Omaha-based billionaire Warren Buffett late last month gave his annual accounting of the results of the Berkshire Hathaway (BH) conglomerate, which includes various energy utility and pipeline holdings, and all are doing quite well, contributing $24.1 billion to 2015 profits from $19.9 in 2014.

Despite BH stock taking a nosedive and concerns about the “Oracle of Omaha,” the $82 billion in assets in BH Energy, which is 89.9% owned by the conglomerate, racked up $2.37 billion net in 2015 from $2.09 billion in 2014.

Likewise, BH’s railroad and a major energy transporter, BNSF, earned $4.24 billion last year, compared with $3.86 billion in 2014.

Buffett said BH’s traditional focus on efficiency in the operation of all of the companies is particularly helpful in the energy sector, leaving the utilities and natural gas pipelines “particularly competitive in today’s market (and more important, in tomorrow’s as well).”

BH’s natural gas pipelines, Northern Natural Gas and Kern River Gas Transmission, saw overall revenues dip slightly year/year to $1.01 billion from $1.09 billion, but earnings increased to $401 million from $379 million in 2014. Combined, the two U.S. interstate pipelines represent 7.8 Bcf/d of capacity.

Buffett said the slight drop in revenues was due to reduced system and operational balancing activities, which were partially offset by higher transportation revenues. The pipelines also lowered their cost of gas sold and operating expenses during the year, he said. While the year’s growth was modest it came on the heels of a 13% jump, or $122 million in added revenues in 2014.

Renewables are also a growing part of the energy companies.

“Both BH Energy and BNSF have been leaders in pursuing planet-friendly technology,” Buffett wrote in his annual letter to shareholders. “In wind generation, no state comes close to Iowa, where last year megawatt-hours we generated from wind equaled 47% of all the power sold to retail customers [in the state].” Additional projects being pursued by BH will take the proportion to 58% in 2017.

Electric utilities, headed by Portland, OR-based PacifiCorp and Las Vegas-based NV Energy, provide the bulk of energy assets and earnings. The two large western power utilities provided $1.5 billion in earnings last year, with PacifiCorp providing slightly more than $1 billion.

Buffett’s shareholder letter noted that in the electric utility business there is a “changing economic model,” as the advent of government-subsidized renewables and distributed generation is injecting more competition.

“Society has decided that federally subsidized wind and solar generation is in our country’s long-term interest,” he said. “Federal tax credits, or other government-mandated help for renewables, may eventually erode the economics of the incumbent utility, particularly if it is a high-cost operator.” BH’s focus on efficiency fits well with this shift, he said.

As examples, Buffett noted that MidAmerican Energy Co. had 3,700 employees and produced 19 million MWh when it was acquired in 1999. Today it has 3,500 employees and produces 29 million MWh. Similarly, PacifiCorp had 6,750 employees and was producing 52.6 million MWh in 2005, the year before BH bought it, and now it has 5,700 employees and produces 56.3 million MWh.

Those performances explain why BH Energy “is welcomed by regulators when it proposes to buy a utility in their jurisdiction,” Buffett said. “The regulators know the company will run an efficient, safe and reliable operation and also arrive with unlimited capital to fund whatever projects make sense.”