Optimizing Heat Recovery Systems for Power Generation

in Rural Alaska

Tanana Chiefs Conference and Alaska Center for Energy and Power

Dr. Chuen-sen Lin • Ross Coen • September 28, 2009

Chena Hot Springs

Project Summary

Power generation through use of an Organic Rankine Cycle (ORC) unit with heat recovery from diesel generator.

Laboratory and field tests. Preferred vendor:

ElectraTherm.

ORC Technology

Project Objectives To achieve ORC efficiency of 10% and

corresponding fuel efficiency by ~3%. Reduced fuel consumption. Lower costs. Reduced greenhouse gas emissions.

Project Objectives To achieve ORC efficiency of 10% and

corresponding fuel efficiency by ~3%. Reduced fuel consumption. Lower costs. Reduced greenhouse gas emissions.

To evaluate feasibility, operation / maintenance requirements, and economic impact.

Project Objectives To achieve ORC efficiency of 10% and

corresponding fuel efficiency by ~3%. Reduced fuel consumption. Lower costs. Reduced greenhouse gas emissions.

To evaluate feasibility, operation / maintenance requirements, and economic impact.

To develop guidelines for ORC application, particularly in rural Alaska.

Tanana Chiefs Conference

Galena, Alaska

~ 650 people 270 air miles west of Fairbanks Transportation, economic, and

government hub of Yukon-Koyukuk sub-region

Supply access by barge (river ice-free from mid-May to mid-October); regular air access year-round

Galena, Alaska City Power Plant Fuel consumption (2007) =

574,000 gallons diesel Total fuel cost (574,000gal x

$6.50) = $3.73 million Total electric costs (fuel + non-

fuel) = $4.69 million Average load = 501 kW Peak load = 1000 kW

ORC efficiency improvement (%) 10 9 5 ORC fuel efficiency improvement (kW-hr/gal) 1.6675 1.50075 0.83375

Net fuel efficiency (kW-hr/gal) 16.1675 16.00075 15.33375

Gal fuel per 1000 kW-hr 61.8525 62.4971 65.2156

Cost per 1000 kW-hr (at $6.50/gal) $402.04 $406.23 $423.90

Starting engine fuel efficiency (kw-hr/gal) 14.5 14.5 14.5

Gal fuel per 1000 kW-hr 68.9655 68.9655 68.9655

Cost per 1000 kW-hr (at $6.50/gal) $448.28 $448.28 $448.28

Cost savings $46.24 $42.05 $24.38

Effect of ORC on overall efficiency

Potential total cost savings

In 2007, the approximate electric production in Galena was 4,387,284 kW-hr.

ORC efficiency improvement (%) 10 9 5

Cost savings per 1000 kW-hr/gal $46.24 $42.05 $24.38

Potential annual savings with ORC

$202,868 $184,485 $106,961

Economic analysis (payback time) Cost of ORC unit = $128,000

Fuel efficiency = 14 kW-hr/gal, Operation = 24 hr/day

Potential Economic Impact… ACROSS RURAL ALASKA:

Electric power generation in rural Alaska in 2007 = 375,000 MW-hr

Fuel consumption = 26 million gallons

With ORC operating at 10% efficiency, total potential savings in 2007 = $17,340,000

With ORC in every village over 20 years = $346,800,000

Current Status of ORC for Mid-sized engines

Power capacity: Less than 100 kW Development status: R&D and prototype (pre-

commercial) Efficiency of prototypes:

7% from jacket coolant / exhaust gas recirculation 12.5% from jacket coolant / exhaust of long-haul truck 9% from hot coolant

Now is the right time for a small-scale field test in Alaska!

Relevance to Alaska

ORC technology is currently being used in large-scale and industrial applications around the world…however…

Few data exist on small-scale applications, especially in Alaska’s unique environmental and climatic conditions.

There is a need for laboratory / field performance data for optimal application and design improvement.

A successful ORC project has the potential…

• To provide data and insight on small- to mid-scale ORC applications.

A successful ORC project has the potential…

• To provide data and insight on small- to mid-scale ORC applications. • To reduce fuel consumption and greenhouse gas emissions.

A successful ORC project has the potential…

• To provide data and insight on small- to mid-scale ORC applications. • To reduce fuel consumption and greenhouse gas emissions. • To be replicated in other villages in rural Alaska.

Tanana Chiefs Conference

Alaska Center for Energy and Power