The White House has installed a 6.3 kW rooftop solar system
The White House has installed a 6.3 kW rooftop solar system
Credit: Matt H Wade/Wikimedia Commons


Tildy Bayar looks at major combined heat and power, on-site renewable power and district energy projects in the US.


Combined heat and power (CHP) could contribute up to 20% of US electrical capacity by 2030 according to a recent study, while energy efficiency measures received $23 million in government investment after the Energy Efficiency Improvement Act was passed in March, and renewables are targeted to make up 20% of the nation’s energy mix by 2020. The government’s goal to grow CHP by 40 per cent by 2020 is working through the Environmental Protection Agency’s (EPA) CHP Partnership programme and the Department of Energy’s (DOE) CHP Technical Assistance Program, joined by federal initiatives such as the business energy investment tax credit, the Rural Energy for America programme and the Green Power Incentives for on-site renewables, alongside numerous state support programmes.

A September report from DNV GL found that the adoption of distributed energy is ‘well underway’ in the US and is ‘relatively strong and growing’. While all distributed energy resources have seen growth in installed capacity, solar photovoltaics (PV) has seen the largest adoption in recent years, making up 80%–90% of the total installed capacity among distributed energy installations equal to or less than 2 MW. Among states, California, New Jersey and Arizona lead in newly installed PV capacity, while Louisiana and Texas lead in CHP, with two-thirds of recently installed capacity located in the region.

However, barriers still exist. In July, Iowa’s Luther College scrapped plans to install a 1.4 MW gas turbine-based CHP system due to ‘prohibitive’ standby rates charged by the local utility, Alliant Energy. A report by the Energy Resources Center determined that Alliant Energy’s charges ‘financially burden otherwise economically viable distributed generation, including combined heat and power.’ And the problem is wider than just a single utility. Jennifer Kefer, programme manager at the Alliance for Industrial Efficiency, said she suspects that ‘the motivation for high standby rates often is to discourage CHP. Utilities often have concerns that CHP undermines their business model.’


Boston-Cambridge's Kendall Cogeneration Station
Boston-Cambridge’s Kendall Cogeneration Station
Credit: Fletcher6/ Wikimedia Commons

Research firm GlobalData forecasts that the nation’s CHP capacity is set to rise from its current 93.5 GW to a total of 115.9 GW by 2020. In addition to proactive policy measures, the government is currently promoting the use of CHP for renewable installed capacity, while a number of coal-based CHP power plants are being decommissioned or shifted to biomass technology.

CHP ‘Energy Stars’

The EPA recently recognised three combined heat and power projects with Energy Star awards.

Eastman Chemical Company’s Kingsport, Tennessee campus plant was recognised for its 200 MW CHP system, which includes 17 GE steam turbine generators.

Seventeen boilers produce steam to support manufacturing processes, help meet the space heating and cooling needs of 550 buildings, and drive 17 GE and two ABB steam turbine generators with a combined output of 200 MW. With an operating efficiency of more than 78%, the predominantly coal-fired system requires approximately 14% less fuel than grid-supplied electricity and conventional steam production, saving around $45 million per year.

Janssen Research & Development, LLC was granted an award for its 3.8 MW CHP system, powered by a Caterpillar lean-burn low-emissions reciprocating natural gas generator set. The system supplies 60% of the annual power needs for the site and approximately 40% of the thermal energy used to support R&D operations and heat, cool, and dehumidify the facility’s buildings.

With an operating efficiency of more than 62%, the system requires 29% less fuel than grid power and conventional steam production, saving around $1.1 million per year.

Finally, Merck’s CoGen3 CHP system at its West Point, Pennsylvania facility was also recognised by the EPA. The project is powered by a 38 MW GE 6B heavy-duty gas turbine and recovers heat to produce steam to heat, cool and dehumidify manufacturing, laboratory and office spaces.

With an operating efficiency of over 75%, the natural gas-fired system requires approximately 30% less fuel than grid-supplied electricity and conventional steam production.

District heating

‘Green Steam’ for Boston-Cambridge

While district heating is common in, for example, northern European countries, it is used in only a handful of US locations, although its use is growing. One such location is the Boston-Cambridge area in Massachusetts, a northern state that features some of the country’s harshest winter weather. The neighbouring cities’ joint ‘Green Steam’ project came online in May, and utility Veolia says it will cut the cities’ CO2 emissions by 475,000 tonnes.

The $112 million project includes a 48-km pipe network serving 250 state government, business and biotechnology customers in both cities, including 14 high-rise buildings, with steam from the 256 MW natural gas-fired Kendall CHP station in Cambridge.

According to Veolia’s figures, the network produces 2.8 million pounds per hour of steam; 44,625 tonnes of chilled water capacity; 47.5 MW of cogeneration capacity; and 36.7 MW of peaking and backup electricity generating capacity. It uses 1.3 miles (2 km) of steam and hot water distribution pipe and 0.8 miles of chilled water distribution pipe.

Montpelier, Vermont’s district energy success

Vermont is another northern state that features very cold winters. The capital city of Montpelier’s biomass district heating scheme, District Heat Montpelier, came online in early October and is already garnering attention for its success.

Montpelier’s biomass boilers will provide 41 million Btu of biomass-derived heat to 22 state- and city-owned buildings, with the potential for an additional 8.1 million Btu for neighbouring buildings. The system will replace around 300,000 gallons (1,364,000 litres) of fuel oil per year with locally and regionally produced wood chips; the heating facility will consume 12,200 tonnes of green wood chips per year.


The US is the world leader in microgrid development and is expected to maintain that lead in the coming decades. According to a report from GTM Research, 81 US microgrids are currently operational and 35 more are in the pipeline. With the nation’s focus on emergency preparedness, microgrids offer energy self-sufficiency and the possibility of operating in island mode given a natural disaster such as 2012’s Superstorm Sandy.

The northeast leads

The northeastern states boast the largest share of community microgrids of any US region according to GTM. New York has opened a $40 million microgrid tender as part of its disaster preparedness plan, while neighbouring Connecticut has a microgrid pilot programme in co-operation with local utilities.

New Jersey’s transit grid

New Jersey recently launched a $200 million Energy Resiliency Bank with the aim of funding distributed energy resources at critical facilities, with microgrids forming a key focus.

The state and the DOE are already working together on a microgrid project, NJ TransitGrid, which will provide critical power to part of NJ Transit and Amtrak’s rail system. In September, governor Chris Christie announced a new award of $1.28 billion in federal funding for the project, which will incorporate renewable energy, distributed generation and other technologies, as well as a microgrid.

The military puts grids on the ground

The US military microgrid market is anticipated to grow by upwards of 54.8 MW by 2018. The Department of Defense (DOD) is working on establishing a network of independent microgrids that integrate distributed renewable generation, electric vehicles and demand response. More than 40 military bases either have operating microgrids, planned microgrids, or have conducted studies of microgrid technologies.

MCAS Miramar

An on-site renewable power installation at the US Marine Corps Air Station (MCAS) in Miramar, California, is to gain a battery energy storage system in order to become a microgrid. A 250 kW, 1 MWh battery system from Primus Power, called the EnergyPod, will be integrated with the air station’s existing 230 kW PV array this year. The combined microgrid system is expected to reduce the station’s peak electrical demand on weekday afternoons and power critical military systems when grid power is unavailable.

The installation is part of the air station’s plan to rely solely on on-site power by 2017, and to generate enough electricity to support the surrounding city of San Diego in the event of a grid outage.

On-site renewables

solar on the White House

The White House’s rooftop solar array came online this summer. The 6.3 kW system is expected to generate 19,700 kWh per year. While the government has not released many details about the system, it is said to contain between 20–50 solar panels made by US-based companies.

Verizon invests in solar

America’s largest wireless carrier is investing almost $40 million to triple its use of on-site solar energy this year. Solar firm SunPower is to install 10.2 MW of PV at eight sites in New York, California, Maryland, Massachusetts and New Jersey. Verizon invested $100 million last year for about 5 MW of solar capacity and 10 MW of fuel cells.

Military renewables

The US Army, Navy and Air Force together aim to install 3 GW of on-site renewable power by 2020. The Army’s Energy Initiatives Task Force (EITF) has launched a $7 billion renewable energy programme for power purchase agreements with energy companies under a streamlined contracting process.

Under the programme, work on a solar PV plant at Arizona’s Fort Huachuca began in April. The 14 MW plant will be the largest on any US military base, meeting one quarter of the base’s electricity needs. Fort Huachuca also recently installed a microgrid, making it entirely independent of grid power.

Work on a solar PV plant began in April at Fort Huachaca in Arizona
Work on a solar PV plant began in April at Fort Huachaca in Arizona
Credit: Vanessa Valentine

Meanwhile, Tooele Army Depot in Utah is to install a wind turbine. The Tooele Army Depot Wind Project is currently in the development stage and is scheduled to come online by early 2015. The US Army Corps of Engineers has contracted a partnership led by Juhl Energy to develop, construct and install the 1.5 MW–2 MW machine in a deal worth $5.5 million.