0123456789

10

0 500 1,000 1,500 2,000 2,500

Marginal CO2 emissions, lb/MWh

Ret

ail P

rice

to In

dust

rial

Cus

tom

ers,

c/k

Wh

How Turbosteam solutions stack up:

US Avg

Natural gas @ $4/MMBtu

Marginal CO2 emissions as provided by the Oregon Climate Trust

#6 Oil @ 60 cents/gallon

Coal @ $25/tonWood @ $15/ dry ton

Electric Price & CO2 Emission Variation, by State

0123456789

10

0 500 1,000 1,500 2,000 2,500

Marginal CO2 emissions, lb/MWh

Ret

ail P

rice

to In

dust

rial

Cus

tom

ers,

c/k

Wh

How Turbosteam solutions stack up:

US Avg

Marginal CO2 emissions as provided by the Oregon Climate Trust

Economic – Environmental win-win

So where are the opportunities?

Turbosteam’s installations, worldwide:• Chemical/Pharmaceuticals 22• Food processing 21• District Energy 20• Lumber & Wood Products 18• Petroleum/Gas Processing 17• Colleges & Universities 12• Commercial Buildings 8• Pulp & Paper Mills 6• Hospitals 6• Military Bases 5• Waste-to-Energy 3 • Textiles 1• Prisons 1• Auto manufacturing 1

All were installed primarily to save $:

CO2 savings were an added (and, for most

customers, unexpected) bonus

>10,000 kW

5001 – 10000 kW

1001 – 5000 kW

501 – 1000 kW

1 – 500 kW

We have installed 95 systems in the U.S., and 155 worldwide.

NonNon--U.S.U.S.

• 17 countries• 60 installations• 36,000 kW

These systems consistently upend the conventional, technology-dependent view of efficiency improvements.

Adapted from EPRI data

10

30

20

40

50

60

70

1 10 100 1,000 10,000 100,000 500,000

Elec

tric

al G

ener

atio

n Ef

ficie

ncy

%LH

V

Size in kW

0

80

I.C.engines

Simple cycle gas turbines

Low temperature fuel cells (target)

High temperature fuel cells (target)

Combined cycle gas turbines

Backpressure Steam Turbines

Micro-turbines

Thermodynamics 101

saturation line

Entropy (S)

Enth

alpy

(H)

Isenthalpic PRV

Constant P

Isentropicturbine

Realturbine

Thermodynamics 101

Entropy (S)

Enth

alpy

(H)

Isenthalpic PRV

Constant P

Isentropicturbine

Realturbine

Isentropic efficiency = typically 50 – 65%

saturation line

Net impacts of TG set installation:

Entropy (S)

Enth

alpy

(H)

Isenthalpic PRV

Constant P

Realturbine

saturation line

Changes in Steam Condition

• Fewer Btu/lb = fewer Btus/hour at comparable flow

• Lower temperature (lower Btu/lb at constant P = lower T)

To put this another way…

PRVL.P. steamH.P. steam

L.P. steam

H.P. steamkWh

TG Set“Spinning PRV”

ThermodynamicsThermodynamics

H.P. energy = L.P. energy PRV Eff. ~100%Power Gen Eff. = 0%

H.P. energy = L.P. energy + kWhPRV Eff. ~ 94%

Power Gen Eff ~ Boiler Eff (80-85%)

11stst Law BalanceLaw Balance EfficiencyEfficiency

This is almost 3X the efficiency of the grid!

However, the real world differs from thermodynamics, in ways that all tend to favor backpressure economics:

1. The reduction in exhaust steam temperature often doesn’t matter, as process heat exchangers generally prefer saturated steam

PRV L.P., superheated

steam, X Btu/hr

H.P. steam, X Btu/hr

De-superheater

Cold waterInjection, Y

Btu/hr (Y<<X)

L.P., saturated steam @

increased mass flow, X+Y Btu/hr

L.P., saturated steam,X+Y Btu/hr

X+Y+Z Btu/hr H.P. steam(Z<<X+Y) Z Btu/hr electricity

TG Set

Note that if a desuperheater is not present, it usually implies substantial reductions in heat transfer effectiveness – in which case a BP installation allows an end-user to “make do with less”

The real world differs from thermodynamics, in ways that all tend to favor backpressure economics:

2. Marginal boiler fuel efficiency is almost always higher than average boiler fuel efficiency

Boiler Efficiency Curve with Constant Marginal Efficiency

0%10%20%30%40%50%60%70%80%90%

100%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Load

Effic

ienc

y

User-Defined Point

Example: If boiler flow increases from 70% to 74% of rated flow, and efficiency increases from 80% to 80.5%, then the efficiency with which the 4% marginal steam is generated is 4*1/(74/80.5 – 70/80) = 85%

The real world differs from thermodynamics, in ways that all tend to favor backpressure economics:

3. Post TG-set installation, most users discover that their processes/heaters were over-designed.

BoilerHeat Exchanger

How Steam Systems Are Designed

Steam Supply Pipe

Condensate Return

Heat FluxTo Process

Estimated based on maximum expected heat flux over life of equipment

Surface area sized to deliver maximum estimated heat flux

Operating pressure selected based on maximum estimated heat flux and projected distribution losses

Careful, conservative engineers overestimate likely system losses

when designing boilerNET RESULT: AS ENTHALPY AVAILABLE IN STEAM SUPPLY FALLS, CONDENSATE RETURN AND/OR REJECTION TEMPERATURE FALLS, BUT HEAT FLUX TO PROCESS (OFTEN) REMAINS UNCHANGED!

CondensateLosses?

Real data: Middlebury College (TG sets installed in 1980, 1985 and 2000)

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

1981 1986 1991 1996 2001Year

Fuel

pur

chas

e (g

allo

ns/y

ear)

0200,000400,000600,000800,0001,000,0001,200,0001,400,0001,600,0001,800,0002,000,000

Pow

er G

ener

atio

n (k

Wh/

year

)

Boiler fuel purchasePower generation

TG Set #2 Installed

TG Set #3 Installed

108% kWh increase6% fuel purchase increase

35% kWh increase14% fuel purchase increase

HOWEVER…

• This logic only applies for backpressure applications– Condensing systems only become economically beneficially

when fuel is free (or nearly so)• Therefore, systems must be sized for thermal flows

– Requests for “a ___ kW system” are a waste of everyone’s time –politely redirect the customer who makes such a request.

Where to look for opportunities in a typical steam plant:

Boiler Header

Thermal Process

Thermal Process

Motor Mechanically-driven process

Cooling LoadDATank

Condensate Return

PRV


Boiler Header

Thermal Process

Thermal Process


Cooling LoadDATank

Condensate Return

PRV

HP Steam In LP Steam Out

HP Steam In

LP Steam Out

High valueElectricity out

Replace Replace PRVs PRVs with Backpressure TG setswith Backpressure TG sets


Boiler Header

Thermal Process

Thermal Process


Cooling LoadDATank

Condensate Return

PRV

LP Steam to header


Increase Boiler Pressure / Install HP boilersIncrease Boiler Pressure / Install HP boilers

BoilerLP Steam From Boiler

Header

Boiler

HP Steam From Boiler


Boiler Header

Thermal Process

Thermal Process


Cooling LoadDATank

Condensate Return

PRV


Replace DA Tank Replace DA Tank PRVsPRVs

DATank

HP Steam From Header

LP Steam to DA

DATank


LP Steam to DA


Boiler Header

Thermal Process

Thermal Process


Cooling LoadDATank

Condensate Return

PRV


Create Steam Pressure DropsCreate Steam Pressure Drops



LP Steam to Process

Thermal Process

Modified thermal Process


Boiler Header

Thermal Process

Thermal Process


Cooling LoadDATank

Condensate Return

PRV


“Return of the Absorber”“Return of the Absorber”


LP Steam to Chiller

Cooling Load

Absorption Chiller

Energy to cooling load(mechanical, electric, etc.)


Boiler Header

Thermal Process

Thermal Process


Cooling LoadDATank

Condensate Return

PRV

VariableVariable--speed drivesspeed drives


LP Steam to other processes


Mechanically-driven process

Some rough rules of thumb.

Steam flow rate

Pressure drop

Inlet pressure

Cost of electricity

Probably not Probably not attractiveattractive

<4,000 lbs/hr

<100 psi

<125 psig

<1.5 ¢/kWh

<25%

Probably attractiveProbably attractive

>4,000 lbs/hr

>100 psi

>125 psig

>2 ¢/kWh

>25%

DropDrop--dead dead gorgeousgorgeous

>10,000 lbs/hr

>150 psi

>150 psig

>6 ¢/kWh

>50%Capacity factor

A final thought to ponder…

If it’s such a good idea, why aren’t I doing it already?

The answer (in three parts) follows.

Three widely held misconceptions

1. The Tragedy of Regulation: “Our electricity system is at or near its economic optimum”

2. President Carter’s Sweater-Theorem: “Concern for the environment must be balanced by concern for my wallet”

3. Friedman’s Joke: “If a $20 is on the ground, someone must have already picked it up”

0%0%

10%10%

20%20%

30%30%

40%40%

50%50%

60%60%

70%70%

80%80%

90%90%

100%100%

18801880 18901890 19001900 19101910 19201920 19301930 19401940 19501950 19601960 19701970 19801980 19901990

CHP Plants

U.S. Average Electric Only

Power Industry

Efficiency

Recovered Heat

Misconception 1: The power industry near-optimal

Misconception 2: Efficiency costs money

• More efficient fuel use = lower cost electricity• Reduced fuel consumption = reduced emissions of all major pollutants (SO2,

NOx, CO2, etc.)• Saving fuel saves money

An Inversion of Conventional Environmental Wisdom?

Environmental BenefitEnvironmental Damage

Revenues

Costs Conventional environmental

wisdom

Perceived Corporate Position

Annual $ Savings

Rat

e of

Ret

urn Customer IRR for non-core

Customer$ threshold

Equipment mfr$ threshold

Typical Backpressure Turbine-Generator Opportunity

Misconception 3: There are no $20 bills on the ground

Annual $ Savings

Rat

e of

Ret

urn Customer IRR for non-core

Customer IRR for core = Turbosteam IRR for customer non-core

Customer$ threshold

Equipment mfr$ threshold

Shared Savings$ threshold

Addressing financial and technical risk: Shared Savings

Typical Backpressure Turbine-Generator Opportunity

creating value from steam pressure - midwest chp ... more expensive, more co 2-intensive power from...

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